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The Gynecologic Cancer InterGroup (GCIG) Endometrial Cancer Consensus Conference on Clinical Research (ECCC) was held in Incheon, South Korea, Nov 2-3, 2023. The aims were to develop consensus statements for future trials in endometrial cancer to achieve harmonisation on design elements, select important questions, and identify unmet needs. All 33 GCIG member groups participated in the development, refinement, and finalisation of 18 statements within four topic groups, addressing adjuvant treatment in high-risk disease; treatment for metastatic and recurrent disease; trial designs for rare endometrial cancer subgroups and special circumstances; and specific methodology and adaptation for trials in low-resource settings. In addition, eight areas of unmet need were identified. This was the first GCIG Consensus Conference to include patient advocates and an expert on inclusion, diversity, equity, and access to take part in all aspects of the process and output. Four early-career investigators were also selected for participation, ensuring that they represented different GCIG member groups and regions. Unanimous consensus was obtained for 16 of the 18 statements, with 97% concordance for the remaining two. Using the described methodology from previous Ovarian Cancer Consensus Conferences, this conference did not require even one minority statement. The high acceptance rate following active involvement in the preparation, discussion, and refinement of the statements by all representatives confirmed the consensus progress within a global academic setting, and the expectation that the ECCC will lead to greater harmonisation, actualisation, inclusion, and resolution of unmet needs in clinical research for individuals living with and beyond endometrial cancer worldwide., Competing Interests: Declaration of interests All authors report that the KGOG paid for their 2-night hotel stay and basic meals during the 2 days of the ECCC on Clinical Research meeting. CLC reports a research grant paid to her institution from Varian; payment to her institution for participation on a data safety monitoring board from Merck; and unpaid roles as chair of GCIG Endometrial Committee and member of Guidelines Committees for Endometrial cancer of the European Society of Gynaecologic Oncology (ESGO) and the European Society of Radiotherapy and Oncology. GE reports personal consulting fees from MSD, personal fees from Eisai, and support for attending a meeting or travel from MSD. LE reports personal consulting fees AstraZeneca, GSK, and MSD; personal fees from AstraZeneca and GSK, and support for attending a meeting or travel from AstraZeneca and GSK. RAN reports research grants paid to his institution from Elekta, Varian, and Accuray; and payment to his institution for presentations from Elekta and MSD. DL reports research grants both personal and paid to her institution from AstraZeneca, Clovis Oncology, Genmab, GSK, Immunogen, MSD, Novartis, Pharmamar, and Seagen; personal grants from Corcept, Oncoinvest, and Sutro; and grants to her institution from Incyte and Roche; consulting fees from AstraZeneca, Clovis Oncology, Corcept, Genmab, GSK, Immunogen, MSD, Novartis, Oncoinvest, Pharmamar, Seagen, and Sutro; payment for presentations from Clovis Oncology, Corcept, Genmab, GSK, Immunogen, MSD, Novartis, Oncoinvest, Pharmamar, Seagen, and Sutro; support for attending a meeting or travel from AstraZeneca, Clovis Oncology, MSD and GSK; and payments for participation on a data safety monitoring board from AstraZeneca, Clovis Oncology, Corcept, Genmab, GSK, Immunogen, MSD, Novartis, Oncoinvest, Pharmamar, Seagen, and Sutro. AO reports research grants paid to his institution from AstraZeneca; consulting fees from Bristol Myers Squibb, uncompensated participation on data and safety monitoring boards of studies funded by AstraZeneca and GlaxoSmithKline; and unpaid roles as principal investigator on investigator-initiated trials and on steering committees of trials funded by AstraZeneca and GlaxoSmithKline. BP reports research grants from Tesaro/GSK, Merck, AstraZeneca, Karyopharm Therapeutics, Sutro, Incyte, Clovis Oncology, Roche/Genentech, Mersana, Celsion/Immunon, Imab, Takeda, Toray, VBL Therapeutics, InxMed, Agenus, Seagen, NRG Oncology, Duality Bio, Xencor, Onconova, Celgene, Sutro Biopharma, Novocure, Immunogen, Eisai, Acrivon, and Alkermes; consulting fees from Tesaro/GSK, AstraZeneca, Merck, Immunogen, Gynecologic Oncology Group (GOG) Foundation, SeaGen, Lily, Eisai, Signatera, Celsion, Butro Biopharma, Imvax, Incyte, InxMed, Onconova Therapeutics, R Pharm, Regeneron, and Duality Bio; payment for presentations from Bioascend, PERS, Vanium, Curio, OncLive, Yale University and PeerView; support for attending a meeting or travel from GOG Partners, payment for participation on a data safety monitoring board or advisory board from Sutro, AstraZeneca, GOG Foundation, Celsion/Immunon, Toray, InxMed, Imvax, Imab, Tesaro/GSK, Merck, Mersana, Nuvation, and BioNtech; and unpaid leadership roles in boards, societies and committees: Society of Gynecologic Oncology (SGO) Clinical Practice Committee Chair, SGO Board of Directors, SGO COVID-19 Taskforce co-chair, GOG Partners, and New York Obstetrical Society Second VP. BH reports textbook royalties from Elsevier; consulting fees from Tempus; honoraria for lectures from Leica and Projects in Knowledge; and unpaid leadership roles on the International Society of Gynecological Pathologists Board of Directors (as member at large) and on the Endometrial Cancer MSI Committee of the College of American Pathologists. IR-C reports research grants from AstraZeneca, Clovis, GSK, Mersana, BMS, and MSD; payment for presentations from AstraZeneca, Clovis, GSK, Mersana, BMS, MSD, Roche, Pharmamar, Seagen, Eisai, and Novartis; support for attending a meeting or travel from Roche, GSK, AstraZeneca, Pharmamar, and MSD; and payment for participation on a data safety monitoring board or advisory board from Clovis, Deciphera, Adaptimmue, Sutro, and Immunogen. DG reports support for attending meetings or travel from IGCS Board of Directors; payment for participation on a data and safety monitoring board from Merck, and a leadership role in NRG Oncology. AM reports payment for participation as independent statistician on data safety monitoring boards from ONY Biotech, Regeneron, and Genentech/Roche. NC reports payments or honoraria for presentations from GSK, Seagen, Akesobio, AstraZeneca, eTheRNA immunotherapies NV, Kartos, MSD, Mersana, ImmunoGen, Eisai, Seattle Genetics, TouchIME, and Medscape Oncology; support for attending a meeting or travel from Roche, Genmab, and Amgen; payment for participation on a data safety monitoring board or advisory board from GSK, Mersana, Seagen, ImmunoGen, Akesobio, Eisai, AstraZeneca, Mersana, Seattle Genetics, eTheRNA immunotherapies NV, and Kartos; and leadership roles as President of ESGO and Chair of European Network for Gynaecological Oncological Trial groups Early Drug Development Network. MAP reports grants paid to his institution from GSK; payment for participation on a data and safety monitoring board from GSK, AstraZeneca, Eisai, Merck, Immunogen, Clovis Oncology, Jazz Pharma, and SeaGen; and payment to his institution for a leadership role on a board or committee from NRG Oncology. MAB reports payment to his institution for participation on a data and safety monitoring board from Immunogen; and employment as physician at The Permanente Medical Group. J-WK, EA, SIK, J-YP, LM, PBO, AB, DM, VG, TB, CG, TM, HW, XM-G, WS, and GS declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Predicting distant recurrence of endometrial cancer (EC) is crucial for personalized adjuvant treatment. The current gold standard of combined pathological and molecular profiling is costly, hampering implementation. Here we developed HECTOR (histopathology-based endometrial cancer tailored outcome risk), a multimodal deep learning prognostic model using hematoxylin and eosin-stained, whole-slide images and tumor stage as input, on 2,072 patients from eight EC cohorts including the PORTEC-1/-2/-3 randomized trials. HECTOR demonstrated C-indices in internal (n = 353) and two external (n = 160 and n = 151) test sets of 0.789, 0.828 and 0.815, respectively, outperforming the current gold standard, and identified patients with markedly different outcomes (10-year distant recurrence-free probabilities of 97.0%, 77.7% and 58.1% for HECTOR low-, intermediate- and high-risk groups, respectively, by Kaplan-Meier analysis). HECTOR also predicted adjuvant chemotherapy benefit better than current methods. Morphological and genomic feature extraction identified correlates of HECTOR risk groups, some with therapeutic potential. HECTOR improves on the current gold standard and may help delivery of personalized treatment in EC., (© 2024. The Author(s).)

Background: Numerous studies have shown that older women with endometrial cancer have a higher risk of recurrence and cancer-related death. However, it remains unclear whether older age is a causal prognostic factor, or whether other risk factors become increasingly common with age. We aimed to address this question with a unique multimethod study design using state-of-the-art statistical and causal inference techniques on datasets of three large, randomised trials., Methods: In this multimethod analysis, data from 1801 women participating in the randomised PORTEC-1, PORTEC-2, and PORTEC-3 trials were used for statistical analyses and causal inference. The cohort included 714 patients with intermediate-risk endometrial cancer, 427 patients with high-intermediate risk endometrial cancer, and 660 patients with high-risk endometrial cancer. Associations of age with clinicopathological and molecular features were analysed using non-parametric tests. Multivariable competing risk analyses were performed to determine the independent prognostic value of age. To analyse age as a causal prognostic variable, a deep learning causal inference model called AutoCI was used., Findings: Median follow-up as estimated using the reversed Kaplan-Meier method was 12·3 years (95% CI 11·9-12·6) for PORTEC-1, 10·5 years (10·2-10·7) for PORTEC-2, and 6·1 years (5·9-6·3) for PORTEC-3. Both overall recurrence and endometrial cancer-specific death significantly increased with age. Moreover, older women had a higher frequency of deep myometrial invasion, serous tumour histology, and p53-abnormal tumours. Age was an independent risk factor for both overall recurrence (hazard ratio [HR] 1·02 per year, 95% CI 1·01-1·04; p=0·0012) and endometrial cancer-specific death (HR 1·03 per year, 1·01-1·05; p=0·0012) and was identified as a significant causal variable., Interpretation: This study showed that advanced age was associated with more aggressive tumour features in women with endometrial cancer, and was independently and causally related to worse oncological outcomes. Therefore, our findings suggest that older women with endometrial cancer should not be excluded from diagnostic assessments, molecular testing, and adjuvant therapy based on their age alone., Funding: None., Competing Interests: Declaration of interests JW is supported by core funding of the University of Zurich to the Computational and Translational Pathology Lab led by VHK at the Department of Pathology and Molecular Pathology, University Hospital and University of Zurich. RAN has received grants (to institution) from the Dutch Cancer Society, Dutch Research Council, Elekta, Varian, and Accuray; payment or honoraria (to institution) for lectures and presentations from Elekta; and is chair of the Dutch Gynecological Oncology Group. AL-C declares having received payment or honoraria for multiple lectures and presentations. AL has received a PhD student grant from AstraZeneca; honoraria (to institution) for presentations from GSK, AstraZeneca, and MSD; support for attending meetings from OSEimmuno, AstraZeneca, and MSD; and honoraria (to institution) for participation on Data Safety Monitoring Board or Advisory Board from Genmab, AstraZeneca, MSD, and GSK. NS declares having received personal payment for participation in Advisory Boards of Astra-Zeneca–MSD and Glaxo-SmithKline. HWN has received grants or contracts (to institution) from Merck and the Dutch Cancer Society. VHK receives funding by the University of Zurich; has acted as an invited speaker for Sharing Progress in Cancer Care (SPCC) and holds sponsored research agreements with Roche and IAG unrelated to the content of this study; has served as an invited speaker on behalf of Indica Labs unrelated to the content of this study; is on an advisory board of Takeda (unrelated to the content of this study); and is a member of the European Key Opinion Leader Network in Digital Pathology supported by Roche. CLC has received clinical trial grants for the PORTEC-1, PORTEC-2, and PORTEC-3 trials (to institution) from the Dutch Cancer Society. NH has received unrestricted research grants (to institution) from the Dutch Cancer Society; personal payment for an educational lecture for specialist nurses in oncology (V&VN), unrelated to the current work; has a patent on a deep learning algorithm on endometrial cancer, unrelated to the current work; and is a member of a Data Safety Monitoring Board of the Apollo study (EudraCT number: 2022-002500-21). All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Universal tumor screening in endometrial carcinoma (EC) is increasingly adopted to identify individuals at risk of Lynch syndrome (LS). These cases involve mismatch repair-deficient (MMRd) EC without MLH1 promoter hypermethylation (PHM). LS is confirmed through the identification of germline MMR pathogenic variants (PV). In cases where these are not detected, emerging evidence highlights the significance of double-somatic MMR gene alterations as a sporadic cause of MMRd, alongside POLE/POLD1 exonuclease domain (EDM) PV leading to secondary MMR PV. Our understanding of the incidence of different MMRd EC origins not related to MLH1-PHM, their associations with clinicopathologic characteristics, and the prognostic implications remains limited. In a combined analysis of the PORTEC-1, -2, and -3 trials (n = 1254), 84 MMRd EC not related to MLH1-PHM were identified that successfully underwent paired tumor-normal tissue next-generation sequencing of the MMR and POLE/POLD1 genes. Among these, 37% were LS associated (LS-MMRd EC), 38% were due to double-somatic hits (DS-MMRd EC), and 25% remained unexplained. LS-MMRd EC exhibited higher rates of MSH6 (52% vs 19%) or PMS2 loss (29% vs 3%) than DS-MMRd EC, and exclusively showed MMR-deficient gland foci. DS-MMRd EC had higher rates of combined MSH2/MSH6 loss (47% vs 16%), loss of >2 MMR proteins (16% vs 3%), and somatic POLE-EDM PV (25% vs 3%) than LS-MMRd EC. Clinicopathologic characteristics, including age at tumor onset and prognosis, did not differ among the various groups. Our study validates the use of paired tumor-normal next-generation sequencing to identify definitive sporadic causes in MMRd EC unrelated to MLH1-PHM. MMR immunohistochemistry and POLE-EDM mutation status can aid in the differentiation between LS-MMRd EC and DS-MMRd EC. These findings emphasize the need for integrating tumor sequencing into LS diagnostics, along with clear interpretation guidelines, to improve clinical management. Although not impacting prognosis, confirmation of DS-MMRd EC may release patients and relatives from burdensome LS surveillance., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: The clinical significance of the p53-abnormal (p53abn) molecular subtype in stage I low-grade endometrioid endometrial carcinoma (EEC) is debated. We aimed to review pathologic and molecular characteristics, and outcomes of stage I low-grade p53abn EEC in a large international cohort., Experimental Design: Previously diagnosed stage I p53abn EC (POLE-wild-type, mismatch repair-proficient) low-grade EEC from Canadian retrospective cohorts and PORTEC-1&2 trials were included. Pathology review was performed by six expert gynecologic pathologists blinded to p53 status. IHC profiling, next-generation sequencing, and shallow whole-genome sequencing was performed. Kaplan-Meier method was used for survival analysis., Results: We identified 55 stage I p53abn low-grade EEC among 3,387 cases (2.5%). On pathology review, 17 cases (31%) were not diagnosed as low-grade EEC by any pathologists, whereas 26 cases (47%) were diagnosed as low-grade EEC by at least three pathologists. The IHC and molecular profile of the latter cases were consistent with low-grade EEC morphology (ER/PR positivity, patchy p16 expression, PIK3CA and PTEN mutations) but they also showed features of p53abn EC (TP53 mutations, many copy-number alterations). These cases had a clinically relevant risk of disease recurrence (5-year recurrence-free survival 77%), with pelvic and/or distant recurrences observed in 12% of the patients., Conclusions: A subset of p53abn EC is morphologically low-grade EEC and exhibit genomic instability. Even for stage I disease, p53abn low-grade EEC are at substantial risk of disease recurrence. These findings highlight the clinical relevance of universal p53-testing, even in low-grade EEC, to identify women at increased risk of recurrence., (©2023 The Authors; Published by the American Association for Cancer Research.)

