Molecular analysis of familial endometrial carcinoma: a manifestation of hereditary nonpolyposis colorectal cancer or a separate syndrome?

Predicting Mismatch Repair Deficiency Status in Endometrial Cancer through Multi-Resolution Ensemble Learning in Digital Pathology

For molecular classification of endometrial carcinoma, testing for mismatch repair (MMR) status is becoming a routine process. Mismatch repair deficiency (MMR-D) is caused by loss of expression in one or more of the 4 major MMR proteins: MLH1, MSH2, MSH6, PHS2. Over 30% of patients with endometrial cancer have MMR-D. Determining the MMR status holds significance as individuals with MMR-D are potential candidates for immunotherapy. Pathological whole slide image (WSI) of endometrial cancer with immunohistochemistry results of MMR proteins were gathered. Color normalization was applied to the tiles using a CycleGAN-based network. The WSI was divided into tiles at three different magnifications (2.5 × , 5 × , and 10 ×). Three distinct networks of the same architecture were employed to include features from all three magnification levels and were stacked for ensemble learning. Three architectures, InceptionResNetV2, EfficientNetB2, and EfficientNetB3 were employed and subjected to comparison. The per-tile results were gathered to classify MMR status in the WSI, and prediction accuracy was evaluated using the following performance metrics: AUC, accuracy, sensitivity, and specificity. The EfficientNetB2 was able to make predictions with an AUC of 0.821, highest among the three architectures, and an overall AUC range of 0.767 - 0.821 was reported across the three architectures. In summary, our study successfully predicted MMR classification from pathological WSIs in endometrial cancer through a multi-resolution ensemble learning approach, which holds the potential to facilitate swift decisions on tailored treatment, such as immunotherapy, in clinical settings.

Novel insights into tumorigenesis revealed by molecular analysis of Lynch syndrome cases with multiple colorectal tumors

Background

Lynch syndrome (LS) is an autosomal dominant multi-organ cancer syndrome with a high lifetime risk of cancer. The number of cumulative colorectal adenomas in LS does not generally exceed ten, and removal of adenomas via routine screening minimizes the cancer burden. However, abnormal phenotypes may mislead initial diagnosis and subsequently cause suboptimal treatment.

Aim

Currently, there is no standard guide for the care of multiple colorectal adenomas in LS individuals. We aimed to shed insight into the molecular features and reasons for multiplicity of adenomas in LS patients.

Methods

We applied whole exome sequencing on nine adenomas (ten samples) and three assumed primary carcinomas (five samples) of an LS patient developing the tumors during a 21-year follow-up period. We compared the findings to the tumor profiles of two additional LS cases ascertained through colorectal tumor multiplicity, as well as to ten adenomas and 15 carcinomas from 23 unrelated LS patients with no elevated adenoma burden from the same population. As LS associated cancers can arise via several molecular pathways, we also profiled the tumors for CpG Island Methylator Phenotype (CIMP), and LINE-1 methylation.

Results

All tumors were microsatellite unstable (MSI), and MSI was present in several samples derived from normal mucosa as well. Interestingly, frequent frameshift variants in RNF43 were shared among substantial number of the tumors of our primary case and the tumors of LS cases with multiple tumors but almost absent in our control LS cases. The RNF43 variants were completely absent in the normal tissue, indicating tumor-associated mutational hotspots. The RNF43 status correlated with the mutational signature SBS96. Contrary to LS tumors from the reference set with no elevated colorectal tumor burden, the somatic variants occurred significantly more frequently at C>T in the CpG context, irrespective of CIMP or LINE-1 status, potentially indicating other, yet unknown methylation-related mechanisms. There were no signs of somatic mosaicism affecting the MMR genes. Somatic variants in APC and CTNNB1 were unique to each tumor.

Conclusion

Frequent somatic RNF43 hot spot variants combined with SBS96 signature and increased tendency to DNA methylation may contribute to tumor multiplicity in LS.

Counselling and management of women with genetic predisposition to gynaecological cancers

OBJECTIVE

To review the literature with reference to counselling and management of women with genetic predisposition to gynaecological cancers.

METHODS

Histochemical analysis, ultrasound, blood investigations, genetic testing, screening and risk-reducing surgery (RRS) are important tools for the management of gynaecological cancers and mortality reduction. Counselling can assist in timely management of gynaecological cancers. Systematic reviews, review articles, observational studies and clinical trials on PubMed, published in the English language, were included in this review.

RESULTS

The management of women with genetic predisposition to gynaecological cancers through screening tests and RRS has led to a significant decrease in the risk of malignancy through RRS in cases with BRCA1 and BRCA2 gene mutations. RRS and screening have also been found to reduce the mortality rate and increase the survival rate in women with BRCA1 and BRCA2 gene mutations. The efficacy of endometrial cancer surveillance in women with Lynch syndrome is still unproven. RRS has not been reported to be effective in women with Cowden syndrome. The risk of ovarian malignancies in individuals with germline mutations remains minimal in the general population in comparison with genetic mutations.

CONCLUSION

Genetic testing and RRS should be implemented in addition to genetic counselling for proper management and mortality reduction of women predisposed to gynaecological cancers.

Comparison of Methods for Testing Mismatch Repair Status in Endometrial Cancer

Approximately 20-30% of endometrial carcinomas (EC) are characterized by mismatch repair (MMR) deficiency (dMMR) or microsatellite instability (MSI), and their testing has become part of the routine diagnosis. The aim of this study was to establish and compare the MMR status using various approaches. Immunohistochemistry (IHC), PCR-based MSI, and the detection of defects in the four key MMR genes (MLH1, PMS2, MSH2, and MSH6) via methylation-specific multiplex ligation-dependent probe amplification (MLPA) and targeted next-generation sequencing (NGS) were performed. MSH3 expression was also evaluated. A set of 126 early-stage EC samples were analyzed, 53.2% of which were dMMR and 46.8% of which were proficient MMR (pMMR) as determined using IHC, whereas 69.3% were classified as microsatellite stable, while 8.8% and 21.9% were classified MSI-low (MSI-L) and MSI-high (MSI-H), respectively. In total, 44.3% of the samples showed genetic or epigenetic alterations in one or more genes; MLH1 promoter methylation was the most common event. Although acceptable concordance was observed, there were overall discrepancies between the three testing approaches, mainly associated with the dMMR group. IHC had a better correlation with MMR genomic status than the MSI status determined using PCR. Further studies are needed to establish solid conclusions regarding the best MMR assessment technique for EC.

The Role of Genetic Mutations in Mitochondrial-Driven Cancer Growth in Selected Tumors: Breast and Gynecological Malignancies

There is an increasing understanding of the molecular and cytogenetic background of various tumors that helps us better conceptualize the pathogenesis of specific diseases. Additionally, in many cases, these molecular and cytogenetic alterations have diagnostic, prognostic, and/or therapeutic applications that are heavily used in clinical practice. Given that there is always room for improvement in cancer treatments and in cancer patient management, it is important to discover new therapeutic targets for affected individuals. In this review, we discuss mitochondrial changes in breast and gynecological (endometrial and ovarian) cancers. In addition, we review how the frequently altered genes in these diseases (BRCA1/2, HER2, PTEN, PIK3CA, CTNNB1, RAS, CTNNB1, FGFR, TP53, ARID1A, and TERT) affect the mitochondria, highlighting the possible associated individual therapeutic targets. With this approach, drugs targeting mitochondrial glucose or fatty acid metabolism, reactive oxygen species production, mitochondrial biogenesis, mtDNA transcription, mitophagy, or cell death pathways could provide further tailored treatment.

The Role of Immunohistochemistry Markers in Endometrial Cancer with Mismatch Repair Deficiency: A Systematic Review

The objective of this systematic review was to summarize our current knowledge of the role of immunohistochemistry (IHC) markers for identifying mismatch repair-deficient (MMRd) tumors in endometrial cancer (EC). Identification of MMRd tumors, which occur in 13% to 30% of all ECs, has become critical for patients with colorectal and endometrial cancer for therapeutic management, clinical decision making, and prognosis. This review was conducted by two authors applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using the following terms: “immunohistochemistry and microsatellite instability endometrial cancer” or “immunohistochemistry and mismatch repair endometrial cancer” or “immunohistochemistry and mismatch repair deficient endometrial cancer”. Among 596 retrieved studies, 161 fulfilled the inclusion criteria. Articles were classified and presented according to their interest for the diagnosis, prognosis, and theragnostics for patients with MMRd EC. We identified 10, 18, and 96 articles using IHC expression of two, three, or four proteins of the MMR system (MLH1, MSH2, MHS6, and PMS2), respectively. MLH1 promoter methylation was analyzed in 57 articles. Thirty-four articles classified MMRd tumors with IHC markers according to their prognosis in terms of recurrence-free survival (RFS), overall survival (OS), stage, grade, and lymph node invasion. Theragnostics were studied in eight articles underlying the important concentration of PD-L1 in MMRd EC. Even though the role of IHC has been challenged, it represents the most common, robust, and cheapest method for diagnosing MMRd tumors in EC and is a valuable tool for exploring novel biotherapies and treatment modalities.

