Revised Bethesda Guidelines Research Articles

Novel MLH1 nonsense variant in a patient with suspected Lynch syndrome

Loss-of-function germline variants of MLH1 cause Lynch syndrome. Here, we present the case of a 43-year-old male patient diagnosed with cecal and transverse colon adenocarcinomas. The characteristics of the case met the revised Bethesda guidelines, and the tumors demonstrated a high frequency of microsatellite instability. Genetic testing for mismatch repair genes (indicative of Lynch syndrome) revealed a novel heterozygous germline pathogenic variant, NM_000249.4:c.856A>T/NP_000240.1:p.(Lys286Ter), in MLH1.

Clinicopathological characteristics of Lynch-like syndrome.

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

Universal screening for Lynch syndrome in operated colorectal cancer by immunohistochemistry: a cohort of patients in Liaoning province, China.

Lynch syndrome (LS) is the most common hereditary colorectal cancer syndrome worldwide. Due to the decreasing family size in Liaoning province. The Bethesda and Amsterdam II criteria have lower sensitivity and specificity and are not suitable for the local population. Immunohistochemistry screening for mutations in DNA mismatch repair (MMR) in newly diagnosed colorectal cancer can improve the detection rate of LS. All newly diagnosed colorectal cancer patients who underwent surgery between January 2018 and June 2020 at Cancer Hospital of China Medical University and Shengjing Hospital of China Medical University from Liaoning China were included retrospectively, and the ratio of universal LS screening by immunohistochemistry, MMR protein deficiency (dMMR) ratio, MLH1 loss, MSH2 loss, MSH6 loss, and PMS2 loss was analyzed. The clinicopathological characteristics of patients with pMMR and dMMR were analyzed. A total of 7019 colorectal cancer patients underwent surgery and 4802 (68.41%) patients were screened by immunohistochemistry for MMR, 258 (5.37%) cases were reported to have a loss of MMR expression. In the dMMR group, a higher number of patients were under 50 years old, more tumors were located at the right colon, less patients have lymph node metastasis, more tumors were stage II, and histological types of mucinous carcinoma or signet ring carcinoma were more common, compared with the pMMR group. Only 2.71% dMMR patients meet Amsterdam criteria II, 2.71% of patients meet Revised Bethesda guidelines, and 17.83% meet Chinese LS criteria. Twenty-five dMMR patients were confirmed by next-generation sequencing and five families were confirmed as Lynch family. These data imply that universal screening for LS by immunohistochemistry may be effective in Liaoning province.

Comprehensive characterisation of Lynch syndrome and screening strategies: a cohort study of individuals at risk from Latin American genetic registries

Systematic screening for Lynch syndrome is non-existent in most Latin American countries. Until regional guidelines are developed and implemented, patients with colorectal cancer in Latin America are being followed up according to international recommendations. The aim of this study was to characterise the current Lynch syndrome screening method in the region, and to explore the prevalence of Lynch syndrome in a large cohort of individuals at risk. We collected clinical, molecular, and genetic data from patients with high-risk colorectal cancer from 24 existing genetic registries and centres from nine countries in Latin America (Argentina, Brazil, Chile, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and Uruguay). Information on clinical history, personal or family history of cancer, screening strategy, and molecular and genetic testing was collected by the participating registries through standardised reporting tools. The compiled information was curated and imported into a PostgreSQL database at the Institute of Cancer Research (Oslo, Norway). Data from 1684 patients were included. Universal screening was the most commonly reported screening strategy involved in detection of Lynch syndrome (used to detect Lynch syndrome in 1133 [67·3%] of 1684 patients). The most common method included only immunohistochemistry (336 [29·7%] of 1133), followed by a combination of immunohistochemistry plus microsatellite instability assay (168 [14·8%] of 1133), or immunohistochemistry, BRAFV600E testing, microsatellite instability assay, and MLH1 methylation analysis (133 [11·7%] of 1133). The mutation rate detected with germline mismatch repair sequencing when applying the universal screening strategy was 60 (51%) of 117 versus 87 (47%) of 182 with the clinical criteria. The median age of patients with Lynch syndrome was 40 years (IQR 34-49) and the predominant tumour location was the right colon (109 [43%] of 254), for which the most common stage at diagnosis was stage II (92 [36%] of 254). No multiple tumours were detected in 171 (67%) of 252 patients. Amsterdam criteria were met by 159 (63%) of 254 patients and revised Bethesda guidelines were met by 136 (54%) patients. Our results have implications for the design of future Lynch syndrome screening programmes, but further studies are needed to assess the cost-effectiveness and burden on genetic counselling services with expanded universal testing for Lynch syndrome. Norwegian Cancer Society (contract 194751-2017).