Purpose: The molecular classification of endometrial cancer (EC) has proven to have prognostic value and is predictive of response to adjuvant chemotherapy. Here, we investigate its predictive value for response to external beam radiotherapy (EBRT) and vaginal brachytherapy (VBT) in early-stage endometrioid EC (EEC)., Methods: Data of the randomized PORTEC-1 trial (n = 714) comparing pelvic EBRT with no adjuvant therapy in early-stage intermediate-risk EC and the PORTEC-2 trial (n = 427) comparing VBT with EBRT in early-stage high-intermediate-risk EC were used. Locoregional (including vaginal and pelvic) recurrence-free survival was compared between treatment groups across the four molecular classes using Kaplan-Meier's methodology and log-rank tests., Results: A total of 880 molecularly classified ECs, 484 from PORTEC-1 and 396 from PORTEC-2, were included. The majority were FIGO-2009 stage I EEC (97.2%). The median follow-up was 11.3 years. No locoregional recurrences were observed in EC with a pathogenic mutation of DNA polymerase-ε ( POLE mut EC). In mismatch repair-deficient (MMRd) EC, locoregional recurrence-free survival was similar after EBRT (94.2%), VBT (94.2%), and no adjuvant therapy (90.3%; P = .74). In EC with a p53 abnormality (p53abn EC), EBRT (96.9%) had a substantial benefit over VBT (64.3%) and no adjuvant therapy (72.2%; P = .048). In EC with no specific molecular profile (NSMP EC), both EBRT (98.3%) and VBT (96.2%) yielded better locoregional control than no adjuvant therapy (87.7%; P < .0001)., Conclusion: The molecular classification of EC predicts response to radiotherapy in stage I EEC and may guide adjuvant treatment decisions. Omitting radiotherapy seems to be safe in POLE mut EC. The benefit of radiotherapy seems to be limited in MMRd EC. EBRT yields a significantly better locoregional recurrence-free survival than VBT or no adjuvant therapy in p53abn EC. VBT is the treatment of choice for NSMP EC as it is as effective as EBRT and significantly better than no adjuvant therapy for locoregional tumor control.

Background: Risk-assessment of endometrial cancer (EC) is based on clinicopathological factors and molecular subgroup. It is unclear whether adding hormone receptor expression, L1CAM expression or CTNNB1 status yields prognostic refinement., Methods: Paraffin-embedded tumour samples of women with high-risk EC (HR-EC) from the PORTEC-3 trial (n = 424), and a Dutch prospective clinical cohort called MST (n = 256), were used. All cases were molecularly classified. Expression of L1CAM, ER and PR were analysed by whole-slide immunohistochemistry and CTNNB1 mutations were assessed with a next-generation sequencing. Kaplan-Meier method, log-rank tests and Cox's proportional hazard models were used for survival analysis., Results: In total, 648 HR-EC were included. No independent prognostic value of ER, PR, L1CAM, and CTNNB1 was found, while age, stage, and adjuvant chemotherapy had an independent impact on risk of recurrence. Subgroup-analysis showed that only in NSMP HR-EC, ER-positivity was independently associated with a reduced risk of recurrence (HR 0.33, 95%CI 0.15-0.75)., Conclusions: We confirmed the prognostic impact of the molecular classification, age, stage, and adjuvant CTRT in a large cohort of high-risk EC. ER-positivity is a strong favourable prognostic factor in NSMP HR-EC and identifies a homogeneous subgroup of NSMP tumours. Assessment of ER status in high-risk NSMP EC is feasible in clinical practice and could improve risk stratification and treatment., (© 2023. The Author(s).)

Background: Endometrial cancer can be molecularly classified into POLE mut , mismatch repair deficient (MMRd), p53 abnormal (p53abn), and no specific molecular profile (NSMP) subgroups. We aimed to develop an interpretable deep learning pipeline for whole-slide-image-based prediction of the four molecular classes in endometrial cancer (im4MEC), to identify morpho-molecular correlates, and to refine prognostication., Methods: This combined analysis included diagnostic haematoxylin and eosin-stained slides and molecular and clinicopathological data from 2028 patients with intermediate-to-high-risk endometrial cancer from the PORTEC-1 (n=466), PORTEC-2 (n=375), and PORTEC-3 (n=393) randomised trials and the TransPORTEC pilot study (n=110), the Medisch Spectrum Twente cohort (n=242), a case series of patients with POLE mut endometrial cancer in the Leiden Endometrial Cancer Repository (n=47), and The Cancer Genome Atlas-Uterine Corpus Endometrial Carcinoma cohort (n=395). PORTEC-3 was held out as an independent test set and a four-fold cross validation was performed. Performance was measured with the macro and class-wise area under the receiver operating characteristic curve (AUROC). Whole-slide images were segmented into tiles of 360 μm resized to 224 × 224 pixels. im4MEC was trained to learn tile-level morphological features with self-supervised learning and to molecularly classify whole-slide images with an attention mechanism. The top 20 tiles with the highest attention scores were reviewed to identify morpho-molecular correlates. Predictions of a nuclear classification deep learning model serve to derive interpretable morphological features. We analysed 5-year recurrence-free survival and explored prognostic refinement by molecular class using the Kaplan-Meier method., Findings: im4MEC attained macro-average AUROCs of 0·874 (95% CI 0·856-0·893) on four-fold cross-validation and 0·876 on the independent test set. The class-wise AUROCs were 0·849 for POLE mut (n=51), 0·844 for MMRd (n=134), 0·883 for NSMP (n=120), and 0·928 for p53abn (n=88). POLE mut and MMRd tiles had a high density of lymphocytes, p53abn tiles had strong nuclear atypia, and the morphology of POLE mut and MMRd endometrial cancer overlapped. im4MEC highlighted a low tumour-to-stroma ratio as a potentially novel characteristic feature of the NSMP class. 5-year recurrence-free survival was significantly different between im4MEC predicted molecular classes in PORTEC-3 (log-rank p<0·0001). The ten patients with aggressive p53abn endometrial cancer that was predicted as MMRd showed inflammatory morphology and appeared to have a better prognosis than patients with correctly predicted p53abn endometrial cancer (p=0·30). The four patients with NSMP endometrial cancer that was predicted as p53abn showed higher nuclear atypia and appeared to have a worse prognosis than patients with correctly predicted NSMP (p=0·13). Patients with MMRd endometrial cancer predicted as POLE mut had an excellent prognosis, as do those with true POLE mut endometrial cancer., Interpretation: We present the first interpretable deep learning model, im4MEC, for haematoxylin and eosin-based prediction of molecular endometrial cancer classification. im4MEC robustly identified morpho-molecular correlates and could enable further prognostic refinement of patients with endometrial cancer., Funding: The Hanarth Foundation, the Promedica Foundation, and the Swiss Federal Institutes of Technology., Competing Interests: Declaration of interests HWN and JJJ declare grants from Merck, NH declares grants from Varian, and VHK declares research funding from Roche, unrelated to the subject of this manuscript. All other authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Lymphovascular space invasion (LVSI) occurs in a minority of endometrial cancer (EC) cases, and the extent of LVSI is an important risk factor for recurrence and/or metastases. Our aim was to improve the reproducibility of measuring clinically meaningful LVSI by performing a quantitative analysis of the correlation between LVSI and the risk of pelvic lymph node recurrence in EC. EC samples from PORTEC-1 and PORTEC-2 trials were retrieved and used to collect quantitative data, including the number of LVSI-positive vessels per H&E-stained slide. Using a predefined threshold for clinical relevance, the risk of pelvic lymph node recurrence risk was calculated (Kaplan-Meier method, with Cox regression) using a stepwise adjustment for the number of LVSI-positive vessels. This analysis was then repeated in the Danish Gynecological Cancer Database (DGCD) cohort. Among patients in PORTEC-1 and PORTEC-2 trials who did not receive external beam radiotherapy, the 5-yr pelvic lymph node recurrence risk was 3.3%, 6.7% (P=0.51), and 26.3% (P<0.001), respectively when 0, 1 to 3, or ≥4 vessels had LVSI involvement; similar results were obtained for the DGCD cohort. Furthermore, both the average number of tumor cells in the largest embolus and the number of LVSI-positive H&E slides differed significantly between focal LVSI and substantial LVSI. On the basis of these results, we propose a numeric threshold (≥4 LVSI-involved vessels in at least one H&E slide) for defining clinically relevant LVSI in EC, thereby adding supportive data to the semiquantitative approach. This will help guide gynecologic pathologists to differentiate between focal and substantial LVSI, especially in borderline cases., Competing Interests: R.N. reports grants by the Dutch Cancer Society, Dutch Research Council, Elekta, Varian and Accuracy, all unrelated to this work. C.C. reports grants by the Dutch Cancer Society. The remaining authors declare no conflict of interest., (Copyright © 2021 by the International Society of Gynecological Pathologists.)

