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Context.—: Biomarkers in breast cancer need strict monitoring given their role in patient management., Objective.—: To study the impact that regular participation in the National Cancer Grid (NCG) external quality assurance (EQA) system has on concordance rates for biomarkers in breast carcinoma., Design.—: Tissue microarrays (TMAs) containing breast carcinomas were circulated to participating laboratories that performed immunohistochemistry for breast biomarkers. The returned TMAs were then assessed for test concordance., Results.—: A total of 105 laboratories participated in the estrogen receptor (ER) and progesterone receptor (PR) EQA system cycles, and 99 centers participated in the human epidermal growth factor 2 (HER2) EQA system. In the ER EQA in the first cycle only 1 laboratory had a 100% concordance rate, which improved to 59 of 77 (76.6%) and 85 of 97 (87.6%) in the fourth and fifth cycles, respectively. In the PR EQA the 100% pass rate jumped from zero to 52 of 76 (68.4%) in the fourth cycle and 86 of 97 (88.6%) in the last cycle. For HER2 EQA, the 100% pass rates were seen in 7 of 23 laboratories (30.4%) in the first cycle, 49 of 78 laboratories (62.8%) in the fourth cycle, and 48 of 94 laboratories (51.1%) in fifth cycle of EQA. Centers that participated in the NCG EQA system for a longer period often changed testing methodology, with consequent improvement in their laboratory concordance rates. An increasing trend for the use of automated platforms and of the US Food and Drug Administration-approved antibody for HER2 testing was observed., Conclusions.—: Our experience demonstrates that laboratory performance improves with participation in an EQA system even in less perfect settings, and this drives the placement of more proficient practices across the country., Competing Interests: The authors have no relevant financial interest in the products or companies described in this article., (© 2024 College of American Pathologists.)

Background: Neoadjuvant chemotherapy (NACT) is widely used in the treatment of triple-negative and HER2-positive breast cancer (BC), but its use in estrogen receptor (ER) and/or progesterone receptor (PR) positive/HER2-negative BC is questioned because of the low pathologic complete response (pCR) rates. This retrospective study assessed the mRNA-based MammaTyper® assay's capability of predicting pCR with NACT, and ER, PR, Ki67, and HER2 status at immunohistochemical (IHC) through transcriptomics., Methods: Diagnostic biopsies from 76 BC patients treated at the Cremona Hospital between 2012-2018 were analyzed. Relative mRNA expression levels of ERBB2, ESR1, PGR, and MKI67 were measured using the MammaTyper® kit and integrated into a pCR score. Predicting capability of pCR and standard IHC biomarkers could be assessed with ROC curves in 75 and 76 patients, respectively., Results: Overall, 68.0% patients obtained a MammaTyper® high-score and 32.0% a MammaTyper® low-score. Among high-score patients, 62.7% achieved pCR, compared to 16.7% in the low-score group (p = 0.0003). The binary MammaTyper® score showed good prediction of pCR in the overall cohort (area under curve [AUC] = 0.756) and in HR+/HER2-negative cases (AUC = 0.774). In cases with residual disease, the continuous MammaTyper® score correlated moderately with residual tumor size and decrease in tumor size. MammaTyper® showed substantial agreement with IHC for ESR1/ER and ERBB2/HER2, and moderate agreement for PGR/PR and MKI67/Ki67., Conclusion: Overall, MammaTyper® pCR score may serve as a standardized tool for predicting NACT response in HR+/HER2-negative BC, potentially guiding treatment strategies. Additionally, it could provide a more standardized and reproducible assessment of ER, PR, HER2, and Ki67 status., Competing Interests: Declaration of competing interest Francesco Schettini reports honoraria from Novartis, Gilead and Daiichy-Sankyo for educational events/materials and travel expenses from Novartis, Gilead and Daiichy-Sankyo. Daniele Generali declares personal fees for educational events by Novartis, Lilly, Pfizer, Daiichy-Sankyo, Roche; research funds from Astrazeneca, Novartis and LILT. Uğur Şahin is CEO and Mark Laible is an employee of BioNTech SE. Ralph M Wirtz is an employee of STRATIFYER Molecular Pathology GmbH. The other authors have nothing to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Invasive lobular carcinoma (ILC) accounts for 5-15% of invasive breast cancers. Typical ILC is oestrogen receptor (ER) positive and human epidermal growth factor receptor 2 (HER2) negative. Atypical biomarker profiles (ER- and HER2+, ER+ and HER2+ or triple negative) appear to differ from typical ILCs. This study compared subtypes of ILC in terms of clinical and pathological parameters, and response to neoadjuvant chemotherapy (NACT) according to biomarker profile., Methods: All patients with ILC treated in a single centre from January 2005 to December 2020 were identified from a prospectively maintained database. Clinicopathologic and outcome data was collected and analysed according to tumour biomarker profile., Results: A total of 582 patients with ILC were treated. Typical ILC was observed in 89.2% (n = 519) and atypical in 10.8% (n = 63). Atypical ILCs were of a higher grade (35% grade 3 vs 9.6% grade 3, p < 0.001). A larger proportion of atypical ILC received NACT (31.7% vs 6.9% p < 0.001). Atypical ILCs showed a greater response to NACT (mean RCB (Residual Cancer Burden Score) 2.46 vs mean RCB 3.41, p = 0.0365), and higher pathological complete response rates (15% vs 0% p = 0.017). Despite this, overall 5-year disease-free survival (DFS) was higher in patients with typical ILC (91% vs 83%, p = 0.001)., Conclusions: Atypical ILCs have distinct characteristics. They are more frequently of a higher grade and demonstrate a superior response to NACT. Despite the latter, atypical ILCs have a worse 5-year DFS which should be taken into consideration in terms of prognostication and may assist patient selection for NACT., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The aim of this population-based cohort study was to investigate the impact of neoadjuvant chemotherapy (NACT) compared to adjuvant chemotherapy in prognosis among patients with HR+/HER2 negative breast cancer., Method: This population-based study utilized data from the research database BCBaSe 3.0, based on the Swedish National Quality breast cancer register, including all patients with breast cancer diagnosis in Sweden between 2008 and 2019. Propensity score matching approach was applied. The outcomes of interest consisted of distant-disease free (DDFS), breast-cancer specific (BCSS), and overall survival (OS)., Results: In total, 14 459 patients were included in the study cohort of whom 2086 received NACT. After 1:1 propensity score matching (PSM), 1539 patients in each study group were available for analyses. No statistically significant difference in survival outcomes were observed between patients treated with NACT compared to those treated with adjuvant chemotherapy (Hazard Ratio (HR) for DDFS: 1.20; 95 % CI: 0.80-1.79; HR for BCSS: 1.16; 95 % CI: 0.54-2.49; HR for OS: 1.14; 95 % CI: 0.64-2.05)., Conclusion: In this population-based cohort study of patients with HR+/HER2-breast cancer, the use of NACT seems to be comparable to adjuvant chemotherapy in terms of prognosis, although non-inferiority cannot be proven by this study design. Until further evidence suggesting a survival benefit in favor of either treatment is available, NACT can be pursued when surgical-de-escalation is intended., Competing Interests: Declaration of competing interest The authors have no conflict of interest to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The capsule formulation of CDK4/6 inhibitor palbociclib has reduced solubility at gastric pH > 4.5 and may have decreased activity when used with proton-pump inhibitors (PPI). Herein, we report the effect of PPI on palbociclib capsule activity and safety in the PARSIFAL study., Methods: First-line endocrine-sensitive, hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) patients received palbociclib capsules plus fulvestrant or letrozole. The primary endpoint was progression-free survival (PFS). This post-hoc analysis compared PPI use. Patients were PPI-naïve (N-PPI) if not on PPI during the study, and either early (E-PPI) or long-term PPI (LT-PPI) if on PPI at study entry or for at least ≥⅔ of treatment, respectively. PPI groups were not mutually exclusive., Results: Among 486 patients, 66.9 % were N-PPI, 13.2 % E-PPI, 18.7 % LT-PPI, and 11.5 % of the PPI users were defined as neither. Median PFS (mPFS) was 29.6 months in the study population, 28.7 months in N-PPI, 23.0 months in E-PPI (Hazard Ratio [HR] 1.5; 95%Confidence Interval [CI] 1.1-2.2; p = 0.024), and 23.0 months in LT-PPI (HR 1.4; 95%CI 1.0-1.9; p = 0.035). By landmark analysis, PPI use was associated with poorer mPFS at 3 and 12 months. Grade ≥3 hematological adverse events occurred in 71.7 % of N-PPI, 57.8 % of E-PPI (p = 0.021), and 54.9 % of LT-PPI (p = 0.003). Dose reductions and dosing delays due to hematological toxicity occurred in 70.8 % of N-PPI, 56.3 % of E-PPI (p = 0.018), and 52.7 % of LT-PPI (p = 0.002)., Conclusions: PPI use may reduce palbociclib capsule toxicity, dose modifications, and clinical activity in HR+/HER2- ABC., Competing Interests: Declaration of competing interest SDC reports consulting for MEDSIR and IQVIA and honoraria from Pierre-Fabre, Novartis, and AstraZeneca. JMPG reports consulting for Roche, Eiasi, Daichii Sankyo, AstraZeneca, Gilead, MSD and Seagen and travel expenses from Roche. MB reports consulting fees from Pfizer, Novartis, Lilly, and Steamline-Menarini; honoraria from Pfizer, Novartis, and Lilly; and trave support from Pfizer. FD reports travel grants for Daichii, Novartis, and Pfizer, and participation in monitor/advisory boards for Daiichi, Seagen, Novartis, Gilead, Lilly, and MSD. MGG reports honoraria from Pfizer, Novartis, and AstraZeneca, travel grants from Lilly, Daiichi-Sankyo, and Pfizer, and participation in monitoring/advisory boards for AstraZeneca, Seagen, and Gilead. MRB reports honoraria from Pfizer, Novartis, AstraZenca, and Daiichi Sankyo. JG reports consulting fees from Novartis, Pfizer, AstraZeneca; honoraria from Novartis; and travel support from Roche and AstraZeneca. EAO reports consulting for AstraZeneca, Daichii, Gilead, MSD, and Seagen; honoraria from AstraZeneca, Daichii, Lilly, MSD, and Seagen; travel support from Daichii, Lilly, Gilead, and AstraZeneca; and participation in monitor/advisory boards for Gilead, AstraZeneca, Seagen, and Dachii. PS reports honoraria from Pfizer, AstraZeneca, Novartis, Roche, Merck, and Boehringer Ingelheim; a consulting role for Pfizer, AstraZeneca, Novartis, Roche, Merck, Boehringer Ingelheim, Bayer, Eisai, Celgene, and Puma; and institutional grants from Roche, Genentech, Oncogenex, and Novartis. FM reports grants from Roche, Novartis, AstraZeneca, GSK, MSD, Clovis, Vaccibody, Gilead Sciences, and Esai; consulting fees from AstraZeneca, GSK, and Roche; honoraria from AstraZeneca, MSD, Lilly, Pfizer, Novartis, GSK, Clovis, Myriad, Daiich Sankyo, Seagen, Pierre-Fabre, and Agendia; travel support from AstraZeneca, GSK, Pfizer, and Roche; and participation in advisory boards for Palleos and Amgen. JG reports grant/research support from Roche, Eiasi, and Exact Science; honoraria or consultation fees from AstraZeneca, Daiichi, Eisai, Exact Science, Evapharm, GE Healthcare, Gilead, Lilly, MSD, Novartis, Pfizer, Pierre Fabre, Roche, Seagen, Sothema and participation in company sponsored speaker's bureaus for Exact Science, Lilly, and Novartis. AS reports grants from Celgene, Roche, Abbvie; travel grants from Celgene, Roche, Pfizer, AstraZeneca, and honoraria from Roche, Celgene, Pfizer, AstraZeneca, Novartis, MSD, Tesaro, Lilly, Seagen, Gilead, GSK, Bayer, Amgen, Pierre Fabre. JA reports trial funding from MEDSIR and consulting for Pfizer, Lilly, and Novartis. PZ reports honoraria from Pfizer, Novartis, Roche, and Pierre Fabre; and travel support from Pfizer, Novartis, Roche, and Lilly. DW reports honoraria from Pfizer, Novartis, AstraZeneca and travel grants from Roche, and Novartis. JC reports consulting for Roche, Celgene, Cellestia, AstraZeneca, Seattle Genetics, Daiichi Sankyo, Erytech, Athenex, Polyphor, Lilly, Merck Sharp&Dohme, GSK, Leuko, Bioasis, Clovis Oncology, Boehringer Ingelheim, Ellipses, Hibercell, BioInvent, Gemoab, Gilead, Menarini, Zymeworks, Reveal Genomics, Expres2ion Biotechnologies; honoraria from Roche, Novartis, Celgene, Eisai, Pfizer, Samsung Bioepis, Lilly, Merck Sharp&Dohme, Daiichi Sankyo.; research funding to the Institution from Roche, Ariad pharmaceuticals, AstraZeneca, Baxalta GMBH/Servier Affaires, Bayer healthcare, Eisai, F. Hoffman-La Roche, Guardanth health, Merck Sharp&Dohme, Pfizer, Piqur Therapeutics, Puma C, Queen Mary University of London; stock shares for MEDSIR, Nektar Pharmaceuticals, Leuko (relative); Travel, accommodation, expenses from Roche, Novartis, Eisai, Pfizer, Daiichi Sankyo, Astrazeneca, Gilead; and Patents: Pharmaceutical Combinations of A Pi3k Inhibitor And A Microtubule Destabilizing Agent. Javier Cortés Castán, Alejandro Piris Giménez, Violeta Serra Elizalde. WO 2014/199294 A. ISSUED Her2 as a predictor of response to dual HER2 blockade in the absence of cytotoxic therapy. Aleix Prat, Antonio Llombart, Javier Cortés. US 2019/0338368 A1. LICENSED. ALC reports research support from Roche, Agendia, Lilly, Pfizer, Novartis, Merck Sharp & Dohme, Gilead, and Daichii-Sanyo; consulting for Lilly, Roche, Pfizer, and Novartis; participation in speakers' bureaus for Lilly, AstraZeneca, Merck Sharp & Dohme; travel support from Roche, Pfizer, AstraZeneca; and stock or other ownership in MEDSIR and Initia-Research. The remaining authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Hormone receptor positivity predicts benefit from endocrine therapy but the knowledge about the long-term survival of patients with different tumor receptor levels is limited. In this study, we describe the 25 years outcome of tamoxifen (TAM) treated patients., Patients and Methods: Between 1983 and 1992, a total of 4,610 postmenopausal patients with early-stage breast cancer were randomized to receive totally 2 or 5 years of TAM therapy. After 2 years, 4,124 were alive and free of breast cancer recurrence. Among these, 2,481 had demonstrated estrogen receptor positive (ER+) disease. From 1988, the Abbot enzyme immunoassay became available and provided quantitative receptor levels for 1,210 patients, for which our analyses were done., Results: After 5 years of follow-up, when all TAM treatment was finished, until 15 years of follow-up, breast cancer mortality for patients with ER+ disease was significantly reduced in the 5-year group as compared with the 2-year group (hazard ratios [HR] 0.67, 95% confidence intervals [CI] 0.55-0.83, p < 0.001). After 15 years, the difference between the groups remained but did not increase further. A substantial benefit from prolonged TAM therapy was only observed for the subgroup of patients with ER levels below the median (HR = 0.62, 95% CI 0.46-0.84, p = 0.002). Similarly, patients with progesterone receptor negative (PR-) disease did benefit from prolonged TAM treatment. For patients with progesterone receptor positive (PR+) disease, there was no statistically significant benefit from more than 2 years of TAM.  Interpretation: As compared with 2 years of adjuvant TAM, 5 years significantly prolonged breast cancer-specific survival. The benefit from prolonged TAM therapy was statistically significant for patients with ER levels below median or PR-negative disease. There was no evident benefit from prolonged TAM for patients with high ER levels or with PR+ tumors.

