Cancer risk in hereditary nonpolyposis colorectal cancer due to MSH6 mutations: impact on counseling and surveillance

Germline Variants in Patients Affected by Both Uveal and Cutaneous Melanoma

Uveal melanoma (UM) and nonacral cutaneous melanoma (CM) are distinct entities with varied genetic landscapes despite both arising from melanocytes. There are, however, similarities in that they most frequently affect people of European ancestry, and high penetrance germline variants in BAP1, POT1 and CDKN2A have been shown to predispose to both UM and CM. This study aims to further explore germline variants in patients affected by both UM and CM, shedding light on the underlying genetic mechanism causing these diseases. Using exome sequencing we analysed germline DNA samples from a cohort of 83 Australian patients diagnosed with both UM and CM. Eight (10%) patients were identified that carried pathogenic mutations in known melanoma predisposition genes POT1, MITF, OCA2, SLC45A2 and TYR. Three (4%) patients carried pathogenic variants in genes previously linked with other cancer syndromes (ATR, BRIP1 and MSH6) and another three cases carried monoallelic pathogenic variants in recessive cancer genes (xeroderma pigmentosum and Fanconi anaemia), indicating that reduced penetrance of phenotype in these individuals may contribute to the development of both UM and CM. These findings highlight the need for further studies characterising the role of these genes in melanoma susceptibility.

[Gender-specific differences in the development of colorectal cancer in Lynch syndrome patients-A systematic review]

BACKGROUND

Lynch syndrome (LS) is the most frequent hereditary tumor syndrome and is associated with an increased risk of colorectal cancer (CRC). While gene-specific and age-specific differences are considered in patient surveillance, gender-specific risks in the development of CRC have been reported in many studies but are not consistently documented.

OBJECTIVE

This systematic review aims to investigate gender-specific differences in CRC development among LS patients.

MATERIAL AND METHODS

A systematic literature search following PRISMA 2020 guidelines was conducted in the PubMed, Ovid, The Cochrane Library and Web of Science databases. A total of 688 studies were screened, and 41 met the inclusion criteria.

RESULTS

Men have a higher risk of CRC and develop CRC earlier compared to women.

CONCLUSION

These findings indicate gender-specific differences in the risk of CRC among LS patients, although they do not currently justify separate surveillance strategies.

Integrating surgical intervention and watch-and-wait approach in dMMR metastatic rectal cancer with pembrolizumab: a case report

BACKGROUND

Treating rectal cancer presents challenges due to postoperative complications and reduced quality of life (QOL). Recent evidence supports the watch-and-wait (WW) approach for patients with a clinical complete response (cCR) following preoperative treatment. In this report, we discuss a case of metastatic rectal cancer with deficient mismatch repair (dMMR) treated successfully with pembrolizumab.

CASE PRESENTATION

A 47-year-old male with dMMR rectal cancer and a single liver metastasis underwent treatment with pembrolizumab as neoadjuvant therapy. After 10 courses, the rectal lesion achieved cCR, prompting the selection of the WW approach. The liver metastasis showed significant shrinkage; however, the presence of a residual tumor was suspected, leading to a metastasectomy. A pathological complete response (pCR) was confirmed via histological examination. During a 24-month follow-up, there was no evidence of tumor regrowth, local recurrence, or distant metastasis.

CONCLUSIONS

The WW strategy is increasingly accepted for patients achieving cCR after preoperative treatment. While pCR in dMMR rectal cancer patients treated with immune checkpoint inhibitors (ICIs) has been documented, accurately predicting pCR from imaging remains challenging. This case illustrates that integrating ICI therapy, surgical interventions, and the WW approach can effectively achieve both oncological safety and improved QOL in the treatment of dMMR metastatic rectal cancer.

Targeted sequencing for hereditary breast and ovarian cancer in BRCA1/2-negative families reveals complex genetic architecture and phenocopies

Approximately 20% of breast cancer cases are attributed to increased family risk, yet variation in BRCA1/2 can only explain 20%-25% of cases. Historically, only single gene or single variant testing were common in at-risk family members, and further sequencing studies were rarely offered after negative results. In this study, we applied an efficient and inexpensive targeted sequencing approach to provide molecular diagnoses in 245 human samples representing 134 BRCA mutation-negative (BRCAX) hereditary breast and ovarian cancer (HBOC) families recruited from 1973 to 2019 by Dr. Henry Lynch. Sequencing identified 391 variants, which were functionally annotated and ranked based on their predicted clinical impact. Known pathogenic CHEK2 breast cancer variants were identified in five BRCAX families in this study. While BRCAX was an inclusion criterion for this study, we still identified a pathogenic BRCA2 variant (p.Met192ValfsTer13) in one family. A portion of BRCAX families could be explained by other hereditary cancer syndromes that increase HBOC risk: Li-Fraumeni syndrome (gene: TP53) and Lynch syndrome (gene: MSH6). Interestingly, many families carried additional variants of undetermined significance (VOUSs) that may further modify phenotypes of syndromic family members. Ten families carried more than one potential VOUS, suggesting the presence of complex multi-variant families. Overall, nine BRCAX HBOC families in our study may be explained by known likely pathogenic/pathogenic variants, and six families carried potential VOUSs, which require further functional testing. To address this, we developed a functional assay where we successfully re-classified one family's PMS2 VOUS as benign.