Approximately 15% of patients with endometrial cancer present with high-risk disease (HREC). Moreover, assessing the extent of lymphovascular space invasion (LVSI) may provide prognostic insight among patients with HREC. The aim of this study was to determine whether the extent of LVSI can serve as a prognostic factor in HREC. All cases of ESMO-ESGO-ESTRO 2016 classified HREC in the Danish Gynecological Cancer Database (DGCD) diagnosed from 2005 to 2012 were reviewed for the presence and extent of LVSI (categorized using a 3-tiered definition). We used the Kaplan-Meier analysis to calculate actuarial survival rates, both adjusted and unadjusted Cox regression analyses were used to calculate the proportional hazard ratio (HR). A total of 376 patients were included in our analysis. Among 305 patients with stage I/II HREC, 8.2% and 6.2% had focal or substantial LVSI, respectively, compared with 12.7% and 38.0% of 71 patients with stage III/IV HREC, respectively. Moreover, the estimated 5-yr recurrence-free survival rate was significantly lower among patients with substantial LVSI compared with patients with no LVSI for both stage I/II (HR: 2.8; P=0.011) and stage III/IV (HR: 2.9; P=0.003) patients. Similarly, overall survival was significantly lower among patients with substantial LVSI for both stage I/II (HR: 3.1; P<0.001) and stage III/IV (HR: 3.2; P=0.020) patients. In patients with HREC, substantial LVSI is an independent adverse prognostic factor for lymph node and distant metastases, leading to reduced survival. Thus, the extent of LVSI should be incorporated into routine pathology reports in order to guide the appropriate choice of adjuvant treatment., Competing Interests: R.A.N. reports grants by the Dutch Cancer Society, Dutch Research Council, Elekta, Varian and Accuracy, all unrelated to this work. C.L.C. reports grants from the Dutch Cancer Society. The remaining authors declare no conflict of interest., (Copyright © 2021 by the International Society of Gynecological Pathologists.)

B-cells play a key role in cancer suppression, particularly when aggregated in tertiary lymphoid structures (TLS). Here, we investigate the role of B-cells and TLS in endometrial cancer (EC). Single cell RNA-sequencing of B-cells shows presence of naïve B-cells, cycling/germinal center B-cells and antibody-secreting cells. Differential gene expression analysis shows association of TLS with L1CAM overexpression. Immunohistochemistry and co-immunofluorescence show L1CAM expression in mature TLS, independent of L1CAM expression in the tumor. Using L1CAM as a marker, 378 of the 411 molecularly classified ECs from the PORTEC-3 biobank are evaluated, TLS are found in 19%. L1CAM expressing TLS are most common in mismatch-repair deficient (29/127, 23%) and polymerase-epsilon mutant EC (24/47, 51%). Multivariable Cox regression analysis shows strong favorable prognostic impact of TLS, independent of clinicopathological and molecular factors. Our data suggests a pivotal role of TLS in outcome of EC patients, and establishes L1CAM as a simple biomarker., (© 2022. The Author(s).)

Adjuvant radiotherapy is an important component of post-operative therapy for patients with early-stage endometrial cancer. In the past decades, many trials have been conducted to determine the optimal adjuvant treatment strategy, pelvic external beam radiotherapy or vaginal brachytherapy. As a result, vaginal brachytherapy became the treatment of choice for patients with early-stage endometrial cancer at high-intermediate risk, based on clinicopathological risk factors. Vaginal brachytherapy maximizes local control and has only mild side effects with limited impact on quality of life, in comparison with pelvic external beam radiotherapy. The most frequently used treatment schedule is the one which was used in the PORTEC-2 trial (21 Gy in three fractions specified at 5 mm depth) and, whenever available, image-guided brachytherapy should be used. However, the most convenient and effective treatment schedule remains to be established. More recently, the discovery and integration of four molecular classes in the risk assessment of endometrial cancer patients has created new opportunities to prevent over- and undertreatment. The 2021 endometrial cancer guideline of the European Society of Gynaecological Oncology (ESGO), European Society for Radiotherapy and Oncology (ESTRO), and the European Society of Pathology (ESP) now proposes an integrated risk stratification, in which both clinicopathologic and molecular factors are combined, to direct adjuvant therapy. This rationale is now investigated in multiple prospective trials. This review provides an overview of the rationale and currently recommended and new strategies for vaginal brachytherapy in patients with stage I and II endometrial cancer., Competing Interests: Competing interests: ASVMH reports a research grant from the Dutch Cancer Society, during the conduct of the PORTEC-4a study, outside the submitted work. NH reports grants from Dutch Cancer Society and Varian outside the submitted work. CLC report grants from Varian, non-financial support from Elekta, other from Merck, outside the submitted work; and Dutch Cancer Society clinical trial grants. RAN reports grants from Dutch Cancer Society, Dutch Research Council, Elekta, Varian, Accuray, outside the submitted work., (© IGCS and ESGO 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: The clinical role of the molecular endometrial cancer (EC) classification has not been fully explored in patients staged with lymphadenectomy or without adjuvant treatment, conditions that could potentially moderate the prognostic value of the classification. We aimed to evaluate the clinical outcome of the molecular subgroups in patients with high-grade EC staged by lymphadenectomy and those without adjuvant treatment., Methods: DNA-sequencing for the detection of pathogenic POLE-exonuclease domain mutations and immunohistochemistry for mismatch repair (MMR) proteins and p53 expression were performed on 412 high-grade EC from the Danish Gynaecological Cancer Database (2005-2012) to classify them as POLE-ultramutated (POLEmut), MMR-deficient (MMRd), p53-mutant (p53abn), or no specific molecular profile (NSMP). Patients with stage IV or residual disease after surgery were excluded. Kaplan-Meier method, log-rank test and Cox proportional hazard models were used for analysis., Results: Molecular analysis was successful in 367 EC; 251 patients had undergone lymphadenectomy. Five-year recurrence rates in this subgroup of patients was 36.7% for women with p53abn EC, 0.0% for POLEmut EC, 13.4% for MMRd EC and 42.9% for NSMP EC (p < 0.001). Similar results were observed among stage IA-IB patients. Among patients without adjuvant treatment (n = 264), none with POLEmut EC (n = 26) had a recurrence., Conclusion: The molecular EC classification has strong prognostic value, independent of clinicopathological factors, also among high-grade EC patients staged by lymphadenectomy and those without adjuvant treatment. The unfavourable prognosis of early-stage p53abn EC is not due to undetected lymph node metastasis, and the indolent behaviour of POLEmut EC is independent of adjuvant treatment., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Standard screening of endometrial cancer (EC) for Lynch syndrome (LS) is gaining traction; however, the prognostic impact of an underlying hereditary etiology is unknown. We established the prevalence, prognosis, and subsequent primary cancer incidence of patients with LS-associated EC in relation to sporadic mismatch repair deficient (MMRd)-EC in the large combined Post Operative Radiation Therapy in Endometrial Carcinoma-1, -2, and -3 trial cohort., Methods: After MMR-immunohistochemistry, MLH1-promoter methylation testing, and next-generation sequencing, tumors were classified into 3 groups according to the molecular cause of their MMRd-EC. Kaplan-Meier method, log-rank test, and Cox model were used for survival analysis. Competing risk analysis was used to estimate the subsequent cancer probability. All statistical tests were 2-sided., Results: Among the 1336 ECs, 410 (30.7%) were MMRd. A total of 380 (92.7%) were fully triaged: 275 (72.4%) were MLH1-hypermethylated MMRd-ECs; 36 (9.5%) LS MMRd-ECs, and 69 (18.2%) MMRd-ECs due to other causes. Limiting screening of EC patients to 60 years or younger or to 70 years or younger would have resulted in missing 18 (50.0%) and 6 (16.7%) LS diagnoses, respectively. Five-year recurrence-free survival was 91.7% (95% confidence interval [CI] = 83.1% to 100%; hazard ratio = 0.45, 95% CI = 0.16 to 1.24, P = .12) for LS, 95.5% (95% CI = 90.7% to 100%; hazard ratio = 0.17, 95% CI = 0.05 to 0.55, P = .003) for "other" vs 78.6% (95% CI = 73.8% to 83.7%) for MLH1-hypermethylated MMRd-EC. The probability of subsequent LS-associated cancer at 10 years was 11.6% (95% CI = 0.0% to 24.7%), 1.5% (95% CI = 0.0% to 4.3%), and 7.0% (95% CI = 3.0% to 10.9%) within the LS, "other," and MLH1-hypermethylated MMRd-EC groups, respectively., Conclusions: The LS prevalence in the Post Operative Radiation Therapy in Endometrial Carcinoma trial population was 2.8% and among MMRd-ECs was 9.5%. Patients with LS-associated ECs showed a trend towards better recurrence-free survival and higher risk for second cancers compared with patients with MLH1-hypermethylated MMRd-EC., (© The Author(s) 2021. Published by Oxford University Press.)

Background: Endometrial cancers (ECs) with somatic mutations in DNA polymerase epsilon (POLE) are characterized by unfavorable pathological features, which prompt adjuvant treatment. Paradoxically, women with POLE-mutated EC have outstanding clinical outcomes, and this raises concerns of overtreatment. The authors investigated whether favorable outcomes were independent of treatment., Methods: A PubMed search for POLE and endometrial was restricted to articles published between March 1, 2012, and March 1, 2018, that provided individual patient data (IPD), adjuvant treatment, and survival. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) reporting guidelines for IPD, the authors used univariate and multivariate one-stage meta-analyses with mixed effects Cox models (random effects for study cohorts) to infer the associations of treatment, traditional prognostic factors, and outcome, which was defined as the time from first diagnosis to any adverse event (progression/recurrence or death from EC)., Results: Three hundred fifty-nine women with POLE-mutated EC were identified; 294 (82%) had pathogenic mutations. Worse outcomes were demonstrated in patients with nonpathogenic POLE mutations (hazard ratio, 3.42; 95% confidence interval, 1.47-7.58; log-rank P < .01). Except for stage (P < .01), traditional prognosticators were not associated with progression/recurrence or death from disease. Adverse events were rare (11 progressions/recurrences and 3 disease-specific deaths). Salvage rates in patients who experienced recurrence were high and sustained, with 8 of 11 alive without evidence of disease (range, 5.5-14.2 years). Adjuvant treatment was not associated with outcome., Conclusions: Clinical outcomes for ECs with pathogenic POLE mutations are not associated with most traditional risk parameters, and patients do not appear to benefit from adjuvant therapy. The observed low rates of recurrence/progression and the high and sustained salvage rates raise the possibility of safely de-escalating treatment for these patients., Lay Summary: Ten percent of all endometrial cancers have mutations in the DNA repair gene DNA polymerase epsilon (POLE). Women who have endometrial cancers with true POLE mutations experience almost no recurrences or deaths from their cancer even when their tumors appear to have very unfavorable characteristics. Additional therapy (radiation and chemotherapy) does not appear to improve outcomes for women with POLE-mutated endometrial cancer, and this supports the move to less therapy and less associated toxicity. Diligent classification of endometrial cancers by molecular features provides valuable information to inform prognosis and to direct treatment/no treatment., (© 2021 American Cancer Society.)

