Prevalence of defective DNA mismatch repair and MSH6 mutation in an unselected series of endometrial cancers

Are all mismatch repair deficient endometrial cancers created equal? A large, retrospective, tertiary center experience

BACKGROUND

One third of endometrial carcinomas (ECs) presents with mismatch repair deficiency (MMRd). Of these, 70 % are caused by somatic hypermethylation of MLH1 promoter; the remaining cases are determined by Lynch syndrome or double somatic inactivation of MMR genes. Although associated with good-intermediate prognosis, heterogeneity in treatment response and survival has been reported among MMRd ECs. We aim to investigate differences in pathologic aggressiveness and event-free survival (EFS) among three MMRd EC subtypes, classified by immunohistochemistry (IHC) and MLH1 methylation analysis.

METHODS

Subjects undergone surgical staging for EC were retrospectively included. IHC analysis was performed in all patients to assess MMR and p53 status. Methylation analysis was performed in MMRd patients with IHC-negative MLH1. The MMRd population was classified into: 1)MLH1-hypermethylated (MLH1-HyMet); 2)MLH1-unmethylated (MLH1-UnMet); 3)IHC-negative MSH2 and/or MSH6 or PMS2 alone (non-MLH1).

RESULTS

Of 1171 patients undergoing surgical staging and IHC assessment, 362 (30.9 %) were classified as MMRd and included in the analysis. Among these, 59.7 % (n = 216) were MLH1-HyMet, 11 % (n = 40) MLH1-UnMet, and 29.3 % (n = 106) non-MLH1. Compared to MLH1-UnMet and non-MLH1, MLH1-HyMet was associated with older age, higher BMI, larger tumor size, deeper myometrial invasion, substantial lymphovascular space invasion, lower frequency of early-stage and low-risk disease. EFS was similar when comparing the MMRd subtypes, even after adjusting for stage and tumor histology. However, a trend of MLH1-HyMet toward poorer prognosis can be observed, particularly in the advanced/metastatic setting.

CONCLUSIONS

MLH1-hypermethylated MMRd ECs display more aggressive clinicopathologic features compared to the other MMRd subgroups. However, although a suggestive trend toward poorer EFS was observed in the hypermethylated subset, particularly in the advanced setting, no significant differences in prognosis were detected among the MMRd subtypes.

Coexisting germline variants of MLH1 and MSH6 in a patient with Lynch syndrome who had uterine and ovarian cancer

Lynch syndrome is an autosomal dominant disorder caused by a heterozygous pathogenic germline variant in mismatch repair (MMR) genes including MLH1, MSH2, MSH6, PMS2, and EPCAM. This disease often causes a familial cluster of patients with malignant tumors. In this report, we describe a 37-year-old woman who presented with endometrioid carcinoma in the ovary and uterine corpus associated with Lynch syndrome. She carried two germline pathogenic variants, a recurrently reported MLH1 c.2250C > G (p.Tyr750*) and a previously unreported MSH6 c.2385del (p.Ile795Metfs*15). The tumor cells showed microsatellite instability. Immunohistochemistry for the endometrial tumor showed decreased MLH1 expression, loss of PMS2 expression, retained MSH2 expression, and loss of MSH6 expression, which suggests that both variants impair each protein stability and thus cause MMR deficiency. Whether these variants were inherited from her parents or occurred de novo was unknown. The tumor cells had somatic variants BRCA1 c.1016del and BRCA2 c.36dupT that might be due to secondary mutation by MMR deficiency. The use of an immune checkpoint inhibitor pembrolizumab resulted in durable partial response of metastatic lung tumors. This case reminds clinicians of the rare possibility of multiple germline variants in MMR genes in individuals with Lynch syndrome.

Molecular and clinical insights into early-onset endometrial cancer

The global incidence of endometrial cancer is on the rise, marked by a notable surge in early-onset endometrial cancer (EOEC; age at diagnosis <50 years). By contrast to late-onset cases, EOEC displays distinct clinical, pathological, and molecular characteristics. The enhanced understanding of the disease's pathophysiology, enabling a more precise differentiation between low-risk and high-risk patients, could facilitate the establishment of risk-stratified treatments that preserve ovarian function and fertility in low-risk EOEC cases. In this review, we delve into the distinctive epidemiological, molecular, and clinical characteristics of EOEC, as well as early noninvasive screening and fertility preservation treatments.

Altered chromatin landscape and 3D interactions associated with primary constitutional MLH1 epimutations

BACKGROUND

Lynch syndrome (LS), characterised by an increased risk for cancer, is mainly caused by germline pathogenic variants affecting a mismatch repair gene (MLH1, MSH2, MSH6, PMS2). Occasionally, LS may be caused by constitutional MLH1 epimutation (CME) characterised by soma-wide methylation of one allele of the MLH1 promoter. Most of these are "primary" epimutations, arising de novo without any apparent underlying cis-genetic cause, and are reversible between generations. We aimed to characterise genetic and gene regulatory changes associated with primary CME to elucidate possible underlying molecular mechanisms.

METHODS

Four carriers of a primary CME and three non-methylated relatives carrying the same genetic haplotype were included. Genetic alterations were sought using linked-read WGS in blood DNA. Transcriptome (RNA-seq), chromatin landscape (ATAC-seq, H3K27ac CUT&Tag) and 3D chromatin interactions (UMI-4C) were studied in lymphoblastoid cell lines. The MLH1 promoter SNP (c.-93G > A, rs1800734) was used as a reporter in heterozygotes to assess allele-specific chromatin conformation states.

RESULTS

MLH1 epimutant alleles presented a closed chromatin conformation and decreased levels of H3K27ac, as compared to the unmethylated allele. Moreover, the epimutant MLH1 promoter exhibited differential 3D chromatin contacts, including lost and gained interactions with distal regulatory elements. Of note, rare genetic alterations potentially affecting transcription factor binding sites were found in the promoter-contacting region of CME carriers.

CONCLUSIONS

Primary CMEs present allele-specific differential interaction patterns with neighbouring genes and regulatory elements. The role of the identified cis-regulatory regions in the molecular mechanism underlying the origin and maintenance of CME requires further investigation.

Universal testing in endometrial cancer in Sweden

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.

Characterization of mismatch-repair/microsatellite instability-discordant endometrial cancers

BACKGROUND

Mismatch-repair (MMR)/microsatellite instability (MSI) status has therapeutic implications in endometrial cancer (EC). The authors evaluated the concordance of testing and factors contributing to MMR expression heterogeneity.

METHODS

Six hundred sixty-six ECs were characterized using immunohistochemistry (IHC), MSI testing, and mut-L homolog 1 (MLH1) methylation. Select samples underwent whole-transcriptome analysis and next-generation sequencing. MMR expression of metastatic/recurrent sites was evaluated.