Importance: There are insufficient data comparing 16α-18F-fluoro-17β-estradiol (FES) positron emission tomography (PET) computed tomography (CT) with standard-of-care imaging (SOC) for staging locally advanced breast cancer (LABC) or evaluating suspected recurrence., Objective: To determine the detection rate of FES PET/CT and SOC for distant metastases in patients with estrogen receptor (ER)-positive LABC and recurrences in patients with ER-positive BC and suspected recurrence., Design, Setting, and Participants: This diagnostic study was conducted as a single-center phase 2 trial, from January 2021 to September 2023. The study design provided 80% power to find a 20% detection rate difference. Participants included patients with ER-positive LABC (cohort 1) or suspected recurrence (cohort 2). Data were analyzed from September 2023 to February 2024., Exposure: Participants underwent both SOC imaging and experimental FES PET/CT. When there were suspicious lesions on imaging, 1 was biopsied for histopathological reference standard to confirm presence (true positive) or absence (false positive) of malignant neoplasm., Main Outcomes and Measures: The outcome of interest was the detection rate of FES PET CT vs SOC for distant metastases and recurrences., Results: A total of 124 patients were accrued, with 62 in cohort 1 (median [IQR] age, 52 [32-84] years) and 62 in cohort 2 (median [IQR] age, 66 [30-93] years). In cohort 1, of 14 true-positive findings, SOC imaging detected 12 and FES detected 11 (P > .99). In cohort 2, of 23 true-positive findings, SOC detected 16 and FES detected 18 (P = .77). In 30 patients with lobular histology, of 11 true-positive findings, SOC detected 5 and FES detected 9 (P = .29). There were 6 false-positive findings on SOC and 1 false-positive finding on FES PET/CT (P = .13)., Conclusions and Relevance: In this diagnostic study with pathological findings as the reference standard, no difference was found between FES PET/CT and current SOC imaging for detecting distant metastases in patients with ER-positive LABC or recurrences in patients with ER-positive tumors and suspected recurrence. FES PET/CT could be considered for both clinical indications, which are not part of current Appropriate Use Criteria for FES PET. The findings regarding FES PET/CT in patients with lobular tumors, and for lower false positives than current SOC imaging, warrant further investigation.

Background: Direct evidence for the relationship between a large prostate (≥80 ml) and androgen receptor/PSA signal remains lacking in benign prostatic hyperplasia (BPH). Our aim is to identify whether the cause of a large prostate is related to progesterone receptor (PGR) androgen receptor (AR), oestrogen receptor α, β (ERα,β) and prostate-specific antigen (PSA)., Materials and Methods: Surgical specimens of BPH in plasmakinetic resection of the prostate (PKRP) with three groups of different prostate-sizes with mean volumes of 25.97 ml, 63.80 ml, and 122.37 ml were collected for immunohistochemical analysis of the tissue microarray with PGR, AR, PSA and ERs. Rats were castrated and treated with testosterone replacement to explore androgen and PGR, AR and ERs expression levels in the prostate. Quantitative real-time reverse transcription polymerase chain reaction (Rt-PCR) for mRNA detection of above genes was conducted., Results: Immunoblotting, Rt-PCR and immunohistochemistry assays showed that PGR, PSA, AR, ERα expression levels were positively correlated with prostate size and that ERβ expression levels were negatively correlated with prostate volume. Animal experiments have shown that prostate volume is decreased in castrated rats with decreased PGR, AR, ERα and increased ERβ expression levels., Conclusion: PGR, AR, ERs signals can be regarded as important factors for large-sized prostates in BPH patients (≥100 ml).