Impact of Different Selection Approaches for Identifying Lynch Syndrome-Related Colorectal Cancer Patients: Unity Is Strength.

Lynch syndrome (LS) is an inherited genetic condition associated with increased predisposition to colorectal cancer (CRC) and other tumors and is caused by germline mutations in Mismatch Repair (MMR) or EPCAM genes. The identification of LS carriers is currently based on germline testing of subjects with MMR-deficient (dMMR) tumors or fulfilling clinical criteria, but the most efficient strategies to select patients who should be offered genetic testing are yet not well defined. In order to assess the most suitable selection mode to identify LS-related CRC patients, we retrospectively collected and analyzed all clinical and molecular information of 854 CRC patients, recruited from 2013 to 2021 at the University Hospital Policlinico “P. Giaccone” of Palermo (Italy), 100 of which were selected based on revised Bethesda guidelines, Amsterdam criteria II, or tissue MMR deficiency, and genetically tested for germline variants in LS-susceptibility genes. Our study showed that 32 out of 100 CRC patients harbored germline likely pathogenic/pathogenic variants in MMR genes. The analysis of tissue microsatellite instability (MSI) status according to the revised Bethesda guidelines has been to be the best selection approach. However, using different selection approaches as complementary strategies is useful to identify LS carriers, reducing underdiagnosis of this syndrome.

When to Consider Lynch Syndrome in Non-Colon and Non-Endometrial Malignancies.

Lynch syndrome (LS) is a common genetic syndrome characterized by pathogenic mutations of DNA mismatch repair genes resulting in a hereditary predisposition to cancer. While typically associated with colonic and endometrial cancer, LS additionally influences the development of many other malignancies. The Amsterdam II and Revised Bethesda Guidelines are the established clinical criteria for diagnosing LS. These guidelines are based on the most general characteristics of LS and do not address specific characteristics of the less commonly LS-associated malignancies. For individuals that present initially with a non-colon and non-endometrial malignancy, recommendations and guidelines on when to consider screening for LS are limited. Therefore, it is essential that clinicians are familiar with distinct LS-associated patient- and tumor-specific characteristics, especially of the less common LS-associated cancers, so that LS's diagnosis is not missed. In this review article, we focus on extra-colonic and extra-endometrial LS-associated cancers, paying particular attention to any established or currently investigated cancer features that help raise suspicion for LS and potentially lead to its earlier diagnosis. This review will also discuss current guidelines specific to each LS-associated malignancy.

Double heterozygotes of BRCA1/BRCA2 and mismatch repair gene pathogenic variants: case series and clinical implications.

Hereditary breast and ovarian cancer syndrome (HBOC) and Lynch syndrome (LS), the most common inherited cancer syndromes, are attributed to a single heterozygous pathogenic variant (PV) in BRCA1/2 or in a DNA MMR gene, respectively. Little is known about the phenotype in double heterozygotes who carry PVs in both genes. Carriers of double-PVs in any DNA MMR gene and BRCA1/2 attending one of three tertiary oncogenetic clinics between 1/2005 and 1/2020 were identified by database search, and their relevant data were retrieved and analyzed. Eleven double carriers from four seemingly unrelated Ashkenazi Jewish families were evaluated. All carried an Ashkenazi Jewish founder BRCA PV, BRCA2 c.5946delT/c.6174delT (n = 10) or BRCA1 c.185delAG (n = 1). Four carried the MSH2 c.1906G > C founder PV, and 3, the MSH6 c.3984_3987dupGTCA founder PV; 3 patients had the MSH6 c.3956_3957dup PV. Eight double carriers (73%) had cancer: breast cancer (5 cases, 2 bilateral), melanoma (2 cases), urothelial cancer (2 cases), and colon, endometrial, prostate, cutaneous squamous cell cancer, glioblastoma, gastric stromal tumor, and lymphoma (1 case each). Six carriers had 1-2 tumors, one had 3 tumors, and one had 5 primary tumors. Age at diagnosis of the first tumor was 36-76years. All carriers met NCCN BRCA1/2 testing criteria, and 3 met the revised Bethesda guidelines. This case series, supported by the literature, suggests that the phenotype of double MSH2/6 and BRCA1/2 carriers is not associated with early disease onset or a more severe phenotype. The findings have implications for improved genetic testing guidelines and treatment strategies.

