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Glioblastoma is a clinically and molecularly heterogeneous disease, and new predictive biomarkers are needed to identify those patients most likely to respond to specific treatments. Through prospective genomic profiling of 459 consecutive primary treatment-naïve IDH-wildtype glioblastomas in adults, we identified a unique subgroup (2%, 9/459) defined by somatic hypermutation and DNA replication repair deficiency due to biallelic inactivation of a canonical mismatch repair gene. The deleterious mutations in mismatch repair genes were often present in the germline in the heterozygous state with somatic inactivation of the remaining allele, consistent with glioblastomas arising due to underlying Lynch syndrome. A subset of tumors had accompanying proofreading domain mutations in the DNA polymerase POLE and resultant "ultrahypermutation". The median age at diagnosis was 50 years (range 27-78), compared with 63 years for the other 450 patients with conventional glioblastoma (p

Background: Lynch syndrome represents the most common hereditary cause of both colorectal and endometrial cancer. It is caused by defects in mismatch repair genes, as well as EPCAM. Universal screening of colon tumors for Lynch syndrome via microsatellite instability (MSI) and/or immunohistochemistry (IHC) can identify patients and families at risk to develop further cancers and potentially impact surveillance and treatment options. The approach to implementation of universal screening, taking ethical considerations into account, is critical to its effectiveness, with patient perspectives providing valuable insight. Methods: Patients whose colon tumors underwent universal screening at Penn State Hershey Medical Center over a period of 2.5 years were mailed a survey on universal screening in 2017. Along with the survey, they received a recruitment letter and a summary explanation of research. The survey included both multiple choice and free-response questions that covered topics including respondent knowledge of Lynch syndrome, attitudes toward universal screening and experiences with the screening protocol as implemented. Results: Sixty-six of 297 possible patients (22.2%) responded to the survey, including 13 whose screening results raised concern for Lynch syndrome. 75.8% of respondents supported universal tumor screening without informed consent. 92.4% preferred receiving screening results regardless of outcome. Respondents described benefits to screening for themselves and their families. Conclusions: While broadly supporting universal tumor screening without informed consent, respondents also wanted more information shared about the screening policy, as well as their results. These patient preferences should be one of many factors considered when implementing universal screening and can also inform practices regarding both tumor profiling and universal genetic testing, which is becoming more prevalent. [ABSTRACT FROM AUTHOR]

Pembrolizumab and other immunotherapies have become central in treating metastatic colon cancer, particularly effective in patients with mismatch repair deficiencies. We report a case involving a man who initially underwent radical surgery for sigmoid colon cancer on April 27, 2011, followed by hepatic tumor resection on September 21, 2017. Post-surgery, he received eight cycles of adjuvant chemotherapy with the CAPEOX regimen and was regularly monitored through CT and MRI scans. On August 24, 2022, liver metastases were detected, and he was diagnosed with Lynch syndrome (LS) due to germline mutation in the MSH2 and EPCAM genes. He commenced treatment with 200mg of pembrolizumab intravenously every three weeks on September 2, 2022, and demonstrated a sustained response. However, after 17 cycles, he developed a treatment related adverse event (TRAE) of pancreatic endocrine dysfunction, leading to type 1 diabetes, managed with subcutaneous insulin injections. After 30 cycles of treatment, no evidence of disease was observed. This case underscores the significant clinical benefits of first-line pembrolizumab in managing hepatic metastasis in colonic carcinoma associated with LS, despite the occurrence of TRAEs. It raises critical questions regarding the optimal duration of immunotherapy following a complete or partial response and whether treatment should be discontinued upon the emergency of TRAEs. Continued research and forthcoming clinical trials with checkpoint inhibitors are expected to refine treatment protocols for LS-associated carcinoma. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the risk of metachronous colorectal cancer (CRC) after resection of index (first) rectal cancer in patients with Lynch syndrome (LS). Methods: Clinicopathological data of patients with genetically proven LS were retrospectively analyzed in this multicenter Japanese study. The cumulative incidence of metachronous CRC and the overall survival were compared between patients with index rectal cancer (rectal group) and those with index colon cancer (colon group). Results: The median age at index CRC surgery was lower in the rectal group than in the colon group (37 vs. 46 years old, P = 0.01). The cumulative 5-, 10-, and 20-year incidences of metachronous CRC were 3.5%, 13.9%, and 21.1%, respectively, in the rectal cancer group and 14.9%, 22.0%, and 57.9%, respectively, in the colon cancer group (P = 0.02). The overall survival curves were not significantly different between two groups (P = 0.23). Conclusion: This is the first report from an East Asian country to report the risk of metachronous CRC after resection of index rectal cancer in patients with LS. Despite this study having several limitations, we cannot recommend extended resection, such as total proctocolectomy, for index rectal cancer as a standard surgical treatment in patients with LS. [ABSTRACT FROM AUTHOR]