Background: Early invasive ductal carcinoma (IDC) breast cancer often presents with a coexisting ductal carcinoma in situ (DCIS) component, while about 5 % of cases present with an extensive (>25 %) intraductal component (EIC). The impact of EIC on the genomic risk of recurrence is unclear., Methods: Patients with early hormone receptor-positive HER2neu-negative (HR + HER2-) IDC breast cancer and a known OncotypeDX Breast Recurrence Score® (RS) who underwent breast surgery at our institute were included. Using a rule-based text-analysis algorithm, we analyzed pathological reports and categorized patients into three groups: EIC, non-extensive DCIS (DCIS-L), and pure-IDC (NO-DCIS). Genomic risk was determined using OncotypeDX RS., Results: A total of 33 (4.6 %) EIC cases, 377 (57.2 %) DCIS-L cases and 307 (42.8 %) NO-DCIS cases were identified. Patients in the EIC group were younger and had lower tumor grades than other groups. The distribution of genomic risk varied between the groups, with EIC tumors significantly less likely to have a high RS (>25) compared to DCIS-L and No-DCIS tumors (3 % vs 20 % and 20 %, respectively; p = 0.03). When adjusted to age, tumor size, grade and LNs involvement, both DCIS-L and NO-DCIS groups were significantly correlated with a higher probability of high RS compared to the EIC group (OR 12.3 and OR 13.1, respectively; p < 0.02). Moreover, patients with EIC had a lower likelihood for adjuvant chemotherapy recommendation., Conclusions: In early HR + HER2- IDC, an EIC correlates with a reduced genomic recurrence risk. The impact on genomic risk seems to be influenced by the extent, not merely the presence, of DCIS., Competing Interests: Declaration of competing interest Y.Bar reports consulting fees from Eli lilly, Roche, Stemline and Gilead and travel fees from Gilead. A.Sonnenblick reports consulting fees from Eli lilly, Teva, Pfizer, Novartis, Roche, Gilead, MSD, Astra-Zenca, Progenetics and Rhenium; Travel fees from Neopharm, Celgene, Medison, Roche and MSD and grant support from Novartis and Roche, all outside the submitted work. I.Wolf reports research grants from MSD, BMS, Roche and Novartis; S. Strulov Shachar reports consulting fees from: Pfizer, Novartis, Roche, Medison, MSD, AstraZeneca, Eli Lilly, ProGenetics, Gilead and Stemline and travel fees from Pfizer, Roche, Gilead and AstraZeneca, all outside the submitted work. The rest of the authors declare that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Most premenopausal patients with early breast cancer (eBC) are diagnosed with hormone receptor-positive disease and therefore candidate for adjuvant endocrine therapy (ET)., Patients and Methods: The Gruppo Italiano Mammella (GIM) 23-POSTER (GIM23) is a multicenter, prospective, observational study conducted in 26 Italian institutions, aiming to evaluate ET choices for premenopausal patients affected by hormone receptor-positive eBC in a real-world setting. Here we report also the results in terms of type of ET prescribed according to the definition of high-risk patients by monarchE and NATALEE trials., Results: Between October 2019 and June 2022, 600 premenopausal patients were included, with a median age of 46 years. Almost half (271, 45.2 %) of the patients had stage I disease, while 254 (42.3 %) and 60 (10.0 %) patients had stage II and III, respectively. Overall, 149 (25.1 %) patients received tamoxifen alone, 83 (14.0 %) tamoxifen with ovarian function suppression (OFS), while 361 (60.9 %) received aromatase inhibitor (AI) with OFS. Patients treated with AI and OFS had higher number of metastatic axillary nodes, higher grade and more often received chemotherapy (all p < 0.001). According to the inclusion criteria of the monarchE and NATALEE trials, 81 patients (15.6 %) were considered high-risk for the monarchE and received AI with OFS in 88.9 % of the cases, while 231 patients (44.4 %) were considered high-risk for the NATALEE trial and received AI with OFS in 74.5 % of cases., Conclusions: AI with OFS is the most prescribed adjuvant ET among premenopausal patients, especially in the presence of high-risk features., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Eva Blondeaux: speaker fee from Eli Lilly and research support from Gilead Science (to the institution). Valentina Guarneri: personal fees from EliLilly, Exact Sciences, Novartis, Pfizer, Gilead, MSD, Amgen, Sanofi, Merck Serono, and Eisai outside the submitted work. Eleonora Mioranza: personal fee from Novartis e Lilly. Fabio Puglisi: advisory role for and receiving speaker honoraria from Amgen, AstraZeneca, Daichii Sankyo, Celgene, Eisai, Eli Lilly, Exact Sciences, Gilead, Ipsen, Menarini, MSD, Novartis, Pierre Fabre, Pfizer, Roche, Seagen, Takeda, and Viatris. Travel grants from AstraZeneca, Daichii Sankyo, Novartis, Roche. Research grants (to his institution) from Astrazeneca, Eisai, Roche. Antonella Ferro: support for attending meeting from Gilead, MSD and Pfizer; honoraria from Pfizer, Novartis, Daiichi Sankyo, Ely Lilly, Seagen, Gilead, Astra Zeneca, MSD. Vincenzo Adamo: consultancy/advisory role/speaker bureau from Amgen, Astra Zeneca, BMS, Gilead, Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi, Sevier, Takeda. Laura Biganzoli: Personal financial interests (Honoraria, consultancy or advisory role): Amgen, AstraZeneca, Boehringer-Ingelheim, Daiichi-Sankyo, Eisai, Exact Sciences, Gilead, Lilly, Menarini, Novartis, Pfizer, Pierre Fabre, Roche, Sanofi, SeaGen. Institutional financial interests: Celgene, Genomic Health, Novartis. Travel grant: AstraZeneca, Daiichi-Sankyo. Evandro de Azambuja: honoraria from or participation in advisory boards for Roche, Genentech, Novartis, SeaGen, Zodiac, Libbs, Pierre Fabre, Eli Lilly, and AstraZeneca. Francesca Poggio: fees and other support from AstraZeneca and personal fees from Eli Lilly, Novartis, Daichii Sankyo, and Gilead outside the submitted work. Matteo Lambertini: advisory role for Roche, Lilly, Novartis, AstraZeneca, Pfizer, Seagen, Gilead, MSD, and Exact Sciences; receiving speaker honoraria from Roche, Lilly, Novartis, Pfizer, Sandoz, Libbs, Daiichi Sankyo, Takeda, Knight, Ipsen, and AstraZeneca; receiving travel grants from Gilead and Daiichi Sankyo; receiving research funding (to his institution) from Gilead. Lucia Del Mastro: grants from Eli Lilly, Novartis, Roche, Daiichi Sankyo, Seagen, AstraZeneca, Gilead, and Pierre Fabre; receiving consulting fees from Eli Lilly, Gilead, and Daiichi Sankyo; receiving speaker honoraria from Roche, Novartis, Pfizer, Eli Lilly, AstraZeneca, MSD, Seagen, Gilead, Pierre Fabre, Eisai, Exact Sciences, Ipsen, GSK, and Agendia-Stemline; receiving travel grants from Roche, Pfizer, Eisai, Daiichi Sankyo, and AstraZeneca; and having an advisory role for Novartis, Roche, Eli Lilly, Pfizer, Daiichi Sakyo, Exact Sciences, Gilead, Pierre Fabre, Eisai, AstraZeneca, Agendia, GSK, and Seagen. All the other authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background and Objectives: Patients with human epidermal growth factor receptor 2 (HER2) -positive, hormone receptor-positive (HR-positive) metastatic breast cancer (MBC) usually undergo trastuzumab emtansine (T-DM1) therapy in subsequent lines. Combining endocrine therapy (ET) with T-DM1 can improve treatment outcomes in this subtype. Therefore, this study aimed to investigate the benefits of using T-DM1 with ET in HER2-positive and HR-positive MBC. This study was the first to investigate the benefits of combining ET with T-DM1. Material and Methods: This study analyzed the medical records of patients with HER2-positive and HR-positive MBC who were treated with T-DM1 from June 2010 to December 2021. The patients were divided into groups based on whether they received concomitant ET with T-DM1. The primary endpoint was to determine the progression-free survival (PFS), while the secondary endpoints were overall survival (OS), objective response rate, and safety of the treatment. Results: Our analysis examined 88 patients, of whom 32 (36.4%) were treated with T-DM1 in combination with ET. The combination therapy showed a significant improvement in median PFS (15.4 vs. 6.4 months; p = 0.00004) and median OS (35.0 vs. 23.1 months; p = 0.026) compared to T-DM1 alone. The ORR was also higher in the combination group (65.6% vs. 29.3%; p = 0.026). Patients treated with pertuzumab priorly had reduced median PFS on T-DM1 compared to those who were not treated with pertuzumab (11.7 vs. 5.4 months, respectively; p < 0.01). T-DM1 demonstrated better median PFS in HER2 3+ patients compared to HER2 2+ patients, with an amplification ratio of >2.0 (10.8 vs 5.8 months, respectively; p = 0.049). The safety profiles were consistent with previous T-DM1 studies. Conclusions: The combination of T-DM1 with ET can significantly improve PFS and OS in patients with HER2-positive and HR-positive MBC. Our study suggests that prior pertuzumab treatment plus trastuzumab treatment might decrease T-DM1 efficacy.

Purpose: It remains unclear whether patients with HER2-negative, low-estrogen receptor (ER-low)-positive early breast cancer (BC) benefit from Oncotype DX® (ODX) testing., Methods: We conducted a retrospective review of cases referred for ODX testing over a seven-year period from a breast biomarker testing referral center (n = 854). For each case, we recorded the ODX Recurrence Score (RS) along with percentage of ER nuclear positivity and staining intensity on immunohistochemistry. Our criteria for ER-low was defined as ≤10% cells with nuclear positivity and/or weak intensity of staining. Slides from all ER-low cases were reviewed and the reported ODX ER gene scores were recorded. We randomly selected a comparator group of 56 patients with ER > 10% positivity and non-weak staining intensity (ER-high)., Results: We identified 27 cases (3.2%) that met our criteria for ER-low. Of these, 92.6% had a high RS (>25), and 7.4% had a RS of 25. All cases with ≤10% ER nuclear positivity had a high RS. Most ER-low cases (85.2%) had ODX quantitative ER gene scores in the negative range, whereas all (100%) ER-high cases had positive ER gene scores., Conclusion: ODX does not appear to add significant additional information to inform treatment decisions for most patients with ER-low BC. Incorporating weak ER staining intensity in addition to low percentage of nuclear positivity identifies about twice as many ER-low patients, although with reduced specificity for high RS. Our study supports the contention that most ER-low early BC should be regarded similarly to ER-negative BC., Competing Interests: Declaration of competing interest J. Loggie, P. Barnes, M. Carter, and G. Bethune do not have any conflicts of interest to declare. D. Rayson declares the following: - Honoraria for CME lectures from IPSEN, Novartis, Gilead, Astra Zeneca, Pfizer, Merck, Lilly. - Clinical Trial Funding to Institution from IPSEN, Gilead, Astra Zeneca, Novartis, Pfizer., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: This study aims to evaluate the response to and surgical benefits of neoadjuvant endocrine therapy (NET) in ER+/HER2-breast cancer patients who are clinically high risk, but genomic low risk according to the 70-gene signature (MammaPrint)., Methods: Patients with ER+/HER2-invasive breast cancer with a clinical high risk according to MINDACT, who had a genomic low risk according to the 70-gene signature and were treated with NET between 2015 and 2023 in our center, were retrospectively analyzed. RECIST 1.1 criteria were used to assess radiological response using MRI or ultrasound. Surgical specimens were evaluated to assess pathological response. Two breast cancer surgeons independently scored the eligibility of breast conserving therapy (BCS) pre- and post- NET., Results: Of 72 included patients, 23 were premenopausal (100% started with tamoxifen of which 4 also received OFS) and 49 were postmenopausal (98% started with an aromatase inhibitor). Overall, 8 (11%) showed radiological complete response. Only 1 (1.4%) patient had a pathological complete response (RCB-0) and 68 (94.4%) had a pathological partial response (RCB-1 or RCB-2). Among the 26 patients initially considered for mastectomy, 14 (53.8%) underwent successful BCS. In all 20 clinical node-positive patients, a marked axillary lymph node was removed to assess response. Four out of 20 (20%) patients had a pathological complete response of the axilla., Conclusion: The study showed that a subgroup of patients with a clinical high risk and a genomic low risk ER+/HER2-breast cancer benefits from NET resulting in BCS instead of a mastectomy. Additionally, NET may enable de-escalation in axillary treatment., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:J.P.O., C.F.J., S.A.L.B., C.E.L., J.S., M.T.F.D.V., C.A.D., F.H.D. declare no competing financial or non-financial interests. M.K. reports research funding paid to the institute from BMS, Roche and AstraZeneca and an advisory for AstraZeneca, Daiichi Sankyo, Domain Therapeutics, Alderaan, BMS, MSD and Roche., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Primary metastatic breast cancer (pMBC) accounts for 5-10% of annual breast cancers with a median survival of 3-4 years, varying among subtypes. In Denmark, the incidence of breast cancer increased until 2010, followed by a stabilisation. Several factors influencing pMBC incidence and survival, including screening prevalence, staging methods, and classification standards, remain pivotal but inadequately documented., Material and Method: This retrospective observational study involving pMBC patients diagnosed between 2000 and 2020 encompassed all Danish oncology departments. Data from the Danish Breast Cancer Group database and the National Patient Register included diagnosis specifics, demographics, treatment, and follow-up., Results: Between 2000 and 2020, 3,272 patients were diagnosed with pMBC, a rise from 355 patients in 2000-2004 to 1,323 patients in 2015-2020. The increase was particularly observed in patients aged 70 years or older. Changes in tumour subtypes were observed, notably with a rise in human epidermal growth factor receptor 2 (HER2)-positive cases but a steady distribution of estrogen receptor (ER) status. Diagnostic practices changed over the two decades, with 6% evaluated with PET/CT (positron emission tomography-computed tomography) or CT (computed tomography) with a bone evaluation in 2000-2004 and 65% in 2015-2020. Overall survival (OS) improved from 23 months in 2000-2004 to 33 months in 2015-2020. In patients with ER-positive and HER2-positive disease, the multivariable model showed improved survival by year of diagnosis, and further, patients with ER-negative/HER2-negative disease fared worse the first 2 years after diagnosis., Interpretation: Our study delineates changes in the treatment and survival of pMBC over two decades. Stage migration, screening introduction, and changes in registration practice, however, prevent a valid assessment of a possible causal relationship.

Background and Objectives : The association between endometriosis and breast cancer still remains controversial. The aim of this study was to investigate the different subtypes of breast cancer, immunohistochemical markers, hormone receptors, and ki67 proliferation indexes in patients with and without endometriosis and/or adenomyosis. Materials and Methods : All patients with endometriosis and breast cancer were enrolled. Women with endometriosis and breast cancer (Group BC+EN+) were compared to patients with breast cancer without endometriosis (group BC+EN-) and those with endometriosis without breast cancer (group BC-EN+). General population characteristics and histological and immunohistochemical subtypes of breast cancer were compared between groups. Results : Our study included 41 cases affected by both endometriosis and/or adenomyosis and breast cancer (Group BC+EN+) that were matched (1:2) with 82 patients affected only by breast cancer (group BC+EN-) and 82 patients affected only by endometriosis and/or adenomyosis (group BC-EN+). Group BC+EN+ presented a higher percentage of ER receptor expression (83% vs. 70%, p = 0.02), as well as lower values of Ki 67% (15% vs. 24%, p < 0.0001) and HER2+ (9.8% vs. 28%, p = 0.022). These findings were more evident when comparing patients with premenopausal status, while in postmenopausal patients, this difference was no longer significant. Regarding endometriosis, no statistical differences were observed in type or specific localization of the disease among the groups with and without breast cancer. Conclusions : Patients with endometriosis presented lower aggressive breast cancer rates with higher values of ER% and lower values of Ki 67 and HER2neu+. The type and severity of endometriotic diseases seemed not to influence breast cancer occurrence.