Lynch Syndrome in Thai Endometrial Cancer Patients.

Background:Lynch syndrome increases lifetime risk of endometrial cancer to 40-60%. Screening with molecular tumor testing for mismatch repair (MMR) proteins have been recommended. This study aims to evaluate the incidence of MMR deficiency and germline mutation in endometrial cancer Thai patients. Methods:Immunohistochemistry for MMR proteins, including MLH1, MSH2, MSH6 and PMS2 were tested in 166 surgical specimens. Patients who had MMR deficiencies were offered genetic counseling and a germline testing using gene-panel next generation sequencing. Results:Fifty-eight of 166 patients (34.9%) had one or more MMR deficiencies which were: MLH1 and PMS2 in 42 patients (25.3%), MSH2 and MSH6 in 11 patients (6.6%), and MSH6 in 5 patients (3.0%). Of the 40 patients (24.1%) who met the revised Bethesda guidelines, 19 patients (47.5%) had MMR deficiency. In contrast, MMR deficiency was found in 39 of the 126 patients (31.0%) who did not meet the revised Bethesda guidelines. A total of 27 patients with MMR deficiencies agreed to have germline genetic testing. Germline MMR mutations were detected in 5 patients (18.5%) including MSH6 (n=2), PMS2 (n=2), and MLH1 mutations (n=1). Incidental germline mutations in other genes were detected in 3 patients (1 BRCA1, 1 PTEN, and 1 BARD1). Among 5 Lynch syndrome patients, 2 patients (40%) did not meet the revised Bethesda guidelines. Eight patients who met the revised Bethesda Guidelines but having MMR proficiency had genetic testing, but no germline mutation was detected. Conclusion:MMR deficiencies were detected in 34.9% of the endometrial cancer patients. Germline mutations were diagnosed in 3.0% of this cohort (5/166 patients). Lynch syndrome screening with MMR immunohistochemistry should be considered in all patients regardless of personal or family history of Lynch syndrome-related cancers.

Interval between the First Cancer and the Genetic Diagnosis in Lynch Syndrome Probands.

Objective Little is known about the time from developing a first cancer to confirming the presence of a mismatch repair (MMR) gene mutation for Lynch syndrome (LS) probands. Methods This was a retrospective single center study. LS probands, who have an MMR gene mutation that was confirmed first in a pedigree and thereafter developed at least one cancer, were included in this study. Results There were 21 LS probands who had developed at least one cancer; 6 with MLH1 mutations, 9 with MSH2 mutations, 4 with MSH6 mutations, and 2 with EPCAM deletions. The median ages at the first cancer and the genetic diagnosis were 47 (34-71) and 62 (38-84) years old, respectively. The mean interval between the first cancer and the genetic diagnosis was 11.0 (0-25) years, and 20 years or longer interval was required for the 5 probands. Six (28.6%) probands were older than 70 years, and 3 (14.3%) were in their 80s when they were diagnosed to have LS. The genetic diagnosis was confirmed at the first, second, third, and fourth cancer or later in 5, 5, 6, and 5 probands, respectively. Of the 16 cancers examined, 2 (12.5%) were microsatellite stable (MSS), both of whom had germline MSH6 mutations. All 17 LS probands who developed colorectal cancer met the revised Bethesda guidelines at the genetic diagnosis, but only 7 of 11 (63.6%) met them at the first cancer. Twelve out of 21 (57.1%) met the revised Amsterdam criteria. Conclusion It took 11 years for the LS probands from the first cancer to the diagnostic confirmation by genetic tests. A quarter of the probands were in their 70s or 80s at genetic diagnosis.