Universal tumor screening in a population with MSH6- and PMS2-associated Lynch syndrome

PURPOSE

Universal screening for Lynch syndrome (LS) on resected colorectal carcinomas (CRCs) and endometrial carcinomas (ECs) was implemented in Iceland in 2017 using immunohistochemistry (IHC) for mismatch repair (MMR) proteins. We examined the efficacy of the universal screening algorithm to detect LS and the diagnostic accuracy of MMR IHC by comparing results with a population-based genotype database.

METHODS

All patients diagnosed with CRC or EC per the Icelandic Cancer Registry from 2017 to 2019 who had tumor MMR IHC performed were included. Pathology reports and patient charts were reviewed. MMR IHC stains were crossmatched with genotyping results obtained from the deCODE database.

RESULTS

IHC staining was done on 404 patients with CRC and 74 patients with EC. A total of 61 (15.1%) patients with CRC and 15 (20.3%) patients with EC were MMR-deficient. MMR IHC had 88.9% sensitivity in identifying patients with LS and a positive predictive value of 10.7%. Only 50% of individuals were appropriately referred for genetic testing, leading to underdiagnosis of LS.

CONCLUSION

Universal screening for LS using MMR protein IHC in CRC and EC accurately identified patients appropriate for genetic testing in a population with MSH6 and PMS2 LS predominance. Because of lack of referral to genetic counseling, only 50% of patients with LS were identified through the screening algorithm.

Histopathologic diagnosis of endometrial precancers: Updates and future directions

Early detection of endometrial cancer, especially its precancers, remains a critical and evolving issue in patient management and the quest to decrease mortality due to endometrial cancer. Due to many factors such as specimen fragmentation, the confounding influence of endogenous or exogenous hormones, and variable or overlapping histologic features, identification of bona fide endometrial precancers and their reliable discrimination from benign mimics remains one of the most challenging areas in diagnostic pathology. At the same time, the diagnosis of endometrial precancer, or the presence of suspicious but subdiagnostic features in an endometrial biopsy, can lead to long clinical follow-up with multiple patient visits and serial endometrial sampling, emphasizing the need for accurate diagnosis. Our understanding of endometrial precancers and their diagnosis has improved due to systematic investigations into morphologic criteria, the molecular genetics of endometrial cancer and their precursors, the validation of novel biomarkers and their use in panels, and more recent methods such digital image analysis. Although precancers for both endometrioid and non-endometrioid carcinomas will be reviewed, emphasis will be placed on the former. We review these advances and their relevance to the histopathologic diagnosis of endometrial precancers, and the recently updated 2020 World Health Organization (WHO) Classification of Female Genital Tumors.

Lost opportunities for mismatch repair (MMR) screening among minority women with endometrial cancer

Lynch Syndrome (LS) prevalence in underrepresented minorities are lacking. The objective of this study was to assess the prevalence of LS in a minority patient population. Secondary objectives included identifying factors associated with successful LS screening and to characterize clinicopathologic features. Women with endometrial cancer treated within a university system from 2014 and 2016 were included. Immunohistochemistry (IHC) results of MLH1, PMS2, MSH2 and MSH6 were obtained from medical records and clinicopathologic factors abstracted. Patients not previously screened for LS were screened. 276 patients were evaluable. More minority women were screened as part of their routine cancer care (p = 0.005). Additionally, women 50 years or younger were more likely to be screened for LS compared to women older than 51(p = 0.009) and uninsured or reliant on Medicaid patients (p = 0.011) were more likely to be screened during routine care. Six patients received confirmatory germline testing for LS (4.3%), and another 8 patients had a staining pattern suggestive of LS. In an underrepresented population, the rate of LS in endometrial cancer is similar to previous reports. LS may be under diagnosed and opportunities missed when universal screening is not applied in minority women.

Testing strategies for Lynch syndrome in people with endometrial cancer: systematic reviews and economic evaluation

BACKGROUND

Lynch syndrome is an inherited genetic condition that is associated with an increased risk of certain cancers. The National Institute for Health and Care Excellence has recommended that people with colorectal cancer are tested for Lynch syndrome. Routine testing for Lynch syndrome among people with endometrial cancer is not currently conducted.

OBJECTIVES

To systematically review the evidence on the test accuracy of immunohistochemistry- and microsatellite instability-based strategies to detect Lynch syndrome among people who have endometrial cancer, and the clinical effectiveness and the cost-effectiveness of testing for Lynch syndrome among people who have been diagnosed with endometrial cancer.

DATA SOURCES

Searches were conducted in the following databases, from inception to August 2019 - MEDLINE ALL, EMBASE (both via Ovid), Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (both via Wiley Online Library), Database of Abstracts of Reviews of Effects, Health Technology Assessment Database (both via the Centre for Reviews and Dissemination), Science Citation Index, Conference Proceedings Citation Index - Science (both via Web of Science), PROSPERO international prospective register of systematic reviews (via the Centre for Reviews and Dissemination), NHS Economic Evaluation Database, Cost-Effectiveness Analysis Registry, EconPapers (Research Papers in Economics) and School of Health and Related Research Health Utilities Database. The references of included studies and relevant systematic reviews were also checked and experts on the team were consulted.

REVIEW METHODS

Eligible studies included people with endometrial cancer who were tested for Lynch syndrome using immunohistochemistry- and/or microsatellite instability-based testing [with or without mutL homologue 1 (MLH1) promoter hypermethylation testing], with Lynch syndrome diagnosis being established though germline testing of normal (non-tumour) tissue for constitutional mutations in mismatch repair. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, the Consolidated Health Economic Reporting Standards and the Philips' checklist. Two reviewers independently conducted each stage of the review. A meta-analysis of test accuracy was not possible because of the number and heterogeneity of studies. A narrative summary of test accuracy results was provided, reporting test accuracy estimates and presenting forest plots. The economic model constituted a decision tree followed by Markov models for the impact of colorectal and endometrial surveillance, and aspirin prophylaxis with a lifetime time horizon.

RESULTS

The clinical effectiveness search identified 3308 studies; 38 studies of test accuracy were included. (No studies of clinical effectiveness of endometrial cancer surveillance met the inclusion criteria.) Four test accuracy studies compared microsatellite instability with immunohistochemistry. No clear difference in accuracy between immunohistochemistry and microsatellite instability was observed. There was some evidence that specificity of immunohistochemistry could be improved with the addition of methylation testing. There was high concordance between immunohistochemistry and microsatellite instability. The economic model indicated that all testing strategies, compared with no testing, were cost-effective at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year. Immunohistochemistry with MLH1 promoter hypermethylation testing was the most cost-effective strategy, with an incremental cost-effectiveness ratio of £9420 per quality-adjusted life-year. The second most cost-effective strategy was immunohistochemistry testing alone, but incremental analysis produced an incremental cost-effectiveness ratio exceeding £130,000. Results were robust across all scenario analyses. Incremental cost-effectiveness ratios ranged from £5690 to £20,740; only removing the benefits of colorectal cancer surveillance produced an incremental cost-effectiveness ratio in excess of the £20,000 willingness-to-pay threshold. A sensitivity analysis identified the main cost drivers of the incremental cost-effectiveness ratio as percentage of relatives accepting counselling and prevalence of Lynch syndrome in the population. A probabilistic sensitivity analysis showed, at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year, a 0.93 probability that immunohistochemistry with MLH1 promoter hypermethylation testing is cost-effective, compared with no testing.

LIMITATIONS

The systematic review excluded grey literature, studies written in non-English languages and studies for which the reference standard could not be established. Studies were included when Lynch syndrome was diagnosed by genetic confirmation of constitutional variants in the four mismatch repair genes (i.e. MLH1, mutS homologue 2, mutS homologue 6 and postmeiotic segregation increased 2). Variants of uncertain significance were reported as per the studies. There were limitations in the economic model around uncertainty in the model parameters and a lack of modelling of the potential harms of gynaecological surveillance and specific pathway modelling of genetic testing for somatic mismatch repair mutations.

CONCLUSION

The economic model suggests that testing women with endometrial cancer for Lynch syndrome is cost-effective, but that results should be treated with caution because of uncertain model inputs.

FUTURE WORK

Randomised controlled trials could provide evidence on the effect of earlier intervention on outcomes and the balance of benefits and harms of gynaecological cancer surveillance. Follow-up of negative cases through disease registers could be used to determine false negative cases.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019147185.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 42. See the NIHR Journals Library website for further project information.