Context.—: Breast cancer with low (1%-10%) estrogen receptor (ER) expression (ER-low positive) constitutes a small portion of invasive breast cancers, and the treatment strategy for these tumors remains debatable., Objective.—: To characterize the features and outcomes of ER-low positive patients, and clarify the clinical significance of FOXC1 and SOX10 expression in ER-low positive/HER2-negative tumors., Design.—: Among 9082 patients diagnosed with primary invasive breast cancer, the clinicopathologic features of those with ER-low positive breast cancer were characterized. FOXC1 and SOX10 mRNA levels were analyzed in ER-low positive/HER2-negative cases from public data sets. The expression of FOXC1 and SOX10 in ER-low positive/HER2-negative tumors was evaluated by immunohistochemistry., Results.—: The clinicopathologic study of ER-low positive tumors indicated more aggressive characteristics compared with those tumors with ER >10%, while they had more overlapping features with ER-negative tumors irrespective of the HER2 status. The intrinsic molecular subtype of ER-low positive cases with high FOXC1 and SOX10 mRNA expression was more likely to be nonluminal. Among the ER-low positive/HER2-negative tumors, 56.67% (51 of 90) and 36.67% (33 of 90) were positive for FOXC1 and SOX10, respectively, which was significantly positively correlated with CK5/6 expression. In addition, the survival analysis demonstrated no significant difference between patients who received and who did not receive endocrine therapy., Conclusions.—: ER-low positive breast cancers biologically overlap more with ER-negative tumors. ER-low positive/HER2-negative cases demonstrate a high rate of FOXC1 or SOX10 expression, and these cases might be better categorized as a basal-like phenotype/subtype. FOXC1 and SOX10 testing may be used for the intrinsic phenotype prediction for ER-low positive/HER2-negative patients., (© 2024 College of American Pathologists.)

Purpose: The status of hormone receptors (HR) is an independent factor affecting survival and chemotherapy sensitivity in breast cancer (BC) patients, with estrogen receptor (ER) and progesterone receptor (PR) having the most significant effects. The ER-/PR + phenotype has been controversial in BC, and experts will face many challenges in determining treatment strategies. Herein, we systematically analyzed the clinicopathological characteristics of the ER-/PR + phenotype in BC patients and the response to chemotherapy., Patients and Methods: We included two cohorts. The first cohort counted the relationship between clinicopathologic data and survival outcomes for 72,666 female patients in the Surveillance, Epidemiology, and End Results (SEER) database. The second cohort analyzed the relationship between clinicopathological data and pathologic complete response (pCR) rate in 879 patients at the Harbin Medical University Cancer Hospital. The classification data were compared by the chi-square test and Fister's exact test of the Logistic regression model, and predictor variables with P < 0.05 in the univariate analysis were included in the multivariate regression analysis. The Kaplan-Meier method evaluated breast cancer-specific survival (BCSS) and overall survival (OS) to investigate the relationship between different HR typing and survival and pCR., Results: In the two cohorts, 704 (0.9%) and 11 (1.3%) patients had the ER-/PR + phenotype, respectively. The clinicopathologic features of patients with the ER-/PR + phenotype are more similar to those of the ER-/PR- phenotype. The ER-/PR + phenotype is more common in younger and premenopausal women, and most ER-/PR + phenotypes exhibit higher histological grades. Survival analysis showed that there were significant differences in OS and BCSS among patients with different HR states (P < 0.001). The survival results of patients with the ER + /PR + phenotype were the best. The prognosis of the ER-/PR + phenotype was similar to that of the ER-/PR- phenotype. On the other hand, we found that HR status was also an independent predictor of post-NAC pCR rate in BC patients. The ER + /PR- and ER-/PR- phenotypes were more sensitive to chemotherapy than the ER + /PR + phenotypes., Conclusion: HR status is the main factor affecting BC's survival outcome and pCR rate. Patients with the ER-/PR + phenotype possess more aggressive biological factors and can benefit significantly from chemotherapy. We need to pay more attention to this group and achieve individualized treatment, which will help us treat BC better and provide new targets and blueprints for our clinical treatment., (© 2023. The Author(s).)

Background: Neoadjuvant endocrine therapy (NET) in oestrogen receptor-positive (ER+) /HER2-negative (HER2-) breast cancer allows real-time evaluation of drug efficacy as well as investigation of the biological and molecular changes that occur after estrogenic deprivation. Clinical and pathological evaluation after NET may be used to obtain prognostic and predictive information of tumour response to decide adjuvant treatment. In this setting, clinical scales developed to evaluate response after neoadjuvant chemotherapy are not useful and there are not validated biomarkers to assess response to NET beyond Ki67 levels and preoperative endocrine prognostic index score (mPEPI)., Methods: In this prospective study, we extensively analysed radiological (by ultrasound scan (USS) and magnetic resonance imaging (MRI)) and pathological tumour response of 104 postmenopausal patients with ER+ /HER2- resectable breast cancer, treated with NET for a mean of 7 months prior to surgery. We defined a new score, tumour cellularity size (TCS), calculated as the product of the residual tumour cellularity in the surgical specimen and the tumour pathological size., Results: Our results show that radiological evaluation of response to NET by both USS and MRI underestimates pathological tumour size (path-TS). Tumour size [mean (range); mm] was: path-TS 20 (0-80); radiological-TS by USS 9 (0-31); by MRI: 12 (0-60). Nevertheless, they support the use of MRI over USS to clinically assess radiological tumour response (rad-TR) due to the statistically significant association of rad-TR by MRI, but not USS, with Ki67 decrease (p = 0.002 and p = 0.3, respectively) and mPEPI score (p = 0.002 and p = 0.6, respectively). In addition, we propose that TCS could become a new tool to standardize response assessment to NET given its simplicity, reproducibility and its good correlation with existing biomarkers (such as ΔKi67, p = 0.001) and potential added value., Conclusion: Our findings shed light on the dynamics of tumour response to NET, challenge the paradigm of the ability of NET to decrease surgical volume and point to the utility of the TCS to quantify the scattered tumour response usually produced by endocrine therapy. In the future, these results should be validated in independent cohorts with associated survival data., (© 2024. The Author(s).)

The use of chemotherapy in breast cancer management has significantly contributed to the decrease in its mortality. Currently, the prognosis is determined by molecular biomarkers, such as oestrogen receptors, and human epidermal growth factor receptor 2. However, the increasing use of advanced molecular technologies, including oncotype DX recurrence score (ODX-RS), has provided the ability to estimate the risk of recurrence. Research has demonstrated that the ODX-RS helps to predict recurrence risk and the potential benefit of chemotherapy in breast cancer. As a result, it can assist clinicians in making decisions regarding using the chemotherapy. The goal of work is to explore the correlation between the ODX-RS and Ki-67 proliferative index (Ki-67-PI). This study included 137 patients with oestrogen positive, human epidermal growth factor receptor 2-negative early breast cancer, and had non- or early axillary disease. Patients with low Ki-67-PI were as follows: low ODX-RS in 17%, intermediate ODX-RS in 80%, and high ODX-RS in 2%. In the high Ki-67-PI group: low ODX-RS in 12%, intermediate ODX-RS in 48%, and high ODX-RS in 40%. In conclusion, the results show no significant correlation between the ODX-RS and Ki-67-PI (r = 0.511, p-value < 0.9).

Cyclin-dependent kinases 4/6 (CDK4/6) inhibitors such as palbociclib are approved for the treatment of metastatic estrogen receptor-positive (ER+) breast cancer in combination with endocrine therapies and significantly improve outcomes in patients with this disease. However, given the large number of possible pairwise drug combinations and administration schedules, it remains unclear which clinical strategy would lead to best survival. Here, we developed a computational, cell cycle-explicit model to characterize the pharmacodynamic response to palbociclib-fulvestrant combination therapy. This pharmacodynamic model was parameterized, in a Bayesian statistical inference approach, using in vitro data from cells with wild-type estrogen receptor (WT-ER) and cells expressing the activating missense ER mutation, Y537S, which confers resistance to fulvestrant. We then incorporated pharmacokinetic models derived from clinical data into our computational modeling platform. To systematically compare dose administration schedules, we performed in silico clinical trials based on integrating our pharmacodynamic and pharmacokinetic models as well as considering clinical toxicity constraints. We found that continuous dosing of palbociclib is more effective for lowering overall tumor burden than the standard, pulsed-dose palbociclib treatment. Importantly, our mathematical modeling and statistical analysis platform provides a rational method for comparing treatment strategies in search of optimal combination dosing strategies of other cell-cycle inhibitors in ER+ breast cancer., Significance: We created a computational modeling platform to predict the effects of fulvestrant/palbocilib treatment on WT-ER and Y537S-mutant breast cancer cells, and found that continuous treatment schedules are more effective than the standard, pulsed-dose palbociclib treatment schedule., (© 2023 The Authors; Published by the American Association for Cancer Research.)

Background: The percentage of cells staining positive for Ki67 is sometimes used for decision-making in patients with early invasive breast cancer (IBC). However, there is uncertainty regarding the most appropriate Ki67 cut points and the influence of interlaboratory measurement variability. We examined the relationship between breast cancer mortality and Ki67 both before and after accounting for interlaboratory variability and 8 patient and tumor characteristics., Methods: A multicenter cohort study of women with early IBC diagnosed during 2009-2016 in more than 20 NHS hospitals in England and followed until December 31, 2020., Results: Ki67 was strongly prognostic of breast cancer mortality in 8212 women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative early IBC (Ptrend < .001). This relationship remained strong after adjustment for patient and tumor characteristics (Ptrend < .001). Standardization for interlaboratory variability did little to alter these results. For women with Ki67 scores of 0%-5%, 6%-10%, 11%-19%, and 20%-29% the corresponding 8-year adjusted cumulative breast cancer mortality risks were 3.3% (95% confidence interval [CI] = 2.8% to 4.0%), 3.7% (95% CI = 3.0% to 4.4%), 3.4% (95% CI = 2.8% to 4.1%), and 3.4% (95% CI = 2.8% to 4.1%), whereas for women with Ki67 scores of 30%-39% and 40%-100%, these risks were higher, at 5.1% (95% CI = 4.3% to 6.2%) and 7.7% (95% CI = 6.6% to 9.1) (Ptrend < .001). Similar results were obtained when the adjusted analysis was repeated with omission of pathological information about tumor size and nodal involvement, which would not be available preoperatively for patients being considered for neoadjuvant therapy., Conclusion: Our findings confirm the prognostic value of Ki67 scores of 30% or more in women with ER-positive, HER2-negative early IBC, irrespective of interlaboratory variability. These results also suggest that Ki67 may be useful to aid decision-making in the neoadjuvant setting., (© The Author(s) 2023. Published by Oxford University Press.)