Clinicopathological and Histomorphological Evaluation of Colorectal Cancers for Features of Microsatellite Instability

Introduction: Colorectal Cancer (CRC) is the fourth most common cancer in men and third most common cancer in women. Microsatellite Instability-High (MSI-H) is a distinctive feature of Hereditary non-polyposis CRC syndrome (HNPCC) and it accounts for 15% of sporadic CRC. Identification of MSI-H colorectal tumours serves as a prognostic marker of patient outcome, as a predictive marker of response to chemotherapy and as a screening tool for HNPCC. Aim: The purpose of this study was to describe the clinical presentation and the histomorphological features of MSI. Materials and Methods: An ambispective type of validation study was carried out in Father Muller Medical College Hospital, Mangalore, Karnataka, India. The total duration of the study was 2.5 years. Whereas case collection was done from October 2017 to April 2019 for a period of 17 months. Surgical resection specimens of all the age groups for CRC were included in the study. Relevant patient history and clinical details were noted. Histomorphological features for MSI in CRC were noted using Revised Bethesda Guidelines. The results were analysed using Chi-square test. Results: A total of 104 cases were analysed during the study period. Majority of the patients with CRCs were in the age group of 51-60 years (30 cases, 28.84%), followed by 61-70 years age group (25 cases, 24.03%). Out of 104 cases, 72 (69.23%) of them were located in distal colon and among the various histomorphological types, adenocarcinoma accounted for 93 (89.42%) cases. Forty-nine (47.11%) of them were found to be in stage III disease. Crohn like lymphocytic reaction was a frequent histomorphological feature of MSI in about 50 (48.07%) cases of CRCs. Conclusion: The IHC test is the gold standard for MSI testing and most literature on Hospital-based study recommend IHC as the first line of testing. Identification of MSI-H by conventional histopathology by following Revised Bethesda Guidelines can be used as a screening tool for rapid selection of sporadic CRC for molecular testing, with the potential to recover a majority of MSI-H cases. MSI-H have better prognosis than stable cancers. MSI, particularly in stage II CRCs have better prognosis and do not benefit from 5FU- based adjuvant chemotherapy. Therefore, it is the most important prognostic marker in CRC and especially in stage II CRC.

S1647 A Surprising Diagnosis of Lynch Syndrome at Age 86

INTRODUCTION: Lynch syndrome (LS) is the most common inherited colorectal cancer (CRC) syndrome and accounts for up to 6% of all CRCs in the United States. The lifetime risk of CRC is near 75% for individuals with this inheritable highly expressed gene making identification of individuals and at-risk family members important for cancer prevention and management. CASE DESCRIPTION/METHODS: 86-year-old male in excellent physical condition with history of right-sided poorly differentiated invasive stage IIa adenocarcinoma status post right hemicolectomy 12 years ago presented after 6 episodes of painless hematochezia (hemoglobin 11.9 g/dL). He chose not to undergo chemotherapy and never had a follow-up colonoscopy following his initial CRC. He reported a family history of 1 sister who recovered from breast cancer and 2 deceased younger brothers who passed from colon cancer after his original diagnosis of CRC. Both parents experienced early death from cardiovascular disease. He had 6 children. Colonoscopy revealed normal ileocolonic anastomosis but with a 3 cm ulcerated, friable mass in transverse colon, a 2.5 cm mass in rectosigmoid colon, and a large, fungating 4cm ulcerated mass 5 cm from the anal verge. CT chest/abdomen/pelvis scan demonstrated extension of the transverse colonic mass through the colon wall into the mesentery with extensive nodal and hepatic metastatic disease. Pathology revealed invasive moderately differentiated adenocarcinoma positive for MLH1, MHS2, and PMS2 suggestive of Lynch syndrome; absent MSH6 staining was noted. Family members were recommended for genetic testing. The patient ultimately opted against treatment. DISCUSSION: The average age of colon cancer diagnosis for those with LS is 44 as compared to 68 for men without the genetic syndrome. This case demonstrates a particularly unique diagnosis of Lynch syndrome in an elderly male that was not diagnosed until his second bout of CRC. Of note, both cancers occurred after age 70. Strict adherence to the revised Bethesda guidelines can miss 68% of high microsatellite instability CRCs suggesting these guidelines are inadequate for LS screening, particularly if a full multigenerational family cancer history is not available. Multiple studies have demonstrated economic feasibility and advocate for universal LS testing of CRC tumors. This case supports such a paradigm. For identifying those who may be at risk for LS, we would prefer a predictive model without an overreliance on age to determine those appropriate for screening.Figure 1.: Endoscopic view of the 3 cm transverse colon (A), 2.5 cm rectosigmoid colon (B), and 4 cm anal verge (C) masses in an 86-year-old male discovered to have Lynch syndrome.Figure 2.: CT abdomen/pelvis showing transverse colon carcinoma with direct extension through the colon wall (red arrow) and into the mesentery associated with extensive nodal, as well as hepatic (yellow arrows) metastatic disease in an 86-year-old male discovered to have Lynch syndrome.