Counselling and management of women with genetic predisposition to gynaecological cancers

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Comparison of immediate germline sequencing and multi-step screening for Lynch syndrome detection in high-risk endometrial and colorectal cancer patients

OBJECTIVE

Lynch syndrome (LS) is a hereditary cancer predisposition syndrome with a significantly increased risk of colorectal and endometrial cancers. Current standard practice involves universal screening for LS in patients with newly diagnosed colorectal or endometrial cancer using a multi-step screening protocol (MSP). However, MSP may not always accurately identify LS cases. To address this limitation, we compared the diagnostic performance of immediate germline sequencing (IGS) with MSP in a high-risk group.

METHODS

A total of 31 Taiwanese women with synchronous or metachronous endometrial and colorectal malignancies underwent MSP which included immunohistochemical staining of DNA mismatch repair (MMR) proteins, MLH1 promoter hypermethylation analysis, and germline sequencing to identify pathogenic variants. All patients who were excluded during MSP received germline sequencing for MMR genes to simulate IGS for the detection of LS.

RESULTS

Our findings indicate that IGS surpassed MSP in terms of diagnostic yield (29.0% vs. 19.4%, respectively) and sensitivity (90% vs. 60%, respectively). Specifically, IGS successfully identified nine LS cases, which is 50% more than the number detected through MSP. Additionally, germline methylation analysis revealed one more LS case with constitutional MLH1 promoter hypermethylation, bringing the total LS cases to ten (32.3%). Intriguingly, we observed no significant differences in clinical characteristics or overall survival between patients with and without LS in our cohort.

CONCLUSION

Our study suggests that IGS may potentially offer a more effective approach compared to MSP in identifying LS among high-risk patients. This advantage is evident when patients have been pre-selected utilizing specific clinical criteria.

MTHFR C677T and A1298C polymorphism's effect on risk of colorectal cancer in Lynch syndrome

Lynch syndrome (LS) is characterised by an increased risk of developing colorectal cancer (CRC) and other extracolonic epithelial cancers. It is caused by pathogenic germline variants in DNA mismatch repair (MMR) genes or the EPCAM gene, leading to a less functional DNA MMR system. Individuals diagnosed with LS (LS individuals) have a 10-80% lifetime risk of developing cancer. However, there is considerable variability in the age of cancer onset, which cannot be attributed to the specific MMR gene or variant alone. It is speculated that multiple genetic and environmental factors contribute to this variability, including two single nucleotide polymorphisms (SNPs) in the methylenetetrahydrofolate reductase (MTHFR) gene: C677T (rs1801133) and A1298C (rs1801131). By decreasing MTHFR activity, these SNPs theoretically reduce the silencing of DNA repair genes and increase the availability of nucleotides for DNA synthesis and repair, thereby protecting against early-onset cancer in LS. We investigated the effect of these SNPs on LS disease expression in 2,723 LS individuals from Australia, Poland, Germany, Norway and Spain. The association between age at cancer onset and SNP genotype (risk of cancer) was estimated using Cox regression adjusted for gender, country and affected MMR gene. For A1298C (rs1801131), both the AC and CC genotypes were significantly associated with a reduced risk of developing CRC compared to the AA genotype, but no association was seen for C677T (rs1801133). However, an aggregated effect of protective alleles was seen when combining the alleles from the two SNPs, especially for LS individuals carrying 1 and 2 alleles. For individuals with germline pathogenic variants in MLH1, the CC genotype of A1298C was estimated to reduce the risk of CRC significantly by 39% (HR = 0.61, 95% CI 0.42, 0.89, p = 0.011), while for individuals with pathogenic germline MSH2 variants, the AC genotype (compared to AA) was estimated to reduce the risk of CRC by 26% (HR = 0.66, 95% CI 0.53, 0.83, p = 0.01). In comparison, no association was observed for C677T (rs1801133). In conclusion, our study suggests that combining the MMR gene information with the MTHFR genotype, including the aggregated effect of protective alleles, could be useful in developing an algorithm that estimates the risk of CRC in LS individuals.