Background: Cyclin-dependent kinase 4/6 inhibitor (CDK4/6) therapy plus endocrine therapy (ET) is an effective treatment for patients with hormone receptor-positive/human epidermal receptor 2-negative metastatic breast cancer (HR+/HER2- MBC); however, resistance is common and poorly understood. A comprehensive genomic and transcriptomic analysis of pretreatment and post-treatment tumors from patients receiving palbociclib plus ET was performed to delineate molecular mechanisms of drug resistance., Methods: Tissue was collected from 89 patients with HR+/HER2- MBC, including those with recurrent and/or metastatic disease, receiving palbociclib plus an aromatase inhibitor or fulvestrant at Samsung Medical Center and Seoul National University Hospital from 2017 to 2020. Tumor biopsy and blood samples obtained at pretreatment, on-treatment (6 weeks and/or 12 weeks), and post-progression underwent RNA sequencing and whole-exome sequencing. Cox regression analysis was performed to identify the clinical and genomic variables associated with progression-free survival., Results: Novel markers associated with poor prognosis, including genomic scar features caused by homologous repair deficiency (HRD), estrogen response signatures, and four prognostic clusters with distinct molecular features were identified. Tumors with TP53 mutations co-occurring with a unique HRD-high cluster responded poorly to palbociclib plus ET. Comparisons of paired pre- and post-treatment samples revealed that tumors became enriched in APOBEC mutation signatures, and many switched to aggressive molecular subtypes with estrogen-independent characteristics. We identified frequent genomic alterations upon disease progression in RB1, ESR1, PTEN, and KMT2C., Conclusions: We identified novel molecular features associated with poor prognosis and molecular mechanisms that could be targeted to overcome resistance to CKD4/6 plus ET., Trial Registration: ClinicalTrials.gov, NCT03401359. The trial was posted on 18 January 2018 and registered prospectively., (© 2023. The Author(s).)

Patients with breast cancer (BC) with low levels of human epidermal growth factor receptor 2 (HER2) expression (HER2-low) could benefit from novel antibody-drug conjugates. However, there is conflicting information regarding the characteristics of HER2-low BC and its outcome. We assessed the clinicopathologic characteristics and outcomes of HER2-low BC using real-world data from the Dutch National Pathology Registry. This retrospective study incorporated all patients with primary invasive BC, without neoadjuvant therapy, reported in the Dutch National Pathology Registry synoptic reporting module between 2014 and 2022. HER2 status was categorized as HER2-0 (defined as an immunohistochemistry score of 0 according to the current American Society of Clinical Oncology/College of American Pathologists guidelines) or HER2-low (immunohistochemistry score 1+ or 2+ without amplification). Clinicopathologic characteristics and overall survival of HER2-low BC were compared with HER2-0, adjusted for estrogen receptor (ER) status. We included 65,035 patients with BC, resulting in 69,424 tumors. The proportion of HER2-low BC was 62% in the ER+ cohort and 38% in the ER- cohort. A substantial number of patients had a different HER2 category between the needle biopsy and the corresponding surgical resection (28%) or among multiple tumors (28%). After multivariable logistic analysis, HER2-low tumors were significantly associated with histologic subtype, a higher ER, and lower progesterone receptor expression in the ER+ cohort, whereas within the ER-cohort, HER2-low tumors were associated with a lower tumor grade. However, the absolute differences were limited, and there was no significant difference in overall survival between HER2-low and HER2-0 tumors within the ER+ or ER- cohort. The classification of HER2 expression (HER2-0 vs HER2-low) varies between biopsies and corresponding resection specimens and within multiple tumors in the same patient, which could affect clinical decision making in case only HER2-low cases are eligible for novel HER2-targeting agents. The limited follow-up time and the lack of substantial clinicopathologic differences between HER2-low and HER2-0-cases could explain the lack of differences in overall survival., (Copyright © 2022 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Image analysis assistance with artificial intelligence (AI) has become one of the great promises over recent years in pathology, with many scientific studies being published each year. Nonetheless, and perhaps surprisingly, only few image AI systems are already in routine clinical use. A major reason for this is the missing validation of the robustness of many AI systems: beyond a narrow context, the large variability in digital images due to differences in preanalytical laboratory procedures, staining procedures, and scanners can be challenging for the subsequent image analysis. Resulting faulty AI analysis may bias the pathologist and contribute to incorrect diagnoses and, therefore, may lead to inappropriate therapy or prognosis. In this study, a pretrained AI assistance tool for the quantification of Ki-67, estrogen receptor (ER), and progesterone receptor (PR) in breast cancer was evaluated within a realistic study set representative of clinical routine on a total of 204 slides (72 Ki-67, 66 ER, and 66 PR slides). This represents the cohort with the largest image variance for AI tool evaluation to date, including 3 staining systems, 5 whole-slide scanners, and 1 microscope camera. These routine cases were collected without manual preselection and analyzed by 10 participant pathologists from 8 sites. Agreement rates for individual pathologists were found to be 87.6% for Ki-67 and 89.4% for ER/PR, respectively, between scoring with and without the assistance of the AI tool regarding clinical categories. Individual AI analysis results were confirmed by the majority of pathologists in 95.8% of Ki-67 cases and 93.2% of ER/PR cases. The statistical analysis provides evidence for high interobserver variance between pathologists (Krippendorff's α, 0.69) in conventional immunohistochemical quantification. Pathologist agreement increased slightly when using AI support (Krippendorff α, 0.72). Agreement rates of pathologist scores with and without AI assistance provide evidence for the reliability of immunohistochemical scoring with the support of the investigated AI tool under a large number of environmental variables that influence the quality of the diagnosed tissue images., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Importance: While low income has been associated with a higher incidence of triple-negative breast cancer, its association with 21-gene recurrence score (RS) among patients with estrogen receptor (ER)-positive breast cancer remains unclear., Objective: To evaluate the association of household income with RS and overall survival (OS) among patients with ER-positive breast cancer., Design, Setting, and Participants: This cohort study used data from the National Cancer Database. Eligible participants included women diagnosed between 2010 and 2018 with ER-positive, pT1-3N0-1aM0 breast cancer who received surgery followed by adjuvant endocrine therapy with or without chemotherapy. Data analysis was performed from July 2022 to September 2022., Exposures: Low vs high neighborhood-level household income levels defined as below vs above the median household income of $50 353 based on each patient's zip code., Main Outcomes and Measures: RS (a score ranged from 0 to 100 based on gene expression signatures indicating the risk of distant metastasis, with RS of 25 or below indicating non-high risk and RS above 25 indicating high risk) and OS., Results: Among 119 478 women (median [IQR] age, 60 [52-67] years; 4737 [4.0%] Asian and Pacific Islander, 9226 [7.7%] Black, 7245 [6.1%] Hispanic, 98 270 [82.2%] non-Hispanic White), 82 198 (68.8%) and 37 280 (31.2%) patients had high and low income, respectively. Logistic multivariable analysis (MVA) showed that, compared with high income, low income was associated with higher RS (adjusted odds ratio [aOR], 1.11; 95% CI, 1.06-1.16). Cox MVA showed that low income was also associated with worse OS (adjusted hazards ratio [aHR], 1.18; 95% CI, 1.11-1.25). Interaction term analysis showed a statistically significant interaction between income levels and RS (interaction P < .001). On subgroup analysis, significant findings were noted among those with RS below 26 (aHR, 1.21; 95% CI, 1.13-1.29), while there was no significant OS difference between income levels among others with RS of 26 or higher (aHR, 1.08; 95% CI, 0.96-1.22)., Conclusions and Relevance: Our study suggested that low household income was independently associated with higher 21-gene recurrence scores and significantly worse survival outcomes among those with scores below 26, but not 26 or higher. Further studies are warranted to investigate the association between socioeconomic determinants of health and intrinsic tumor biology among patients with breast cancer.

Background: Multigene assays, such as MammaPrint and BluePrint, provide additional information other than conventional immunohistochemistry (IHC) to help making decision of treatment. This study aims to compare the clinical correlation between molecular subtyping (MS) versus surrogate pathological subtyping (PS)., Methods: A database from patients receiving MS evaluation in Taipei Veterans General Hospital from 2013 to 2018 was reviewed retrospectively. Patients were categorized as luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) and basal type from MS results and also centrally assessed according to PS (estrogen receptor [ER], progesterone receptor [PgR], HER2, and Ki-67). The clinical correlation between two different subtyping methodologies was analyzed, and the application of chemotherapy was compared., Results: From 2013 to 2018, a total of 130 patients received MS testing in our institute, and 132 tumor samples were sent for analysis. From MammaPrint, 64 (48.5%) and 55 (41.7%) samples were defined as low and high risks, respectively. The other 13 (9.8%) tumor samples were identified as late recurrence low risk. MS restratified 44 tumors as subtype shifting including 20 tumors from A to B in intrinsic subtypes and 24 tumors from B to A after MS evaluation. Chemotherapy was conducted in only one (1.3%) patient with MS-luminal A but in 87.8% (n = 43) of MS-luminal B subtypes., Conclusion: The MS results restratify the subtypes of hormone receptor positive breast cancer and dominate decision-making of adjuvant therapy. The role of surrogate biomarkers as an alternative tool needs further elucidation. The treatment outcome in different subtypes categorized by MS or PS will be the interesting focus of research., Competing Interests: Conflicts of interest: The authors declare that they have no conflicts of interest related to the subject matter or materials discussed in this article., (Copyright © 2022, the Chinese Medical Association.)

Purpose: To assess the role of ultrasound (US) in detecting and characterizing ductal carcinoma in situ (DCIS) of the breast and to investigate the correlation between ultrasonographic and biological features of DCIS., Methods: In total, 171 patients (mean age 44; range 39-62) with 178 lesions were retrospectively evaluated by two independent radiologists searching for US mass or non-mass lesions. Immunohistochemistry analysis was performed to determine estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. The US detection rate and pattern distribution among the lesion types were evaluated. The χ 2 test was used to evaluate the correlation between the US findings and the biological factors. Statistical significance was indicated by p values < 0.05. Inter-observer agreement was calculated by Kohen's k test., Results: US detected 35% (63/178) of all lesions. Fifty-two (83%) lesions were classified as mass lesions, and 11 (17%) as non-mass lesions (p < 0.0001). Among the mass lesions, the most common shape was irregular (79%; p < 0.0001), with 45 (87%) lesions having indistinct margins. Hypoechogenicity was the most common echo pattern (49 cases, 94%; p < 0.0001). Microcalcifications were found in 23 cases (37%; p = 0.004) and were associated with mass lesions in 15 cases (65%) and with non-mass lesions in 8 cases (35%) (p = 0.21). An almost perfect inter-observer agreement (k = 0.87) was obtained between the two radiologists. A significant ER expression was found in mass lesions (83%; p < 0.0001), with no significant PR (p = 0.89) or HER2 expression (p = 0.81). Among the lesions with microcalcifications, only 7 out of 23 cases (30%) were positive for HER2 (p = 0.09)., Conclusion: DCIS represents a heterogeneous pathological process with variable US appearance (mass-like, non-mass-like, or occult). The most common US finding is represented by mass-type, hypoechogenic lesions with indistinct margins. A significant ER expression exists among mass-type lesions, while microcalcifications seem not to be associated with HER2 expression., (© 2021. Società Italiana di Ultrasonologia in Medicina e Biologia (SIUMB).)