Analysis of genomic pathogenesis according to the revised Bethesda guidelines and additional criteria.

As few genotype-phenotype correlations are available for nonsyndromic hereditary colorectal cancer (CRC), we implemented genomic analysis on the basis of the revised Bethesda guideline (RBG) and extended (12 items) to verify possible subtypes. Patients with sporadic CRC (n = 249) were enrolled, stratified according to the revised Bethesda guidelines (RBG+ and RBG- groups) plus additional criteria. Exome/transcriptome analyses (n = 98) and cell-based functional assays were conducted. We detected 469 somatic and 830 germline gene mutations differing significantly between the positive and negative groups, associated with 12 RBG items/additional criteria. Twenty-one genes had significantly higher mutation rates in left, relative to right, colon cancer, while USP40, HCFC1, and HSPG2 mutation rates were higher in rectal than colon cancer. FAT4 mutation rates were lower in early-onset CRC, in contrast to increased rates in microsatellite instability (MSI)-positive tumors, potentially defining an early-onset microsatellite-stable subtype. The mutation rates of COL6A5 and MGAM2 were significantly and SETD5 was assumably, associated CRC pedigree with concurrent gastric cancer (GC). The predicted deleterious/damaging germline variants, SH2D4A rs35647122, was associated with synchronous/metachronous CRC with related tumors, while NUP160 rs381660 and KRTAP27-1 rs2244485 were potentially associated with a GC pedigree and less strictly defined hereditary CRC, respectively. SH2D4A and NUP160 acted as oncogenic facilitators. Our limited genomic analysis for RBG and additional items suggested that specific somatic alterations in the respective items may enlighten relevant pathogenesis along with the knowledge of germline mutations. Further validation is needed to indicate appropriate surveillance in suspected individuals.

The proportion of endometrial tumours associated with Lynch syndrome (PETALS): A prospective cross-sectional study