RESULTS

MSI testing identified 27.3% of cases as MSI-high (n = 182), MMR IHC identified 25.1% cases as MMR-deficient (n = 167), and 3.8% of cases (n = 25) demonstrated discordant results. A review of IHC staining explained discordant results in 18 cases, revealing subclonal loss of MLH1/Pms 1 homolog 2 (PMS2) (n = 10) and heterogeneous MMR IHC (mut-S homolog 6 [MSH6], n = 7; MLH1/PMS2, n = 1). MSH6-associated Lynch syndrome was diagnosed in three of six cases with heterogeneous expression. Subclonal or heterogeneous cases had a 38.9% recurrence rate (compared with 16.7% in complete MMR-deficient cases and 9% in MMR-proficient cases) and had abnormal MMR IHC results in all metastatic recurrent sites (n = 7). Tumors with subclonal MLH1/PMS2 demonstrated 74 differentially expressed genes (determined using digital spatial transcriptomics) when stratified by MLH1 expression, including many associated with epithelial-mesenchymal transition.

CONCLUSIONS

Subclonal/heterogeneous MMR IHC cases showed epigenetic loss in 66.7%, germline mutations in 16.7%, and somatic mutations in 16.7%. MMR IHC reported as intact/deficient missed 21% of cases of Lynch syndrome. EC with subclonal/heterogeneous MMR expression demonstrated a high recurrence rate, and metastatic/recurrent sites were MMR-deficient. Transcriptional analysis indicated an increased risk for migration/metastasis, suggesting that clonal MMR deficiency may be a driver for tumor aggressiveness. Reporting MMR IHC only as intact/deficient, without reporting subclonal and heterogeneous staining, misses opportunities for biomarker-directed therapy.

PLAIN LANGUAGE SUMMARY

Endometrial cancer is the most common gynecologic cancer, and 20%-40% of tumors have a defect in DNA proofreading known as mismatch-repair (MMR) deficiency. These results can be used to guide therapy. Tests for this defect can yield differing results, revealing heterogeneous (mixed) proofreading capabilities. Tumors with discordant testing results and mixed MMR findings can have germline or somatic defects in MMR genes. Cells with deficient DNA proofreading in tumors with mixed MMR findings have DNA expression profiles linked to more aggressive characteristics and cancer spread. These MMR-deficient cells may drive tumor behavior and the risk of spreading cancer.

Japanese Society of Medical Oncology/Japan Society of Clinical Oncology/Japanese Society of Pediatric Hematology/Oncology-led clinical recommendations on the diagnosis and use of immunotherapy in patients with DNA mismatch repair deficient (dMMR) tumors, third edition

BACKGROUND

Clinical trials have reported the efficacy of immune checkpoint inhibitors in the treatment of mismatch repair-deficient (dMMR) advanced solid tumors. The accumulated evidence of tumor agnostic agent has been made since PD-1 inhibitor was approved and used in clinical practice. Therefore, we have revised the guideline "Japan Society of Clinical Oncology provisional clinical opinion for the diagnosis and use of immunotherapy in patients with deficient DNA mismatch repair tumors, cooperated by Japanese Society of Medical Oncology, First Edition".

METHODS

Clinical questions regarding medical care were formulated for patients with dMMR advanced solid tumors. Relevant publications were searched by PubMed and Cochrane Database. Critical publications and conference reports were added manually. Systematic reviews were performed for each clinical question for the purpose of developing clinical recommendations. The committee members identified by Japan Society of Clinical Oncology (JSCO), Japanese Society of Medical Oncology (JSMO), and Japanese society of pediatric hematology/oncology (JSPHO) voted to determine the level of each recommendation considering the strength of evidence, expected risks and benefits to patients, and other related factors. Thereafter, a peer review by experts nominated from JSCO, JSMO, and JSPHO and the public comments among all societies' members were done.

RESULTS

The current guideline describes two clinical questions and eight recommendations for whom, when, and how MMR status should be tested.

CONCLUSION

In this guideline, the committee proposed eight recommendations for performing MMR testing properly to select patients who are likely to benefit from immunotherapy.

A retrospective study of consistency between immunohistochemistry and polymerase chain reaction of microsatellite instability in endometrial cancer

Objectives

Identification of endometrial cancers (EC) with mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H) is essential for Lynch syndrome screening and treatment stratification. We aimed to assess the utility of immunohistochemistry (IHC) staining for MMR protein expression and polymerase chain reaction (PCR)-based MSI assays in EC and the correlation between MMR/MSI status and various clinicopathological parameters.

Methods

We reviewed the clinical and pathological information of 333 patients with EC. MMR protein expression was assessed as retained or lost to determine MMR status by IHC staining, and MSI status was identified by PCR capillary electrophoresis (PCR-CE) testing with a National Cancer Institute (NCI) panel. The correlation of MMR/MSI status with clinicopathological features was determined by statistical analysis. Discrepant results were further analyzed using an alternative PCR-CE MSI (Promega panel) method, MLH1 promoter methylation assays, and next-generation sequencing (NGS).

Results

Among the EC patients, the overall percentage of dMMR was 25.2%, and the overall percentage of MSI-H was 24%. Among the dMMR patients, 50 (59.5%) showed loss of MLH1 and PMS2 expression, 19 (22.6%) loss of MSH2 and MSH6 expression, and seven (8.3%) and eight (9.5%) loss of PMS2 and MSH6 expression, respectively. The dMMR subgroup was significantly younger than the pMMR subgroup, especially for <60-years-old patients (p = 0.038). In addition, we identified a strong correlation between MMR/MSI status and high-grade endometrioid or nonendometrioid components (p = 0.004 or p = 0.003). IHC staining and PCR-CE assay results showed a high level of overall concordance (98.8%, Cohen's κ = 0.98). Four patients were found to have dMRR/MSS in both examinations. We reanalyzed them with additional methods. One case showed MLH1 promotor methylation, and the other three cases harbored MSH6 germline pathogenic variations. One of the cases with MSH6 deficiency was reanalyzed as MSI-H by alternative PCR-CE assay or NGS testing.

Conclusions

This study indicates that the combined use of MMR-IHC and PCR-CE MSI analyses may effectively avoid misdiagnoses of EC patients with dMMR/MSI-H. However, use of PCR-CE alone to evaluate MMR/MSI status may lead to missed diagnosis, especially for EC patients with MSH6 deficiency and presenting MSS.

Alternative splicing of PSMD13 mediated by genetic variants is significantly associated with endometrial cancer risk

OBJECTIVE

Accumulating evidence has shown that aberrant alternative splicing events are closely associated with the onset and development of cancer. However, whether genetic variants-associated alternative splicing is linked to risk of endometrial cancer remains largely uncertain.