Endometrial cancer in Lynch syndrome is characterized by a higher incidence, younger age at onset, and increased recurrence rates compared to sporadic cases, while the safety and efficacy of fertility-sparing treatments remain uncertain. This case report presents the oncology outcome of fertilitypreserving treatment in a 39-year-old woman diagnosed with Lynch syndrome and atypical endometrial hyperplasia. Initially, she responded favorably to fertility-preserving treatment but subsequently experienced disease relapse and rapid progression during retreatment. Final pathology revealed endometrial cancer with metastasis to the right ovary, categorized as FIGO 2023 stage IIIA1. This population's unique molecular mechanisms and genetic mutations warrant special consideration when opting for fertility-sparing treatment. We have reviewed and summarized the oncology and pregnancy outcomes among Lynch syndrome and MMR-deficient patients through previous literature. However, no studies have investigated retreatment after recurrence in Lynch syndrome. Our case highlights the potential risks associated with retreatment following relapse. Vigilant monitoring and prompt consideration of surgical intervention are recommended upon disease relapse. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) ranks as the third most prevalent cancer globally. It's recognized that the molecular subtype of CRC, characterized by mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H), plays a critical role in determining appropriate treatment strategies. This review examines the current molecular classifications, focusing on dMMR/MSI-H CRC and its subtypes: Lynch syndrome (LS), Lynch-like syndrome (LLS), and sporadic cases. Despite advances in understanding of these genetic backgrounds, clinical trials have not conclusively differentiated the efficacy of immune checkpoint inhibitors among these subgroups. Therefore, while this review details the molecular characteristics and their general implications for treatment and prognosis, it also highlights the limitations and the need for more refined clinical studies to ascertain tailored therapeutic strategies for each subtype. Furthermore, this review summarizes completed and ongoing clinical studies, emphasizing the importance of developing treatments aligned more closely with molecular profiles. By discussing these aspects, the review seeks to provide a comprehensive analysis of oncological characteristics, presenting a detailed understanding of their implications for treatment and prognosis in dMMR/MSI-H CRC. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to test a universal screening strategy on endometrial cancer to evaluate its effectiveness to find Lynch Syndrome (LS) cases to two established clinical criteria: Amsterdam II criteria, and the revised Bethesda criteria to select cases for prescreening with immunohistochemistry (IHC). Cases were subsequently screened for germline disease causing variants regarding the DNA mismatch repair (MMR) genes. Methods: IHC was performed on 221 endometrial cancer (EC) cases, using antibodies against the DNA mismatch repair proteins MLH1, PMS2, MSH2, and MSH6. MMR loss was found in 54 cases, and gene mutation screening was undertaken in 52 of those. Results: In this set of patients, the use of Amsterdam II criteria detected two (0.9%), the Bethesda criteria two (0.9%), and universal testing five (2.3%) cases of LS. The combination of universal testing and family history criteria resulted in detection of five patients (2.3%) with LS. Conclusions: Based on our results and other similar studies to date we propose a screening protocol for LS on EC tumors with prescreening using IHC for the four MMR proteins on all new EC cases diagnosed before 70 years of age, followed by mutation screening of all tumors with loss of MSH2 and/or MSH6 or only PMS2, plus consideration for mutation screening of all LS genes in cases fulfilling the clinical Amsterdam II criteria regardless of MMR status on IHC. [ABSTRACT FROM AUTHOR]