Discordant Staining Patterns and Microsatellite Results in Tumors of MSH6 Pathogenic Variant Carriers

Diagnosis of Lynch syndrome (LS) caused by a pathogenic germline MSH6 variant may be complicated by discordant immunohistochemistry (IHC) and/or by a microsatellite stable (MSS) phenotype. This study aimed to identify the various causes of the discordant phenotypes of colorectal cancer (CRC) and endometrial cancer (EC) in MSH6-associated LS. Data were collected from Dutch family cancer clinics. Carriers of a (likely) pathogenic MSH6 variant diagnosed with CRC or EC were categorized based on an microsatellite instability (MSI)/IHC test outcome that might fail to result in a diagnosis of LS (eg, retained staining of all 4 mismatch repair proteins, with or without an MSS phenotype, and other staining patterns). When tumor tissue was available, MSI and/or IHC were repeated. Next-generation sequencing (NGS) was performed in cases with discordant staining patterns. Data were obtained from 360 families with 1763 (obligate) carriers. MSH6 variant carriers with CRC or EC (n = 590) were included, consisting of 418 CRCs and 232 ECs. Discordant staining was reported in 77 cases (36% of MSI/IHC results). Twelve patients gave informed consent for further analysis of tumor material. Upon revision, 2 out of 3 MSI/IHC cases were found to be concordant with the MSH6 variant, and NGS showed that 4 discordant IHC results were sporadic rather than LS-associated tumors. In 1 case, somatic events explained the discordant phenotype. The use of reflex IHC mismatch repair testing, the current standard in most Western countries, may lead to the misdiagnosis of germline MSH6 variant carriers. The pathologist should point out that further diagnostics for inheritable colon cancer, including LS, should be considered in case of a strong positive family history. Germline DNA analysis of the mismatch repair genes, preferably as part of a larger gene panel, should therefore be considered in potential LS patients.

A Novel Mutation of MSH2 Gene in a Patient with Lynch Syndrome Presenting with Thirteen Metachronous Malignancies

Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer (HNPCC), accounts for 2-3% of all colorectal cancers. This autosomal dominant disorder is associated with a predisposition to endometrial, stomach, small bowel, pancreatic, biliary tract, ovary, urinary tract, brain, and skin tumors. Lynch syndrome is caused by the mutation of the MLH1, MSH2 (EPCAM), MSH6, and PMS2 genes. In this article, a case study of a 70-year-old female patient with Lynch syndrome is presented. Over a span of 30 years, the patient underwent multiple surgical procedures for a total of thirteen different malignancies. She was found to have a deleterious pathogenic gene MSH2 (NM_000251.2) variant (mutation) c.1774_1775insT in the 12th exon. This variant, c.1774_1775insT, represents a novel finding, as it has not been previously reported in existing databases or literature. No other case of 13 metachronous tumors in a patient with Lynch syndrome was found in the literature.

Young-onset colorectal cancer

In the past decades the incidence of colorectal cancer (CRC) in people under the age of 50 years has increased, which is referred to as early-onset CRC or young-onset CRC (YO-CRC). YO-CRC is expected to account for 11% of colon cancers and 23% of rectal cancers by 2030. This trend is observed in different parts of the world and in both men and women. In 20% of patients with YO-CRC, a hereditary cancer syndrome is found as the underlying cause; however, in the majority of patients no genetic predisposition is present. Beginning in the 1950s, major changes in lifestyle such as antibiotic use, low physical activity and obesity have affected the gut microbiome and may be an important factor in YO-CRC development. Owing to a lack of screening, patients with YO-CRC are often diagnosed with advanced-stage disease. Long-term treatment-related complications should be taken into account in these younger patients, making the more traditional sequential approaches of drug therapy not always the most appropriate option. To better understand the underlying mechanism and define relationships between environmental factors and YO-CRC development, long-term prospective studies are needed with lifestyle data collected from childhood.

The Potential of Liquid Biopsy in Detection of Endometrial Cancer Biomarkers: A Pilot Study

Endometrial cancer belongs to the most common gynecologic cancer types globally, with increasing incidence. There are numerous ways of classifying different cases. The most recent decade has brought advances in molecular classification, which show more accurate prognostic factors and the possibility of personalised adjuvant treatment. In addition, diagnostic approaches lag behind these advances, with methods causing patients discomfort while lacking the reproducibility of tissue sampling for biopsy. Minimally invasive liquid biopsies could therefore represent an alternative screening and diagnostic approach in patients with endometrial cancer. The method could potentially detect molecular changes in this cancer type and identify patients at early stages. In this pilot study, we tested such a detection method based on circulating tumour DNA isolated from the peripheral blood plasma of 21 Slovak endometrial cancer patients. We successfully detected oncomutations in the circulating DNA of every single patient, although the prognostic value of the detected mutations failed to offer certainty. Furthermore, we detected changes associated with clonal hematopoiesis, including DNMT3A mutations, which were present in the majority of circulating tumour DNA samples.