METHODS

We identified single nucleotide polymorphisms (SNPs) locates in the splicing number trait locus (sQTL) of endometrial cancer using the CancerSplicing QTL database. In parallel with bioinformatics analysis, we conducted a case-control study comprising 2,000 cases and 2,013 controls to assess the association between identified SNP which possesses mRNA splicing function and endometrial cancer susceptibility. Furthermore, we used the Kaplan-Meier Plotter, The Human Protein Atlas, SPNR, and Spliceman2 databases for sQTL and differential gene expression analyses to identify the genetic variant which most potentially influence the risk of endometrial cancer through alternative splicing to reveal the potential mechanism by which candidate SNPs regulate the risk of endometrial cancer.

RESULTS

The results indicated that SNP rs7128029 A

CONCLUSION

These findings suggest that SNP rs7128029-mediated alternative splicing events in PSMD13 are associated with endometrial cancer risk and may be a potential early screening biomarker for endometrial cancer-susceptible populations.

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Key Words

• 26S Proteasome Non-ATPase Regulatory Subunit 13
• Alternative Splicing
• Endometrial Cancer
• Single Nucleotide Polymorphism

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MESH Headings

• Female
• Humans
• Alternative Splicing/genetics
• Case-Control Studies
• Databases, Factual
• Endometrial Neoplasms/genetics
• Odds Ratio
• Risk
• Polymorphism, Single Nucleotide

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Grants

• (2022)626 Natural Science Foundation of Guangzhou City
• (2022)402 Zunyi City Science and Technology Plan Project
• 2018 F-913 Zunyi Medical University

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Affiliation(s)

Sisi He Department of Oncology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
Rong Cao The Second Clinical College, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
Yan Mao Department of Oncology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
Na Li Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
Yanzhe Wang Department of Oncology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
Hu Ma Department of Oncology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
Kunming Tian Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China Department of Preventive Medicine, School of Public Health, Zunyi Medical University, Zunyi, China.

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Clinicopathologic significance of DNA mismatch repair protein status in endometrial cancer

OBJECTIVE

The prognostic implications of DNA mismatch repair protein (MMRP) have not been determined in endometrial cancer. Therefore, in this study, we aimed to evaluate the clinicopathologic characteristics of DNA MMRP deficiency in endometrial cancer.

MATERIALS AND METHODS

We examined the MMRP status of 206 patients with endometrial carcinomas, using immunohistochemistry, and analyzed their clinicopathologic factors and survival outcomes stratified by MMRP status using the Kaplan-Meier method and Cox regression analysis.

RESULTS

Forty-three cases were deficient for at least one MMRP (20.9%). Loss of MLH1 was the most common (13.1%), followed by MSH6 (7.8%). MMRP deficiency was significantly associated with lympho-vascular space invasion, deep myometrial invasion, and adjuvant treatment (P = 0.032, 0.041, and 0.047, respectively). MMRP-deficient patients had a better overall survival (OS), particularly at advanced cancer stages (III/IV) (100% vs. 73.7%, P = 0.170) or if they had received adjuvant treatment (100% vs. 86.7%, P = 0.087).

CONCLUSION

Although MMRP deficiency was associated with unfavorable prognostic risk factors in endometrial cancer, we found a trend in favor of OS in MMRP-deficient patients. More studies are needed to confirm its prognostic implication.

Up-Front Multigene Panel Testing for Cancer Susceptibility in Patients With Newly Diagnosed Endometrial Cancer: A Multicenter Prospective Study

PURPOSE

Clinical utility of up-front multigene panel testing (MGPT) is directly related to the frequency of pathogenic variants (PVs) in the population screened and how genetic findings can be used to guide treatment decision making and cancer prevention efforts. The benefit of MGPT for many common malignancies remains to be determined. In this study, we evaluated up-front MGPT in unselected patients with endometrial cancer (EC) to determine the frequency of PVs in cancer susceptibility genes.

METHODS

Patients with EC were prospectively enrolled at nine Ohio institutions from October 1, 2017, to December 31, 2020. Nine hundred and sixty-one patients with newly diagnosed EC underwent clinical germline MGPT for 47 cancer susceptibility genes. In addition to estimating the prevalence of germline PVs, the number of individuals identified with Lynch syndrome (LS) was compared between MGPT and tumor-based screening.

RESULTS

Likely pathogenic variants or PVs were identified in 97 of 961 women (10.1%). LS was diagnosed in 29 of 961 patients (3%; 95% CI, 2.1 to 4.3), with PVs in PMS2 most frequent. MGPT revealed nine patients with LS in addition to the 20 identified through routine tumor-based screening. BRCA1 and BRCA2 PVs were found in 1% (10 of 961; 95% CI, 0.6 to 1.9) of patients and that group was significantly enriched for type II ECs.

CONCLUSION

This prospective, multicenter study revealed potentially actionable germline variants in 10% of unselected women with newly diagnosed EC, supporting the use of up-front MGPT for all EC patients. The discovery that BRCA1 or BRCA2 heterozygotes frequently had type II cancers points to therapeutic opportunities for women with aggressive histologic EC subtypes.

A Timely Update of Immunohistochemistry and Molecular Classification in the Diagnosis and Risk Assessment of Endometrial Carcinomas

CONTEXT.—

Endometrial carcinoma is the most common gynecologic malignancy in the United States and has been traditionally classified based on histology. However, the distinction of certain histologic subtypes based on morphology is not uncommonly problematic, and as such, immunohistochemical study is often needed. Advances in comprehensive tumor sequencing have provided novel molecular profiles of endometrial carcinomas. Four distinct molecular subtypes with different prognostic values have been proposed by The Cancer Genome Atlas program: polymerase epsilon ultramutated, microsatellite instability hypermutated, copy number low (microsatellite stable or no specific molecular profile), and copy number high (serouslike, p53 mutant).

OBJECTIVE.—

To discuss the utilities of commonly used immunohistochemical markers for the classification of endometrial carcinomas and to review the recent advancements of The Cancer Genome Atlas molecular reclassification and their potential impact on treatment strategies.

DATA SOURCES.—

Literature review and authors' personal practice experience.

CONCLUSIONS.—

The current practice of classifying endometrial cancers is predominantly based on morphology. The use of ancillary testing, including immunohistochemistry, is helpful in the identification, differential diagnosis, and classification of these cancers. New developments such as molecular subtyping have provided insightful prognostic values for endometrial carcinomas. The proposed The Cancer Genome Atlas classification is poised to gain further prominence in guiding the prognostic evaluation for tailored treatment strategies in the near future.

MLH1 promoter hypermethylation predicts poorer prognosis in mismatch repair deficiency endometrial carcinomas

Objective

The antitumor effects of anti-PD-1 antibody against mismatch repair deficiency (MMR-D)-associated cancers have been reported. MMR-D is found in approximately 20%–30% of endometrial carcinomas (ECs) and frequently occurs due to MLH1 promoter hypermethylation (MLH1-PHM). ECs with MLH1-PHM are classified according to the molecular screening of Lynch syndrome (LS), but few detailed reports are available. The purpose of this study was to clarify the clinical features of EC with MLH1-PHM.