Purpose: The survival results of the PORTEC-3 trial showed a significant improvement in both overall and failure-free survival with chemoradiation therapy versus pelvic radiation therapy alone. The present analysis was performed to compare long-term adverse events (AE) and health-related quality of life (HRQOL)., Methods and Materials: In the study, 660 women with high-risk endometrial cancer were randomly assigned to receive chemoradiation therapy (2 concurrent cycles of cisplatin followed by 4 cycles of carboplatin/paclitaxel) or radiation therapy alone. Toxicity was graded using Common Terminology Criteria for Adverse Events, version 3.0. HRQOL was measured using EORTC QLQ-C30 and CX24/OV28 subscales and compared with normative data. An as-treated analysis was performed., Results: Median follow-up was 74.6 months; 574 (87%) patients were evaluable for HRQOL. At 5 years, grade ≥2 AE were scored for 78 (38%) patients who had received chemoradiation therapy versus 46 (24%) who had received radiation therapy alone (P = .008). Grade 3 AE did not differ significantly between the groups (8% vs 5%, P = .18) at 5 years, and only one new late grade 4 toxicity had been reported. At 3 and 5 years, sensory neuropathy toxicity grade ≥2 persisted after chemoradiation therapy in 6% (vs 0% after radiation therapy, P < .001) and more patients reported significant tingling or numbness at HRQOL (27% vs 8%, P < .001 at 3 years; 24% vs 9%, P = .002 at 5 years). Up to 3 years, more patients who had chemoradiation therapy reported limb weakness (21% vs 5%, P < .001) and lower physical (79 vs 87, P < .001) and role functioning (78 vs 88, P < .001) scores. Both treatment groups reported similar long-term global health/quality of life scores, which were better than those of the normative population., Conclusions: This study shows a long-lasting, clinically relevant, negative impact of chemoradiation therapy on toxicity and HRQOL, most importantly persistent peripheral sensory neuropathy. Physical and role functioning impairments were seen until 3 years. These long-term data are essential for patient information and shared decision-making regarding adjuvant chemotherapy for high-risk endometrial cancer., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

A European consensus conference on endometrial carcinoma was held in 2014 to produce multidisciplinary evidence-based guidelines on selected questions. Given the large body of literature on the management of endometrial carcinoma published since 2014, the European Society of Gynaecological Oncology (ESGO), the European SocieTy for Radiotherapy & Oncology (ESTRO) and the European Society of Pathology (ESP) jointly decided to update these evidence-based guidelines and to cover new topics in order to improve the quality of care for women with endometrial carcinoma across Europe and worldwide. ESGO/ESTRO/ESP nominated an international multidisciplinary development group consisting of practicing clinicians and researchers who have demonstrated leadership and expertise in the care and research of endometrial carcinoma (27 experts across Europe). To ensure that the guidelines are evidence-based, the literature published since 2014, identified from a systematic search was reviewed and critically appraised. In the absence of any clear scientific evidence, judgment was based on the professional experience and consensus of the development group. The guidelines are thus based on the best available evidence and expert agreement. Prior to publication, the guidelines were reviewed by 191 independent international practitioners in cancer care delivery and patient representatives. The guidelines comprehensively cover endometrial carcinoma staging, definition of prognostic risk groups integrating molecular markers, pre- and intra-operative work-up, fertility preservation, management for early, advanced, metastatic, and recurrent disease and palliative treatment. Principles of radiotherapy and pathological evaluation are also defined.

Optimum risk stratification in early-stage endometrial cancer combines clinicopathologic factors and the molecular endometrial cancer classification defined by The Cancer Genome Atlas (TCGA). It is unclear whether analysis of intratumoral immune infiltrate improves this. We developed a machine-learning, image-based algorithm to quantify density of CD8 + and CD103 + immune cells in tumor epithelium and stroma in 695 stage I endometrioid endometrial cancers from the PORTEC-1 and -2 trials. The relationship between immune cell density and clinicopathologic/molecular factors was analyzed by hierarchical clustering and multiple regression. The prognostic value of immune infiltrate by cell type and location was analyzed by univariable and multivariable Cox regression, incorporating the molecular endometrial cancer classification. Tumor-infiltrating immune cell density varied substantially between cases, and more modestly by immune cell type and location. Clustering revealed three groups with high, intermediate, and low densities, with highly significant variation in the proportion of molecular endometrial cancer subgroups between them. Univariable analysis revealed intraepithelial CD8 + cell density as the strongest predictor of endometrial cancer recurrence; multivariable analysis confirmed this was independent of pathologic factors and molecular subgroup. Exploratory analysis suggested this association was not uniform across molecular subgroups, but greatest in tumors with mutant p53 and absent in DNA mismatch repair-deficient cancers. Thus, this work identified that quantification of intraepithelial CD8 + cells improved upon the prognostic utility of the molecular endometrial cancer classification in early-stage endometrial cancer., (©2020 American Association for Cancer Research.)

Background: Vaginal brachytherapy is currently recommended as adjuvant treatment in patients with high-intermediate risk endometrial cancer to maximize local control and has only mild side effects and no or limited impact on quality of life. However, there is still considerable overtreatment and also some undertreatment, which may be reduced by tailoring adjuvant treatment to the patients' risk of recurrence based on molecular tumor characteristics., Primary Objectives: To compare the rates of vaginal recurrence in women with high-intermediate risk endometrial cancer, treated after surgery with molecular-integrated risk profile-based recommendations for either observation, vaginal brachytherapy or external pelvic beam radiotherapy or with standard adjuvant vaginal brachytherapy STUDY HYPOTHESIS: Adjuvant treatment based on a molecular-integrated risk profile provides similar local control and recurrence-free survival as current standard adjuvant brachytherapy in patients with high-intermediate risk endometrial cancer, while sparing many patients the morbidity of adjuvant treatment and reducing healthcare costs., Trial Design: A multicenter, international phase III randomized trial (2:1) of molecular-integrated risk profile-based adjuvant treatment (experimental arm) or adjuvant vaginal brachytherapy (standard arm)., Major Inclusion/exclusion Criteria: Women aged 18 years and over with a histological diagnosis of high-intermediate risk endometrioid endometrial cancer after total abdominal or laparoscopic hysterectomy and bilateral salpingo-oophorectomy. High-intermediate risk factors are defined as: (i) International Federation of Gynecology and Obstetrics stage IA (with invasion) and grade 3; (ii) stage IB grade 1 or 2 with age ≥60 and/or lymph-vascular space invasion; (iii) stage IB, grade 3 without lymph-vascular space invasion; or (iv) stage II (microscopic and grade 1)., Endpoints: The primary endpoint is vaginal recurrence. Secondary endpoints are recurrence-free and overall survival; pelvic and distant recurrence; 5-year vaginal control (including treatment for relapse); adverse events and patient-reported symptoms and quality of life; and endometrial cancer-related healthcare costs., Sample Size: 500 eligible and evaluable patients., Estimated Dates for Completing Accrual and Presenting Results: Estimated date for completing accrual will be late 2021. Estimated date for presentation of (first) results is expected in 2023., Trial Registration: The trial is registered at clinicaltrials.gov (NCT03469674) and ISRCTN (11659025)., Competing Interests: Competing interests: ASVMvdH and NH report a research grant from the Dutch Cancer Society, during the conduct of the PORTEC-4a study. HWN reports non-financial support from Merck, grants from the Dutch Cancer Society, grants from AIMM, outside the submitted work. RAN reports grants from the Dutch Cancer Society, grants from the Dutch Research Council, grants from Elekta, grants from Varian, grants from Accuray, outside the submitted work. CC reports non-financial support from Roche, non-financial support from TherAguix, personal fees from Elekta, personal fees from MSD, personal fees from GSK, outside the submitted work. CLC reports grants from the Dutch Cancer Society, non-financial support from Elekta-Nucletron, during the conduct of the PORTEC-4a study. SK reports personal fees from GSK, personal fees from Roche, personal fees from MSD, personal fees from AstraZeneca, outside the submitted work., (© IGCS and ESGO 2020. Re-use permitted under CC BY. Published by BMJ.)

Purpose: The randomized Adjuvant Chemoradiotherapy Versus Radiotherapy Alone in Women With High-Risk Endometrial Cancer (PORTEC-3) trial investigated the benefit of combined adjuvant chemotherapy and radiotherapy (CTRT) versus radiotherapy alone (RT) for women with high-risk endometrial cancer (EC). Because The Cancer Genome Atlas defined an EC molecular classification with strong prognostic value, we investigated prognosis and impact of chemotherapy for each molecular subgroup using tissue samples from PORTEC-3 trial participants., Methods: Paraffin-embedded tissues of 423 consenting patients were collected. Immunohistochemistry for p53 and mismatch repair (MMR) proteins, and DNA sequencing for POLE exonuclease domain were done to classify tumors as p53 abnormal (p53abn), POLE- ultramutated ( POLE mut), MMR-deficient (MMRd), or no specific molecular profile (NSMP). The primary end point was recurrence-free survival (RFS). Kaplan-Meier method, log-rank test, and Cox model were used for analysis., Results: Molecular analysis was successful in 410 high-risk EC (97%), identifying the 4 subgroups: p53abn EC (n = 93; 23%), POLE mut (n = 51; 12%), MMRd (n = 137; 33%), and NSMP (n = 129; 32%). Five-year RFS was 48% for patients with p53abn EC, 98% for POLE mut EC, 72% for MMRd EC, and 74% for NSMP EC ( P < .001). The 5-year RFS with CTRT versus RT for p53abn EC was 59% versus 36% ( P = .019); 100% versus 97% for patients with POLE mut EC ( P = .637); 68% versus 76% ( P = .428) for MMRd EC; and 80% versus 68% ( P = .243) for NSMP EC., Conclusion: Molecular classification has strong prognostic value in high-risk EC, with significantly improved RFS with adjuvant CTRT for p53abn tumors, regardless of histologic type. Patients with POLE mut EC had an excellent RFS in both trial arms. EC molecular classification should be incorporated in the risk stratification of these patients as well as in future trials to target specific subgroups of patients.

Endometrial carcinoma (EC) molecular classification based on four molecular subclasses identified in The Cancer Genome Atlas (TCGA) has gained relevance in recent years due to its prognostic utility and potential to predict benefit from adjuvant treatment. While most ECs can be classified based on a single classifier (POLE exonuclease domain mutations - POLEmut, MMR deficiency - MMRd, p53 abnormal - p53abn), a small but clinically relevant group of tumours harbour more than one molecular classifying feature and are referred to as 'multiple-classifier' ECs. We aimed to describe the clinicopathological and molecular features of multiple-classifier ECs with abnormal p53 (p53abn). Within a cohort of 3518 molecularly profiled ECs, 107 (3%) tumours displayed p53abn in addition to another classifier(s), including 64 with MMRd (MMRd-p53abn), 31 with POLEmut (POLEmut-p53abn), and 12 with all three aberrations (MMRd-POLEmut-p53abn). MMRd-p53abn ECs and POLEmut-p53abn ECs were mostly grade 3 endometrioid ECs, early stage, and frequently showed morphological features characteristic of MMRd or POLEmut ECs. 18/28 (60%) MMRd-p53abn ECs and 7/15 (46.7%) POLEmut-p53abn ECs showed subclonal p53 overexpression, suggesting that TP53 mutation was a secondary event acquired during tumour progression. Hierarchical clustering of TCGA ECs by single nucleotide variant (SNV) type and somatic copy number alterations (SCNAs) revealed that MMRd-p53abn tumours mostly clustered with single-classifier MMRd tumours (20/23) rather than single-classifier p53abn tumours (3/23), while POLEmut-p53abn tumours mostly clustered with single-classifier POLEmut tumours (12/13) and seldom with single-classifier p53abn tumours (1/13) (both p ≤ 0.001, chi-squared test). Finally, the clinical outcome of patients with MMRd-p53abn and POLEmut-p53abn ECs [stage I 5-year recurrence-free survival (RFS) of 92.2% and 94.1%, respectively] was significantly different from single-classifier p53abn EC (stage I RFS 70.8%, p = 0.024 and p = 0.050, respectively). Our results support the classification of MMRd-p53abn EC as MMRd and POLEmut-p53abn EC as POLEmut. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., (© 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

Pathogenic somatic missense mutations within the DNA polymerase epsilon (POLE) exonuclease domain define the important subtype of ultramutated tumours ('POLE-ultramutated') within the novel molecular classification of endometrial carcinoma (EC). However, clinical implementation of this classifier requires systematic evaluation of the pathogenicity of POLE mutations. To address this, we examined base changes, tumour mutational burden (TMB), DNA microsatellite instability (MSI) status, POLE variant frequency, and the results from six in silico tools on 82 ECs with whole-exome sequencing from The Cancer Genome Atlas (TCGA). Of these, 41 had one of five known pathogenic POLE exonuclease domain mutations (EDM) and showed characteristic genomic alterations: C>A substitution > 20%, T>G substitutions > 4%, C>G substitutions < 0.6%, indels < 5%, TMB > 100 mut/Mb. A scoring system to assess these alterations (POLE-score) was developed; based on their scores, 7/18 (39%) additional tumours with EDM were classified as POLE-ultramutated ECs, and the six POLE mutations present in these tumours were considered pathogenic. Only 1/23 (4%) tumours with non-EDM showed these genomic alterations, indicating that a large majority of mutations outside the exonuclease domain are not pathogenic. The infrequent combination of MSI-H with POLE EDM led us to investigate the clinical significance of this association. Tumours with pathogenic POLE EDM co-existent with MSI-H showed genomic alterations characteristic of POLE-ultramutated ECs. In a pooled analysis of 3361 ECs, 13 ECs with DNA mismatch repair deficiency (MMRd)/MSI-H and a pathogenic POLE EDM had a 5-year recurrence-free survival (RFS) of 92.3%, comparable to previously reported POLE-ultramutated ECs. Additionally, 14 cases with non-pathogenic POLE EDM and MMRd/MSI-H had a 5-year RFS of 76.2%, similar to MMRd/MSI-H, POLE wild-type ECs, suggesting that these should be categorised as MMRd, rather than POLE-ultramutated ECs for prognostication. This work provides guidance on classification of ECs with POLE mutations, facilitating implementation of POLE testing in routine clinical care. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., (© 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