Mismatch Repair Universal Screening of Endometrial Cancers (MUSE) in a Canadian Cohort

Background: Approximately 2–6% of endometrial cancers (ECs) are due to Lynch Syndrome (LS), a cancer predisposition syndrome caused by germline pathogenic variants (PVs) affecting the DNA mismatch repair (MMR) pathway. Increasingly, universal tissue-based screening of ECs has been proposed as an efficient and cost-effective way to identify families with LS, though few studies have been published on Canadian cohorts. The purpose of this study was to evaluate the feasibility and overall performance of a universal immunohistochemistry (IHC) screening program for women with EC within a single Canadian university hospital centre. Methods and Results: From 1 October 2015 to 31 December 2017, all newly diagnosed ECs (n = 261) at our centre were screened for MMR protein deficiency by IHC. MMR deficiency was noted in 69 tumours (26.4%), among which 53 had somatic MLH1 promoter hypermethylation and were considered “screen-negative”. The remaining MMR-deficient cases (n = 16) were considered “screen-positive” and were referred for genetic counselling and testing. Germline PVs were identified in 12/16 (75%). One additional PV was identified in a screen-negative individual who was independently referred to the Genetics service. This corresponds to an overall LS frequency of 5.0% among unselected women with EC, and 6.4% among women diagnosed under age 70 years. Our algorithm detected MMR gene pathogenic variants in 4.6% and 6.2% of unselected individuals and individuals under age 70 years, respectively. Four germline PVs (30.8%) were identified in individuals who did not meet any traditional LS screening criteria. Conclusions: Universal IHC screening for women with EC is an effective and feasible method of identifying individuals with LS in a Canadian context.

Testing for lynch syndrome in people with endometrial cancer using immunohistochemistry and microsatellite instability-based testing strategies - A systematic review of test accuracy

BACKGROUND

Lynch syndrome is an inherited genetic condition that is associated with an increased risk of cancer, including endometrial and colorectal cancer. We assessed the test accuracy of immunohistochemistry and microsatellite instability-based testing (with or without MLH1 promoter methylation testing) for Lynch syndrome in women with endometrial cancer.

METHODS

We conducted a systematic review of literature published up to August 2019. We searched bibliographic databases, contacted experts and checked reference lists of relevant studies. Two reviewers conducted each stage of the review.

RESULTS

Thirteen studies were identified that included approximately 3500 participants. None of the studies was at low risk of bias in all domains. Data could not be pooled due to the small number of heterogeneous studies. Sensitivity ranged from 60.7-100% for immunohistochemistry, 41.7-100% for microsatellite instability-based testing, and 90.5-100% for studies combining immunohistochemistry, microsatellite instability-based testing, and MLH1 promoter methylation testing. Specificity ranged from 60.9-83.3% (excluding 1 study with highly selective inclusion criteria) for immunohistochemistry, 69.2-89.9% for microsatellite instability-based testing, and 72.4-92.3% (excluding 1 study with highly selective inclusion criteria) for testing strategies that included immunohistochemistry, microsatellite instability-based testing, and MLH1 promoter methylation. We found no statistically significant differences in test accuracy estimates (sensitivity, specificity) in head-to-head studies of immunohistochemistry versus microsatellite instability-based testing. Reported test failures were rare.

CONCLUSIONS

Sensitivity of the index tests were generally high, though most studies had much lower specificity. We found no evidence that test accuracy differed between IHC and MSI based strategies. The evidence base is currently small and at high risk of bias.

Universal screening for Lynch syndrome in uterine cancer patients: A quality improvement initiative

OBJECTIVE

To determine the feasibility and effectiveness of a quality improvement initiative (QI) to adopt universal screening for Lynch syndrome in uterine cancer patients at an institution that previously employed age-based screening.

METHODS

Prior to the initiative, tumors of patients with uterine cancer diagnosed at age ≤ 60 years were screened for mismatch repair deficiency (MMR) and microsatellite instability (MSI). The QI process change model adopted universal testing of all uterine cancer specimens and implemented provider training, standardized documentation, and enhanced use of the electronic medical record (EMR). We compared screening rates, results of screening, follow up of abnormal results, and final diagnoses from the pre- and post-implementation periods.

RESULTS

Pre- and post-implementation screening rates for women age ≤ 60 years at the time of diagnosis were 45/78 (57.7%) and 64/68 (94.5%), respectively. The screening rate for all patients with uterine cancer increased from 73/190 (38.4%) to 172/182 (94.5%). The rate of abnormal screening results increased from 15/190 (7.9%) to 44/182 (24.0%) cases. Genetics referral rates among screen positives increased from 3/15 (20.0%) to 16/44 (36.4%). Germline diagnoses increased from 2/190 (1.1%) with two Lynch syndrome diagnoses to 4/182 (2.2%) including three Lynch syndrome diagnoses and one BRCA1 germline diagnosis. The number of patients errantly not screened decreased from at least 32 patients to 3 patients after the intervention.

CONCLUSIONS

Adherence to screening guidelines significantly improved after interventions involving provider education, optimal use of the EMR, and simplification of screening indications. These interventions are feasible at other institutions and translatable to other screening indications.

Molecular Basis of Mismatch Repair Protein Deficiency in Tumors from Lynch Suspected Cases with Negative Germline Test Results

Some 10–50% of Lynch-suspected cases with abnormal immunohistochemical (IHC) staining remain without any identifiable germline mutation of DNA mismatch repair (MMR) genes. MMR proteins form heterodimeric complexes, giving rise to distinct IHC patterns when mutant. Potential reasons for not finding a germline mutation include involvement of an MMR gene not predicted by the IHC pattern, epigenetic mechanism of predisposition, primary mutation in another DNA repair or replication-associated gene, and double somatic MMR gene mutations. We addressed these possibilities by germline and tumor studies in 60 Lynch-suspected cases ascertained through diagnostics (n = 55) or research (n = 5). All cases had abnormal MMR protein staining in tumors but no point mutation or large rearrangement of the suspected MMR genes in the germline. In diagnostic practice, MSH2/MSH6 (MutS Homolog 2/MutS Homolog 6) deficiency prompts MSH2 mutation screening; in our study, 3/11 index individuals (27%) with this IHC pattern revealed pathogenic germline mutations in MSH6. Individuals with isolated absence of MSH6 are routinely screened for MSH6 mutations alone; we found a predisposing mutation in MSH2 in 1/7 such cases (14%). Somatic deletion of the MSH2-MSH6 region, joint loss of MSH6 and MSH3 (MutS Homolog 3) proteins, and hindered MSH2/MSH6 dimerization offered explanations to misleading IHC patterns. Constitutional epimutation hypothesis was pursued in the MSH2 and/or MSH6-deficient cases plus 38 cases with MLH1 (MutL Homolog 1)-deficient tumors; a primary MLH1 epimutation was identified in one case with an MLH1-deficient tumor. We conclude that both MSH2 and MSH6 should be screened in MSH2/6- and MSH6-deficient cases. In MLH1-deficient cases, constitutional epimutations of MLH1 warrant consideration.

Clinicopathologic features of endometrial cancer with mismatch repair deficiency

The inclusion of DNA mismatch repair (MMR) evaluation as a standard of care for endometrial cancer management will result in a growing population of patients with MMR deficiency and negative germline Lynch syndrome testing (MMR-deficient). In this systematic review and study, the clinicopathologic features of endometrial cancer in patients with MMR-intact, MLH1 methylation positive, MMR-deficient or Lynch syndrome are evaluated. A systematic search of online databases between 1990 and 2018 identified studies of endometrial cancer patients with tumour testing (MMR protein immunohistochemistry or microsatellite instability) and germline assessment for Lynch syndrome. Extracted data included tumour testing, germline genetic testing, age, body mass index (BMI), family history, tumour stage, grade and histologic type. Associations between MMR-intact, MLH1 methylation positive, MMR-deficient and Lynch syndrome groups were analysed using descriptive statistics. The comprehensive search produced 4,400 publications, 29 met inclusion criteria. A total of 7,057 endometrial cancer cases were identified, 1,612 with abnormal immunohistochemistry, 977 with microsatellite instability. Nine-hundred patients underwent germline genetic testing, identifying 212 patients with Lynch syndrome. Patients in the Lynch syndrome and MMR-deficient groups were significantly younger than patients in the MMR-intact and MLH1 methylation positive groups. Patients with MMR-intact tumours had the highest BMI, followed by MMR-deficient, then Lynch syndrome. MMR-intact tumours were more likely to be grade I at diagnosis than other groups. Patients with Lynch syndrome and MMR-deficient tumours were less likely to have stage I disease as compared to patients with MMR-intact tumours. Endometrial cancer patients with MMR-deficient tumours have similar features to those with germline Lynch syndrome mutations, including age, grade, histology and stage. Even in the absence of a germline mutation, tumour evaluation for MMR status may have important clinical implications.

Imaging-based definition of lower uterine segment carcinoma to improve the detection sensitivity of probable Lynch syndrome

OBJECTIVE

The aim of this study was to investigate a magnetic resonance imaging-based definition of lower uterine segment carcinoma.