Methods

Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6, and PMS2) was performed on specimens from 527 ECs treated at our university hospital from 2003 to 2018. MLH1 methylation analysis was added to cases with MLH1/PMS2 loss. ECs were classified as follows: cases that retained MMR proteins as “MMR-proficient;” cases with MLH1/PMS2 loss and MLH1-PHM as “met-EC;” and cases with other MMR protein loss and MLH1/PMS2 loss without MLH1-PHM as “suspected-LS.” The clinical features, including long-term prognosis, of each group, were analyzed.

Results

Accordingly, 419 (79.5%), 65 (12.3%), and 43 (8.2%) cases were categorized as “MMR-proficient,” “suspected-LS,” and “met-EC,” respectively. Significantly, “met-EC” had a lower proportion of grade 1 tumors (37.5%) and a higher proportion of stage III/IV tumors (37.2%) than the other groups. The overall and progression-free survival of “met-EC” were significantly worse than those of “suspected-LS” in all cases.

Conclusion

In ECs with MMR-D, “met-ECs” were a subgroup with a poorer prognosis than “suspected-LS.” “Met-ECs” would be the main target for anti-PD-1 antibody treatment, and its clinical susceptibility should be verified individually.

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.

Frequent CTNNB1 or PIK3CA Mutations Occurred in Endometrial Endometrioid Adenocarcinoma With High Levels of Microsatellite Instability and Loss of MSH2/MSH6 Expression

BACKGROUND

DNA mismatch repair (MMR) proteins form 2 heterodimers-MutSα formed by MSH2 and MSH6, and MutLα by MLH1 and PMS2. In endometrial endometrioid adenocarcinomas, cases with MMR protein defect also usually harbor other recurrent genetic mutations of the neoplasm. However, it remains unknown whether defects of the 2 functionally different heterodimers are linked to mutations in different genes. We aimed to study the MMR protein expression, microsatellite instability (MSI), and other common genetic mutations of endometrial endometrioid adenocarcinoma.

MATERIALS AND METHODS

We investigated the MSI status of 107 endometrial endometrioid adenocarcinoma patients. MMR protein expression, and mutation of KRAS, CTNNB1, and PIK3CA were also evaluated by immunohistochemistry and sequencing.

RESULTS

An overall 34.6% (37/107) of endometrial endometrioid adenocarcinomas were MSI-H. All MSI-H tumors exhibited loss of MMR protein expression (loss of MLH1, PMS2, MSH6, and MSH2 was noted in 22, 25, 12, and 7 cases, respectively). CTNNB1, PIK3CA, and KRAS mutation were present in 9, 7, and 7 MSI-H tumors. Compared with patients with loss of PMS2 and/or MLH1 expression, patients with loss of MSH6 and/or MSH2 expression were associated with higher frequencies of CTNNB1 mutation (P=0.036) and PIK3CA mutation (P=0.025).

CONCLUSIONS

In MSI-H endometrial endometrioid adenocarcinomas, different types of MMR protein deficiency indicate different molecular genetic alterations.

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.

Managing Difficulties of Microsatellite Instability Testing in Endometrial Cancer-Limitations and Advantages of Four Different PCR-Based Approaches

Microsatellite instability (MSI), a common alteration in endometrial cancers (EC) is known as a biomarker for immune checkpoint therapy response alongside screening for Lynch Syndrome (LS). However, former studies described challenging MSI profiles in EC hindering analysis by using MSI testing methods intensively validated for colorectal cancer (CRC) only. In order to reduce false negatives, this study examined four different PCR-based approaches for MSI testing using 25 EC samples already tested for mismatch repair deficiency (dMMR). In a follow up validation set of 75 EC samples previously tested both for MMR and MSI, the efficiency of a seven-marker system corresponding to the Idylla system was further analyzed. Both Bethesda and Promega marker panels require trained operators to overcome interpretation complexities caused by either hardly visible additional peaks of one and two nucleotides, or small shifts in microsatellite repeat length. Using parallel sequencing adjustment of bioinformatics is needed. Applying the Idylla MSI assay, an evaluation of input material is more crucial for reliable results and is indispensable. Following MMR deficiency testing as a first-line screening procedure, additional testing with a PCR-based method is necessary if inconclusive staining of immunohistochemistry (IHC) must be clarified.

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.

Prevalence and molecular characteristics of DNA mismatch repair deficient endometrial cancer in a Japanese hospital-based population

BACKGROUND

The prevalence and molecular characteristics of defective DNA mismatch repair endometrial cancers in the Japanese population have been underexplored. Data supporting clinical management of patients with Lynch-like syndrome and germline variant of uncertain significance of mismatch repair genes are still lacking.

METHODS

Immunohistochemistry of mismatch repair proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary endometrial cancers in 395 women with a median age of 59 years. Genetic and/or epigenetic alterations of the mismatch repair genes were also investigated.

RESULTS

Loss of expression of one or more mismatch repair proteins was observed in 68 patients (17.2%). A total of 17 out of 68 patients (25%, 4.3% of all cases) were identified as candidates for genetic testing for Lynch syndrome after excluding 51 patients with MLH1 hypermethylated cancer. Fourteen of these 17 patients subjected to genetic testing were found to have Lynch syndrome (n = 5), germline variant of uncertain significance (n = 2) or Lynch-like syndrome (n = 7). Compared with patients with Lynch syndrome, those with germline variant of uncertain significance and Lynch-like syndrome tended to demonstrate an older age at the time of endometrial cancer diagnosis (P = 0.07), less fulfillment of the revised Bethesda guidelines (P = 0.09) and lower prevalence of Lynch syndrome-associated tumors in their first-degree relatives (P = 0.01).

CONCLUSIONS

This study provides useful information for management in patients with DNA mismatch repair endometrial cancer. Specifically, cancer surveillance as recommended in patients with Lynch syndrome might not be necessary in patients with germline variant of uncertain significance and Lynch-like syndrome and their relatives.

The immunologic tumor microenvironment in endometrioid endometrial cancer in the morphomolecular context: mutual correlations and prognostic impact depending on molecular alterations

OBJECTIVE

POLE-mutant, microsatellite-instable (MSI), p53-mutant and non-specific molecular profile (NSMP) are TCGA-defined molecular subgroups of endometrial cancer (EC). Hypothesizing that morphology and tumor immunology might differ depending on molecular background concerning composition and prognostic impact, we aimed to comprehensively interconnect morphologic, immunologic and molecular data.

METHODS

TCGA-defined molecular groups were determined by immunohistochemistry and sequencing in n = 142 endometrioid EC. WHO-defined histopathological grading was performed. The immunologic microenvironment (iTME) was characterised by the quantification of intraepithelial and stromal populations of tumor-infiltrating lymphocytes (TIL: overall T-cells; T-Killer cells; regulatory T-cells (Treg)). Immunologic parameters were correlated with WHO-grading, TCGA-subgroups and prognosis.