Ductal carcinoma in situ (DCIS) often upgrade to invasive breast cancer at surgery. The current study aimed to identify factors associated with pathological underestimation and evaluate concordance rates of biomarkers between biopsy and surgery. Patients diagnosed with DCIS at needle biopsy from 2009 to 2020 were retrospectively reviewed. Univariate and multivariate analyses were performed to identify factors associated with pathological underestimation. Concordance rates between paired biopsy samples and surgical specimens were evaluated. A total of 735 patients with pure DCIS at biopsy were included, and 392 patients (53.3%) underwent pathological underestimation at surgery. Multivariate analysis demonstrated that tumor size > 5.0 cm [odds ratio (OR) 1.79], MRI BI-RADS ≥ 5 categories (OR 2.03), and high nuclear grade (OR 2.01) were significantly associated with pathological underestimation. Concordance rates of ER, PR, HER2 status and Ki-67 between biopsy and surgery were 89.6%, 91.9%, 94.8%, and 76.4% in lesions without pathological underestimation, and were 86.4%, 93.2%, 98.2% and 76.3% for in situ components in lesions with pathological underestimation. Meanwhile, in situ components and invasive components at surgery had concordance rates of 92.9%, 93.8%, 97.4%, and 86.5% for those biomarkers, respectively. In conclusion, lesions diagnosed as DCIS at biopsy have a high rate of pathological underestimation, which was associated with larger tumor size, higher MRI BI-RADS category, and higher nuclear grade. High concordances were found in terms of ER, PR, and HER2 status evaluation between biopsy and surgery, regardless of the pathological underestimation., (© 2022. The Author(s).)

Meningiomas are common intracranial tumors with a female predominance. Their etiology is still poorly documented. The role of sexual hormones has long been evoked, and data have been conflicting across studies. However, a dose-dependent relationship between the incidence and growth of meningiomas and hormonal treatment with the progestin cyproterone acetate (CPA) has recently been established. CPA-associated meningiomas seem to be mainly located in the anterior and middle skull base, are more likely to be multiple, may harbor P1K3CA mutations in up to one-third of cases, and are more common with a longer duration of treatment. A similar but lower risk of meningiomas has been recently reported with the use of chlormadinone acetate and nomegestrol acetate as progestin treatments. Concerning hormonal replacement therapy (HRT) in menopausal patients, evidence from epidemiological studies seem to favor an increased risk of meningiomas in treated patients although a recent study failed to show an increased growth of meningiomas in HRT treated vs nontreated patients. Until larger studies are available, it seems wise to recommend avoiding HRT in patients with meningiomas. Evidence from published data does not seem to support an increased risk of meningiomas with oral contraceptive oral contraceptive (OR) use. Data are too scarce to conclude on fertility treatments. Based on studies demonstrating the expression of hormonal receptors in meningiomas, therapies targeting these receptors have been tried but have failed to show an overall favorable clinical outcome in meningioma treatment., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: To determine (i) the relationship between candidate biomarkers of the antiproliferative (Ki67) response to letrozole and palbociclib alone and combined in ER + /HER2 - breast cancer; and (ii) the pharmacodynamic effect of the agents on the biomarkers., Experimental Design: 307 postmenopausal women with ER + /HER2 - primary breast cancer were randomly assigned to neoadjuvant treatment with letrozole for 14 weeks; letrozole for 2 weeks, then letrozole+palbociclib to 14 weeks; palbociclib for 2 weeks, then letrozole+palbociclib to 14 weeks; or letrozole+palbociclib for 14 weeks. Biopsies were taken at baseline, 2 and 14 weeks and surgery at varying times after stopping palbociclib. Immunohistochemical analyses were conducted for Ki67, c-PARP, ER, PgR, RB1, CCNE1, and CCND1., Results: Higher baselines ER and PgR were significantly associated with a greater chance of complete cell-cycle arrest (CCCA: Ki67 <2.7%) at 14 weeks and higher baseline Ki67, c-PARP, and CCNE1 with a lower chance. The interaction with treatment was significant only for c-PARP. CCND1 levels were decreased c.20% by letrozole at 2 and 14 weeks but showed a tendency to increase with palbociclib. CCNE1 levels fell 82% (median) in tumors showing CCCA but were unchanged in those with no CCCA. Only 2/9 tumors showed CCCA 3-9 days after stopping palbociclib. ESR1 mutations were found in 2/4 tumors for which surgery took place ≥6 months after starting treatment., Conclusions: High CCNE1 levels were confirmed as a biomarker of resistance to letrozole+palbociclib. Ki67 recovery within 3-9 days of discontinuing palbociclib indicates incomplete suppression of proliferation during the "off" week of its schedule., (©2021 The Authors; Published by the American Association for Cancer Research.)

Progression in digital pathology has yielded new opportunities for a remote work environment. We evaluated the utility of digital review of breast cancer immunohistochemical prognostic markers (IHC) using whole slide images (WSI) from formalin fixed paraffin embedded (FFPE) cytology cell block specimens (CB) using three different scanners.CB from 20 patients with breast cancer diagnosis and available IHC were included. Glass slides including 20 Hematoxylin and eosin (H&E), 20 Estrogen Receptor (ER), 20 Progesterone Receptor (PR), 16 Androgen Receptor (AR), and 20 Human Epidermal Growth Factor Receptor 2 (HER2) were scanned on 3 different scanners. Four breast pathologists reviewed the WSI and recorded their semi-quantitative scoring for each marker. Kappa concordance was defined as complete agreement between glass/digital pairs. Discordances between microscopic and digital reads were classified as a major when a clinically relevant change was seen. Minor discordances were defined as differences in scoring percentages/staining pattern that would not have resulted in a clinical implication. Scanner precision was tabulated according to the success rate of each scan on all three scanners.In total, we had 228 paired glass/digital IHC reads on all 3 scanners. There was strong concordance kappa ≥0.85 for all pathologists when comparing paired microscopic/digital reads. Strong concordance (kappa ≥0.86) was also seen when comparing reads between scanners.Twenty-three percent of the WSI required rescanning due to barcode detection failures, 14% due to tissue detection failures, and 2% due to focus issues. Scanner 1 had the best average precision of 92%. HER2 IHC had the lowest intra-scanner precision (64%) among all stains.This study is the first to address the utility of WSI in breast cancer IHC in CB and to validate its reporting using 3 different scanners. Digital images are reliable for breast IHC assessment in CB and offer similar reproducibility to microscope reads., (© 2021. The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.)

Aim: To report the Europe Ibrance Real World Insights study findings. Methods: Physicians abstracted demographic/clinical characteristics, treatment and outcomes data for women with HR+/HER2- locally advanced breast cancer (ABC) or metastatic  breast cancer (MBC) receiving palbociclib + aromatase inhibitor (AI) or palbociclib + fulvestrant. Kaplan-Meier analysis estimated progression-free rates (PFRs) and survival rates (SRs). Results: 238 physicians abstracted data for 1723 patients. For patients (>90%) initiating at 125 mg/day, dose was reduced in 18.9% of palbociclib + AI and 12.3% of palbociclib + fulvestrant patients. At 12 months, PFR for palbociclib + AI was 88.1%, and SR was 97.3%; PFR for palbociclib + fulvestrant was 79.8%, and SR was 97.5%. Conclusion: Low dose-reduction rates and favorable PFRs and SRs suggest that palbociclib + AI/fulvestrant is well tolerated and effective for HR+/HER2- ABC/MBC in real-world clinical practice.

There have been many breast cancer prognostic models proposed in the last few decades, varying in their methods of development and validation, predictors, outcomes, and patients included. Most models were developed to assess prognostic outcomes for early breast cancers. In this study, we established a simplified prognostic score to predict survival outcomes in all breast cancer patients. A total of 36,152 breast cancer patients diagnosed between 2010 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database were used as the training dataset. Multivariate analyses were performed to identify independent factors for disease-specific survival (DSS). A prognostic score was calculated by summing the point values based on the magnitude of the hazard ratio for all independent factors. The authors institutional cohort (n = 4982) was used as the validation dataset. The prognostic score model consisting of histologic grade, ER, PR, HER2, and TNM status demonstrated a similar predictive power when compared to the revised 8th AJCC Clinical Prognostic Staging system in both training and validation datasets, whereas the addition of age and race did not facilitate stratification of prognostic groups. Pairwise comparison of hazard ratios showed a significant difference in all categories when compared to their proximate groups in both prognostic schemes in the SEER database, while the prognostic score model demonstrated a slightly better discriminating power in the validation dataset. Thus, the proposed prognostic score showed at least a comparable predicting power for survival outcomes in breast cancer patients receiving standard-of-care treatment when compared to the AJCC Clinical Prognostic Stage. This prognostic model provides a convenient and alternative modality in clinical practice thus warranting further validation using larger cohorts with longer follow-up., (© 2021. The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.)

Peri-implantitis could lead to progressive bone loss and implant failure; however, the mechanism of peri-implantitis remains unclear. Based on emerging evidence, pyroptosis, a novel proinflammatory programmed death, contributes to different oral infectious diseases. In the present study, we investigated the involvement of cleaved caspase-3 and gasdermin E (GSDME) in peri-implantitis and established a pyroptosis model in vitro. By collecting and examining the inflamed biopsies around peri-implantitis, we found that the pyroptosis-related markers (caspase-3, GSDME, and IL-1β) were enhanced relative to levels in control individuals. Furthermore, human gingival epithelium cells (HGECs) induced by tumor necrosis factor-α (TNF-α) exhibited pyroptosis morphological changes (cell swelling and balloon-shaped bubbles) and upregulated expression of pyroptosis-related markers. Pretreated with Ac-DEVD-CHO (a caspase-3 inhibitor) or GSDME small interference RNA (siRNA) were found to attenuate pyroptosis in HGECs. In conclusion, our findings revealed a high expression of caspase-3 and GSDME in the inflamed biopsies of peri-implantitis and confirmed that the caspase-3/GSDME pathway mediates TNF-α-triggered pyroptosis in human gingival epithelium cells, which provides a new target for peri-implantitis treatment., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Purpose: To validate the clinical performance of the OncoMasTR Risk Score in the biomarker cohort of Austrian Breast and Colorectal Cancer Study Group (ABCSG) Trial 8., Experimental Design: We evaluated the OncoMasTR test in 1,200 formalin-fixed, paraffin-embedded (FFPE) surgical specimens from postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative primary breast cancer with 0 to 3 involved lymph nodes in the prospective, randomized ABCSG Trial 8. Time to distant recurrence (DR) was analyzed by Cox models., Results: The OncoMasTR Risk Score categorized 850 of 1,087 (78.2%) evaluable patients as "low risk". At 10 years, the DR rate for patients in the low-risk group was 5.8% versus 21.1% for patients in the high-risk group ( P < 0.0001, absolute risk reduction 15.3%). The OncoMasTR Risk Score was highly prognostic for prediction of DR in years 0 to 10 in all patients [HR 1.91, 95% confidence interval (CI) 1.62-2.26, P < 0.0001; C-index 0.73], in patients that were node negative (HR 1.79, 95% CI, 1.43-2.24, P < 0.0001; C-index 0.72), and in patients with 1 to 3 involved lymph nodes (HR 1.93, 95% CI, 1.44-2.58, P < 0.0001; C-index 0.71). The OncoMasTR Risk Score provided significant additional prognostic information beyond clinical parameters, Ki67, Nottingham Prognostic Index, and Clinical Treatment Score., Conclusions: OncoMasTR Risk Score is highly prognostic for DR in postmenopausal women with ER-positive, HER2-negative primary breast cancer with 0 to 3 involved lymph nodes. In combination with prior validation studies, this fully independent validation in ABCSG Trial 8 provides level 1B evidence for the prognostic capability of the OncoMasTR Risk Score., (©2021 American Association for Cancer Research.)