Lynch syndrome, a hereditary cancer susceptibility syndrome, arises from pathogenic mutations in mismatch repair genes. This syndrome is strongly linked to colorectal and endometrial cancers, as well as an elevated risk for other cancers such as gastric, ovarian, renal pelvis/ureter, and prostate. Notably, Lynch syndrome is rarely associated with cholangiocarcinoma (CCA). In this case study, we present a unique instance of Lynch syndrome-related CCA resulting from a singular MSH6 mutation. Notably, our findings reveal discrepancies between immunohistochemistry (IHC) and microsatellite stability results compared to genetic testing outcomes. This discrepancy underscores the limitations of solely relying on IHC analysis and microsatellite stability testing for the detection of hereditary tumors, emphasizing the crucial role of genetic testing in such cases. This insight enhances our comprehension of the mechanisms involved in cancer development and underscores the significance of thorough analysis integrating immunohistochemistry and genetic testing for diagnosing Lynch syndrome-related cancers. [ABSTRACT FROM AUTHOR]

Women with Lynch Syndrome (LS) have a high risk of colorectal and endometrial cancer. They are recommended regular colonoscopies, and some choose prophylactic hysterectomy. The aim of this study was to determine the impact of hysterectomy on subsequent colonoscopy in these women. A total of 219 LS women >30 years of age registered in the clinical registry at Section for Hereditary Cancer, Oslo University Hospital, were included. Data included hysterectomy status, other abdominal surgeries, and time of surgery. For colonoscopies, data were collected on cecal intubation rate, challenges, and level of pain. Observations in women with and without hysterectomy, and pre- and post-hysterectomy were compared. Cecal intubation rate was lower in women with hysterectomy than in those without (119/126 = 94.4% vs 88/88 = 100%, p = 0.025). Multivariate regression analysis showed an increased risk of challenging colonoscopies (OR,3.58; CI: 1.52–8.43; p = 0.003), and indicated a higher risk of painful colonoscopy (OR, 3.00; 95%CI: 0.99–17.44, p = 0.052), in women with hysterectomy compared with no hysterectomy. Comparing colonoscopy before and after hysterectomy, we also found higher rates of reported challenging colonoscopies post-hysterectomy (6/69 = 8.7% vs 23/69 = 33.3%, p < 0.001). Women with hysterectomy had a lower cecal intubation rate and a higher number of reported challenging colonoscopy than women with no hysterectomy. However, completion rate in the hysterectomy group was still as high as 94.4%. Thus, LS women who consider hysterectomy should not be advised against it. [ABSTRACT FROM AUTHOR]

Background Aim Materials and methods Results Conclusion Universal mismatch repair immunohistochemistry (MMR IHC) tumour testing in endometrial cancer (EC) for Lynch syndrome (LS) was introduced in Auckland, New Zealand, in January 2017. Identifying patients with LS allows them and their families to access risk reduction strategies. Universal MMR IHC testing aids in the molecular classification of EC and has prognostic and therapeutic implications.We aimed to determine the incidence of LS in women with EC in Auckland, New Zealand, following the introduction of MMR testing and the impact of universal screening on local genetic services.This is a retrospective clinicopathological evaluation of women with a new EC diagnosis referred to the Auckland Gynaecological Oncology Unit from 1/1/17 to 31/12/18. Patient data were extracted from the Gynaecological Oncology Unit database and electronic records, and analysed using descriptive statistics.During the study period, 409 patients were diagnosed with EC, with an over‐representation of Pacific Islanders (32.5%). Of these, 82.6% underwent MMR IHC testing, 20% were MMR‐deficient (MMRd), and 71% had somatic hypermethylation. The Pacific Islander population had a 64% (odds ratio 0.36, P = 0.005) reduction in the odds of having MMRd tumours compared with Europeans. Of the patients who underwent MMR IHC testing, 5.5% were referred to a genetic clinic for germline testing. LS was confirmed in eight patients (2.3%).LS was diagnosed in 2.3% of patients. There was an over‐representation of Pacific Islanders in the EC group but not among those diagnosed with LS. [ABSTRACT FROM AUTHOR]