Tumor-independent Detection of Inherited Mismatch Repair Deficiency for the Diagnosis of Lynch Syndrome with High Specificity and Sensitivity

Lynch syndrome (LS) is the most common hereditary cancer syndrome. Early diagnosis improves prognosis and reduces health care costs, through existing cancer surveillance methods. The problem is finding and diagnosing the cancer predisposing genetic condition. The current workup involves a complex array of tests that combines family cancer history and clinical phenotypes with tumor characteristics and sequencing data, followed by a challenging task to interpret the found variant(s). On the basis of the knowledge that an inherited mismatch repair (MMR) deficiency is a hallmark of LS, we have developed and validated a functional MMR test, DiagMMR, that detects inherited MMR deficiency directly from healthy tissue without need of tumor and variant information. The validation included 119 skin biopsies collected from clinically pathogenic MMR variant carriers (MSH2, MSH6) and controls, and was followed by a small clinical pilot study. The repair reaction was performed on proteins extracted from primary fibroblasts and the interpretation was based on the MMR capability of the sample in relation to cutoff, which distinguishes MMR proficient (non-LS) from MMR deficient (LS) function. The results were compared with the reference standard (germline NGS). The test was shown to have exceptional specificity (100%) with high sensitivity (89%) and accuracy (97%). The ability to efficiently distinguish LS carriers from controls was further shown with a high area under the receiving operating characteristic (AUROC) value (0.97). This test offers an excellent tool for detecting inherited MMR deficiency linked to MSH2 or MSH6 and can be used alone or with conventional tests to recognize genetically predisposed individuals.

SIGNIFICANCE

Clinical validation of DiagMMR shows high accuracy in distinguishing individuals with hereditary MSH2 or MSH6 MMR deficiency (i.e., LS). The method presented overcomes challenges faced by the complexity of current methods and can be used alone or with conventional tests to improve the ability to recognize genetically predisposed individuals.

Lynch Syndrome and Gynecologic Tumors: Incidence, Prophylaxis, and Management of Patients with Cancer

This review provides a comprehensive update on recent evidence regarding gynecologic tumors associated with Lynch Syndrome (LS). Endometrial cancer (EC) and ovarian cancer (OC) are the first and second most common gynecologic malignancies in developed countries, respectively, and LS is estimated to be the hereditary cause in 3% of both EC and OC. Despite the increasing evidence on LS-related tumors, few studies have analyzed the outcomes of LS-related EC and OC stratified by mutational variant. This review aims to provide a comprehensive overview of the literature and comparison between updated international guidelines, to help outline a shared pathway for the diagnosis, prevention, and management of LS. Through the widespread adoption of the immunohistochemistry-based Universal Screening, LS diagnosis and identification of mutational variants could be standardized and recognized by international guidelines as a feasible, reproducible, and cost-effective method. Furthermore, the development of a better understanding of LS and its mutational variants will support our ability to better tailor EC and OC management in terms of prophylactic surgery and systemic treatment in the light of the promising results shown by immunotherapy.

Characterization of a germline variant MSH6 c.4001G > C in a Lynch syndrome family

BACKGROUND

Germline variants in the DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) cause Lynch syndrome, an autosomal dominant hereditary cancer susceptibility syndrome. The risk for endometrial cancer is significantly higher in women with MSH6 pathogenic/likely pathogenic (P/LP) variants compared with that for MLH1 or MSH2 variants.

METHODS

The proband was tested via a clinical testing, Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT). RT-PCR was performed using patient's blood DNA and cDNA was analyzed by DNA sequencing and a cloning approach.

RESULTS

We report a 56-year-old female with endometrial cancer who carries a germline variant, MSH6 c.4001G > C, located at the last nucleotide of exon 9. While the pathogenicity of this variant was previously unknown, functional studies demonstrated that this variant completely abolished normal splicing and caused exon 9 skipping, which is expected to lead to a prematurely truncated or abnormal protein.

CONCLUSION

Our results indicate that this variant likely contributes to cancer predisposition through disruption of normal splicing, and is classified as likely pathogenic.