METHODS

We retrospectively reviewed 587 consecutive patients with endometrial cancer who underwent hysterectomy. Lower uterine segment carcinoma was determined through pathological examination and magnetic resonance imaging assessment. For imaging assessment, the location of the inner lining of the uterus was classified into four equal parts on a sagittal section image. A tumor was defined as lower uterine segment carcinoma when its thickest part was located in the second or the third part from the uterine fundus. Lower uterine segment carcinoma was further divided into lower uterine segment in a narrow sense, upon which diagnosis was exclusively based on pathological findings, and lower uterine segment in a broad sense that were the remaining lower uterine segment carcinomas except lower uterine segment carcinomas in a narrow sense. The relationship between lower uterine segment carcinoma and probable Lynch syndrome was investigated. Patients with loss of MSH2, MSH6, and PMS2 expression or those with tumors with loss of MLH1 and absence of MLH1 promoter methylation were diagnosed as probable Lynch syndrome.

RESULTS

Lower uterine segment carcinoma was identified in 59 (10.2%) patients. Twenty-eight (47.5%) patients were categorized as lower uterine segment in a narrow sense and 31 (52.5%) as lower uterine segment in a broad sense. Among them, probable Lynch syndrome was identified in 12 (20.3%) cases. There was no difference in clinical profiles, including the prevalence of probable Lynch syndrome between the two categories.

CONCLUSIONS

A magnetic resonance imaging-based expanded definition of lower uterine segment carcinoma is likely to secure characteristics equivalent to a conventional pathology-based definition of lower uterine segment carcinoma. The novel definition of lower uterine segment carcinoma might improve the detection of probable Lynch syndrome.

Diagnostic Accuracy of Immunohistochemistry for Mismatch Repair Proteins as Surrogate of Microsatellite Instability Molecular Testing in Endometrial Cancer

Microsatellite instability (MSI) defines one of the four molecular groups of endometrial carcinoma identified by The Cancer Genome Atlas (TCGA). Immunohistochemistry for mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, PMS2) has been proposed as a widely applicable technique to identify this group in the common practice. However, the diagnostic accuracy of such approach has never been calculated. We aimed to assess: 1) the diagnostic accuracy of MMR proteins immunohistochemistry as surrogate of MSI molecular testing in endometrial carcinoma; 2) whether a combination of only two MMR proteins may be used as a still cheaper test. A systematic review and meta-analysis of was performed by searching electronic databases from their inception to September 2019. All studies assessing endometrial carcinoma with both MMR proteins immunohistochemistry and MSI molecular testing were included. Diagnostic accuracy was assessed as sensitivity, specificity, positive and negative likelihood ratios (LR+, LR-), diagnostic odds ratio (DOR) and area under the curve (AUC) on SROC curves. A subgroup analysis was performed for a combination of only two MMR proteins (MLH1-MSH2 vs MSH6-PMS2). Ten studies with 3097 patients were included. Out of these, 1110 were suitable for the meta-analysis. Immunohistochemistry for all the four MMR proteins showed sensitivity = 0.96, specificity = 0.95, LR + =17.7, LR- = 0.05, DOR = 429.77, and high diagnostic accuracy (AUC = 0.988). The combination of MLH1 and MSH2 showed sensitivity = 0.88, specificity = 0.96, LR + =22.36, LR- = 0.15, DOR = 200.69, and high diagnostic accuracy (AUC = 0.9838). The combination of MSH6 and PMS2 showed the same results as the complete panel of four MMR proteins. In conclusion, MMR proteins immunohistochemistry is a highly accurate surrogate of MSI molecular testing in endometrial carcinoma. A combination of MSH6 and PMS2 may allow reducing the cost without decrease in the diagnostic accuracy.

Does breast carcinoma belong to the Lynch syndrome tumor spectrum? - Somatic mutational profiles vs. ovarian and colorectal carcinomas

Inherited DNA mismatch repair (MMR) defects cause predisposition to colorectal, endometrial, ovarian, and other cancers occurring in Lynch syndrome (LS). It is unsettled whether breast carcinoma belongs to the LS tumor spectrum. We approached this question through somatic mutational analysis of breast carcinomas from LS families, using established LS-spectrum tumors for comparison. Somatic mutational profiles of 578 cancer-relevant genes were determined for LS-breast cancer (LS-BC, n = 20), non-carrier breast cancer (NC-BC, n = 10), LS-ovarian cancer (LS-OC, n = 16), and LS-colorectal cancer (LS-CRC, n = 18) from the National LS Registry of Finland. Microsatellite and MMR protein analysis stratified LS-BCs into MMR-deficient (dMMR, n = 11) and MMR-proficient (pMMR, n = 9) subgroups. All NC-BCs were pMMR and all LS-OCs and LS-CRCs dMMR. All but one dMMR LS-BCs were hypermutated (> 10 non-synonymous mutations/Mb; average 174/Mb per tumor) and the frequency of MMR-deficiency-associated signatures 6, 20, and 26 was comparable to that in LS-OC and LS-CRC. LS-BCs that were pMMR resembled NC-BCs with respect to somatic mutational loads (4/9, 44%, hypermutated with average mutation count 33/Mb vs. 3/10, 30%, hypermutated with average 88 mutations/Mb), whereas mutational signatures shared features of dMMR LS-BC, LS-OC, and LS-CRC. Epigenetic regulatory genes were significantly enriched as mutational targets in LS-BC, LS-OC, and LS-CRC. Many top mutant genes of our LS-BCs have previously been identified as drivers of unselected breast carcinomas. In conclusion, somatic mutational signatures suggest that conventional MMR status of tumor tissues is likely to underestimate the significance of the predisposing MMR defects as contributors to breast tumorigenesis in LS.

Mismatch Repair Protein Expression in Endometrioid Intraepithelial Neoplasia/Atypical Hyperplasia: Should We Screen for Lynch Syndrome in Precancerous Lesions?

Screening for Lynch syndrome (LS) is routinely performed in patients with endometrial carcinoma. Currently, no screening recommendations exist for LS in precancerous lesions. The study goal was to determine the incidence of abnormal protein expression in endometrioid intraepithelial neoplasia/atypical hyperplasia (EIN/AH). We analyzed mismatch repair (MMR) protein expression by immunohistochemistry in EIN/AH concurrent with MMR-deficient endometrial carcinomas, and in endometrial biopsy/curettage specimens with EIN/AH from an unselected group of patients. Of 63 patients with MMR-deficient endometrial carcinoma, 34 demonstrated loss of MLH1/PMS2 expression; 1 showed loss of PMS2 alone; 12 showed loss of MSH2/MSH6, and 15 had loss of MSH6 alone. Genetic testing identified deleterious mutations in 14 cases (LS). 15 tumors demonstrated MLH1 promoter hypermethylation. Abnormal MMR expression in EIN/AH and adjacent carcinoma was concordant in 100% of LS cases and 71% of MLH1 promoter hypermethylation cases. Of 118 patients from the unselected group with EIN/AH, 4 (3%) cases demonstrated absent expression of one or more MMR proteins. Of these, 2 patients were later confirmed to have deleterious mutations in subsequent specimens with endometrial carcinoma. The prevalence of abnormal MMR expression in EIN/AH adjacent to carcinoma and in the unselected group of patients with EIN/AH is similar to the reported prevalence of LS in endometrial carcinoma. Identifying patients at high risk for LS through abnormal MMR expression in EIN/AH provides the benefit of early surveillance, treatment and timely diagnosis for the patient and affected family members.

Thyroid Carcinomas That Occur in Familial Adenomatous Polyposis Patients Recurrently Harbor Somatic Variants in APC, BRAF, and KTM2D

Background: Familial adenomatous polyposis (FAP) is a condition typically caused by pathogenic germline mutations in the APC gene. In addition to colon polyps, individuals with FAP have a substantially increased risk of developing papillary thyroid cancer (PTC). Little is known about the events underlying this association, and the prevalence of somatic "second-hit" mutations in APC is controversial. Methods: Whole-genome sequencing was performed on paired thyroid tumor and normal DNA from 12 FAP patients who developed PTC. Somatic mutation profiles were compared with clinical characteristics and previously sequenced sporadic PTC cases. Germline variant profiling was performed to assess the prevalence of variants in genes previously shown to have a role in PTC predisposition. Results: All 12 patients harbored germline mutations in APC, consistent with FAP. Seven patients also had somatic mutations in APC, and seven patients harbored somatic mutations in KMT2D, which encodes a lysine methyl transferase. Mutation of these genes is extremely rare in sporadic PTCs. Notably, only two of the tumors harbored the somatic BRAF p.V600E mutation, which is the most common driver mutation found in sporadic PTCs. Six tumors displayed a cribriform-morular variant of PTC (PTC-CMV) histology, and all six had somatic mutations in APC. Additionally, nine FAP-PTC patients had rare germline variants in genes that were previously associated with thyroid carcinoma. Conclusions: Our data indicate that FAP-associated PTCs typically have distinct mutations compared with sporadic PTCs. Roughly half of the thyroid cancers that arise in FAP patients have somatic "second-hits" in APC, which is associated with PTC-CMV histology. Somatic BRAF p.V600E variants also occur in some FAP patients, a novel finding. We speculate that in carriers of heterozygous pathogenic mutations of tumor suppressor genes such as APC, a cooperating second-hit somatic variant may occur in a different gene such as KTM2D or BRAF, leading to differences in phenotypes. The role of germline variance in genes other than APC (9 of the 12 patients in this series) needs further research.