BackgroundLynch syndrome (LS) predisposes to endometrial cancer (EC), colorectal cancer, and other cancers through inherited pathogenic variants affecting mismatch-repair (MMR) genes. Diagnosing LS in women with EC can reduce subsequent cancer mortality through colonoscopic surveillance and aspirin chemoprevention; it also enables cascade testing of relatives. A growing consensus supports LS screening in EC; however, the expected proportion of test positives, and optimal testing strategy is uncertain. Previous studies from insurance-based healthcare systems were limited by narrow selection criteria, failure to apply reference standard tests consistently, and poor conversion to definitive testing. The aim of this study was to establish the prevalence of LS and the diagnostic accuracy of LS testing strategies in an unselected EC population.Methods and findingsThis was a prospective cross-sectional study carried out at a large United Kingdom gynaecological cancer centre between October 2015 and January 2017. Women diagnosed with EC or atypical hyperplasia (AH) were offered LS testing. Tumours underwent MMR immunohistochemistry (IHC), microsatellite instability (MSI), and targeted MLH1-methylation testing. Women <50 years, with strong family histories and/or indicative tumour molecular features, underwent MMR germline sequencing. Somatic MMR sequencing was performed when indicative molecular features were unexplained by LS or MLH1-hypermethylation. The main outcome measures were the prevalence of LS in an unselected EC population and the diagnostic accuracy of clinical and tumour testing strategies for risk stratifying women with EC for MMR germline sequencing. In total, 500 women participated in the study; only 2 (<1%) declined. Germline sequencing was indicated and conducted for 136 and 135 women, respectively. A total of 16/500 women (3.2%, 95% CI 1.8% to 5.1%) had LS, and 11 more (2.2%) had MMR variants of uncertain significance. Restricting testing to age <50 years, indicative family history (revised Bethesda guidelines or Amsterdam II criteria) or endometrioid histology alone would have missed 9/16 (56%), 8/13 (62%) or 9/13 (69%), and 5/16 (31%) cases of LS, respectively. In total 132/500 tumours were MMR deficient by IHC of which 83/132 (63%) had MLH1-hypermethylation, and 16/49 (33%) of the remaining patients had LS (16/132 with MMR deficiency, 12%). MMR-IHC with targeted MLH1-methylation testing was more discriminatory for LS than MSI with targeted methylation testing, with 100% versus 56.3% (16/16 versus 9/16) sensitivity (p = 0.016) and equal 97.5% (468/484) specificity; 64% MSI-H and 73% MMR deficient tumours unexplained by LS or MLH1-hypermethylation had somatic MMR mutations. The main limitation of the study was failure to conduct MMR germline sequencing for the whole study population, which means that the sensitivity and specificity of tumour triage strategies for LS detection may be overestimated, although the risk of LS in women with no clinical or tumour predictors is expected to be extremely low.ConclusionsIn this study, we observed that age, family history, and histology are imprecise clinical correlates of LS-EC. IHC outperformed MSI for tumour triage and reliably identified both germline and somatic MMR mutations. The 3.2% proportion of LS-EC is similar to colorectal cancer, supporting unselected screening of EC for LS.

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

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. 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 59years. Genetic and/or epigenetic alterations of the mismatch repair genes were also investigated. 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). 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.

Prevalence of Lynch syndrome among patients with upper urinary tract carcinoma in a Japanese hospital-based population.

The prevalence of Lynch syndrome and the use of universal tumor screening to identify Lynch syndrome among unselected patients with upper urinary tract urothelial carcinoma, which is associated with Lynch syndrome, have not been closely investigated yet. A total of 166 tumors from 164 upper urinary tract urothelial carcinoma patients were tested for microsatellite instability and expression of mismatch repair proteins (MLH1, MHS2, MSH6 and PMS2) by immunohistochemistry. Genetic testing was performed for patients suspected of having Lynch syndrome. Clinicopathological factors, including familial and personal cancer history associated with mismatch repair deficiency, were evaluated. The frequency of high-level microsatellite instability and loss of at least one mismatch repair protein was 2.4% (4/164); the microsatellite instability and immunohistochemistry results showed complete concordance. Of these four patients, three were genetically proven to have Lynch syndrome, while the remaining one was highly suggestive for Lynch syndrome based on their personal cancer history. Univariate analysis showed that age<70years (P=0.04), ureter as the tumor location (P=0.052), previous history/synchronous diagnosis of colorectal cancer (P<0.01) and fulfillment of the criteria per the revised Bethesda guideline (P<0.01) tended to be or were significantly associated with high-level microsatellite instability/mismatch repair loss. The prevalence of Lynch syndrome among unselected upper urinary tract urothelial carcinoma patients was at least 1.8% in our study population. The screening efficacies of the microsatellite instability test and immunohistochemistry appear equivalent. Universal tumor screening may be a valid approach; however, selective screening methods that consider factors associated with mismatch repair loss/high-level microsatellite instability tumors require further investigation.

Germline mutations in cancer-predisposition genes in patients with biliary tract cancer.