Hereditary Colorectal Cancer: State of the Art in Lynch Syndrome

Hereditary non-polyposis colorectal cancer is also known as Lynch syndrome. Lynch syndrome is associated with pathogenetic variants in one of the mismatch repair (MMR) genes. In addition to colorectal cancer, the inefficiency of the MMR system leads to a greater predisposition to cancer of the endometrium and other cancers of the abdominal sphere. Molecular diagnosis is performed to identify pathogenetic variants in MMR genes. However, for many patients with clinically suspected Lynch syndrome, it is not possible to identify a pathogenic variant in MMR genes. Molecular diagnosis is essential for referring patients to specific surveillance to prevent the development of tumors related to Lynch syndrome. This review summarizes the main aspects of Lynch syndrome and recent advances in the field and, in particular, emphasizes the factors that can lead to the loss of expression of MMR genes.

Biallelic PMS2 Mutations in a Family with Uncommon Clinical and Molecular Features

We describe a patient with constitutional mismatch repair-deficiency (CMMR-D) in whom the syndrome started at age 10 with the development of multiple adenomas in the large bowel. In the successive 25 years, four malignancies developed in different organs (rectum, ileum, duodenum, and lymphoid tissue). The patient had biallelic constitutional pathogenic variants in the PMS2 gene. We speculate that besides the PMS2 genotype, alterations of other genes might have contributed to the development of the complex phenotype. In the nuclear family, both parents carried different PMS2 germline mutations. They appeared in good clinical condition and did not develop polyps or cancer. The index case had a brother who died at age three of lymphoblastic leukemia, and a sister who was affected by sarcoidosis. Tumor tissue showed diffuse DNA microsatellite instability. A complete absence of immunoreactivity was observed for the PMS2 protein both in the tumors and normal tissues. Next-generation sequencing and multiple ligation-dependent probe amplification analyses revealed biallelic PMS2 germline pathogenic variants in the proband (genotype c.[137G>T];[(2174+1_2175-1)_(*160_?)del]), and one of the two variants was present in both parents—c.137G>T in the father and c.(2174+1-2175-1)_(*160_?)del in the mother—as well as c.137G>T in the sister. Moreover, Class 3 variants of MSH2 (c.1787A>G), APC (c.1589T>C), and CHEK2 (c.331G>T) genes were also detected in the proband. In conclusion, the recognition of CMMR-D may sometimes be difficult; however, the possible role of constitutional alterations of other genes in the development of the full-blown phenotype should be investigated in more detail.

Prevalence of DNA Mismatch Repair Deficiency in Endometrial Cancer Using Immunohistochemistry

Background: Endometrial cancer (EC) is known as the most common malignancy of the female reproductive system, suggested to be associated with hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome (LS). Objectives: Therefore, the aim of the present study was to screen for LS in patients with EC using immunohistochemistry (IHC). Methods: In this retrospective cross-sectional study, the patients with EC, referred to Qaem Hospital, Mashhad, Iran, from 2015 - 2019, were enrolled. Paraffin-embedded tissue blocks were then examined via IHC for the expression of four mismatch repair (MMR) proteins, including MLH1, MSH2, MSH6, and PMS2. The demographic and tumor-related data were also extracted from medical records and pathology reports. The data were consequently analyzed at the significance level of P < 0.05. Results: A total number of 100 patients with EC were evaluated using IHC, and 12 (12%) cases were found suspected. As well, no significant relationship was observed between LS and age, tumor site, tumor histology, tumor size, tumor grade, tumor-infiltrating lymphocytes (TILs), and a family/personal history of malignancies. Conclusions: The prevalence of LS based on the IHC expression of the MMR proteins (MLH1, MSH2, MSH6, and PMS2) was 12% in the patients with EC. There was also no significant relationship between the cases suspected and the demographic and tumor-related data.

Approach to Familial Predisposition to Colorectal Cancer

The traditional approach of one-size-fits-all for colorectal cancer has been replaced by personalized interventions to an individual's unique genetic, molecular, and environmental profile, seeking to identify high-risk individuals who would benefit from individualized screening and surveillance. This change in approach is due, in part, to emerging technologies, such as next-generation DNA sequencing.

Gynecological Cancers in Lynch Syndrome: A Comparison of the Histological Features with Sporadic Cases of the General Population