Universal endometrial cancer tumor typing: How much has immunohistochemistry, microsatellite instability, and MLH1 methylation improved the diagnosis of Lynch syndrome across the population?

BACKGROUND

Universal tumor testing for defective DNA mismatch repair (MMR) is recommended for all women diagnosed with endometrial cancer to identify those with underlying Lynch syndrome. However, the effectiveness of these screening methods in identifying individuals with Lynch syndrome across the population has not been well studied. The aim of this study was to evaluate outcomes of MMR immunohistochemistry (IHC), mutL homolog 1 (MLH1) methylation, and microsatellite instability (MSI) analysis among patients with endometrial cancer.

METHODS

A complete systematic search of online databases (PubMed, EMBASE, MEDLINE, and the Cochrane Library) for 1990-2018 was performed. A DerSimonian-Laird random effects model meta-analysis was used to estimate the weighted prevalence of Lynch syndrome diagnoses.

RESULTS

The comprehensive search produced 4400 publications. Twenty-nine peer-reviewed studies met the inclusion criteria. Patients with endometrial cancer (n = 6649) were identified, and 206 (3%) were confirmed to have Lynch syndrome through germline genetic testing after positive universal tumor molecular screening. Among 5917 patients who underwent tumor IHC, 28% had abnormal staining. Among 3140 patients who underwent MSI analysis, 31% had MSI. Among patients with endometrial cancer, the weighted prevalence of Lynch syndrome germline mutations was 15% (95% confidence interval [CI], 11%-18%) with deficient IHC staining and 19% (95% CI, 13%-26%) with a positive MSI analysis. Among 1159 patients who exhibited a loss of MLH1 staining, 143 (13.7%) were found to be MLH1 methylation-negative among those who underwent methylation testing, and 32 demonstrated a germline MLH1 mutation (2.8% of all absent MLH1 staining cases and 22.4% of all MLH1 methylation-negative cases). Forty-three percent of patients with endometrial cancer who were diagnosed with Lynch syndrome via tumor typing would have been missed by family history-based screening alone.

CONCLUSIONS

Despite the widespread implementation of universal tumor testing in endometrial cancer, data regarding testing results remain limited. This study provides predictive values that will help practitioners to evaluate abnormal results in the context of Lynch syndrome and aid them in patient counseling.

Epidemiological, clinical and molecular characterization of Lynch-like syndrome: A population-based study

Colorectal carcinomas that are mismatch repair (MMR)-deficient in the absence of MLH1 promoter methylation or germline mutations represent Lynch-like syndrome (LLS). Double somatic events inactivating MMR genes are involved in the etiology of LLS tumors. Our purpose was to define the clinical and broader molecular hallmarks of LLS tumors and the population incidence of LLS, which remain poorly characterized. We investigated 762 consecutive colorectal carcinomas operated in Central Finland in 2000-2010. LLS cases were identified by a stepwise protocol based on MMR protein expression, MLH1 methylation and MMR gene mutation status. LLS tumors were profiled for CpG Island Methylator Phenotype (CIMP) and somatic mutations in 578 cancer-relevant genes. Among 107 MMR-deficient tumors, 81 (76%) were attributable to MLH1 promoter methylation and 9 (8%) to germline mutations (Lynch syndrome, LS), leaving 14 LLS cases (13%) (3 remained unclassified). LLS carcinomas were diagnosed at a mean age of 65 years (vs. 44 years in LS, p < 0.001), had a proximal to distal ratio of 1:1, and all were BRAF V600E-negative. Two somatic events in MMR genes were identifiable in 11 tumors (79%). As novel findings, the tumors contained an average of 31 nonsynonymous somatic mutations/Mb and 13/14 were CIMP-positive. In conclusion, we establish the epidemiological, clinical and molecular characteristics of LLS in a population-based study design. Significantly more frequent CIMP-positivity and lower rates of somatic mutations make a distinction to LS. The absence of BRAF V600E mutation separates LLS colorectal carcinomas from MLH1-methylated colorectal carcinomas with CIMP-positive phenotype.

Targeted Next-Generation Sequencing of MLH1, MSH2, and MSH6 Genes in Patients with Endometrial Carcinoma under 50 Years of Age

Background

Lynch syndrome is an inherited cancer disorder that causes an increased lifetime risk of various types of cancers. Endometrial cancer is the most common extracolonic cancer in Lynch syndrome. Guidelines recommend that patients with endometrial cancer younger than 50 years of age should be evaluated for Lynch syndrome. Molecular analysis of the mismatch repair genes and EPCAM gene is required for a definitive diagnosis of Lynch syndrome.

Aims

To report the mutation analysis of mismatch repair genes using targeted next-generation sequencing in endometrial cancer diagnosed patients <50 years of age.

Study Design

Retrospective cross-sectional study.

Methods

Seventy-nine endometrial cancer diagnosed patients <50 years of age underwent genetic counseling. They were selected among 1094 consecutive endometrial cancer patients between 2006 and 2017. Molecular analysis of MLH1, MSH2, and MSH6 genes was performed in 79 patients by using next-generation sequencing. Deletion/duplication analysis of mismatch repair genes and EPCAM gene was also performed in 79 patients by using the multiplex ligation-dependent probe amplification method.

Results

Germline testing of mismatch repair genes was performed in 79 endometrial cancer patients. Lynch syndrome was confirmed in 4 patients (5%; 4/79). A total of 14 variants (6 in MSH2, 5 in MLH1, 3 in MSH6 genes) were found in 14 patients. Four variants were assessed as pathogenic/likely pathogenic, and 10 variants were assessed as variants of uncertain significance.

Conclusion

Lynch syndrome should be investigated in patients diagnosed with endometrial cancer that are less than 50 years of age due to the increased lifetime risk of developing cancer.

Rare compound heterozygous mutations in gene MSH6 cause constitutive mismatch repair deficiency syndrome

Few studies reported patients who harbored three kinds of primary tumors simultaneously. Here, we present a 9-year-old boy with colon carcinoma, brain medulloblastoma, and lymphoma. Genetic mutation detection was explored with next-generation sequencing, and compound heterozygous mutations in gene MSH6 c.3103C>T p.Arg1035Ter and c.3261dupC p.Phe1088LeufsTer were discovered.

Molecular changes preceding endometrial and ovarian cancer: a study of consecutive endometrial specimens from Lynch syndrome surveillance

Molecular alterations preceding endometrial and ovarian cancer and the sequence of events are unknown. Consecutive specimens from lifelong surveillance for Lynch syndrome provides a natural setting to address such questions. To molecularly define the multistep gynecological tumorigenesis, DNA mismatch repair gene mutation carriers with endometrial or ovarian carcinoma or endometrial hyperplasia were identified from a nation-wide registry and endometrial biopsy specimens taken from these individuals during 20 years of screening were collected. A total of 213 endometrial and ovarian specimens from Lynch syndrome individuals and 197 histology-matched (non-serous) samples from sporadic cases were available for this investigation. The specimens were profiled for markers linked to endometrial and ovarian tumorigenesis, including ARID1A protein expression, mismatch repair status, and tumor suppressor gene promoter methylation. In Lynch syndrome-associated endometrial and ovarian carcinomas, ARID1A protein was lost in 61-100% and mismatch repair was deficient in 97-100%, compared to 0-17% and 14-44% in sporadic cases (P = 0.000). ARID1A loss appeared in complex hyperplasia and deficient mismatch repair and tumor suppressor gene promoter methylation in histologically normal endometrium. Despite quantitative differences between Lynch syndrome and sporadic cases, ARID1A expression, mismatch repair, and tumor suppressor gene promoter methylation divided endometrial samples from both patient groups into three categories of increasing abnormality, comprising normal endometrium and simple hyperplasia (I), complex hyperplasia with or without atypia (II), and endometrial cancer (III). Complex hyperplasias without vs. with atypia were molecularly indistinguishable. In conclusion, surveillance specimens from Lynch syndrome identify mismatch repair deficiency, tumor suppressor gene promoter methylation, and ARID1A loss as early changes in tumor development. Our findings are clinically relevant for the classification of endometrial hyperplasias and have potential implications in cancer prevention in Lynch syndrome and beyond.

The practice of universal screening for Lynch syndrome in newly diagnosed endometrial carcinoma

BACKGROUND

Lynch syndrome (LS) accounts for 5% of all endometrial cancer (EC) cases and 4% of all lifetime risk of developing colorectal cancer. While current guidelines recommend LS screening for all patients with newly diagnosed colorectal cancer, there is no such guideline for screening patients with EC.

DISCUSSION

This review addresses LS screening and discusses algorithms for testing patients in the setting of newly diagnosed EC.

CONCLUSION

The successful diagnosis of LS has important implications, including prevention of LS-associated cancers among relatives and immunotherapy recommendations for patients with advanced EC and loss of expression of mismatch repair immunohistochemistry and microsatellite instability positive following failure of traditional treatment.