Simple Summary: Germline and somatic deficiencies of mismatch repair proteins (MMRd) are related to colorectal and endometrial cancers, but the survival impact in Asian patients remains unclear. We investigated the prevalence and outcomes of patients with germline and/or somatic MMRd. Germline and somatic MMRd were determined by gene sequencing and protein staining of tumor samples, respectively. We found that colorectal and endometrial cancer patients with germline MMRd have favorable survival outcomes compared to those without, regardless of somatic MMRd status. These findings highlight the importance of germline genetic testing when tumor MMRd is detected. Germline (Lynch syndrome, LS) and somatic deficiencies of mismatch repair proteins (MMRd) are linked to colorectal and endometrial cancer; however, their prognostic impact in Asian populations remains unclear. This prospective cohort study aimed to determine the prevalence and outcome of germline and somatic MMRd in cancer patients suspected of LS. Patients with colorectal or endometrial cancer suspected of LS were enrolled and underwent gene sequencing for germline MMRd (gMMRd) and immunohistochemistry staining of MMR proteins in a subset of the pathological samples (pMMRd). Among the 451 enrolled patients, 36 patients were gMMRd (+). Compared with gMMRd (−) patients, the 10-year relapse-free survival in gMMRd (+) patients was significantly higher (100% vs. 77.9%; p = 0.006), whereas the 10-year overall survival was similar (100% vs. 90.9%; p = 0.12). Among the 102 gMMRd (−) patients with available pMMR status, 13.7% were pMMRd (+). The 5-year relapse-free survival was 62.9% in gMMRd (−) pMMRd (+) patients and 35.0% in gMMRd (−) pMMRd (−) patients, both lower than gMMRd (+) patients (100%; p < 0.001). This study showed that having LS confers a favorable outcome in colorectal and endometrial cancer patients and highlights the importance of germline genetic testing following the detection of somatic MMRd. [ABSTRACT FROM AUTHOR]

Background: Lynch-like syndrome (LLS) has recently been proposed as a third type of microsatellite instability (MSI) tumor after Lynch syndrome (LS) and sporadic MSI colorectal cancer (CRC) without either a germline variant of mismatch repair (MMR) genes or hypermethylation of the MLH1 gene. The present study aimed to clarify and compare the clinicopathological characteristics of LLS with those of the other MSI CRC subtypes. Methods: In total, 2634 consecutive patients with CRC who underwent surgical resection and subsequently received universal tumor screening (UTS), including MSI analysis were enrolled between January 2008 and November 2019. Genetic testing was performed in patients suspected of having Lynch syndrome. Results: UTS of the cohort found 146 patients with MSI CRC (5.5%). Of these, excluding sporadic MSI CRC, 30 (1.1%) had a diagnosis of LS, and 19 (0.7%) had no germline pathogenic variants of the MMR gene. The CRC type in the latter group was identified as LLS. LLS occurred significantly more often in young patients, was left-sided, involved a KRAS variant and BRAF wild-type, and had a higher concordance rate with the Revised Bethesda Guidelines than sporadic MSI CRC. No significant differences were observed in terms of the clinicopathological factors between LLS and LS-associated MSI CRC; however, LLS had a lower frequency of LS-related neoplasms compared with LS. Conclusions: Distinguishing clinically between LS and LLS was challenging, but the incidence of neoplasms was higher in LS than in LLS, suggesting the need for different screening and surveillance methods for the two subtypes. [ABSTRACT FROM AUTHOR]