The prevalence of germline mutations in patients with biliary tract carcinoma (BTC) remains unclear. Here, we investigated the prevalence and types of germline mutations in patients with BTC. We reviewed 269 patients with pathologically proven BTC and collected clinical characteristics, including medical and family histories. Additionally, we evaluated germline variants in 21 genes associated with hereditary predisposition for cancer by targeted sequencing in patients meeting ≥1 of the following criteria: 1) hereditary breast and/or ovarian cancer (HBOC) testing criteria modified for BTC, 2) Revised Bethesda Guidelines (RBGs) modified for BTC (modified RBG), 3) familial BTC criteria, or 4) young BTC criteria. Among the 269 patients, 80 met at least one criterion. Three pathogenic mutations in three patients were identified: two in BRCA2 and one in BRCA1. Among the 16 patients meeting modified HBOC testing criteria, 2 harbored germline BRCA2 mutations, and 1 harbored a germline BRCA1 mutation. However, no mutation in mismatch-repair genes were detected, despite 63 patients meeting modified RBG screening criteria and 18 qualifying as young BTC patients. We detected high prevalence of pathogenic germline mutations in BRCA1/2 and none in mismatch-repair genes in BTC patients following enrichment according to family or medical history in this study.

Comparison of screening strategies for Lynch syndrome in patients with newly diagnosed endometrial cancer: a prospective cohort study in China

BackgroundThe prevalence of Lynch syndrome and screening strategies for this disorder in Chinese patients with endometrial cancer have seldom been investigated. Such data would be essential for the screening, prevention, genetic counseling, and treatment of Lynch syndrome. The purpose of this prospective study was to determine the accuracy of the mismatch repair (MMR) protein immunohistochemistry (IHC), microsatellite instability (MSI) test, and clinical diagnostic criteria in screening for Lynch syndrome-associated endometrial cancer (LS-EC) in a prospective Chinese cohort.MethodsAll patients with newly diagnosed endometrial cancer (EC) were evaluated using clinical diagnostic criteria (Amsterdam II criteria and the revised Bethesda guidelines), MSI test, and IHC of MMR proteins in tumor tissues. For all patients, the screening results were compared with results of germline sequencing for pathogenic variants of MMR genes.ResultsBetween December 2017 and August 2018, a total of 111 unselected patients with newly diagnosed EC were enrolled. Six patients (5.4%) harbored a pathogenic germline mutation of MMR genes: 1 had a mutation in MutL homolog 1 (MLH1), 2 in MutS homolog 2 (MSH2), and 3 in MutS homolog 6 (MSH6). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying LS-EC were 33.3%, 88.6%, 14.3%, and 95.9%, for the clinical criteria, 66.7%, 75.0%, 14.3%, and 97.3% for IHC of MMR proteins, 100%, 89.9%, 33.3%, and 100% for MSI test, and 100%, 72.4%, 20.0% and 100% for combined IHC and MSI test, respectively. The combination of IHC and MSI test had higher sensitivity and PPV than the clinical criteria (p = 0.030). MSI test and IHC were highly concordant for LS-EC screening (73/77, 94.8%).ConclusionThe accuracy of the combination of IHC of MMR proteins and MSI test for screening LS among Chinese patients with EC was superior to that of the clinical criteria.Trial registration NCT03291106. Registered on September 25, 2017