Treatment strategies for endometrial cancer: current practice and perspective

PURPOSE OF REVIEW

Endometrial cancer incidence is increasing in North America and is a major cause of morbidity and mortality in women. We review recent literature published on treatment of endometrial cancer and highlight areas of active interest.

RECENT FINDINGS

There has been movement toward minimal invasive surgery at diagnosis; lymph node staging remains controversial and continues to be investigated. Progress has been made to establish consensus on endometrial cancer risk classification to promote consistency for future trial design. Molecular characterization of endometrial cancer and its integration into clinicopathological profiling to develop predictive biomarkers for treatment selection are active areas of research. Optimal adjuvant treatment strategy in high-risk endometrial cancer remains to be defined with recognition of treatment-related toxicity. Despite encouraging results in drug development for treatment of advanced/recurrent endometrial cancer, no targeted therapies beyond hormonal therapy are approved. There is an urgent need for scientifically validated therapy with predictive biomarkers.

SUMMARY

Our understanding of endometrial cancer has evolved through improvements in molecular biology, allowing improved definition of target-specific therapies. The precise role and sequence of conventional and targeted therapies, including immunotherapy, will require careful attention to the design of clinical trials with translational emphasis to allow the discovery, validation, and implementation of predictive biomarkers into clinical care.

Molecular insights into the classification of high-grade endometrial carcinoma

Endometrial carcinoma, which is associated with a mortality rate of approximately 20%, is the most common gynecological malignancy in the Western world. It is a heterogeneous disease, with multiple histotypes, each constituting a different disease entity. However, interobserver diagnostic agreement is suboptimal, particularly among the most lethal histotypes. Most recent data also indicate that histotype assignment is not independently associated with survival, while in contrast, clinicopathological risk stratification and genomic classification are significantly prognostic. Recent work has shown that there are four molecular subgroups of endometrioid carcinomas instead of the two types proposed by Bokhman in the 1970s. Carcinomas with polymerase E (POLE) exonuclease domain hotspot mutations are highly prognostically favourable; those with copy-number alterations and TP53 mutations are highly aggressive; and microsatellite unstable and 'copy-number low' endometrioid carcinomas are associated with intermediate prognoses. This review summarises the genetic foundations of the various histotypes of endometrial carcinoma and synthesises this information in the form of algorithms, or classifiers, that recapitulate genomic classification that is not only prognostic, but also potentially diagnostic and therapeutically predictive. A review of Lynch syndrome and Lynch-like syndrome is also provided.

Sequencing of Lynch syndrome tumors reveals the importance of epigenetic alterations

Genomic instability and epigenetic aberrations are important classifiers of human tumors, yet, their interrelations are poorly understood. We used Lynch syndrome (LS) to address such relationships. Forty-five tumors (11 colorectal adenomas, 18 colorectal carcinomas, and 16 ovarian carcinomas) were profiled for CpG Island Methylator Phenotype (CIMP) and somatic mutations. All tumors showed high-degree microsatellite instability. Panel sequencing of 578 cancer-relevant genes revealed the average number of 1433, 1124, and 657 non-synonymous somatic mutations per colorectal adenoma, colorectal carcinoma, and ovarian carcinoma, respectively. Genes harboring mutations with allele frequency 25 % or higher in at least 31 % of tumors were regarded to be possible drivers. Among 72 and 10 such genes identified in colorectal and ovarian tumors, respectively, the most frequently mutated genes BRD4 and MLL2 (62 % of colorectal tumors) and ARID1A (50 % of ovarian carcinomas) are involved in epigenetic regulation. The total number of somatic mutations or mutant genes per tumor were significantly associated with CIMP. Our results suggest that even in an inherited disease, tumor type-specific epigenetic changes are significant and may result from regulatory changes (CIMP) or structural events (mutations of epigenetic regulatory genes). The findings are clinically relevant since many of the affected pathways can be therapeutically targeted.

Universal screening for Lynch syndrome in endometrial cancers: frequency of germline mutations and identification of patients with Lynch-like syndrome

Lynch syndrome (LS) is an inherited clinical syndrome characterized by a high risk of colorectal, endometrial (lifetime risk of up to 60%), ovarian, and urinary tract cancers. The diagnosis is confirmed by identification of germline mutations in the DNA mismatch repair genes MLH1, PMS2, MSH2, MSH6, or EPCAM. In 2015, our institution implemented universal screening of endometrial cancer (EC) hysterectomy specimens by mismatch repair immunohistochemistry (IHC) with reflex MLH1 promoter hypermethylation analysis for tumors with loss of MLH1/PMS2 expression. Patients with tumors negative for MLH1 methylation and those with a loss of the heterodimer pair MSH2 and MSH6, or isolated loss of either PMS2 or MSH6 were referred to the Familial Cancer Program for genetic counseling and consideration of germline testing. Between May 2015 to Dec 2016, 233 EC patients were screened by IHC for LS with a median age of 63 years. Sixty tumors (27%) had abnormal IHC staining results. Fifty-one (22%) harbored heterodimeric loss of MLH1 and PMS2, 49 of which showed MLH1 promoter methylation (1 failure, 1 negative). One showed loss of MLH1/PMS2 and MSH6, 2 showed loss of MSH2/MSH6, and 6 had isolated loss of MSH6 only. Ten patients underwent genetic counseling, and germline testing was performed in 8; LS was confirmed in 5 patients (2.1%). In addition, 3 patients with negative germline testing and presumed Lynch-like syndrome were identified and offered additional somatic testing. Universal screening for LS in EC patients has yielded positive results for identification of patients at risk for this inherited syndrome.

Germline mutations of the DNA repair pathways in uterine serous carcinoma

OBJECTIVE

Treatment options are limited for patients with uterine serous carcinoma (USC). Knowledge of USC's somatic mutation landscape is rapidly increasing, but its role in hereditary cancers remains unclear. We aim to evaluate the frequency and characteristics of germline mutations in genes commonly implicated in carcinogenesis, including those within homologous recombination (HR) and mismatch repair (MMR) pathways in patients with pure USC.

METHODS

By using targeted capture exome sequencing, 43 genes were analyzed in a cohort of 7 consecutive patients with paired tumor and non-tumor USC samples in our institutional tumor repository. Mutations predicted to have damaging effects on protein function are validated by Sanger Sequencing.

RESULTS

We found 21 germline mutations in 11 genes in our USC cohort. Five patients harbored 7 germline mutations (33.3%) within genes involved in the HR pathway, RAD51D being the most common. Four patients had 9 (42.8%) germline mutations in hereditary colon cancer genes, most commonly MLH. All patients (42.7%) who are platinum-sensitive had HR germline mutations (RAD50, NBN, ATM). Patients with HER2 overexpression (2/7, 28.6%) had germline HR mutations and were platinum-sensitive. Three patients in our cohort reported a personal history of breast cancer, one with HR germline mutation, and 2 in patients with germline mutations in HCC genes. In addition, 5 out of 7 patients had germline mutations in genes associated with growth factor signaling pathway.

CONCLUSIONS

A significant proportion of our cohort harbor germline mutations in DNA repair genes. This may be associated with the high rate of breast cancer in our patients and their family, and suggests a targeted cohort for genetic counseling. If validated in a larger cohort, our findings may allow clinicians to expand therapeutic options to include targeted therapies and inclusion of USC patient in preventative and genetic counseling.

Discordant Mismatch Repair Protein Immunoreactivity in Lynch Syndrome-Associated Neoplasms: A Recommendation for Screening Synchronous/Metachronous Neoplasms

OBJECTIVES

Lynch syndrome (LS) predisposes individuals to developing synchronous and metachronous LS-associated neoplasms (LSANs). Mismatch repair protein (MMRP) immunohistochemistry (IHC) is widely used to identify LS, but its utility in patients with synchronous/metachronous lesions has not been studied. We studied MMRP IHC in patients with LS with more than one LSAN to provide screening recommendations in patients with synchronous/metachronous neoplasms.

METHODS

All patients with LS diagnosed at The Ohio State University Wexner Medical Center from 2009 through 2014 with more than one LSAN and available tumor tissue for immunostaining were identified. Tumors were stained for MLH1, MSH2, MSH6, and PMS-2 proteins, and immunoreactivity was scored as intact or lost.

RESULTS

Thirteen patients with LS with 29 synchronous and/or metachronous primary LSANs were identified. Neoplasms involved large and small intestine (n = 19), ampulla (n = 1), endometrium (n = 1), and skin (sebaceous neoplasms, n = 8). Nine (69%) of 13 patients showed concordant MMRP results in all tumors, and four (31%) showed discordant MMRP results.

CONCLUSIONS

LS diagnosis could have been missed in 31% of the study cases if only the LSAN exhibiting intact MMRP expression was screened. Accordingly, our findings support the recommendation to perform LS screening in all primary, synchronous, and metachronous intestinal and endometrial cancers if a previous tumor screened intact.