Histopathological evaluation including subtyping and grading is the current cornerstone for endometrial cancer (EC) classification. This provides clinicians with prognostic information and input for further treatment recommendations. Nonetheless, patients with histologically similar ECs may have very different outcomes, notably in patients with high-grade endometrial carcinomas. For endometrial cancer, four molecular subgroups have undergone extensive studies in recent years: POLE ultramutated (POLEmut), mismatch repair-deficient (MMRd), p53 mutant (p53abn) and those EC lacking any of these alterations, referred to as NSMP (non-specific molecular profile). Several large studies confirm the prognostic relevance of these molecular subgroups. However, this 'histomolecular' approach has so far not been implemented in clinical routine. The ongoing PORTEC4a trial is the first clinical setting in which the added value of integrating molecular parameters in adjuvant treatment decisions will be determined. For diagnostics, the incorporation of the molecular parameters in EC classification will add a level of objectivity which will yield biologically more homogeneous subclasses. Here we illustrate how the management of individual EC patients may be impacted when applying the molecular EC classification. We describe our current approach to the integrated diagnoses of EC with a focus on scenarios with conflicting morphological and molecular findings. We also address several pitfalls accompanying the diagnostic implementation of molecular EC classification and give practical suggestions for diagnostic scenarios., (© 2019 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Background: The PORTEC-3 trial investigated the benefit of combined adjuvant chemotherapy and radiotherapy versus pelvic radiotherapy alone for women with high-risk endometrial cancer. We updated the analysis to investigate patterns of recurrence and did a post-hoc survival analysis., Methods: In the multicentre randomised phase 3 PORTEC-3 trial, women with high-risk endometrial cancer were eligible if they had International Federation of Gynaecology and Obstetrics (FIGO) 2009 stage I, endometrioid grade 3 cancer with deep myometrial invasion or lymphovascular space invasion, or both; stage II or III disease; or stage I-III disease with serous or clear cell histology; were aged 18 years and older; and had a WHO performance status of 0-2. Participants were randomly assigned (1:1) to receive radiotherapy alone (48·6 Gy in 1·8 Gy fractions given on 5 days per week) or chemoradiotherapy (two cycles of cisplatin 50 mg/m 2 given intravenously during radiotherapy, followed by four cycles of carboplatin AUC5 and paclitaxel 175 mg/m 2 given intravenously), by use of a biased coin minimisation procedure with stratification for participating centre, lymphadenectomy, stage, and histological type. The co-primary endpoints were overall survival and failure-free survival. Secondary endpoints of vaginal, pelvic, and distant recurrence were analysed according to the first site of recurrence. Survival endpoints were analysed by intention-to-treat, and adjusted for stratification factors. Competing risk methods were used for failure-free survival and recurrence. We did a post-hoc analysis to analyse patterns of recurrence with 1 additional year of follow-up. The study was closed on Dec 20, 2013; follow-up is ongoing. This study is registered with ISRCTN, number ISRCTN14387080, and ClinicalTrials.gov, number NCT00411138., Findings: Between Nov 23, 2006, and Dec 20, 2013, 686 women were enrolled, of whom 660 were eligible and evaluable (330 in the chemoradiotherapy group, and 330 in the radiotherapy-alone group). At a median follow-up of 72·6 months (IQR 59·9-85·6), 5-year overall survival was 81·4% (95% CI 77·2-85·8) with chemoradiotherapy versus 76·1% (71·6-80·9) with radiotherapy alone (adjusted hazard ratio [HR] 0·70 [95% CI 0·51-0·97], p=0·034), and 5-year failure-free survival was 76·5% (95% CI 71·5-80·7) versus 69·1% (63·8-73·8; HR 0·70 [0·52-0·94], p=0·016). Distant metastases were the first site of recurrence in most patients with a relapse, occurring in 78 of 330 women (5-year probability 21·4%; 95% CI 17·3-26·3) in the chemoradiotherapy group versus 98 of 330 (5-year probability 29·1%; 24·4-34·3) in the radiotherapy-alone group (HR 0·74 [95% CI 0·55-0·99]; p=0·047). Isolated vaginal recurrence was the first site of recurrence in one patient (0·3%; 95% CI 0·0-2·1) in both groups (HR 0·99 [95% CI 0·06-15·90]; p=0·99), and isolated pelvic recurrence was the first site of recurrence in three women (0·9% [95% CI 0·3-2·8]) in the chemoradiotherapy group versus four (0·9% [95% CI 0·3-2·8]) in the radiotherapy-alone group (HR 0·75 [95% CI 0·17-3·33]; p=0·71). At 5 years, only one grade 4 adverse event (ileus or obstruction) was reported (in the chemoradiotherapy group). At 5 years, reported grade 3 adverse events did not differ significantly between the two groups, occurring in 16 (8%) of 201 women in the chemoradiotherapy group versus ten (5%) of 187 in the radiotherapy-alone group (p=0·24). The most common grade 3 adverse event was hypertension (in four [2%] women in both groups). At 5 years, grade 2 or worse adverse events were reported in 76 (38%) of 201 women in the chemoradiotherapy group versus 43 (23%) of 187 in the radiotherapy-alone group (p=0·002). Sensory neuropathy persisted more often after chemoradiotherapy than after radiotherapy alone, with 5-year rates of grade 2 or worse neuropathy of 6% (13 of 201 women) versus 0% (0 of 187). No treatment-related deaths were reported., Interpretation: This updated analysis shows significantly improved overall survival and failure-free survival with chemoradiotherapy versus radiotherapy alone. This treatment schedule should be discussed and recommended, especially for women with stage III or serous cancers, or both, as part of shared decision making between doctors and patients. Follow-up is ongoing to evaluate long-term survival., Funding: Dutch Cancer Society, Cancer Research UK, National Health and Medical Research Council, Project Grant, Cancer Australia Grant, Italian Medicines Agency, and the Canadian Cancer Society Research Institute., (Copyright © 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Purpose of Review: To provide an overview of common molecular risk factors in endometrial cancer (EC) with the possibility to improve adjuvant treatment selection., Recent Findings: Recent studies have discovered and confirmed four different molecular subclasses in EC, with each having a distinct prognosis; POLE-ultramutated, microsatellite unstable, copy-number low, and copy-number high. Subsequent studies have shown that combining both molecular with clinicopathological risk factors can potentially improve adjuvant treatment selection for women with high-intermediate risk EC. For high risk and advanced stage EC, several molecular alterations are being explored for targeted therapy. Molecular alterations are frequently found in endometrial cancer and have currently not been implemented in the treatment guidelines for EC. Assessment of molecular alterations can distinguish patients that require less or more intensified adjuvant treatment. Trials investigating targeted therapies in EC are ongoing and have shown some promising results, however, more evidence is needed and results of randomized trials have to be awaited.

Aims: Lymphovascular space invasion (LVSI) in endometrial cancer (EC) is an important prognostic variable impacting on a patient's individual recurrence risk and adjuvant treatment recommendations. Recent work has shown that grading the extent of LVSI further improves its prognostic strength in patients with stage I endometrioid EC. Despite this, there is little information on the reproducibility of LVSI assessment in EC. Therefore, we designed a study to evaluate interobserver agreement in discriminating true LVSI from LVSI mimics (Phase I) and reproducibility of grading extent of LVSI (Phase II)., Methods and Results: Scanned haematoxylin and eosin (H&E) slides of endometrioid EC (EEC) with a predefined possible LVSI focus were hosted on a website and assessed by a panel of six European gynaecological pathologists. In Phase I, 48 H&E slides were included for LVSI assessment and in Phase II, 42 H&E slides for LVSI grading. Each observer was instructed to apply the criteria for LVSI used in daily practice. The degree of agreement was measured using the two-way absolute agreement average-measures intraclass correlation coefficient (ICC). Reproducibility of LVSI assessment (ICC = 0.64, P < 0.001) and LVSI grading (ICC = 0.62, P < 0.001) in EEC was substantial among the observers., Conclusions: Given the good reproducibility of LVSI, this study further supports the important role of LVSI in decision algorithms for adjuvant treatment., (© 2019 The Authors. Histopathology Published by John Wiley & Sons Ltd.)

Purpose: The elevated levels of somatic copy-number alterations (SCNAs) in a subset of high-risk endometrial cancers are suggestive of defects in pathways governing genome integrity. We sought to assess the prevalence of homologous recombination deficiency (HRD) in endometrial cancers and its association with histopathologic and molecular characteristics., Experimental Design: Fresh tumor tissue was prospectively collected from 36 endometrial cancers, and functional HRD was examined by the ability of replicating tumor cells to accumulate RAD51 protein at DNA double-strand breaks (RAD51 foci) induced by ionizing radiation. Genomic alterations were determined by next-generation sequencing and array comparative genomic hybridization/SNP array. The prevalence of BRCA -associated genomic scars, a surrogate marker for HRD, was determined in the The Cancer Genome Atlas (TCGA) endometrial cancer cohort., Results: Most endometrial cancers included in the final analysis ( n = 25) were of non-endometrioid (52%), grade 3 (60%) histology, and FIGO stage I (72%). HRD was observed in 24% ( n = 6) of cases and was restricted to non-endometrioid endometrial cancers (NEEC), with 46% of NEECs being HRD compared with none of the endometrioid endometrial cancers (EEC, P = 0.014). All but 1 of the HRD cases harbored either a pathogenic BRCA1 variant or high somatic copy-number (SCN) losses of HR genes. Analysis of TCGA cases supported these results, with BRCA -associated genomic scars present in up to 48% (63/132) of NEEC versus 12% (37/312) of EEC ( P < 0.001)., Conclusions: HRD occurs in endometrial cancers and is largely restricted to non-endometrioid, TP53 -mutant endometrial cancers. Evaluation of HRD may help select patients that could benefit from treatments targeting this defect, including platinum compounds and PARP inhibitors., (©2018 American Association for Cancer Research.)

Introduction: Although the majority of women with endometrial cancer have a favorable prognosis due to early symptoms, 15-20% have high-risk disease features and are at increased risk of recurrence. In order to improve prognosis for these patients, several trials have compared chemotherapy (CT), radiotherapy (RT) or the combination of CTRT. Areas covered: This review focuses on the current evidence on adjuvant treatment for women with high-risk endometrial cancer and future perspectives. Expert commentary: For stage I-II high-risk endometrial cancer, external beam radiotherapy ensured good local control and no significant benefit in progression-free or overall survival was found with the addition of chemotherapy in 2 recent randomized trials. For women with stage III disease, the combination of chemotherapy and radiotherapy improved progression-free survival with a non-significant improvement of overall survival. Adjuvant chemotherapy alone resulted in higher rates of pelvic and para-aortic recurrence. More toxicity and reduced quality of life were found during and after adjuvant CTRT. It is essential to discuss the benefits and disadvantages of chemotherapy and radiotherapy with individual patients for shared decision-making. Translational research is ongoing to further characterize individual tumors, identify sensitivity to (immuno)therapies and find new treatment targets to improve outcomes.