RESULTS

High density TIL were significantly more frequent in high-grade (G3) compared to low-grade (G1/2) EC in the whole cohort and in the subgroup of POLE-wildtype-/microsatellite-stable-EC. MSI was associated with high-level TIL-infiltration when taking into account the type of mismatch repair defect (MLH1/PMS2; MSH2/MSH6). Prognostic impact of biomarkers depended on molecular subgroups: In p53-mutant EC, Treg were independently prognostic, in NSMP, the unique independently prognostic biomarker was WHO-grading.

CONCLUSIONS

EC morphology and immunology differ depending on genetics. Our study delineated two molecularly distinct subgroups of immunogenic EC characterized by high-density TIL-infiltration: MSI EC and high-grade POLE-wildtype/microsatellite-stable-EC. Prognostic impact of TIL-populations relied on TCGA-subgroups indicating specific roles for TIL depending on molecular background. In NSMP, histopathological grading was the only prognostic biomarker demonstrating the relevance of WHO-grading in an era of molecular subtyping.

Tumor Mutational Burden as a Predictive Biomarker in Solid Tumors

Tumor mutational burden (TMB), defined as the number of somatic mutations per megabase of interrogated genomic sequence, varies across malignancies. Panel sequencing-based estimates of TMB have largely replaced whole-exome sequencing-derived TMB in the clinic. Retrospective evidence suggests that TMB can predict the efficacy of immune checkpoint inhibitors, and data from KEYNOTE-158 led to the recent FDA approval of pembrolizumab for the TMB-high tumor subgroup. Unmet needs include prospective validation of TMB cutoffs in relationship to tumor type and patient outcomes. Furthermore, standardization and harmonization of TMB measurement across test platforms are important to the successful implementation of TMB in clinical practice. SIGNIFICANCE: Evaluation of TMB as a predictive biomarker creates the need to harmonize panel-based TMB estimation and standardize its reporting. TMB can improve the predictive accuracy for immunotherapy outcomes, and has the potential to expand the candidate pool of patients for treatment with immune checkpoint inhibitors.

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.

Relationship between MLH1, PMS2, MSH2 and MSH6 gene-specific alterations and tumor mutational burden in 1057 microsatellite instability-high solid tumors

Microsatellite instability-high (MSI-H) and tumor mutational burden (TMB) are predictive biomarkers for immune-checkpoint inhibitors (ICIs). Still, the relationship between the underlying cause(s) of MSI and TMB in tumors remains poorly defined. We investigated associations of TMB to mismatch repair (MMR) protein expression patterns by immunohistochemistry (IHC) and MMR mutations in a diverse sample of tumors. Hypothesized differences were identified by the protein/gene affected/mutated and the tumor histology/primary site. Overall, 1057 MSI-H tumors were identified from the 32 932 tested. MSI was examined by NGS using 7000+ target microsatellite loci. TMB was calculated using only nonsynonymous missense mutations sequenced with a 592-gene panel; a subset of MSI-H tumors also had MMR IHC performed. Analyses examined TMB by MMR protein heterodimer impacted (loss of MLH1/PMS2 vs. MSH2/MSH6 expression) and gene-specific mutations. The sample was 54.6% female; mean age was 63.5 years. Among IHC tested tumors, loss of co-expression of MLH1/PMS2 was more common (n = 544/705, 77.2%) than loss of MSH2/MSH6 (n = 81/705, 11.5%; P < .0001), and was associated with lower mean TMB (MLH1/PMS2: 25.03 mut/Mb vs MSH2/MSH6 46.83 mut/Mb; P < .0001). TMB also varied by tumor histology: colorectal cancers demonstrating MLH1/PMS2 loss had higher TMBs (33.14 mut/Mb) than endometrial cancers (20.60 mut/Mb) and other tumors (25.59 mut/Mb; P < .0001). MMR gene mutations were detected in 42.0% of tumors; among these, MSH6 mutations were most common (25.7%). MSH6 mutation patterns showed variability by tumor histology and TMB. TMB varies by underlying cause(s) of MSI and tumor histology; this heterogeneity may contribute to differences in response to ICI.

Japan Society of Clinical Oncology provisional clinical opinion for the diagnosis and use of immunotherapy in patients with deficient DNA mismatch repair tumors, cooperated by Japanese Society of Medical Oncology, First Edition

Background

Novel therapeutic agents have improved survival outcomes in patients with advanced solid tumors. In parallel, the development of predictive biomarkers to identify patients who are likely to benefit from a certain treatment has also contributed to the improvement of survival. Recently, clinical trials have reported the efficacy of immune checkpoint inhibitors in the treatment of mismatch repair-deficient (dMMR) advanced solid tumors. In Japan, a PD-1 inhibitor for dMMR advanced solid tumors, regardless of the primary tumor site, has been approved. However, there are some issues related to administering immune checkpoint inhibitors in the clinical practice setting, making it necessary to develop the guidelines.

Methods

Clinical questions (CQs) regarding medical care were formulated for patients with dMMR advanced solid tumors, and evidence to the CQs was collected by manual search to prepare recommendations. Then, the committee members voted to determine the level of each recommendation considering the strength of evidence, expected risks and benefits to patients, and other factors.

Results

The current guideline, which we consider a provisional clinical opinion at this point, describes the 11 requirements to be considered in terms of patients for whom dMMR testing is recommended, the timing and methods of dMMR testing, and clinical care systems required to perform dMMR testing properly and to administer immune checkpoint inhibitors safely.

Conclusion

This provisional clinical opinion proposes the requirements for performing dMMR testing properly to select patients who are likely to benefit from immune checkpoint inhibitors and administering them safely.

Electronic supplementary material

The online version of this article (10.1007/s10147-019-01498-8) contains supplementary material, which is available to authorized users.

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.

Prognostic implications of mismatch repair deficiency in patients with nonmetastatic colorectal and endometrial cancer

Background

The clinical relevance of mismatch repair (MMR) status in patients with nonmetastatic cancer across tumour types remains unclear. Our goal was to investigate the prognostic role of MMR deficiency in patients with stage I-III colorectal and endometrial cancer.

Methods

Patients with nonmetastatic colorectal and endometrial cancer with tumour tissue available for analysis were identified through the Hellenic Cooperative Oncology Group (HeCOG)'s tumour repository. Patients had been referred to Departments of Medical Oncology affiliated with HeCOG. MMR protein expression was evaluated by immunohistochemistry. The primary outcome measure was overall survival (OS).