Lynch Syndrome: Female Genital Tract Cancer Diagnosis and Screening

Lynch syndrome is responsible for approximately 5% of endometrial cancers and 1% of ovarian cancers. The molecular basis for Lynch syndrome is a heritable functional deficiency in the DNA mismatch repair system, typically due to a germline mutation. This review discusses the rationales and relative merits of current Lynch syndrome screening tests for endometrial and ovarian cancers and provides pathologists with an informed algorithmic approach to Lynch syndrome testing in gynecologic cancers. Pitfalls in test interpretation and strategies to resolve discordant test results are presented. The potential role for next-generation sequencing panels in future screening efforts is discussed.

Laboratory Assays in Evaluation of Lynch Syndrome in Patients with Endometrial Carcinoma

This article reviews the main tissue testing modalities for Lynch Syndrome in the pathology laboratory, such as immunohistochemistry and PCR based analyses, and discusses their routine application, interpretation pitfalls, and troubleshooting of common technical performance issues. Discrepancies between laboratory and genetic testing may arise, and are examined in the context of the complexity of molecular abnormalities associated with Lynch Syndrome. The merits of targeted versus universal screening in a changing healthcare climate are addressed. In the absence of comprehensive screening programs, specific tumor topography and histological features that may prompt pathologist-initiated molecular tumor testing are outlined.

Mismatch repair deficiency testing in clinical practice

Lynch syndrome, an autosomal dominant inherited disorder, is caused by inactivating mutations involving DNA mismatch repair (MMR) genes. This leads to profound genetic instability, including microsatellite instability (MSI) and increased risk for cancer development, particularly colon and endometrial malignancies. Clinical testing of tumor tissues for the presence of MMR gene deficiency is standard practice in clinical oncology, with immunohistochemistry and PCR-based microsatellite instability analysis used as screening tests to identify potential Lynch syndrome families. The ultimate diagnosis of Lynch syndrome requires documentation of mutation within one of the four MMR genes (MLH1, PMS2, MSH2 and MSH6) or EPCAM, currently achieved by comprehensive sequencing analysis of germline DNA. In this review, the genetic basis of Lynch syndrome, methodologies of MMR deficiency testing, and current diagnostic algorithms in the clinical management of Lynch syndrome, are discussed.

Targeted Screening With Combined Age- and Morphology-Based Criteria Enriches Detection of Lynch Syndrome in Endometrial Cancer

Endometrial cancer is associated with Lynch syndrome in 2% to 6% of cases. Adequate screening may prevent of a second cancer and incident cancers in family members via risk-reducing strategies. The goal of the study was to evaluate the detection rate of Lynch syndrome via a targeted screening approach. In 2009, we incorporated targeted Lynch syndrome screening via immunohistochemistry for MLH1, PMS2, MSH2, and MSH6, followed by MLH1 promoter hypermethylation, in select cases of endometrial carcinoma. Criteria for patient selection included (1) all patients <50 years; (2) patients of any age with tumors showing features of microsatellite instability (lower uterine segment-centered tumors, hard to classify carcinomas, increased peritumoral or tumor infiltrating lymphocytes and cases with synchronous ovarian carcinomas); (3) clinician's request based on family or personal history; and (4) ad hoc retrospective testing based on the established criteria on patients discovered on follow-up visits. By using a targeted screening approach in a 4.5-year period, approximately 2.1% of endometrial cancers (7 of 328) were potentially associated with Lynch syndrome. Therefore, targeted screening with combined age and morphology based criteria enriches detection of Lynch syndrome in endometrial cancer. However, the detection rate is lower than the rates from published series that offer universal screening.

Targeted next-generation sequencing of 22 mismatch repair genes identifies Lynch syndrome families

Causative germline mutations in mismatch repair (MMR) genes can only be identified in ~50% of families with a clinical diagnosis of the inherited colorectal cancer (CRC) syndrome hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch syndrome (LS). Identification of these patients are critical as they are at substantially increased risk of developing multiple primary tumors, mainly colorectal and endometrial cancer (EC), occurring at a young age. This demonstrates the need to develop new and/or more thorough mutation detection approaches. Next‐generation sequencing (NGS) was used to screen 22 genes involved in the DNA MMR pathway in constitutional DNA from 14 HNPCC and 12 sporadic EC patients, plus 2 positive controls. Several softwares were used for analysis and functional annotation. We identified 5 exonic indel variants, 42 exonic nonsynonymous single‐nucleotide variants (SNVs) and 1 intronic variant of significance. Three of these variants were class 5 (pathogenic) or class 4 (likely pathogenic), 5 were class 3 (uncertain clinical relevance) and 40 were classified as variants of unknown clinical significance. In conclusion, we have identified two LS families from the sporadic EC patients, one without a family history of cancer, supporting the notion for universal MMR screening of EC patients. In addition, we have detected three novel class 3 variants in EC cases. We have, in addition discovered a polygenic interaction which is the most likely cause of cancer development in a HNPCC patient that could explain previous inconsistent results reported on an intronic EXO1 variant.

Methyltransferase expression and tumor suppressor gene methylation in sporadic and familial colorectal cancer

Molecular mechanisms underlying coordinated hypermethylation of multiple CpG islands in cancer remain unclear and studies of methyltransferase enzymes have arrived at conflicting results. We focused on DNMT1 and DNMT3B, DNA methyltransferases responsible for (de novo) methylation, and EZH2, histone (H3K27) methyltransferase, and examined their roles in tumor suppressor gene (TSG) methylation patterns we have previously established in sporadic and familial cancers. Our investigation comprised 165 tumors, stratified by tissue of origin (117 colorectal and 48 endometrial carcinomas) and sporadic vs. familial disease (57 sporadic vs. 60 familial, mainly Lynch syndrome, colorectal carcinomas). By immunohistochemical evaluation, EZH2 protein expression was associated with a TSG methylator phenotype. DNMT1, DNMT3B, and EZH2 were expressed at significantly higher levels in tumor vs. normal tissues. DNMT1 and EZH2 expression were positively correlated and higher in microsatellite-unstable vs. microsatellite-stable tumors, whether sporadic or hereditary. Ki-67 expression mirrored the same pattern. Promoter methylation of the methyltransferase genes themselves was addressed as a possible cause behind their altered expression. While DNMT1 or EZH2 did not show differential methylation between normal and tumor tissues, DNMT3B analysis corroborated the regulatory role of a distal promoter region. Our study shows that methyltransferase expression in cancer depends on the tissue of origin, microsatellite-instability status, cellular proliferation, and--in the case of DNMT3B--promoter methylation of the respective gene. Translation of methyltransferase expression into DNA methylation appears complex as suggested by the fact that except for EZH2, no clear association between methyltransferase protein expression and TSG methylation was observed.

Combined Microsatellite Instability, MLH1 Methylation Analysis, and Immunohistochemistry for Lynch Syndrome Screening in Endometrial Cancers From GOG210: An NRG Oncology and Gynecologic Oncology Group Study

PURPOSE

The best screening practice for Lynch syndrome (LS) in endometrial cancer (EC) remains unknown. We sought to determine whether tumor microsatellite instability (MSI) typing along with immunohistochemistry (IHC) and MLH1 methylation analysis can help identify women with LS.

PATIENTS AND METHODS

ECs from GOG210 patients were assessed for MSI, MLH1 methylation, and mismatch repair (MMR) protein expression. Each tumor was classified as having normal MMR, defective MMR associated with MLH1 methylation, or probable MMR mutation (ie, defective MMR but no methylation). Cancer family history and demographic and clinical features were compared for the three groups. Lynch mutation testing was performed for a subset of women.

RESULTS

Analysis of 1,002 ECs suggested possible MMR mutation in 11.8% of tumors. The number of patients with a family history suggestive of LS was highest among women whose tumors were classified as probable MMR mutation (P = .001). Lynch mutations were identified in 41% of patient cases classified as probable mutation (21 of 51 tested). One of the MSH6 Lynch mutations was identified in a patient whose tumor had intact MSH6 expression. Age at diagnosis was younger for mutation carriers than noncarriers (54.3 v 62.3 years; P < .01), with five carriers diagnosed at age > 60 years.

CONCLUSION

Combined MSI, methylation, and IHC analysis may prove useful in Lynch screening in EC. Twenty-four percent of mutation carriers presented with ECs at age > 60 years, and one carrier had an MSI-positive tumor with no IHC defect. Restricting Lynch testing to women diagnosed at age < 60 years or to women with IHC defects could result in missing a substantial fraction of genetic disease.

Screening for Lynch syndrome among patients with newly diagnosed endometrial cancer: a comprehensive review

Lynch syndrome (LS) is an autosomal dominant condition characterized by an increased risk of hereditary colorectal, endometrial, ovarian, pancreatic, urinary tract, and gastric cancer.It is estimated that around 5% of all endometrial cancer (EC) cases are due to an inherited predisposition, of which LS might be the most frequent. The lifetime risk of developing EC in women with LS ranges between 40% and 71% depending on the type of mutation. In many cases, this risk may even exceed their risk of developing colon cancer. Moreover, in 60% of these women, EC will be the first primary malignancy diagnosed and the sentinel diagnosis of the syndrome. Therefore, it is essential to identify which women with EC have LS in order to allow implementation of individualized screening and preventive strategies.