Background: Lynch syndrome (LS) is a genetic disease with increased risk of colorectal cancer and other malignancies. There are few reported cases of thyroid cancer in LS patients. The aim of this study is to investigate the presence of thyroid nodules in LS patients and to explore their association with the genetic features of the disease. Methods: A retrospective and descriptive analysis was conducted to include all LS patients followed at the CEMAD (Centro Malattie Apparato Digerente) of Fondazione Policlinico Universitario A. Gemelli IRCCS. The characteristics of LS disease, gene mutations, and previous history of thyroid disease were evaluated. Majority of patients underwent thyroid ultrasound (US), and nodule cytology was performed when needed. Results: Of a total of 139 patients with LS, 110 patients were included in the study. A total of 103 patients (74%) underwent thyroid ultrasound examinations, and 7 patients (5%) had a previous history of thyroid disease (cancer or multinodular goiter). The mean age was 51.9 years. Thyroid nodules were found in 62 patients (60%) who underwent US, and 9 of them (14%) had suspicious features of malignancy, inducing a fine-needle aspiration biopsy. A cytologic analysis classified 7 of 9 cases (78%) as TIR2 and 2 (22%) as TIR3a. Between patients with nodular thyroid disease (single nodule, multinodular goiter, and cancer), most of them (25 patients, 36% of total) were carriers of the MSH6 mutation, while 22 (32%), 17 (24%), and 5 (7%) had MSH2, MLH1, and PMS2 mutations, respectively. Conclusions: A high prevalence of thyroid nodules was found in patients with LS, especially in MSH6-carrying patients. Performing at least one thyroid ultrasound examination is suggested for the detection of nodular thyroid disease in LS patients. Systematic investigations are needed to estimate their prevalence, features, and risk of malignant transformation. [ABSTRACT FROM AUTHOR]

Introduction: Lynch syndrome (LS) is an inherited cancer predisposition syndrome characterized by a high risk of colorectal and extracolonic tumors. Germline pathogenic variants (GPV) in the PMS2 gene are associated with <15% of all cases. The PMS2CL pseudogene presents high homology with PMS2, challenging molecular diagnosis by next-generation sequencing (NGS). Due to the high methodological complexity required to distinguish variants between PMS2 and PMS2CL, most laboratories do not clearly report the origin of this molecular finding. Objective: The aim of this study was to confirm the GPVs detected by NGS in regions of high homology segments of the PMS2 gene in a Brazilian sample. Methods: An orthogonal and gold standard long-range PCR (LR-PCR) methodology to separate variants detected in the PMS2 gene from those detected in the pseudogene. Results: A total of 74 samples with a PMS2 GPV detected by NGS in exons with high homology with PMS2CL pseudogene were evaluated. The most common was NM_000535.6:c.2182_2184delinsG, which was previously described as deleterious mutation in a study of African-American patients with LS and has been widely reported by laboratories as a pathogenic variant associated with the LS phenotype. Of all GPVs identified, only 6.8% were confirmed by LR-PCR. Conversely, more than 90% of GPV were not confirmed after LR-PCR, and the diagnosis of LS was ruled out by molecular mechanisms associated with PMS2. Conclusion: In conclusion, the use of LR-PCR was demonstrated to be a reliable approach for accurate molecular analysis of PMS2 variants in segments with high homology with PMS2CL. We highlight that our laboratory is a pioneer in routine diagnostic complementation of the PMS2 gene in Brazil, directly contributing to a more assertive molecular diagnosis and adequate genetic counseling for these patients and their families. [ABSTRACT FROM AUTHOR]

Microsatellite instability is rare in rectal cancer and associated with younger age of onset and Lynch syndrome. All rectal cancers should be tested for microsatellite instability prior to treatment decisions. Patients with microsatellite instability are relatively resistant to chemotherapy. However, recent small studies have shown dramatic response with neoadjuvant immunotherapy. Patients with Lynch syndrome have a hereditary predisposition to cancer and thus an elevated risk of metachronous cancer. Therefore, while "watch and wait" is a well-established practice for sporadic rectal cancers that obtain a complete clinical response after chemoradiation, its safety in patients with Lynch syndrome has not yet been defined. The extent of surgery for patients with Lynch syndrome and rectal cancer is controversial and there is significant debate as to the relative advantages of a segmental proctectomy with postoperative endoscopic surveillance versus a therapeutic and prophylactic total proctocolectomy. Surgical decision making for the patient with Lynch syndrome and rectal cancer is complex and demands a multidisciplinary approach, taking into account both patient- and tumor-specific factors. Neoadjuvant immunotherapy show great promise in the treatment of these patients, and further maturation of data from prospective trials will likely change the current treatment paradigm. Patients with Lynch syndrome and rectal cancer who do not undergo total proctocolectomy require yearly surveillance colonoscopies and should consider chemoprophylaxis with aspirin. [ABSTRACT FROM AUTHOR]