Introduction: About 5% of endometrial cancers (ECs) are attributed to an inherited predisposition, for which Lynch syndrome (LS) accounts for the majority of cases. Women with LS have a 40−60% predicted lifetime risk of developing EC, in addition to a 40−80% lifetime risk of developing colorectal cancer and other cancers. In this population, the lifetime risk of developing ovarian cancer (OC) is 10−12%. Object: to compare the histopathological features of LS-associated EC and OC with sporadic cancers in order to evaluate whether there are differences in terms of age at diagnosis, site of occurrence in the uterus, histological type, stage at diagnosis, and tumor grading. Materials and methods: we compared data obtained from 96 patients with LS-associated gynecological cancers (82 with EC and 14 with OC) to a control group (CG) of 209 patients who developed sporadic EC, and a CG of 187 patients with sporadic OC. Results: The mean age at diagnosis of LS-associated EC and OC was much lower than in the control groups. In both groups with EC, the endometrioid histotype was the most frequently occurring histotype. However, among LS women there was a significantly higher incidence of clear cell tumors (11% versus 2.4% in the CG, p = 0.0001). Similar to the sporadic cancer cases, most of the LS-associated ECs presented at an early stage (89% of cases at FIGO I-II stage). In the LS group, the tumor frequently involved only the inner half of the endometrium (77% of cases, p < 0.01). In the LS group, 7.3% of ECs were localized to the lower uterine segment (LUS), whereas no cancer developed in the LUS in the CG. No serous OCs were diagnosed in the LS group (versus 45.5% in the CG, p = 0.0009). Most of the LS-associated OCs presented at an early stage (85% of cases at FIGO I-II stages, p < 0.01). Conclusion: LS-associated EC and OC seem to have peculiar features, occurring at a younger age and at an earlier stage. In LS, EC less frequently involves the outer half of the endometrium, with a more frequent occurrence in the LUS. The presence of clear cell EC was more frequently observed, whereas in OC, the predominant histotype was endometrioid.

Liquid Biopsy as a Source of Nucleic Acid Biomarkers in the Diagnosis and Management of Lynch Syndrome

Lynch syndrome (LS) is an autosomal dominant inherited cancer predisposition disorder, which may manifest as colorectal cancer (CRC), endometrial cancer (EC) or other malignancies of the gastrointestinal and genitourinary tract as well as the skin and brain. Its genetic cause is a defect in one of the four key DNA mismatch repair (MMR) loci. Testing of patients at risk is currently based on the absence of MMR protein staining and detection of mutations in cancer tissue and the germline, microsatellite instability (MSI) and the hypermethylated state of the MLH1 promoter. If LS is shown to have caused CRC, lifetime follow-up with regular screening (most importantly, colonoscopy) is required. In recent years, DNA and RNA markers extracted from liquid biopsies have found some use in the clinical diagnosis of LS. They have the potential to greatly enhance the efficiency of the follow-up process by making it minimally invasive, reproducible, and time effective. Here, we review markers reported in the literature and their current clinical applications, and we comment on possible future directions.

Risk of first onset of colorectal cancer associated with alcohol consumption in Lynch syndrome: a multicenter cohort study

BACKGROUND

Complex interactions among endogenous and exogenous factors influence the incidence of colorectal cancer (CRC). Germline mutations in mismatch repair (MMR) genes causing Lynch syndrome (LS) are major endogenous factors. The exogenous factor, alcohol consumption, is potentially associated with CRC incidence among patients with LS. However, insufficient data are available to determine whether alcohol consumption influences the time of the first onset of CRC associated with sex, MMR gene mutations, and anatomical tumor site.

METHODS

Among 316 patients with LS identified in a Japanese LS cohort, we included 288 with data on age, sex, proband status, alcohol status, smoking status, tumor location, and MMR gene mutations. Multivariable analysis assessed the association of alcohol consumption with earlier onset of the first CRC.

RESULTS

Ever drinkers were associated with higher risk of the first onset of CRC than never drinkers (HR 1.54, 95%CI 1.14-2.07, P = 0.004). The association of the first onset of CRC with alcohol consumption was stronger in men, carriers of pathogenic MLH1 and MSH2 mutations (vs those with pathogenic MSH6, PMS2 and EPCAM mutations), and tumors in the proximal colon cancer (vs distal colon and rectal cancer).

CONCLUSIONS

Alcohol consumption was associated with earlier onset of the first CRC in Japanese LS cohort. The association was stronger in men, carriers of pathogenic MLH1 and MSH2 mutations, and tumors located in the proximal colon. Our findings illuminate the mechanism of LS-associated carcinogenesis and serve as a recommendation for discontinuing or ceasing alcohol consumption.

Synchronous/metachronous endometrial and colorectal malignancies in Taiwanese women: a population-based nationwide study

INTRODUCTION

Endometrial cancer (EC) and colorectal cancer (CRC) may share a common genetic background. In a subset of patients, the two malignancies can coexist either at the time of diagnosis (synchronous) or develop consequently (metachronous). The purpose of this nationwide, population-based study was to investigate the occurrence and clinical outcomes of synchronous/metachronous EC/CRC in Taiwanese women.