The TransPORTEC consortium previouslclassified high-risk endometrial cancer including poor-risk histologies such as clear cells, into four molecular subtypes "POLE mutated," "microsatellite unstable," "TP53 mutated," and "no specific molecular profile." We evaluated whether DNA damage response biomarkers could further refine this high-risk tumors classification, in particular the heterogeneous "no specific molecular profile" and "TP53 mutated" subsets recently qualified as poor prognosis in high-risk endometrial cancer. DNA damage response biomarkers including proteins involved in DNA damage (δ-H2AX), homologous recombination (RAD51), regulators of error-prone Non Homologous End-Joining (DNA-pk, FANCD2), and PARP-1 were evaluated in 116 high-risk tumors by immunohistochemistry. CD8 and PD-1 expression by immunochemistry and mutation analyses were performed previously. Survival outcome were calculated using Kaplan-Meier and Log-rank test. None of the DNA damage response biomarkers alone were prognostic. However markers were informative within molecular subsets. Among the "no specific molecular profile" subset, δ-H2AX+ was significantly predictive of poor disease free survival (Hazard Ratio = 2.56; p = 0.026), and among "TP53 mutated," a DNA-pk+/FANCD2- profile (favouring error-prone Non Homologous End-Joining) predicted worst disease free survival (Hazard Ratio = 4.95; p = 0.009) resulting in five distinct prognostic subgroups from best to worst prognosis: group1 "POLE mutated/Microsatellite unstable" > group2 "no specific molecular profile with no DNA damage" > group3 "TP53 mutated/Non Homologous End-Joining negative" > group4 "no specific molecular profile with high DNA damage" > group5 "TP53 mutated/Non Homologous End-Joining positive"; p = 0.0002). Actionable targets were also different among subsets. Group3 had significantly higher infiltration of PD-1+ immune cells (p = 0.003), segregating with group1. Group2 had frequent PI3K pathway mutations and ER positivity. While group5, with the worst prognosis, had high DNA damage and PARP-1 expression providing a rationale for PARP inhibition. Our findings have refined the TransPORTEC prognostic classification of high-risk endometrial cancer into five distinct subgroups by integrating DNA damage response biomarkers and identified molecular subtype-specific therapeutic strategies.

Our aim was to investigate whether molecular classification can be used to refine prognosis in grade 3 endometrial endometrioid carcinomas (EECs). Grade 3 EECs were classified into 4 subgroups: p53 abnormal, based on mutant-like immunostaining (p53abn); MMR deficient, based on loss of mismatch repair protein expression (MMRd); presence of POLE exonuclease domain hotspot mutation (POLE); no specific molecular profile (NSMP), in which none of these aberrations were present. Overall survival (OS) and recurrence-free survival (RFS) rates were compared using the Kaplan-Meier method (Log-rank test) and univariable and multivariable Cox proportional hazard models. In total, 381 patients were included. The median age was 66 years (range, 33 to 96 y). Federation Internationale de Gynecologie et d'Obstetrique stages (2009) were as follows: IA, 171 (44.9%); IB, 120 (31.5%); II, 24 (6.3%); III, 50 (13.1%); IV, 11 (2.9%). There were 49 (12.9%) POLE, 79 (20.7%) p53abn, 115 (30.2%) NSMP, and 138 (36.2%) MMRd tumors. Median follow-up of patients was 6.1 years (range, 0.2 to 17.0 y). Compared to patients with NSMP, patients with POLE mutant grade 3 EEC (OS: hazard ratio [HR], 0.36 [95% confidence interval, 0.18-0.70]; P=0.003; RFS: HR, 0.17 [0.05-0.54]; P=0.003) had a significantly better prognosis; patients with p53abn tumors had a significantly worse RFS (HR, 1.73 [1.09-2.74]; P=0.021); patients with MMRd tumors showed a trend toward better RFS. Estimated 5-year OS rates were as follows: POLE 89%, MMRd 75%, NSMP 69%, p53abn 55% (Log rank P=0.001). Five-year RFS rates were as follows: POLE 96%, MMRd 77%, NSMP 64%, p53abn 47% (P=0.000001), respectively. In a multivariable Cox model that included age and Federation Internationale de Gynecologie et d'Obstetrique stage, POLE and MMRd status remained independent prognostic factors for better RFS; p53 status was an independent prognostic factor for worse RFS. Molecular classification of grade 3 EECs reveals that these tumors are a mixture of molecular subtypes of endometrial carcinoma, rather than a homogeneous group. The addition of molecular markers identifies prognostic subgroups, with potential therapeutic implications.

Background: Although women with endometrial cancer generally have a favourable prognosis, those with high-risk disease features are at increased risk of recurrence. The PORTEC-3 trial was initiated to investigate the benefit of adjuvant chemotherapy during and after radiotherapy (chemoradiotherapy) versus pelvic radiotherapy alone for women with high-risk endometrial cancer., Methods: PORTEC-3 was an open-label, international, randomised, phase 3 trial involving 103 centres in six clinical trials collaborating in the Gynaecological Cancer Intergroup. Eligible women had high-risk endometrial cancer with FIGO 2009 stage I, endometrioid-type grade 3 with deep myometrial invasion or lymph-vascular space invasion (or both), endometrioid-type stage II or III, or stage I to III with serous or clear cell histology. Women were randomly assigned (1:1) to receive radiotherapy alone (48·6 Gy in 1·8 Gy fractions given on 5 days per week) or radiotherapy and chemotherapy (consisting of two cycles of cisplatin 50 mg/m 2 given during radiotherapy, followed by four cycles of carboplatin AUC5 and paclitaxel 175 mg/m 2 ) using a biased-coin minimisation procedure with stratification for participating centre, lymphadenectomy, stage of cancer, and histological type. The co-primary endpoints were overall survival and failure-free survival. We used the Kaplan-Meier method, log-rank test, and Cox regression analysis for final analysis by intention to treat and adjusted for stratification factors. The study was closed on Dec 20, 2013, after achieving complete accrual; follow-up is ongoing. PORTEC-3 is registered with ISRCTN, number ISRCTN14387080, and ClinicalTrials.gov, number NCT00411138., Results: 686 women were enrolled between Nov 23, 2006, and Dec 20, 2013. 660 eligible patients were included in the final analysis, of whom 330 were assigned to chemoradiotherapy and 330 were assigned to radiotherapy. Median follow-up was 60·2 months (IQR 48·1-73·1). 5-year overall survival was 81·8% (95% CI 77·5-86·2) with chemoradiotherapy versus 76·7% (72·1-81·6) with radiotherapy (adjusted hazard ratio [HR] 0·76, 95% CI 0·54-1·06; p=0·11); 5-year failure-free survival was 75·5% (95% CI 70·3-79·9) versus 68·6% (63·1-73·4; HR 0·71, 95% CI 0·53-0·95; p=0·022). Grade 3 or worse adverse events during treatment occurred in 198 (60%) of 330 who received chemoradiotherapy versus 41 (12%) of 330 patients who received radiotherapy (p<0·0001). Neuropathy (grade 2 or worse) persisted significantly more often after chemoradiotherapy than after radiotherapy (20 [8%] women vs one [1%] at 3 years; p<0·0001). Most deaths were due to endometrial cancer; in four patients (two in each group), the cause of death was uncertain. One death in the radiotherapy group was due to either disease progression or late treatment complications; three deaths (two in the chemoradiotherapy group and one in the radiotherapy group) were due to either intercurrent disease or late treatment-related toxicity., Interpretation: Adjuvant chemotherapy given during and after radiotherapy for high-risk endometrial cancer did not improve 5-year overall survival, although it did increase failure-free survival. Women with high-risk endometrial cancer should be individually counselled about this combined treatment. Continued follow-up is needed to evaluate long-term survival., Funding: Dutch Cancer Society, Cancer Research UK, National Health and Medical Research Council Project Grant and Cancer Australia, L'Agenzia Italiana del Farmaco, and Canadian Cancer Society Research Institute., (Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC-BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Purpose: Molecular classification of endometrial cancer identified distinct molecular subgroups. However, the largest subset of endometrial cancers remains poorly characterized and is referred to as the "nonspecific molecular profile" (NSMP) subgroup. Here, we aimed at refining the classification of this subgroup by profiling somatic copy-number aberrations (SCNAs). Experimental Design: SCNAs were analyzed in 141 endometrial cancers using whole-genome SNP arrays and pooled with 361 endometrial cancers from The Cancer Genome Atlas. Genomic Identification of Significant Targets in Cancer (GISTIC) identified statistically enriched SCNAs and penalized Cox regression assessed survival effects. The prognostic significance of relevant SCNAs was validated using multiplex ligation-dependent probe amplification in 840 endometrial cancers from the PORTEC-1/2 trials. Copy-number status of genes was correlated with gene expression to identify potential cancer drivers. One plausible oncogene was validated in vitro using antisense oligonucleotide-based strategy. Results: SCNAs affecting chromosome 1q32.1 significantly correlated with worse relapse-free survival (RFS) in the NSMP subgroup (HR, 2.12; 95% CI, 1.26-3.59; P = 0.005). This effect was replicated in NSMP endometrial cancers from PORTEC-1/2 (HR, 2.34; 95% CI, 1.17-4.70; P = 0.017). A new molecular classification including the 1q32.1 amplification improved risk prediction of recurrence. MDM4 gene expression strongly correlated with 1q32.1 amplification. Silencing MDM4 inhibited cell growth in cell lines carrying 1q32.1 amplification, but not in those without MDM4 amplification. Vice versa , increasing MDM4 expression in nonamplified cell lines stimulated cell proliferation. Conclusions: 1q32.1 amplification was identified as a prognostic marker for poorly characterized NSMP endometrial cancers, refining the molecular classification of this subgroup. We functionally validated MDM4 as a potential oncogenic driver in the 1q32.1 region. Clin Cancer Res; 23(23); 7232-41. ©2017 AACR ., (©2017 American Association for Cancer Research.)

Introduction: Individual prediction of tumour behaviour based on molecular markers may refine adjuvant treatment strategies in endometrial cancer (EC). As these molecular alterations are determined in a small tumour fraction, high intratumour heterogeneity may interfere with correct risk prediction. This study aimed to investigate to which extent intratumour heterogeneity exists for molecular markers and whether it affects the molecular risk assignment in EC., Methods: Forty-nine ECs (three tumour blocks/case) were selected with alterations in POLE (n=10), CTNNB1 (n=8), p53 (n=10), mismatch repair (n=11), L1CAM (n=10), and ECs without any of these markers (n=9). Nine ECs carried more than one molecular marker. All 147 blocks were analysed for POLE exonuclease domain and CTNNB1 exon 3 mutations, and for p53, mismatch repair and L1CAM protein expression. All blocks were assigned to a favourable, intermediate or unfavourable risk group, based on a molecular risk assignment., Results: Concordance between the three tumour blocks for POLE and CTNNB1 mutational status, and p53, mismatch repair and L1CAM protein expression was found in 100% (48/48), 95.9% (47/49), 93.9% (46/49), 98.0% (48/49), and 91.8% (45/49) of tumours, respectively. These discordances were found in a total of nine cases (18.4%). The intratumour heterogeneity impacted the risk assignment in five cases (10.2%)., Conclusion: Intratumour heterogeneity of prognostic molecular markers in EC without morphologic heterogeneity is uncommon among three tumour fractions, affecting the molecular risk allocation in a limited number of cases. This low intratumour heterogeneity facilitates the implementation of the molecular risk assignment, advocating its use in clinical decision making.

Ki-67, a marker of cellular proliferation, is increasingly being used in pre-surgical window studies in endometrial cancer as a primary outcome measure. Unlike in breast cancer, however, there are no guidelines standardizing its measurement and its clinical relevance as a response biomarker is undetermined. It is, therefore, imperative that Ki-67 scoring protocols are optimized and its association with patient survival rigorously evaluated, in order to be able to clinically interpret the results of these studies. Using the International Ki-67 in Breast Cancer Working Group guidelines as a basis, whole slide, hot spot and invasive edge scoring protocols were evaluated using endometrial biopsies and hysterectomy specimens from 179 women. Whole sections and tissue microarrays, manual and semi-automated scoring using Definiens Developer software were additionally compared. Ki-67 scores were related to clinicopathological variables and cancer-specific survival in uni- and multivariate analysis. Against criteria of time efficiency, intra- and inter-observer variability and consistency, semi-automated hot spot scoring was the preferred method. Ki-67 scores positively correlated with grade, stage and depth of myometrial invasion (P-values all <0.03). By univariate analysis, higher Ki-67 scores were associated with a significant reduction in cancer-specific survival (P≤0.05); however, this effect was substantially attenuated in the multivariate model. In conclusion, hot spot scoring of whole sections using Definiens is an optimal method to quantify Ki-67 in endometrial cancer window study specimens. Measured this way, it is a clinically relevant marker, though further work is required to determine whether reductions in Ki-67 in neoadjuvant intervention studies translate into improved patient outcome.