Results

From May 1990 to September 2012, 1158 patients with nonmetastatic colorectal (N = 991) and endometrial cancer (N = 167) were identified (median age: 64 years, men: 544). All patients with colorectal and 109 (65%) with endometrial cancer had received adjuvant treatment. MMR deficiency was observed in 114 (11.5%) of colorectal and 80 (47.9%) of endometrial tumours. More commonly deficient proteins were PMS2 (69 patients, 7%) and MLH1 (63 patients, 6.5%) in colorectal cancer and MSH2 (58 patients, 34.7%) in endometrial cancer. Colorectal MMR-deficient (dMMR) tumours were more likely to be right sided (65 % dMMR vs 27 % proficient MMR, pMMR; p < 0.001), high grade (31% vs 15%, χ², p < 0.001) and with a mucinous component (64% vs 42%, p < 0.001). Endometrial dMMR tumours were more often of endometrioid histology (51.4 % endometrioid vs 20 % serous/clear cell, p = 0.020). Compared with MMR proficiency, MMR deficiency was associated with improved OS in patients with endometrial cancer (HR = 0.38, 95% CI 0.20 to 0.76, p = 0.006), but not in patients with colorectal cancer (HR = 0.73, 95% CI 0.49 to 1.09, p = 0.130). After adjusting for age, stage and grade, MMR deficiency maintained its favourable prognostic significance in patients with endometrial cancer (HR = 0.42, 95% CI 0.20 to 0.88, p = 0.021).

Conclusions

DMMR was associated with improved outcomes in patients with nonmetastatic endometrial cancer, but not in patients with nonmetastatic colorectal cancer who received adjuvant chemotherapy.

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.

Mismatch repair deficiency assessment by immunohistochemistry: for Lynch syndrome screening and beyond

While mismatch repair (MMR) deficiency has been studied extensively, the assessment of MMR status in colorectal and other cancers remains highly relevant, particularly in light of recent data demonstrating that MMR deficiency is a strong predictor for treatment benefit with immune checkpoint inhibitors across multiple tumor types. In colorectal cancer, there is a growing consensus in support of routine MMR testing for Lynch syndrome screening, to inform prognosis and adjuvant chemotherapy use in early stage disease, and to predict response to immunotherapy in advanced disease. Here, we provide a review of the Ventana MMR Immunohistochemistry Panel, which was recently approved by the US FDA for use in Lynch syndrome screening.

Immunohistochemistry in Gynecologic Pathology: An Example-Based Practical Update

CONTEXT

- Immunohistochemical stains are routinely applied in the pathology diagnostic workup of gynecologic lesions. The rapidly expanding repertoire of available markers helps in refining the diagnostic criteria for each disease entity; however, limitations and pitfalls exist.

OBJECTIVE

- To provide a practical, relevant update on the use of immunohistochemistry for commonly encountered differential diagnoses in gynecologic pathology.

DATA SOURCES

- Literature review and authors' diagnostic experience.

CONCLUSIONS

- Immunohistochemistry is a helpful adjunct tool in gynecologic pathology. Although the primary application is in the diagnostic workup, novel prognostic and predictive markers, and immunostains to screen for genetic cancer syndromes, have also been recently introduced in the field.

Can reduced field‐of‐view diffusion sequence help assess microsatellite instability in FIGO stage 1 endometrial cancer?

Purpose

To determine if a reduced‐field‐of‐view (rFOV) diffusion intravoxel incoherent motion (IVIM) sequence can differentiate the imaging characteristics of tumors with microsatellite instability (MSI) from those that are microsatellite stable (MSS) in patients with clinical FIGO stage IA endometrial cancer and if MRI can be used to determine MSI status.

Materials and Methods

Sagittal rFOV diffusion‐weighted images were obtained in 12 patients on a 3T scanner using six b‐values (0, 50, 100, 150, 200, and 600). These images were used to derive apparent diffusion coefficient (ADC), true diffusion coefficient (Dt), pseudodiffusion (D*), and perfusion fraction (f). Regions of interest (ROIs) were drawn on the dynamic contrast‐enhanced magnetic resonance imaging (MRI) sequence on an Advantage Windows workstation and were copied to the same location on IVIM‐derived images. The ROI mean of these images was recorded and compared with the microsatellite status. The depth of myometrial invasion and IVIM‐derived parameters were tabulated by microsatellite status. The Wilcoxon rank sum test was used to compare T1 postcontrast images and IVIM‐derived images and microsatellite status.

Results

Six patients had MSS tumors and six had MSI tumors. MSS tumors had a significantly higher ADC value (P = 0.03) and Dt (P = 0.045) than the MSI tumors. There was no association between < and ≥ 50% depth of myometrial invasion (measured on pathology and MRI analysis) and MSI stability P > 0.99.

Conclusion

IVIM, ADC and Dt may be able to determine microsatellite status noninvasively in patients with clinical FIGO stage I endometrial cancer.

Level of Evidence: 1

J. Magn. Reson. Imaging 2017;45:1216–1224

Clinical Challenges Associated with Universal Screening for Lynch Syndrome-Associated Endometrial Cancer

Universal testing for Lynch syndrome is now a routine component of the diagnostic work-up of endometrial cancer patients. The purpose of this study was to identify prospectively the barriers to universal screening based on a tissue testing approach [microsatellite instability (MSI) analysis, IHC for DNA mismatch repair proteins, and MLH1 methylation analysis]. Endometrial carcinoma patients (n = 213) prospectively underwent microsatellite instability and IHC testing for expression of DNA mismatch repair (MMR) proteins. Patients with low (MSI-L) or high (MSI-H) levels of tumor MSI or immunohistochemical loss of MLH1 (and absent MLH1 methylation), MSH2, MSH6, or PMS2 were referred to a genetic counselor for consideration of germline testing. Six discordances (3.1% of tested cases) between IHC and MSI were identified. Half of these exhibited heterogeneous immunohistochemical loss of MLH1/PMS2 and were microsatellite stable (MSS). Of the remaining cases, one was MSS with immunohistochemical loss of MSH6, one was MSS with immunohistochemical loss of MLH1/PMS2 and absent MLH1 promoter methylation, and one was MSI-H with intact expression of DNA MMR proteins. Four patients had MSI-L tumors with intact immunohistochemical protein expression; the clinical significance of MSI-L in endometrial cancer is unclear. Eight patients did not have germline mutations despite tissue testing suggesting Lynch syndrome. Including cases with insufficient tissue for testing and patients declining tissue or germline testing, we encountered significant barriers to universal screening in 13.6% of screened patients (29/213) that preclude designation of a tumor as sporadic or hereditary. Cancer Prev Res; 10(2); 108-15. ©2016 AACR.

RNASeq analysis reveals biological processes governing the clinical behaviour of endometrioid and serous endometrial cancers

BACKGROUND

Endometrial carcinoma comprises a group of tumours with distinct histologic and molecular features and clinical behaviour. Here, we sought to define the biological processes that govern the clinical behaviour of endometrial cancers.

METHODS

Sixteen prototype genes representative of different biological processes that would likely play a role in endometrial and other hormone-driven cancers were defined. RNA-sequencing gene expression data from 323 endometrial cancers from The Cancer Genome Atlas (TCGA) were used to determine the transcription module of each prototype gene. The expression of prototype genes and modules and their association with outcome was assessed in univariate and multivariate survival analyses. The association of MSH6 expression with outcome was validated in an independent cohort of 243 primary endometrial cancers using immunohistochemistry.