Lipedema is a painful fat disorder that affects ~11% of the female population. It is characterized by bilateral, disproportionate accumulation of subcutaneous adipose tissue predominantly in the lower body. The onset of lipedema pathophysiology is thought to occur during periods of hormonal fluctuation, such as puberty, pregnancy, or menopause. Although the identification and characterization of lipedema have improved, the underlying disease etiology remains to be elucidated. Estrogen, a key regulator of adipocyte lipid and glucose metabolism, and female-associated body fat distribution are postulated to play a contributory role in the pathophysiology of lipedema. Dysregulation of adipose tissue accumulation via estrogen signaling likely occurs by two mechanisms: (1). altered adipocyte estrogen receptor distribution (ERα/ERß ratio) and subsequent metabolic signaling and/or (2). increased release of adipocyte-produced steroidogenic enzymes leading to increased paracrine estrogen release. These alterations could result in increased activation of peroxisome proliferator-activated receptor γ (PPARγ), free fatty acid entry into adipocytes, glucose uptake, and angiogenesis while decreasing lipolysis, mitochondriogenesis, and mitochondrial function. Together, these metabolic alterations would lead to increased adipogenesis and adipocyte lipid deposition, resulting in increased adipose depot mass. This review summarizes research characterizing estrogen-mediated adipose tissue metabolism and its possible relation to excessive adipose tissue accumulation associated with lipedema.

Background: Breast cancer is a heterogeneous disease, divided into subtypes based on the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Subtypes have different biology and prognosis, with accumulating evidence of different risk factors. The purpose of this study was to compare breast cancer risk factors across tumor subtypes in a large, diverse mammography population., Methods: Women aged 40-84 without a history of breast cancer with a screening mammogram at three United States health systems from 2006 to 2015 were included. Risk factor questionnaires were completed at mammogram visit, supplemented by electronic health records. Invasive tumor subtype was defined by immunohistochemistry as ER/PR+HER2-, ER/PR+HER2+, ER, and PR-HER2+, or triple-negative breast cancer (TNBC). Cox proportional hazards models were run for each subtype. Associations of race, reproductive history, prior breast problems, family history, breast density, and body mass index (BMI) were assessed. The association of tumor subtypes with screen detection and interval cancer was assessed using logistic regression among invasive cases., Results: The study population included 198,278 women with a median of 6.5 years of follow-up (IQR 4.2-9.0 years). There were 4002 invasive cancers, including 3077 (77%) ER/PR+HER2-, 300 (8%) TNBC, 342 (9%) ER/PR+HER2+, and 126 (3%) ER/PR-HER2+ subtype. In multivariate models, Black women had 2.7 times higher risk of TNBC than white women (HR = 2.67, 95% CI 1.99-3.58). Breast density was associated with increased risk of all subtypes. BMI was more strongly associated with ER/PR+HER2- and HER2+ subtypes among postmenopausal women than premenopausal women. Breast density was more strongly associated with ER/PR+HER2- and TNBC among premenopausal than postmenopausal women. TNBC was more likely to be interval cancer than other subtypes., Conclusions: These results have implications for risk assessment and understanding of the etiology of breast cancer subtypes. More research is needed to determine what factors explain the higher risk of TNBC for Black women., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: Cyclin-dependent kinase 4 (CDK4) and CDK6 inhibitors (CDK4/6i) are highly effective against estrogen receptor-positive (ER + )/HER2 - breast cancer; however, intrinsic and acquired resistance is common. Elucidating the molecular features of sensitivity and resistance to CDK4/6i may lead to identification of predictive biomarkers and novel therapeutic targets, paving the way toward improving patient outcomes., Experimental Design: Parental breast cancer cells and their endocrine-resistant derivatives (EndoR) were used. Derivatives with acquired resistance to palbociclib (PalboR) were generated from parental and estrogen deprivation-resistant MCF7 and T47D cells. Transcriptomic and proteomic analyses were performed in palbociclib-sensitive and PalboR lines. Gene expression data from CDK4/6i neoadjuvant trials and publicly available datasets were interrogated for correlations of gene signatures and patient outcomes., Results: Parental and EndoR breast cancer lines showed varying degrees of sensitivity to palbociclib. Transcriptomic analysis of these cell lines identified an association between high IFN signaling and reduced CDK4/6i sensitivity; thus an "IFN-related palbociclib-resistance Signature" (IRPS) was derived. In two neoadjuvant trials of CDK4/6i plus endocrine therapy, IRPS and other IFN-related signatures were highly enriched in patients with tumors exhibiting intrinsic resistance to CDK4/6i. PalboR derivatives displayed dramatic activation of IFN/STAT1 signaling compared with their short-term treated or untreated counterparts. In primary ER + /HER2 - tumors, the IRPS score was significantly higher in lumB than lumA subtype and correlated with increased gene expression of immune checkpoints, endocrine resistance, and poor prognosis., Conclusions: Aberrant IFN signaling is associated with intrinsic resistance to CDK4/6i. Experimentally, acquired resistance to palbociclib is associated with activation of the IFN pathway, warranting additional studies to clarify its involvement in resistance to CDK4/6i., (©2021 American Association for Cancer Research.)

Context: Suboptimal endometrial thickening is associated with lower pregnancy rates and occurs in some infertile women treated with clomiphene., Objective: To examine cellular and molecular differences in the endometrium of women with suboptimal vs optimal endometrial thickening following clomiphene., Methods: Translational prospective cohort study from 2018 to 2020 at a university-affiliated clinic. Reproductive age women with unexplained infertility treated with 100 mg of clomiphene on cycle days 3 to 7 who developed optimal (≥8mm; n = 6, controls) or suboptimal (<6mm; n = 7, subjects) endometrial thickness underwent preovulatory blood and endometrial sampling. The main outcome measures were endometrial tissue architecture, abundance and location of specific proteins, RNA expression, and estrogen receptor (ER) α binding., Results: The endometrium of suboptimal subjects compared with optimal controls was characterized by a reduced volume of glandular epithelium (16% vs 24%, P = .01), decreased immunostaining of markers of proliferation (PCNA, ki67) and angiogenesis (PECAM-1), increased immunostaining of pan-leukocyte marker CD45 and ERβ, but decreased ERα immunostaining (all P < .05). RNA-seq identified 398 differentially expressed genes between groups. Pathway analysis of differentially expressed genes indicated reduced proliferation (Z-score = -2.2, P < .01), decreased angiogenesis (Z-score = -2.87, P < .001), increased inflammation (Z-score = +2.2, P < .01), and ERβ activation (Z-score = +1.6, P < .001) in suboptimal subjects. ChIP-seq identified 6 genes bound by ERα that were differentially expressed between groups (P < .01), some of which may play a role in implantation., Conclusion: Women with suboptimal endometrial thickness after clomiphene exhibit aberrant ER expression patterns, architectural changes, and altered gene and protein expression suggesting reduced proliferation and angiogenesis in the setting of increased inflammation., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Context.—: Invasive micropapillary carcinoma (IMPC) is a rare variant of breast carcinoma, composed of avascular morula-like tumor clusters surrounded by stromal spaces, which can affect the HER2 immunohistochemical (IHC) staining pattern. The 2013 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 testing guideline suggests moderate to intense but incomplete (basolateral) staining be considered equivocal., Objectives.—: To perform a detailed assessment of HER2 IHC staining patterns in IMPC., Design.—: Hematoxylin-eosin and HER2 IHC slides were retrospectively reviewed to assess the morphology and HER2 IHC characteristics of IMPC. The 2018 ASCO/CAP guideline was applied., Results.—: The cohort consisted of 187 IMPCs from 181 patients with median age of 58 years. Homogeneous (≥90%) micropapillary component was found in 40% (75 of 187) of cases. Receptor profile was as follows: 75% (140 of 187) ER+ HER2-, 19% (37 of 187) ER+ HER2+, 4% (7 of 187) ER- HER2+, and 2% (3 of 187) ER- HER2-. Of 26 cases with HER2 IHC 3+, 65% (17 of 26) showed a basolateral staining pattern with strong intensity. HER2 fluorescence in situ hybridization (FISH) showed amplification in 26% (17 of 66) of HER2 IHC equivocal cases: 76% (13 of 17) showed basolateral staining pattern and 24% (4 of 17) complete staining, with weak to moderate (2), moderate (14), or moderate to strong (1) intensity., Conclusions.—: The most frequent staining pattern was basolateral, seen in 49% of cases, including 65% HER2 IHC positive and 76% HER2 IHC equivocal/FISH amplified. If a basolateral pattern and weak to moderate staining is observed in IMPC, alternative testing should be performed to confirm the HER2 status., Competing Interests: The authors have no relevant financial interest in the products or companies described in this article.

Purpose: FGFR1 overexpression has been associated with endocrine resistance in ER + breast cancer. We found FGFR1 localized in the nucleus of breast cancer cells in primary tumors resistant to estrogen suppression. We investigated a role of nuclear FGFR1 on gene transcription and antiestrogen resistance., Experimental Design: Tumors from patients treated with letrozole were subjected to Ki67 and FGFR1 IHC. MCF7 cells were transduced with FGFR1(SP-)(NLS) to promote nuclear FGFR1 overexpression. FGFR1 genomic activity in ER + / FGFR1 -amplified breast cancer cells ± FOXA1 siRNA or ± the FGFR tyrosine kinase inhibitor (TKI) erdafitinib was examined by chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq). The nuclear and chromatin-bound FGFR1 interactome was investigated by mass spectrometry (MS)., Results: High nuclear FGFR1 expression in ER + primary tumors positively correlated with post-letrozole Ki67 values. Nuclear FGFR1 overexpression influenced gene transcription and promoted resistance to estrogen suppression and to fulvestrant in vivo . A gene expression signature induced by nuclear FGFR1 correlated with shorter survival in the METABRIC cohort of patients treated with antiestrogens. ChIP-Seq revealed FGFR1 occupancy at transcription start sites, overlapping with active transcription histone marks. MS analysis of the nuclear FGFR1 interactome identified phosphorylated RNA-Polymerase II and FOXA1, with FOXA1 RNAi impairing FGFR1 recruitment to chromatin. Treatment with erdafitinib did not impair nuclear FGFR1 translocation and genomic activity., Conclusions: These data suggest nuclear FGFR1 contributes to endocrine resistance by modulating gene transcription in ER + breast cancer. Nuclear FGFR1 activity was unaffected by FGFR TKIs, thus supporting the development of treatment strategies to inhibit nuclear FGFR1 in ER+/FGFR1 overexpressing breast cancer., (©2021 The Authors; Published by the American Association for Cancer Research.)

Aromatase inhibitors (AIs) are a key component in the chemoprevention and treatment of hormone receptor-positive (HR+) breast cancer. While the addition of AI therapy has improved cancer-related outcomes in the management of HR+ breast cancer, AIs are associated with musculoskeletal adverse effects known as the aromatase inhibitor-associated musculoskeletal syndrome (AIMSS) that limit its tolerability and use. AIMSS is mainly comprised of AI-associated bone loss and arthralgias that affect up to half of women on AI therapy and detrimentally impact patient quality of life and treatment adherence. The pathophysiology of AIMSS is not fully understood though has been proposed to be related to estrogen deprivation within the musculoskeletal and nervous systems. This review aims to characterize the prevalence, risk factors, and clinical features of AIMSS, and explore the syndrome's underlying mechanisms and management strategies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Hyder, Marino, Ahmad, Nasrazadani and Brufsky.)