Clinical and Pathological Characterization of Lynch-Like Syndrome

Lynch syndrome is characterized by DNA mismatch repair (MMR) deficiency. Some patients with suspected Lynch syndrome have DNA MMR deficiencies but no detectable mutations in genes that encode MMR proteins-this is called Lynch-like syndrome (LLS). There is no consensus on management of patients with LLS. We collected data from a large series of patients with LLS to identify clinical and pathology features. We collected data from a nationwide-registry of patients with colorectal cancer (CRC) in Spain. We identified patients whose colorectal tumors had loss of MSH2, MSH6, PMS2, or MLH1 (based on immunohistochemistry), without the mutation encoding V600E in BRAF (detected by real-time PCR), and/or no methylation at MLH1 (determined by methylation-specific multiplex ligation-dependent probe amplification), and no pathogenic mutations in MMR genes, BRAF, or EPCAM (determined by DNA sequencing). These patients were considered to have LLS. We collected data on demographic, clinical, and pathology features and family history of neoplasms. The χ2 test was used to analyze the association between qualitative variables, followed by the Fisher exact test and the Student t test or the Mann-Whitney test for quantitative variables. We identified 160 patients with LLS; their mean age at diagnosis of CRC was 55 years and 66 patients were female (41%). The Amsterdam I and II criteria for Lynch syndrome were fulfilled by 11% of cases and the revised Bethesda guideline criteria by 65% of cases. Of the patients with LLS, 24% were identified in universal screening. There were no proportional differences in sex, indication for colonoscopy, immunohistochemistry, pathology findings, or personal history of CRC or other Lynch syndrome-related tumors between patients who met the Amsterdam and/or Bethesda criteria for Lynch syndrome and patients identified in universal screening for Lynch syndrome, without a family history of CRC. Patients with LLS have homogeneous clinical, demographic, and pathology characteristics, regardless of family history of CRC.

The Effectiveness of Clinical Guidelines in the Diagnosis of Lynch Syndrome Compared to Microsatellite Instability and Immunohistochemistry Analyses in Southern Thailand

Objective: This study aims to assess the accuracy of Amsterdam II criteria (AMII) and Revised Bethesda Guidelines (RBG) compared to molecular tests in Thai patients.Material and Methods: One hundred eighty-one patients were enrolled. Demographic data and pathological features and locations of tumors were recorded. Family history of the patients was reviewed by AMII and RBG. Tissue samples were collected and molecular testing was tested by microsatellite instability (MSI) analysis and immunohistochemistry (IHC). Statistical analysis was used to estimate the sensitivity and specificity of AMII and RBG compared to molecular testing.Results: Of the patients, 2.8% fulfilled the AMII criteria and 28.1% met the RBG criteria. Molecular testing showed 16.57% and 13.8% of the samples lost at least 1 out of 4 mismatch repair (MMR) proteins in the IHC test. In addition, 10.5% of patients had both microsatellite instability high (MSI-H) and loss of protein MMR expression. The sensitivity and specificity of AMII were 6.7% and 98.0%, respectively, while for the RBG they were 70.0% and 82.1%, respectively.Conclusion: The present study suggests that for patients who complete the AMII, doctors should be highly suspicious of Lynch syndrome, due to its high specificity. The RBG is useful for screening for Lynch syndrome and the selection of individuals for further molecular testing.

Universal screening for Lynch syndrome in a large consecutive cohort of Chinese colorectal cancer patients: High prevalence and unique molecular features

The prevalence of Lynch syndrome (LS) varies significantly in different populations, suggesting that ethnic features might play an important role. We enrolled 3330 consecutive Chinese patients who had surgical resection for newly diagnosed colorectal cancer. Universal screening for LS was implemented, including immunohistochemistry for mismatch repair (MMR) proteins, BRAFV600E mutation test and germline sequencing. Among the 3250 eligible patients, MMR protein deficiency (dMMR) was detected in 330 (10.2%) patients. Ninety-three patients (2.9%) were diagnosed with LS. Nine (9.7%) patients with LS fulfilled Amsterdam criteria II and 76 (81.7%) met the revised Bethesda guidelines. Only 15 (9.7%) patients with absence of MLH1 on IHC had BRAFV600E mutation. One third (33/99) of the MMR gene mutations have not been reported previously. The age of onset indicates risk of LS in patients with dMMR tumors. For patients older than 65 years, only 2 patients (5.7%) fulfilling revised Bethesda guidelines were diagnosed with LS. Selective sequencing of all cases with dMMR diagnosed at or below age 65 years and only of those dMMR cases older than 65 years who fulfill revised Bethesda guidelines results in 8.2% fewer cases requiring germline testing without missing any LS diagnoses. While the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of constitutional mutations and frequency of BRAFV600E mutation is different. Patients older than 65 years who do not meet the revised Bethesda guidelines have a low risk of LS, suggesting germline sequencing might not be necessary in this population.