RESULTS

We observed that the clinical behaviour of endometrial cancers as a group was associated with hormone receptor signalling, PI3K pathway signalling and DNA mismatch repair processes. When analysed separately, in endometrioid carcinomas, hormone receptor, PI3K and DNA mismatch repair modules were significantly associated with outcome in univariate analysis, whereas the clinical behaviour of serous cancers was likely governed by apoptosis and Wnt signalling. Multivariate survival analysis revealed that MSH6 gene expression was associated with outcome of endometrial cancer patients independently from traditional prognostic clinicopathologic parameters, which was confirmed in an independent cohort at the protein level.

CONCLUSION

Endometrioid and serous endometrial cancers are underpinned by distinct molecular pathways. MSH6 expression levels may be associated with outcome in endometrial cancers as a group.

Analysis of Lynch Syndrome Mismatch Repair Genes in Women with Endometrial Cancer

OBJECTIVE

Endometrial cancer is the second most frequent neoplasm in women with Lynch syndrome (LS). We sought to assess whether analyzing women with endometrial cancer would identify families with LS not identified with current clinical criteria.

METHODS

We included women diagnosed with endometrial cancer younger than 50 years and also older if they had a family cancer history associated with LS. In blood samples obtained, we analyzed mutations in mismatch repair (MMR) genes, as well as protein expression by immunohistochemistry and microsatellite instability (MSI) in tumour tissue.

RESULTS

A total of 103 patients were enrolled. We detected 14 pathogenic mutations and 4 genetic variants of unknown clinical significance in MMR genes. We found MSI in 41.66% of the women with a pathogenic mutation. In this group, 76.92% showed loss of at least one MMR protein. Women with mutations were younger at diagnosis, but all of them had a family history compatible with LS.

CONCLUSIONS

Analysis of the MMR genes, in particular MSH6, seems to be appropriate in women with endometrial cancer and a family history of tumours associated with LS.

Preferential Protection of Genetic Fidelity within Open Chromatin by the Mismatch Repair Machinery

Epigenetic systems are well known for the roles they play in regulating the differential expression of the same genome in different cell types. However, epigenetic systems can also directly impact genomic integrity by protecting genetic sequences. Using an experimental evolutionary approach, we studied rates of mutation in the fission yeast Schizosaccharomyces pombe strains that lacked genes encoding several epigenetic regulators or mismatch repair components. We report that loss of a functional mismatch repair pathway in S. pombe resulted in the preferential enrichment of mutations in euchromatin, indicating that the mismatch repair machinery preferentially protected genetic fidelity in euchromatin. This preference is probably determined by differences in the accessibility of chromatin at distinct chromatin regions, which is supported by our observations that chromatin accessibility positively correlated with mutation rates in S. pombe or human cancer samples with deficiencies in mismatch repair. Importantly, such positive correlation was not observed in S. pombe strains or human cancer samples with functional mismatch repair machinery.

Clinical and Pathologic Features of Hispanic Endometrial Cancer Patients With Loss of Mismatch Repair Expression

OBJECTIVES

Approximately 3% to 5% of endometrial cancers (EC) are associated with Lynch syndrome (LS). The clinical characteristics and prevalence of LS have not been well studied in the US Hispanic population. Hispanics are the largest and fastest growing ethnic minority group in the United States. We sought to characterize the demographics, tumor characteristics, and prevalence of loss of mismatch repair (MMR) protein expression in a large Hispanic population with EC.

METHODS

From January 1, 2005, to August 1, 2012, 83 women of Hispanic ethnicity diagnosed with EC 50 years and younger were identified. Clinical and pathologic data were abstracted from the electronic medical record. Tumor studies included immunohistochemistry of MLH1, MSH2, MSH6, and PMS2 and methylation of the MLH1 promoter.

RESULTS

Ninety-five percent of patients were overweight or obese. The mean body mass index was 40.1 kg/m, 75% had irregular menses, 36% had diabetes, 46% were nulliparous, and 95% had endometrioid histology. Thirteen patients (15.7%) had tumor MMR deficiency due to a presumed germline mutation (9 MSH6, 3 MSH2, and 1 MLH1). The pattern of MMR protein loss was consistent with the expected binding properties of the MMR heterodimer complexes. No significant difference was found in clinical or pathological variables between patients with and without MMR deficient tumors.

CONCLUSIONS

The prevalence of molecular findings consistent with LS was at least as high as other populations of varied geography, race, and ethnicity. We found no reliable factors to include body mass index, family history, synchronous tumors, or pathologic tumor features to serve as triage markers for which ECs should be screened for MMR protein loss. Our findings support a recommendation for universal screening of ECs utilizing 2-antibody testing with MLH1 promoter methylation testing as indicated up to 60 years or older. Our recommendations should be generalizable to other Hispanic populations in the Southern United States.

The Significance of Mismatch Repair Deficiency in Young Patients With Endometrial Cancer

The objective of this study was to identify the tumor characteristics associated with mismatch repair deficiency in young patients with endometrial carcinoma. Young patients (45 yr old or younger) with endometrial carcinoma treated by hysterectomy in our institution between July 2001 and June 2009 were identified. The clinical and pathologic data were obtained by review of clinical records. Among the 122 cases identified, paraffin sections were available in 67 cases for immunohistochemical staining and frozen tissue available in 62 cases for microsatellite instability (MSI) analysis. Both paraffin sections and frozen tissue were available in 36 cases. Among the 67 cases with immunohistochemical staining, 22 (32.8%) showed loss of expression of at least 1 mismatch repair protein. Defective MLH1 or MSH2 expression was associated with poor prognostic factors, including a higher incidence of pelvic lymph nodes metastasis (P=0.018) and higher stage (P=0.022) for MLH1, and an increased risk of lymphovascular permeation (P=0.015) for MSH2. On the contrary, defective MSH6 protein expression was associated with a lower incidence of high-grade tumors (P=0.04). Among the 62 cases with MSI analysis, 12 (19.4%) tumors were classified as microsatellite-high (MSI-H), whereas 2 (3.2%) were classified as microsatellite-low (MSI-L). There was no difference in the pathologic characteristics between MSI-stable and MSI-H tumor. We concluded that defective mismatch repair expression is important in young patients with endometrial carcinoma, with MSH6 protein being most commonly affected. The phenotype resulting from defective MSH6 expression was different from that caused by MLH1 or MSH2 loss.

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.

The Immune Biology of Microsatellite-Unstable Cancer

Deficient DNA mismatch repair (MMR) boosts the accumulation of frameshift mutations in genes encompassing coding microsatellites (cMS). This results in the translation of proteins with mutation-induced frameshift peptides (neoantigens) rendering microsatellite-unstable (MSI) cancers highly immunogenic. MSI cancers express a defined set of neoantigens resulting from functionally relevant driver mutations, which are shared by most MSI cancers. Patients with MSI cancers and healthy individuals affected by Lynch syndrome, an inherited predisposition for MSI cancers, develop specific immune responses against these neoantigens. In this review, we summarize our current understanding of the immune biology of MSI cancers and outline new concepts and research directions to develop not only therapeutic treatments, but also preventive vaccines based on the MSI cancer genome landscapes.