Background: We investigated the association between reproductive risk factors and breast cancer subtype in Black women. On the basis of the previous literature, we hypothesized that the relative prevalence of specific breast cancer subtypes might differ according to reproductive factors., Methods: We conducted a pooled analysis of 2,188 (591 premenopausal, 1,597 postmenopausal) Black women with a primary diagnosis of breast cancer from four studies in the southeastern United States. Breast cancers were classified by clinical subtype. Case-only polytomous logistic regression models were used to estimate ORs and 95% confidence intervals (CI) for HER2 + and triple-negative breast cancer (TNBC) status in relation to estrogen receptor-positive (ER + )/HER2 - status (referent) for reproductive risk factors., Results: Relative to women who had ER + /HER2 - tumors, women who were age 19-24 years at first birth (OR, 1.78; 95% CI, 1.22-2.59) were more likely to have TNBC. Parous women were less likely to be diagnosed with HER2 + breast cancer and more likely to be diagnosed with TNBC relative to ER + /HER2 - breast cancer. Postmenopausal parous women who breastfed were less likely to have TNBC [OR, 0.65 (95% CI, 0.43-0.99)]., Conclusions: This large pooled study of Black women with breast cancer revealed etiologic heterogeneity among breast cancer subtypes., Impact: Black parous women who do not breastfeed are more likely to be diagnosed with TNBC, which has a worse prognosis, than with ER + /HER2 - breast cancer., (©2021 American Association for Cancer Research.)

Purpose: YoungPEARL (KCSG-BR15-10) trial demonstrated a significant progression-free survival (PFS) benefit for premenopausal patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC) for palbociclib plus exemestane with ovarian function suppression compared to capecitabine. However, the number of tamoxifen-sensitive premenopausal patients was small because most recurrences occurred early during adjuvant endocrine therapy (ET), with tamoxifen being the only drug used; hence, the data for these patients were limited. Here we present a subgroup analysis according to tamoxifen sensitivity from the YoungPEARL study., Materials and Methods: Patients were randomized 1:1 to receive palbociclib+ET (oral exemestane 25 mg/day for 28 days, palbociclib 125 mg/day for 21 days, plus leuprolide 3.75 mg subcutaneously every 4 weeks) or chemotherapy (oral capecitabine 1,250 mg/m2 twice daily for 14 days every 3 weeks). Tamoxifen resistance was defined as: relapse while on adjuvant tamoxifen, relapse within 12 months of completing adjuvant tamoxifen, or progression while on first-line tamoxifen within 6 months for MBC., Results: In total, 184 patients were randomized and 178 were included in the modified intention-to-treat population. PFS improvement in the palbociclib+ET group was observed in tamoxifen-sensitive patients (hazard ratio, 0.38; 95% confidence interval, 0.12 to 1.19). Furthermore, palbociclib+ET prolonged median PFS compared with capecitabine in tamoxifen-sensitive (20.5 months vs. 12.6 months) and tamoxifen-resistant (20.1 months vs. 14.5 months) patients. Palbociclib+ET demonstrated a higher rate of objective response, disease control, and clinical benefit in tamoxifen-sensitive patients., Conclusion: This post hoc exploratory analysis suggests that palbociclib+ET is a promising therapeutic option for premenopausal HR+/HER2- MBC patients irrespective of tamoxifen sensitivity.

Context.—: Breast cancer biomarker assessment is critical in determining treatment and prognosis. In Tanzania, immunohistochemistry (IHC) is limited to surgical specimens and core biopsies. However, performing IHC on fine-needle aspiration biopsy cell blocks would offer numerous advantages., Objective.—: To compare the performance between estrogen receptor (ER) IHC performed at Muhimbili National Hospital (MNH) in Tanzania and ER IHC performed at University of California, San Francisco (UCSF), to demonstrate feasibility of performing IHC using cell blocks in Tanzania., Design.—: Patients with breast masses were recruited prospectively from the fine-needle aspiration biopsy clinic at MNH. Estrogen receptor IHC results on cell blocks, performed at both MNH and UCSF, and corresponding tissue blocks, performed at MNH, were compared to determine concordance., Results.—: Eighty-six cell blocks were evaluated by ER IHC at MNH, with 41 of 86 (47.7%) positive and 45 of 86 (52.3%) negative. Among 65 UCSF and MNH cell block pairs, overall ER IHC concordance was 93.8% (61 of 65) and positive concordance was 93.5% (29 of 31) (κ = 0.88, P > .99). Among 43 paired UCSF cell blocks and MNH tissue blocks, overall ER IHC concordance was 88.3% (38 of 43) and positive concordance was 90.5% (19 of 21) (κ = 0.77, P > .99). We compared 62 MNH cell block and tissue block pairs. Overall ER IHC concordance was 90.3% and positive concordance was 87.9% (κ = 0.81, P = .69)., Conclusions.—: Pairwise comparisons between ER IHC at MNH, on cell blocks and tissue blocks, with ER IHC at UCSF on cell blocks showed excellent concordance. We demonstrate that ER IHC on fine-needle aspiration biopsy specimens can be implemented in resource-constrained settings.

Importance: Clinically used breast cancer markers, such as tumor size, tumor grade, progesterone receptor (PR) status, and Ki-67 status, are known to be associated with short-term survival, but the association of these markers with long-term (25-year) survival is unclear., Objective: To assess the association of clinically used breast cancer markers with long-term survival and treatment benefit among postmenopausal women with lymph node-negative, estrogen receptor [ER]-positive and ERBB2-negative breast cancer who received tamoxifen therapy., Design, Setting, and Participants: This study was a secondary analysis of data from a subset of 565 women with ER-positive/ERBB2-negative breast cancer who participated in the Stockholm tamoxifen (STO-3) randomized clinical trial. The STO-3 clinical trial was conducted from 1976 to 1990 and comprised 1780 postmenopausal women with lymph node-negative breast cancer who were randomized to receive adjuvant tamoxifen therapy or no endocrine therapy. Complete 25-year follow-up data through December 31, 2016, were obtained from Swedish national registers. Immunohistochemical markers were reannotated in 2014. Data were analyzed from April to December 2020., Interventions: Patients in the original STO-3 clinical trial were randomized to receive 2 years of tamoxifen therapy vs no endocrine therapy. In 1983, patients who received tamoxifen therapy without cancer recurrence during the 2-year treatment and who consented to continued participation in the STO-3 study were further randomized to receive 3 additional years of tamoxifen therapy or no endocrine therapy., Main Outcomes and Measures: Distant recurrence-free interval (DRFI) by clinically used breast cancer markers was assessed using Kaplan-Meier and multivariable Cox proportional hazards analyses adjusted for age, period of primary diagnosis, tumor size (T1a and T1b [T1a/b], T1c, and T2), tumor grade (1-3), PR status (positive vs negative), Ki-67 status (low vs medium to high), and STO-3 clinical trial arm (tamoxifen treatment vs no adjuvant treatment). A recursive partitioning analysis was performed to evaluate which markers were able to best estimate long-term DRFI., Results: The study population comprised 565 postmenopausal women (mean [SD] age, 62.0 [5.3] years) with lymph node-negative, ER-positive/ERBB2-negative breast cancer. A statistically significant difference in long-term DRFI was observed by tumor size (88% for T1a/b vs 76% for T1c vs 63% for T2 tumors; log-rank P < .001) and tumor grade (81% for grade 1 vs 77% for grade 2 vs 65% for grade 3 tumors; log-rank P = .02) but not by PR status or Ki-67 status. Patients with smaller tumors (hazard ratio [HR], 0.31 [95% CI, 0.17-0.55] for T1a/b tumors and 0.58 [95% CI, 0.38-0.88] for T1c tumors) and grade 1 tumors (HR, 0.48; 95% CI, 0.24-0.95) experienced a significant reduction in the long-term risk of distant recurrence compared with patients with larger (T2) tumors and grade 3 tumors, respectively. A significant tamoxifen treatment benefit was observed among patients with larger tumors (HR, 0.53 [95% CI, 0.32-0.89] for T1c tumors and 0.34 [95% CI, 0.16-0.73] for T2 tumors), lower tumor grades (HR, 0.24 [95% CI, 0.07-0.82] for grade 1 tumors and 0.50 [95% CI, 0.31-0.80] for grade 2 tumors), and PR-positive status (HR, 0.38; 95% CI, 0.24-0.62). The recursive partitioning analysis revealed that tumor size was the most important characteristic associated with long-term survival, followed by clinical trial arm among patients with larger tumors., Conclusions and Relevance: This secondary analysis of data from the STO-3 clinical trial indicated that, among the selected subgroup of patients, tumor size followed by tumor grade were the markers most significantly associated with long-term survival. Furthermore, a significant long-term tamoxifen treatment benefit was observed among patients with larger tumors, lower tumor grades, and PR-positive tumors.

Numerous factors influence breast cancer (BC) prognosis, thus complicating the prediction of outcome. By identifying biomarkers that would distinguish the cases with poorer response to therapy already at the time of diagnosis, the rate of survival could be improved. Lately, Piwi-interacting RNAs (piRNAs) have been introduced as potential cancer biomarkers, however, due to the recently raised challenges in piRNA annotations, further evaluation of piRNAs' involvement in cancer is required. We performed small RNA sequencing in 227 fresh-frozen breast tissue samples from the Eastern Finnish Kuopio Breast Cancer Project material to study the presence of piRNAs in BC and their associations with the clinicopathological features and outcome of BC patients. We observed the presence of three small RNAs annotated as piRNA database entries (DQ596932, DQ570994, and DQ571955) in our samples. The actual species of these RNAs however remain uncertain. All three small RNAs were upregulated in grade III tumors and DQ596932 additionally in estrogen receptor negative tumors. Furthermore, patients with estrogen receptor positive BC and higher DQ571955 had shorter relapse-free survival and poorer BC-specific survival, thus indicating DQ571955 as a candidate predictive marker for radiotherapy response in estrogen receptor positive BC. DQ596932 showed possible prognostic value in BC, whereas DQ570994 was identified as a candidate predictive marker for tamoxifen and chemotherapy response. These three small RNAs appear as candidate biomarkers for BC, which could after further investigation provide novel approaches for the treatment of therapy resistant BC. Overall, our results indicate that the prevalence of piRNAs in cancer is most likely not as comprehensive as has been previously thought., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: In estrogen receptor (ER)-positive breast cancer (BC), young age is associated with poor prognosis. While very young patients respond better to chemotherapy, chemotherapy is less effective in ER-positive tumors than in ER-negative tumors. The authors tried to evaluate chemotherapy response of very young patients with ER-positive BC by pathologic complete response (pCR) after neoadjuvant chemotherapy excluding the effect of endocrine treatment to the extent possible., Methods: We collected individual patient data from 1992 to 2013 from the Korean Breast Cancer Society (KBCS). Total 1048 ER-positive and 797 ER-negative patients aged < 50 years who had been treated with neoadjuvant chemotherapy were included for analysis. We compared pCR rate between patients aged < 35 years with ER-positive tumors and the other groups., Results: The proportion of patients aged < 35 years was 14.0% of patients with ER-positive BC in this cohort of under 50 years old, and 16.8% of patients with ER-negative BC in this cohort of under 50 years old. Although most characteristics of tumors according to age were comparable, tumors with high Ki-67 expression were more common in patients aged < 35 years than in patients aged 35-49 years in both ER-positive and -negative group (P = 0.001). Breast conservation rates were not significantly different according to age (44.2% vs. 46.8% in ER-positive group, 55.2% vs. 48.0% in ER-negative group). pCR rate was not different according to age in ER-positive group (P = 0.71) but significantly better in patients aged < 35 years in ER-negative group (P = 0.009). After adjusting for confounding variables, young patients maintained the higher probability of pCR than older patients in ER-negative tumors. However, pCR rate did not differ according to age in ER-positive tumors. In multivariate analysis, young age (< 35 years) was correlated with poor overall survival (P = 0.003, HR = 1.98) and there was only one event in a few patients achieved pCR in ER-positive group., Conclusions: Chemotherapy response based on pCR was not better in young patients (< 35 years) with ER-positive BC than in older premenopausal patients with non-metastatic ER-positive BC. Young age cannot be a predictive factor of response to neoadjuvant chemotherapy in ER-positive BC. Different biological characteristics such as high proliferative index should be considered., Trial Registration: Retrospectively registered.