MATERIALS AND METHODS

Data for women diagnosed with EC and/or CRC between 2007 and 2015 were retrospectively retrieved from the nationwide Taiwan Cancer Registry. Mortality data were obtained from the National Death Registry. Women with synchronous/metachronous EC/CRC versus EC or CRC were compared in terms of clinical characteristics and outcomes.

RESULTS

Of the 62,764 Taiwanese women diagnosed with EC and/or CRC during the study period, 167 (0.3%) had synchronous/metachronous EC/CRC. Among them, 72 cases (43.1%) presented with EC followed by CRC, 66 (39.5%) with CRC followed by EC, and 29 (17.4%) with synchronous EC/CRC. Kaplan-Meier estimates for time-to-event data revealed that the 2-year risk rates of developing a metachronous tumor of interest (CRC or EC) in women diagnosed with an initial EC and CRC were 39.6% and 42.1%, respectively. The 5-year overall survival rates of women with metachronous EC/CRC who had an initial diagnosis of EC, CRC, and synchronous EC/CRC were 73.9%, 70.9%, and 37.0%, respectively.

CONCLUSIONS

Endometrial cancer is the most common first tumor in Taiwanese women with metachronous EC/CRC. The 2-year risk rates of developing a metachronous tumor of interest (CRC or EC) in women diagnosed with an initial EC and CRC are not negligible. Surveillance for CRC is recommended for all women diagnosed with EC. The clinical outcomes of synchronous EC/CRC are markedly less favorable.

Pathogenic genetic variants from highly connected cancer susceptibility genes confer the loss of structural stability

Genetic polymorphisms in DNA damage repair and tumor suppressor genes have been associated with increasing the risk of several types of cancer. Analyses of putative functional single nucleotide polymorphisms (SNP) in such genes can greatly improve human health by guiding choice of therapeutics. In this study, we selected nine genes responsible for various cancer types for gene enrichment analysis and found that BRCA1, ATM, and TP53 were more enriched in connectivity. Therefore, we used different computational algorithms to classify the nonsynonymous SNPs which are deleterious to the structure and/or function of these three proteins. The present study showed that the major pathogenic variants (V1687G and V1736G of BRCA1, I2865T and V2906A of ATM, V216G and L194H of TP53) might have a greater impact on the destabilization of the proteins. To stabilize the high-risk SNPs, we performed mutation site-specific molecular docking analysis and validated using molecular dynamics (MD) simulation and molecular mechanics/Poisson Boltzmann surface area (MM/PBSA) studies. Additionally, SNPs of untranslated regions of these genes affecting miRNA binding were characterized. Hence, this study will assist in developing precision medicines for cancer types related to these polymorphisms.

Endoscopy to Diagnose and Prevent Digestive Cancers in Lynch Syndrome

Lynch syndrome patients could benefit from various recommendations to prevent digestive cancers. In this review, we summarize the criteria to identify Lynch syndrome in patients with digestive cancers. We detail endoscopic screening procedures in patients with Lynch syndrome for gastric, small bowel, pancreatic, and colorectal cancers. We review the precise modalities of endoscopic follow-up, particularly the discrepancies that exist between the guidelines of the various scientific societies. We discuss the treatment of colorectal cancers in Lynch syndrome cases and patient adherence to endoscopic follow-up programs.

Case-case analysis addressing ascertainment bias for multigene panel testing implicates BRCA1 and PALB2 in endometrial cancer

Hereditary endometrial cancer (EC) is most commonly attributed to pathogenic variants in mismatch repair genes. Evidence supports the existence of additional genetic risk factors in the context of multiple cancer diagnoses and/or family history of EC. EC patients (n = 5292) referred for diagnostic multigene cancer panel testing were annotated for presence of a pathogenic gene variant; personal history of prior, concurrent, or subsequent cancer of another type; reported family history of Lynch syndrome or EC. The Pearson χ² test was used to assess differences in gene variant prevalence between case sub-groups defined by personal and/or family history of cancer/s, using cases with no family history of Lynch/EC as reference. Another cancer diagnosis was reported for 55% of EC cases. EC cases with a prior and reported family history of Lynch cancer were enriched for variants in MLH1 (p = 3.5 × 10^-7 ), MSH2 (p = 3.1 × 10^-7 ), and PMS2 (p = .02). Consistent with expectations for a breast cancer gene also predisposing to EC, the variant frequency was increased in EC patients with prior BC and family history of EC for BRCA1 (p = 1.7 × 10^-5 ) and PALB2 (p = .0002). Strategic case-case analyses to address cohort ascertainment bias have provided a rationale to direct future studies of candidate hereditary EC genes.