Purpose: Recommendations for adjuvant treatment for women with early-stage endometrial carcinoma are based on clinicopathologic features. Comprehensive genomic characterization defined four subgroups: p53-mutant, microsatellite instability (MSI), POLE-mutant, and no specific molecular profile (NSMP). We aimed to confirm the prognostic capacity of these subgroups in large randomized trial populations, investigate potential other prognostic classifiers, and integrate these into an integrated molecular risk assessment guiding adjuvant therapy., Experimental Design: Analysis of MSI, hotspot mutations in 14 genes including POLE, protein expression of p53, ARID1a, β-catenin, L1CAM, PTEN, ER, and PR was undertaken on 947 available early-stage endometrioid endometrial carcinomas from the PORTEC-1 and -2 trials, mostly high-intermediate risk (n = 614). Prognostic value was determined using univariable and multivariable Cox proportional hazard models. AUCs of different risk stratification models were compared., Results: Molecular analyses were feasible in >96% of the patients and confirmed the four molecular subgroups: p53-mutant (9%), MSI (26%), POLE-mutant (6%), and NSMP (59%). Integration of prognostic molecular alterations with established clinicopathologic factors resulted in a stronger model with improved risk prognostication. Approximately 15% of high-intermediate risk patients had unfavorable features (substantial lymphovascular space invasion, p53-mutant, and/or >10% L1CAM), 50% favorable features (POLE-mutant, NSMP being microsatellite stable, and CTNNB1 wild-type), and 35% intermediate features (MSI or CTNNB1-mutant)., Conclusions: Integrating clinicopathologic and molecular factors improves the risk assessment of patients with early-stage endometrial carcinoma. Assessment of this integrated risk profile is feasible in daily practice, and holds promise to reduce both overtreatment and undertreatment. Clin Cancer Res; 22(16); 4215-24. ©2016 AACR., (©2016 American Association for Cancer Research.)

Background: About 15% of patients with endometrial cancer have high-risk features and are at increased risk of distant metastases and endometrial cancer-related death. We designed the PORTEC-3 trial to investigate the benefit of adjuvant chemoradiotherapy compared with radiotherapy alone for women with high-risk endometrial cancer., Methods: PORTEC-3 was a multicentre, open-label, randomised, international trial. Women with high-risk endometrial cancer were randomly allocated (1:1) to radiotherapy alone (48·6 Gy) in 1·8 Gy fractions five times a week or chemoradiotherapy (two cycles concurrent cisplatin 50 mg/m(2) and four adjuvant cycles of carboplatin area under the curve [AUC] 5 and paclitaxel 175 mg/m(2)) using a biased coin minimisation procedure with stratification for participating centre, lymphadenectomy, stage of cancer, and histological type. The primary endpoints of the PORTEC-3 trial were overall survival and failure-free survival analysed in the intention-to-treat population. This analysis focuses on 2-year toxicity and health-related quality of life as secondary endpoints; analysis was done according to treatment received. Health-related quality of life was assessed with the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) the cervix cancer module and chemotherapy and neuropathy subscales of the ovarian cancer module at baseline, after radiotherapy and at 6, 12, 24, 36, and 60 months after randomisation. Adverse events were graded with Common Terminology Criteria for Adverse Events version 3.0. The study was closed on Dec 20, 2013, after achieving complete accrual, and follow-up remains ongoing for the primary outcomes analysis. This trial is registered with ISRCTN.com, number ISRCTN14387080, and with ClinicalTrials.gov, number NCT00411138., Findings: Between Sept 15, 2006, and Dec 20, 2013, 686 women were randomly allocated in the PORTEC-3 trial. Of these, 660 met eligibility criteria, and 570 (86%) were evaluable for health-related quality of life. Median follow-up was 42·3 months (IQR 25·8-55·1). At completion of radiotherapy and at 6 months, EORTC QLQ-C30 functioning scales were significantly lower (worse functioning) and health-related quality of life symptom scores higher (worse symptoms) for the chemoradiotherapy group compared with radiotherapy alone, improving with time. At 12 and 24 months, global health or quality of life was similar between groups, whereas physical functioning scores remained slightly lower in patients who received chemoradiotherapy compared with patients who received radiotherapy alone. At 24 months, 48 (25%) of 194 patients in the chemoradiotherapy group reported severe tingling or numbness compared with 11 (6%) of 170 patients in the radiotherapy alone group (p<0·0001). Grade 2 or worse adverse events were found during treatment in 309 (94%) of 327 patients in the chemoradiotherapy group versus 145 (44%) of 326 patients in the radiotherapy alone group, and grade 3 or worse events were found in 198 (61%) of 327 patients in the chemoradiotherapy group versus 42 (13%) of 326 patients in the radiotherapy alone group (p<0·0001), with most of the grade 3 adverse events being haematological (45%). At 12 and 24 months, no significant differences in grade 3 or worse adverse events were found between groups; only grade 2 or higher sensory neuropathy adverse events persisted at 24 months (25 [10%] of 240 patients in the chemoradiotherapy group vs one [<1%] of 247 patients in the radiotherapy alone group; p<0·0001)., Interpretation: Despite the increased physician and patient-reported toxicities, this schedule of adjuvant chemotherapy given during and after radiotherapy in patients with high-risk endometrial cancer is feasible, with rapid recovery after treatment, but with persistence of patient-reported sensory neurological symptoms in 25% of patients. We await the analysis of primary endpoints before final conclusions are made., Funding: Dutch Cancer Society, Cancer Research UK, National Health and Medical Research Council, Project Grant, Cancer Australia Grant, Italian Medicines Agency, and Canadian Cancer Society Research Institute., (Copyright © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND license. Published by Elsevier Ltd.. All rights reserved.)

JAK1 frameshift mutations may promote cancer cell immune evasion by impeding upregulation of the antigen presentation pathway in microsatellite unstable endometrial cancers (ECs). This study investigated the JAK1 mutation frequency, its functional implication in immune evasion and its prognostic significance in microsatellite unstable EC. Microsatellite instability and three microsatellite repeats within JAK1 were analyzed in 181 ECs. Sixty-two (34%) ECs showed microsatellite instability, of which 22 (35%) had a JAK1 mutation. LMP7, TAP1 and HLA class I protein expression and the presence of CD8-positive T-cells were analyzed in the microsatellite unstable ECs. JAK1 mutant microsatellite unstable ECs showed impaired upregulation of LMP7 (P=0.074) and HLA class I (P<0.001), validated using RNAseq data of the TCGA. TAP1 expression and presence of CD8-positive T-cells were not related to JAK1 mutations. In 198 additional microsatellite unstable ECs, the JAK1 mutation frequency was confirmed but no prognostic significance was found. For, JAK1 wildtype (n=135, 72%) and mutant (n=52, 28%) ECs, 10-year recurrence free rates were 84% and 77% (P=0.301). These observations show that JAK1 mutations are highly frequent in microsatellite unstable EC, not associated with survival, but are associated with impaired upregulation of LMP7 and HLA class I and may therefore facilitate immune escape., Competing Interests: The authors declare no conflict of interest.

Studies in early-stage, predominantly low- and intermediate-risk endometrial cancer have demonstrated that L1 cell adhesion molecule (L1CAM) overexpression identifies patients at increased risk of recurrence, yet its prognostic significance in high-risk endometrial cancer is unclear. To evaluate this, its frequency, and the relationship of L1CAM with the established endometrial cancer biomarker p53, we analyzed the expression of both markers by immunohistochemistry in a pilot series of 116 endometrial cancers (86 endometrioid, 30 non-endometrioid subtype) with high-risk features (such as high tumor grade and deep myometrial invasion) and correlated results with clinical outcome. We used The Cancer Genome Atlas (TCGA) endometrial cancer series to validate our findings. Using the previously reported cutoff of 10% positive staining, 51/116 (44%) tumors were classified as L1CAM-positive, with no significant association between L1CAM positivity and the rate of distant metastasis (P=0.195). However, increasing the threshold for L1CAM positivity to 50% resulted in a reduction of the frequency of L1CAM-positive tumors to 24% (28/116), and a significant association with the rate of distant metastasis (P=0.018). L1CAM expression was strongly associated with mutant p53 in the high-risk and TCGA series (P<0.001), although a substantial fraction (36% of endometrioid, 10% of non-endometrioid morphology) of p53-mutant endometrial cancers displayed <10% L1CAM positivity. Moreover, 30% of p53-wild-type non-endometrioid endometrial cancers demonstrated diffuse L1CAM staining, suggesting p53-independent mechanisms of L1CAM overexpression. In conclusion, the previously proposed threshold for L1CAM positivity of >10% does not predict prognosis in high-risk endometrial cancer, whereas an alternative threshold (>50%) does. L1CAM expression is strongly, but not universally, associated with mutant p53, and may be strong enough for clinical implementation as prognostic marker in combination with p53. The high frequency of L1CAM expression in high-risk endometrial cancers suggests that it may also be a promising therapeutic target in this tumor subset.

The first joint European Society for Medical Oncology (ESMO), European SocieTy for Radiotherapy & Oncology (ESTRO) and European Society of Gynaecological Oncology (ESGO) consensus conference on endometrial cancer was held on 11-13 December 2014 in Milan, Italy, and comprised a multidisciplinary panel of 40 leading experts in the management of endometrial cancer. Before the conference, the expert panel prepared three clinically-relevant questions about endometrial cancer relating to the following four areas: prevention and screening, surgery, adjuvant treatment and advanced and recurrent disease. All relevant scientific literature, as identified by the experts, was reviewed in advance. During the consensus conference, the panel developed recommendations for each specific question and a consensus was reached. Results of this consensus conference, together with a summary of evidence supporting each recommendation, are detailed in this article. All participants have approved this final article.