Microsatellite instability in pulmonary adenocarcinomas: a comprehensive study of 480 cases

A major molecular pathway of genetic instability in cancer is DNA mismatch repair deficiency, leading to accumulation of numerous mutations at repetitive DNA sequence stretches (microsatellites), known as high-level microsatellite instability (MSI-H). In colorectal cancer, MSI-H tumors show a clinical behavior different from microsatellite-stable (MSS) tumors. Data about the prevalence of MSI among non-small cell lung cancer (NSCLC) are conflicting, and clinical relevance of MSI is largely unknown. We analyzed a series of 480 pulmonary adenocarcinomas (ADC) for MSI using a sensitive mononucleotide marker panel (BAT25, BAT26, and CAT25). Positive cases were further analyzed by immunohistochemical staining for DNA mismatch repair proteins. Results were correlated with clinicopathological variables. MSI-H was detected in 4/480 (0.8 %) cases. In none of these, a background of Lynch syndrome was found. Three of the patients developed a metachronous carcinoma (esophagus, pancreas, and kidney). All MSI-H cases were stage I and occurred in smokers/ex-smokers. Mutations were found in EGFR (n = 2), KRAS (n = 1), or BRAF (n = 1). MSI-H neoplasms had a higher proliferative activity (38.7 %) than MSS neoplasms (28.3 %). Mean overall survival for MSS and MSI-H cases was 64.8 (CI 60.4-69.1) and 47.1 (CI 21-73.2) months, respectively. When specific mononucleotide marker panels are applied, the MSI-H phenotype is rare and predominantly found in early stage ADC of smokers. However, the frequency of MSI-H is in the range of other relevant molecular alterations. In the era of precision therapy, associations with distinct clinicopathological variables merit further investigation.

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.

Clinical and Molecular Characterization of Brazilian Patients Suspected to Have Lynch Syndrome

Lynch syndrome (LS) accounts for 3–5% of all colorectal cancers (CRC) and is inherited in an autosomal dominant fashion. This syndrome is characterized by early CRC onset, high incidence of tumors in the ascending colon, excess of synchronous/metachronous tumors and extra-colonic tumors. Nowadays, LS is regarded of patients who carry deleterious germline mutations in one of the five mismatch repair genes (MMR), mostly in MLH1 and MSH2, but also in MSH6, PMS1 and PMS2. To comprehensively characterize 116 Brazilian patients suspected for LS, we assessed the frequency of germline mutations in the three minor genes MSH6, PMS1 and PMS2 in 82 patients negative for point mutations in MLH1 and MSH2. We also assessed large genomic rearrangements by MLPA for detecting copy number variations (CNVs) in MLH1, MSH2 and MSH6 generating a broad characterization of MMR genes. The complete analysis of the five MMR genes revealed 45 carriers of pathogenic mutations, including 25 in MSH2, 15 in MLH1, four in MSH6 and one in PMS2. Eleven novel pathogenic mutations (6 in MSH2, 4 in MSH6 and one in PMS2), and 11 variants of unknown significance (VUS) were found. Mutations in the MLH1 and MSH2 genes represented 89% of all mutations (40/45), whereas the three MMR genes (MSH6, PMS1 and PMS2) accounted for 11% (5/45). We also investigated the MLH1 p.Leu676Pro VUS located in the PMS2 interaction domain and our results revealed that this variant displayed no defective function in terms of cellular location and heterodimer interaction. Additionally, we assessed the tumor phenotype of a subset of patients and also the frequency of CRC and extra-colonic tumors in 2,365 individuals of the 116 families, generating the first comprehensive portrait of the genetic and clinical aspects of patients suspected of LS in a Brazilian cohort.

Do hereditary syndrome-related gynecologic cancers have any specific features?

Abstract

Hereditary syndromes are responsible for 10 % of gynaecologic cancers, among which hereditary breast-ovarian cancer and hereditary non-polyposis colon cancer syndromes, known as HBOC and Lynch syndromes respectively, present the highest relative risk. The latter predisposes to endometrial cancer and both contribute to ovarian cancer. Cowden syndrome-related endometrial cancer and the increased risk of ovarian, uterine and cervical cancers associated with Peutz-Jeghers syndrome, are also demonstrated, while Li-Fraumeni syndrome patients are prone to develop ovarian and endometrial cancers. Despite these syndromes’ susceptibility to gynaecologic cancers being consensual, it is still not clear whether these tumours have any epidemiologic, clinical, pathologic or imaging specific features that could allow any of the intervening physicians to raise suspicion of a hereditary syndrome in patients without known genetic risk. Moreover, controversy exists regarding both screening and surveillance schemes. Our literature review provides an updated perspective on the evidence-based specific features of tumours related to each of these syndromes as well as on the most accepted screening and surveillance guidelines. In addition, some illustrative cases are presented.

Teaching Points

• HBOC syndrome is mainly associated with ovarian HGSC, which arises in fallopian fimbriae.

• LS-related endometrial tumours show histological diversity and predilection for lower uterine segment.

• LS and CS-related ovarian cancers are mostly of non-serous type, usually endometrioid.

• Ovarian SCTAT and cervical adenoma malignum are strongly associated with PJS.

• Unfortunately, hereditary gynaecologic cancers do not seem to have distinctive imaging features.

The hMLH1 -93G>A Polymorphism and Risk of Ovarian Cancer in the Chinese Population

Background

As a mismatch repair (MMR) gene, hMLH1 plays an important role in the maintenance of chromosomal integrity. Several studies have investigated the associations of hMLH1 -93G>A (rs1800734) and Ile219Val (rs1799977) in diverse tumor types with discordant results, but their roles in ovarian cancer in the Chinese population remains to be elucidated.

Methods

In a case-control analysis, we assessed the association between these two polymorphisms and ovarian cancer risk in 421 ovarian cancer patients and 689 control subjects in the Chinese population using logistic regression.

Results

We found that the variant hMLH1 genotypes (-93AA and AG) are associated with risk of ovarian cancer (adjusted odds ratio [OR] = 2.02, 95% confidence interval [CI] = 1.42–2.89) compared with the -93GG genotype. The A allele increases the risk of ovarian cancer in a dose-dependent manner (P<10⁻⁴). Functional test showed that -93A allele increased hMLH1 promoter transcriptional activity and the luciferase activity. However, no significant difference was found in the genotype frequencies at the Ile219Val site between the cases and controls.

Conclusions

These findings indicate that the -93G>A polymorphism in hMLH1 may affect ovarian cancer susceptibility in the Chinese population.

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.