Impact of an immunohistochemistry-based universal screening protocol for Lynch syndrome in endometrial cancer on genetic counseling and testing

OBJECTIVE

Evaluate effects of a Lynch syndrome universal screening protocol in newly diagnosed endometrial cancers on subsequent genetic counseling (GC) and germline testing (GT) referral and acceptance rates.

METHODS

We performed a retrospective cohort study of women who underwent a hysterectomy for endometrial cancer at Barnes Jewish Hospital in St. Louis, MO between 1/1/2011 and 12/31/2013 (n=637). An immunohistochemistry-based (IHC) universal screening protocol for Lynch syndrome was initiated on 12/17/2012. The cohorts consisted of women presenting prior to (Pre-Em-USP; n=395) and those presenting following (Em-USP; n=242) initiation of the universal screening protocol. GC and GT referrals were based on risk factors and/or IHC results. Comparisons were made using the Fisher's exact test and the Kruskal-Wallis test.

RESULTS

A greater proportion of individuals in the Em-USP cohort underwent GT than in Pre-Em-USP (9.1% vs 4.8%, p<0.05). Of individuals with an IHC screening result suggestive of LS, those within the Em-USP cohort were significantly more likely to accept GC compared to those in the Pre-Em-USP cohort (95% vs 64%, p=0.02). Specifically within the Em-USP cohort, patients referred to GC due to a concerning IHC screening result, versus those who were referred based on other risk factors, had a higher counseling acceptance rate (95% vs 61%, p=0.03) and underwent genetic testing more readily (76% vs 30%, p<0.001).

CONCLUSIONS

Implementation of an IHC-based universal screening protocol for LS in endometrial cancer leads to higher acceptance of genetic counseling and higher rates of genetic testing compared to referral based on risk factors alone.

Lynch syndrome screening should be considered for all patients with newly diagnosed endometrial cancer

Lynch syndrome (LS) is an autosomal dominant inherited disorder caused by germline mutations in DNA mismatch repair (MMR) genes. Mutation carriers are at substantially increased risk of developing cancers of the colorectum and endometrium, among others. Given recent recommendations for universal, cost-effective screening of all patients with newly diagnosed colorectal cancer using MMR protein immunohistochemistry, we evaluated MMR protein expression in a series of endometrial cancers in the general population. A total of 605 consecutive cases of primary endometrial cancer at a single institution (1997 to 2013) were evaluated regardless of age, family history, or histologic features. Evaluation methods consisted of immunohistochemistry for the MMR proteins MLH1, MSH2, MSH6, and PMS2, followed by DNA methylation analysis for cases with MLH1/PMS2 deficiency. Germline mutation testing was performed on a subset of cases. Forty MMR-deficient, nonmethylated endometrial cancers were identified: 3 MLH1/PMS2 and 37 MSH6/MSH2 protein deficiencies. Only 25% occurred in women below 50 years of age (range, 39 to 88 y), 1 of which was in a risk-reducing hysterectomy specimen. Only 15% of patients had a prior history of carcinoma, including only 2 patients with prior colorectal carcinoma. Most (80%) of the endometrial cancers were purely endometrioid; there were 2 mixed endometrioid/mucinous, 1 mucinous, 1 serous, 2 clear cell, and 2 carcinosarcoma cases. When grading was applicable, 40% of the endometrial malignancies were FIGO grade 1, 34% grade 2, and 26% grade 3. Thirteen percent arose in the lower uterine segment, and 23% had tumor-infiltrating lymphocytes. Of the tumors with known germline testing, 41% with a LS-associated germline mutation were not associated with any of the traditional indicators that have been recommended for LS screening (ie, age 50 y or younger, personal/family cancer pedigree that meets Bethesda guideline criteria, presence of MMR-associated tumor morphology, or location in the lower uterine segment). These data suggest that a significant number of LS-associated endometrial carcinomas are missed using clinical, histologic, and locational screening parameters and provide support for universal screening of all newly diagnosed endometrial cancers.

Familial cancer among consecutive uterine cancer patients in Sweden

Background

Uterine cancer (UC) represents 5.1% of all female malignancies in Sweden. Accumulation of UC in families occurs in around 5% of cases. We wanted to identify any familial association between UC and other selected cancers and to study the frequency of Lynch,Cowden and cancer syndromes among consecutive UC patients in Sweden.

Methods

481 UC patients were included. Information on the cancer diagnoses of their relatives (first- (FDRs) and second-degree (SDRs) relatives and first cousins) was obtained. The relative frequencies of different cancers among relatives were compared to those in the Swedish general cancer population in 1970 and 2010. Families that fulfilled the criteria for hereditary cancer syndromes were tested for mutations in the causative genes. Families with at least one case of UC in addition to the index patient were compared to families with no additional cases to investigate possible characteristics of putative hereditary cancer syndromes.

Results

There was an increased prevalence of UC in our study population compared to the Swedish general cancer population in 1970 and 2010 (6% vs. 4% and 3%, respectively). Seven families had Lynch Syndrome according to the Amsterdam II criteria. No families fulfilled the criteria for Cowden syndrome. In total 13% of index patients had at least one relative with UC and these families tended to have more cases of early onset cancer among family members. In addition, 16% of index patients were diagnosed with at least one other cancer. No families fulfilled the criteria for Cowden syndrome.

Conclusion

We showed a familial clustering of UC among relatives of our index patients. Of the seven families with mutation-verified Lynch Syndrome, only one had been previously diagnosed, highlighting the need to increase gynecologists’ awareness of the importance of taking family history. Our data on multiple cancers and young age of onset in families with uterine cancer is compatible with the existence of additional hereditary uterine cancer syndromes.

Role of the clinical pathology laboratory in the evaluation of endometrial carcinomas for Lynch syndrome

Molecular diagnostic testing of endometrial carcinomas in the pathology laboratory has recently emerged as a key component of the clinical evaluation of Lynch syndrome in many centers. Testing modalities involve immunohistochemical and PCR-based analyses. This article outlines the routine application of these analyses, provides a practical guide for troubleshooting some of the common technical issues related to their performance, and reviews common pitfalls in their interpretation. Discrepancies between tissue testing and genetic testing results are discussed in the context of the current understanding of endometrial cancer biology. The merits of universal versus targeted tissue testing based on clinical patient history and histological tumor appearance are also addressed.

Does risk of endometrial cancer for women without a germline mutation in a DNA mismatch repair gene depend on family history of endometrial cancer or colorectal cancer?

OBJECTIVE

To determine whether risk of endometrial cancer for women without a germline mutation in a DNA mismatch repair (MMR) gene depends on family history of endometrial or colorectal cancer.

METHODS

We retrospectively followed a cohort of 79,166 women who were recruited to the Colon Cancer Family Registry, after exclusion of women who were relatives of a carrier of a MMR gene mutation. The Kaplan-Meier failure method was used to estimate the cumulative risk of endometrial cancer. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for association between family history of endometrial or colorectal cancer and risk of endometrial cancer.

RESULTS

A total of 628 endometrial cancer cases were observed, with mean age at diagnosis of 54.4 (standard deviation: 15.7) years. The cumulative risk of endometrial cancer to age 70 years was estimated to be 0.94% (95% CI 0.83-1.05) for women with no family history of endometrial cancer, and 3.80% (95% CI 2.75-4.98) for women with at least one first- or second-degree relative with endometrial cancer. Compared with women without family history, we found an increased risk of endometrial cancer for women with at least one first- or second-degree relative with endometrial cancer (HR 3.66, 95% CI 2.63-5.08), and for women with one first-degree relative with colorectal cancer diagnosed at age <50 years (HR 1.48, 95% CI 1.15-1.91).

CONCLUSION

An increased risk of endometrial cancer is associated with a family history of endometrial cancer or early-onset colorectal cancer for women without a MMR gene mutation, indicating for potential underlying genetic and environmental factors shared by colorectal and endometrial cancers other than caused by MMR gene mutations.

Epigenetic mechanisms in the pathogenesis of Lynch syndrome

Inherited defects in the DNA mismatch repair (MMR) system, MLH1, MSH2, MSH6, and PMS2 genes, underlie Lynch syndrome, one of the most prevalent cancer syndromes in man. The syndrome offers a model for cancers arising through MMR defects and microsatellite instability, which applies to ~ 15% of all colorectal, endometrial, and other cancers. Lynch syndrome also illustrates the significance of the epigenetic component in cancer development. Inactivation of tumor suppressor genes by epigenetic mechanisms is an acquired property of many tumors developing in Lynch syndrome. Furthermore, constitutional epimutations of MMR genes may explain a proportion of mutation-negative families lacking MLH1 or MSH2 protein expression in tumor tissue. This review provides an update of the molecular basis of Lynch syndrome by focusing on the role of epigenetic mechanisms in the pathogenesis of the disease.