The first joint European Society for Medical Oncology (ESMO), European SocieTy for Radiotherapy & Oncology (ESTRO) and European Society of Gynaecological Oncology (ESGO) consensus conference on endometrial cancer was held on 11-13 December 2014 in Milan, Italy, and comprised a multidisciplinary panel of 40 leading experts in the management of endometrial cancer. Before the conference, the expert panel prepared three clinically-relevant questions about endometrial cancer relating to the following four areas: Prevention and screening, surgery, adjuvant treatment and advanced and recurrent disease. All relevant scientific literature, as identified by the experts, was reviewed in advance. During the consensus conference, the panel developed recommendations for each specific question and a consensus was reached. Results of this consensus conference, together with a summary of evidence supporting each recommendation, are detailed in this article. All participants have approved this final article., (Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Purpose: To evaluate the long-term health-related quality of life (HRQL) after external beam radiation therapy (EBRT) or vaginal brachytherapy (VBT) among PORTEC-2 trial patients, evaluate long-term bowel and bladder symptoms, and assess the impact of cancer on these endometrial cancer (EC) survivors., Patients and Methods: In the PORTEC-2 trial, 427 patients with stage I high-intermediate-risk EC were randomly allocated to EBRT or VBT. The 7- and 10-year HRQL questionnaires consisted of EORTC QLQ-C30; subscales for bowel and bladder symptoms; the Impact of Cancer Questionnaire; and 14 questions on comorbidities, walking aids, and incontinence pads. Analysis was done using linear mixed models for subscales and (ordinal) logistic regression with random effects for single items. A two-sided P value <.01 was considered statistically significant., Results: Longitudinal HRQL analysis showed persisting higher rates of bowel symptoms with EBRT, without significant differences in global health or any of the functioning scales. At 7 years, clinically relevant fecal leakage was reported by 10.6% in the EBRT group, versus 1.8% for VBT (P=.03), diarrhea by 8.4% versus 0.9% (P=.04), limitations due to bowel symptoms by 10.5% versus 1.8% (P=.001), and bowel urgency by 23.3% versus 6.6% (P<.001). Urinary urgency was reported by 39.3% of EBRT patients, 25.5% for VBT, P=.05. No difference in sexual activity was seen between treatment arms. Long-term impact of cancer scores was higher among the patients who had an EC recurrence or second cancer., Conclusions: More than 7 years after treatment, EBRT patients reported more bowel symptoms with impact on daily activities, and a trend for more urinary symptoms, without impact on overall quality of life or difference in cancer survivorship issues., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Lymph-vascular space invasion (LVSI) is an important adverse prognostic factor in endometrial cancer (EC). However, its role in relation to type of recurrence and adjuvant treatment is not well defined, and there is significant interobserver variation. This study aimed to quantify LVSI and correlate this to risk and type of recurrence., Methods: In the post operative radiation therapy in endometrial carcinoma (PORTEC)-trials stage I EC patients were randomised to receive external beam radiotherapy (EBRT) versus no additional treatment after surgery (PORTEC-1, n=714), or to EBRT versus vaginal brachytherapy (PORTEC-2, n=427). In tumour samples of 926 (81.2%) patients with endometrioid tumours LVSI was quantified using 2-, 3- and 4-tiered scoring systems. Cox proportional hazard models were used for time-to-event analysis., Results: Any degree of LVSI was identified in 129 cases (13.9%). Substantial LVSI (n=44, 4.8%) using the 3-tiered approach had the strongest impact on the risk of distant metastasis (hazard ratio (HR) 4.5 confidence interval (CI) 2.4-8.5). In multivariate analysis (including: age, depth of myometrial invasion, grade, treatment) substantial LVSI remained the strongest independent prognostic factor for pelvic regional recurrence (HR 6.2 CI 2.4-16), distant metastasis (HR 3.6 CI 1.9-6.8) and overall survival (HR 2.0 CI 1.3-3.1). Only EBRT (HR 0.3 CI 0.1-0.8) reduced the risk of pelvic regional recurrence., Conclusions: Substantial LVSI, in contrast to focal or no LVSI, was the strongest independent prognostic factor for pelvic regional recurrence, distant metastasis and overall survival. Therapeutic decisions should be based on the presence of substantial, not 'any' LVSI. Adjuvant EBRT and/or chemotherapy should be considered for stage I EC with substantial LVSI., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: Recent studies have shown that 7% to 12% of endometrial cancers are ultramutated due to somatic mutation in the proofreading exonuclease domain of the DNA replicase POLE. Interestingly, these tumors have an excellent prognosis. In view of the emerging data linking mutation burden, immune response, and clinical outcome in cancer, we investigated whether POLE-mutant endometrial cancers showed evidence of increased immunogenicity., Experimental Design: We examined immune infiltration and activation according to tumor POLE proofreading mutation in a molecularly defined endometrial cancer cohort including 47 POLE-mutant tumors. We sought to confirm our results by analysis of RNAseq data from the TCGA endometrial cancer series and used the same series to examine whether differences in immune infiltration could be explained by an enrichment of immunogenic neoepitopes in POLE-mutant endometrial cancers., Results: Compared with other endometrial cancers, POLE mutants displayed an enhanced cytotoxic T-cell response, evidenced by increased numbers of CD8(+) tumor-infiltrating lymphocytes and CD8A expression, enrichment for a tumor-infiltrating T-cell gene signature, and strong upregulation of the T-cell cytotoxic differentiation and effector markers T-bet, Eomes, IFNG, PRF, and granzyme B. This was accompanied by upregulation of T-cell exhaustion markers, consistent with chronic antigen exposure. In silico analysis confirmed that POLE-mutant cancers are predicted to display more antigenic neoepitopes than other endometrial cancers, providing a potential explanation for our findings., Conclusions: Ultramutated POLE proofreading-mutant endometrial cancers are characterized by a robust intratumoral T-cell response, which correlates with, and may be caused by an enrichment of antigenic neopeptides. Our study provides a plausible mechanism for the excellent prognosis of these cancers., (©2015 American Association for Cancer Research.)

This study aimed to investigate whether molecular analysis can be used to refine risk assessment, direct adjuvant therapy, and identify actionable alterations in high-risk endometrial cancer. TransPORTEC, an international consortium related to the PORTEC3 trial, was established for translational research in high-risk endometrial cancer. In this explorative study, routine molecular analyses were used to detect prognostic subgroups: p53 immunohistochemistry, microsatellite instability and POLE proofreading mutation. Furthermore, DNA was analyzed for hotspot mutations in 13 additional genes (BRAF, CDKNA2, CTNNB1, FBXW7, FGFR2, FGFR3, FOXL2, HRAS, KRAS, NRAS, PIK3CA, PPP2R1A, and PTEN) and protein expression of ER, PR, PTEN, and ARID1a was analyzed. Rates of distant metastasis, recurrence-free, and overall survival were calculated using the Kaplan-Meier method and log-rank test. In total, samples of 116 high-risk endometrial cancer patients were included: 86 endometrioid; 12 serous; and 18 clear cell. For endometrioid, serous, and clear cell cancers, 5-year recurrence-free survival rates were 68%, 27%, and 50% (P=0.014) and distant metastasis rates 23%, 64%, and 50% (P=0.001), respectively. Four prognostic subgroups were identified: (1) a group of p53-mutant tumors; (2) microsatellite instable tumors; (3) POLE proofreading-mutant tumors; and (4) a group with no specific molecular profile (NSMP). In group 3 (POLE-mutant; n=14) and group 2 (microsatellite instable; n=19) patients, no distant metastasis occurred, compared with 50% distant metastasis rate in group 1 (p53-mutant; n=36) and 39% in group 4 (NSMP; P<0.001). Five-year recurrence-free survival was 93% and 95% for group 3 (POLE-mutant) and group 2 (microsatellite instable) vs 42% (group 1, p53-mutant) and 52% (group 4, NSMP; P<0.001). Targetable FBXW7 and FGFR2 mutations (6%), alterations in the PI3K-AKT pathway (60%) and hormone receptor positivity (45%) were frequently found. In conclusion, molecular analysis of high-risk endometrial cancer identifies four distinct prognostic subgroups, with potential therapeutic implications. High frequencies of targetable alterations were identified and may serve as targets for individualized treatment.

Purpose: This study investigated the long-term probability of developing a second cancer in a large pooled cohort of patients treated with surgery with or without radiotherapy (RT)., Patients and Methods: All second cancers diagnosed in patients included in the TME, PORTEC-1, and PORTEC-2 trials were analyzed. In the TME trial, patients with rectal cancer (n = 1,530) were randomly allocated to preoperative external-beam RT (EBRT; 25 Gy in five fractions) or no RT. In the PORTEC trials, patients with endometrial cancer were randomly assigned to postoperative EBRT (46 Gy in 2-Gy fractions) versus no RT (PORTEC-1; n = 714) or EBRT versus vaginal brachytherapy (VBT; PORTEC-2; n = 427)., Results: A total of 2,554 patients were analyzed (median follow-up, 13.0 years; range 1.8 to 21.2 years). No differences were found in second cancer probability between patients who were treated without RT (10- and 15-year rates, 15.8% and 26.5%, respectively) and those treated with EBRT (10- and 15-year rates, 15.4% and 25.6%, respectively) or VBT (10-year rate, 14.9%). In the individual trials, no significant differences were found between treatment arms. All cancer survivors had a higher risk of developing a second cancer compared with an age- and sex-matched general population. The standardized incidence ratio for any second cancer was 2.98 (95% CI, 2.82 to 3.14)., Conclusion: In this pooled trial cohort of > 2,500 patients with pelvic cancers, those who underwent EBRT or VBT had no higher probability of developing a second cancer than patients who were treated with surgery alone. However, patients with rectal or endometrial cancer had an increased probability of developing a second cancer compared with the general population., (© 2014 by American Society of Clinical Oncology.)

Background and Purpose: The goals of this study were to determine the rate and risk factors of rectal bleeding (RB) after external beam radiotherapy and vaginal brachytherapy (EBRT +VB), and to compare these data to previously unreported RB rates from PORTEC-2 patients receiving EBRT or VB alone., Materials and Methods: Retrospective chart review identified 212 endometrial cancer patients receiving adjuvant EBRT+VB between 2006 and 2013. Patient-reported RB data were also obtained from PORTEC-2 patients randomized to EBRT (n=166) or VB (n=182). The two populations were compared using an RB scale of symptom severity., Results: After a median 35months, 17.9% of EBRT+VB patients (n=38) experienced any RB with 1.9% (n=4) having bleeding requiring intervention. Age ⩽70years was the only predictor of RB (OR 2.8; 95% CI 1.1-8.7; p=0.027). Rates of patient-reported RB after EBRT were similar with 15.0% (n=25) having any RB and 0.6% (n=1) having "very much" bleeding. On regression analysis, any EBRT (either EBRT alone or EBRT+VB) increased the risk of RB compared to those who received VB alone (OR 3.0; p=0.0028; 95% CI 1.4-6.7). The rates of more severe RB were low and did not significantly differ between treatments., Conclusions: Significant RB is rare after radiation. EBRT has higher rates of rectal bleeding than VB. The addition of VB to EBRT does not significantly alter bleeding rates., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: Postoperative radiation therapy for stage I endometrial cancer improves locoregional control but is without survival benefit. To facilitate treatment decision support for individual patients, accurate statistical models to predict locoregional relapse (LRR), distant relapse (DR), overall survival (OS), and disease-free survival (DFS) are required., Methods and Materials: Clinical trial data from the randomized Post Operative Radiation Therapy for Endometrial Cancer (PORTEC-1; N=714 patients) and PORTEC-2 (N=427 patients) trials and registered group (grade 3 and deep invasion, n=99) were pooled for analysis (N=1240). For most patients (86%) pathology review data were available; otherwise original pathology data were used. Trial variables which were clinically relevant and eligible according to data constraints were age, stage, given treatment (pelvic external beam radiation therapy (EBRT), vaginal brachytherapy (VBT), or no adjuvant treatment, FIGO histological grade, depth of invasion, and lymph-vascular invasion (LVSI). Multivariate analyses were based on Cox proportional hazards regression model. Predictors were selected based on a backward elimination scheme. Model results were expressed by the c-index (0.5-1.0; random to perfect prediction). Two validation sets (n=244 and 291 patients) were used., Results: Accuracy of the developed models was good, with training accuracies between 0.71 and 0.78. The nomograms validated well for DR (0.73), DFS (0.69), and OS (0.70), but validation was only fair for LRR (0.59). Ranking of variables as to their predictive power showed that age, tumor grade, and LVSI were highly predictive for all outcomes, and given treatment for LRR and DFS. The nomograms were able to significantly distinguish low- from high-probability patients for these outcomes., Conclusions: The nomograms are internally validated and able to accurately predict long-term outcome for endometrial cancer patients with observation, pelvic EBRT, or VBT after surgery. These models facilitate decision support in daily clinical practice and can be used for patient counseling and shared decision making, selecting patients who benefit most from adjuvant treatment, and generating new hypotheses., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Current risk stratification in endometrial cancer (EC) results in frequent over- and underuse of adjuvant therapy, and may be improved by novel biomarkers. We examined whether POLE proofreading mutations, recently reported in about 7% of ECs, predict prognosis., Methods: We performed targeted POLE sequencing in ECs from the PORTEC-1 and -2 trials (n = 788), and analyzed clinical outcome according to POLE status. We combined these results with those from three additional series (n = 628) by meta-analysis to generate multivariable-adjusted, pooled hazard ratios (HRs) for recurrence-free survival (RFS) and cancer-specific survival (CSS) of POLE-mutant ECs. All statistical tests were two-sided., Results: POLE mutations were detected in 48 of 788 (6.1%) ECs from PORTEC-1 and-2 and were associated with high tumor grade (P < .001). Women with POLE-mutant ECs had fewer recurrences (6.2% vs 14.1%) and EC deaths (2.3% vs 9.7%), though, in the total PORTEC cohort, differences in RFS and CSS were not statistically significant (multivariable-adjusted HR = 0.43, 95% CI = 0.13 to 1.37, P = .15; HR = 0.19, 95% CI = 0.03 to 1.44, P = .11 respectively). However, of 109 grade 3 tumors, 0 of 15 POLE-mutant ECs recurred, compared with 29 of 94 (30.9%) POLE wild-type cancers; reflected in statistically significantly greater RFS (multivariable-adjusted HR = 0.11, 95% CI = 0.001 to 0.84, P = .03). In the additional series, there were no EC-related events in any of 33 POLE-mutant ECs, resulting in a multivariable-adjusted, pooled HR of 0.33 for RFS (95% CI = 0.12 to 0.91, P = .03) and 0.26 for CSS (95% CI = 0.06 to 1.08, P = .06)., Conclusion: POLE proofreading mutations predict favorable EC prognosis, independently of other clinicopathological variables, with the greatest effect seen in high-grade tumors. This novel biomarker may help to reduce overtreatment in EC., (© The Author 2014. Published by Oxford University Press.)