Abstract Background Lynch syndrome represents the most common hereditary cause of both colorectal and endometrial cancer. It is caused by defects in mismatch repair genes, as well as EPCAM. Universal screening of colon tumors for Lynch syndrome via microsatellite instability (MSI) and/or immunohistochemistry (IHC) can identify patients and families at risk to develop further cancers and potentially impact surveillance and treatment options. The approach to implementation of universal screening, taking ethical considerations into account, is critical to its effectiveness, with patient perspectives providing valuable insight. Methods Patients whose colon tumors underwent universal screening at Penn State Hershey Medical Center over a period of 2.5 years were mailed a survey on universal screening in 2017. Along with the survey, they received a recruitment letter and a summary explanation of research. The survey included both multiple choice and free-response questions that covered topics including respondent knowledge of Lynch syndrome, attitudes toward universal screening and experiences with the screening protocol as implemented. Results Sixty-six of 297 possible patients (22.2%) responded to the survey, including 13 whose screening results raised concern for Lynch syndrome. 75.8% of respondents supported universal tumor screening without informed consent. 92.4% preferred receiving screening results regardless of outcome. Respondents described benefits to screening for themselves and their families. Conclusions While broadly supporting universal tumor screening without informed consent, respondents also wanted more information shared about the screening policy, as well as their results. These patient preferences should be one of many factors considered when implementing universal screening and can also inform practices regarding both tumor profiling and universal genetic testing, which is becoming more prevalent.

Abstract Colorectal cancer (CRC) ranks as the third most prevalent cancer globally. It’s recognized that the molecular subtype of CRC, characterized by mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H), plays a critical role in determining appropriate treatment strategies. This review examines the current molecular classifications, focusing on dMMR/MSI-H CRC and its subtypes: Lynch syndrome (LS), Lynch-like syndrome (LLS), and sporadic cases. Despite advances in understanding of these genetic backgrounds, clinical trials have not conclusively differentiated the efficacy of immune checkpoint inhibitors among these subgroups. Therefore, while this review details the molecular characteristics and their general implications for treatment and prognosis, it also highlights the limitations and the need for more refined clinical studies to ascertain tailored therapeutic strategies for each subtype. Furthermore, this review summarizes completed and ongoing clinical studies, emphasizing the importance of developing treatments aligned more closely with molecular profiles. By discussing these aspects, the review seeks to provide a comprehensive analysis of oncological characteristics, presenting a detailed understanding of their implications for treatment and prognosis in dMMR/MSI-H CRC.

Abstract Background The aim of the study was to test a universal screening strategy on endometrial cancer to evaluate its effectiveness to find Lynch Syndrome (LS) cases to two established clinical criteria: Amsterdam II criteria, and the revised Bethesda criteria to select cases for prescreening with immunohistochemistry (IHC). Cases were subsequently screened for germline disease causing variants regarding the DNA mismatch repair (MMR) genes. Methods IHC was performed on 221 endometrial cancer (EC) cases, using antibodies against the DNA mismatch repair proteins MLH1, PMS2, MSH2, and MSH6. MMR loss was found in 54 cases, and gene mutation screening was undertaken in 52 of those. Results In this set of patients, the use of Amsterdam II criteria detected two (0.9%), the Bethesda criteria two (0.9%), and universal testing five (2.3%) cases of LS. The combination of universal testing and family history criteria resulted in detection of five patients (2.3%) with LS. Conclusions Based on our results and other similar studies to date we propose a screening protocol for LS on EC tumors with prescreening using IHC for the four MMR proteins on all new EC cases diagnosed before 70 years of age, followed by mutation screening of all tumors with loss of MSH2 and/or MSH6 or only PMS2, plus consideration for mutation screening of all LS genes in cases fulfilling the clinical Amsterdam II criteria regardless of MMR status on IHC.