Recent advances in Lynch syndrome

Lynch syndrome is one of the most common hereditary cancer syndromes and is characterized by the development of many cancers, such as colorectal cancer (CRC), endometrial cancer, ovarian cancer, stomach cancer and many other cancers. Lynch syndrome is caused by pathogenic germline variants in one of four DNA mismatch repair genes (MLH1, MSH2, MSH6, or PMS2) or by an EPCAM deletion. The MLH1 variant is correlated with the highest risk of CRC, while the MSH2 variant is correlated with the highest risk of other cancers. CRC is the most common cancer type that develops in individuals with Lynch syndrome, followed by endometrial cancer. Recent advances have been made to help us further understand the molecular pathogenesis of this disease and help improve diagnostic testing efficiency and surveillance strategies. Moreover, recent advances in immunotherapy provided by clinical trials also provide clinicians with more chances to better treat Lynch syndrome. This study aims to review many advances in the molecular genetics, clinical features, diagnosis, surveillance and treatment of Lynch syndrome.

European guidelines from the EHTG and ESCP for Lynch syndrome: an updated third edition of the Mallorca guidelines based on gene and gender

BACKGROUND

Lynch syndrome is the most common genetic predisposition for hereditary cancer but remains underdiagnosed. Large prospective observational studies have recently increased understanding of the effectiveness of colonoscopic surveillance and the heterogeneity of cancer risk between genotypes. The need for gene- and gender-specific guidelines has been acknowledged.

METHODS

The European Hereditary Tumour Group (EHTG) and European Society of Coloproctology (ESCP) developed a multidisciplinary working group consisting of surgeons, clinical and molecular geneticists, pathologists, epidemiologists, gastroenterologists, and patient representation to conduct a graded evidence review. The previous Mallorca guideline format was used to revise the clinical guidance. Consensus for the guidance statements was acquired by three Delphi voting rounds.

RESULTS

Recommendations for clinical and molecular identification of Lynch syndrome, surgical and endoscopic management of Lynch syndrome-associated colorectal cancer, and preventive measures for cancer were produced. The emphasis was on surgical and gastroenterological aspects of the cancer spectrum. Manchester consensus guidelines for gynaecological management were endorsed. Executive and layperson summaries were provided.

CONCLUSION

The recommendations from the EHTG and ESCP for identification of patients with Lynch syndrome, colorectal surveillance, surgical management of colorectal cancer, lifestyle and chemoprevention in Lynch syndrome that reached a consensus (at least 80 per cent) are presented.

The Inherited and Familial Component of Early-Onset Colorectal Cancer

Early-onset colorectal cancer (EOCRC), defined as that diagnosed before the age of 50, accounts for 10–12% of all new colorectal cancer (CRC) diagnoses. Epidemiological data indicate that EOCRC incidence is increasing, despite the observed heterogeneity among countries. Although the cause for such increase remains obscure, ≈13% (range: 9–26%) of EOCRC patients carry pathogenic germline variants in known cancer predisposition genes, including 2.5% of patients with germline pathogenic variants in hereditary cancer genes traditionally not associated with CRC predisposition. Approximately 28% of EOCRC patients have family history of the disease. This article recapitulates current evidence on the inherited syndromes that predispose to EOCRC and its familial component. The evidence gathered support that all patients diagnosed with an EOCRC should be referred to a specialized genetic counseling service and offered somatic and germline pancancer multigene panel testing. The identification of a germline pathogenic variant in a known hereditary cancer gene has relevant implications for the clinical management of the patient and his/her relatives, and it may guide surgical and therapeutic decisions. The relative high prevalence of hereditary cancer syndromes and familial component among EOCRC patients supports further research that helps understand the genetic background, either monogenic or polygenic, behind this increasingly common disease.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

Gynecological Surveillance and Surgery Outcomes in Dutch Lynch Syndrome Carriers

Simple Summary

Female Lynch syndrome (LS) carriers have an increased risk to develop endometrial and ovarian cancer. In the Netherlands, carriers are therefore advised annual gynecological surveillance and eventually, risk-reducing surgery. Global gynecological LS surveillance guidelines are scarce and based on limited evidence. These are, however, warranted to offer accurate surveillance. To provide more insight into surveillance outcomes, this study assessed outcomes of gynecological surveillance and risk-reducing surgery in 164 LS carriers diagnosed in our center, with a median follow-up of 5.6 years per carrier. Although most surveillance visits happened within an advised timeframe, we observed large variability in how gynecological surveillance visits were performed. This finding stresses the need for development of clear and evidence-based guidelines. Endometrial cancers identified at surveillance were all found in early stage, mostly symptomatic, questioning surveillance benefit. Large, prospective studies should assess to what extent current LS surveillance programs contribute to early detection of gynecological tumors.

Abstract

Lynch syndrome (LS) is caused by pathogenic germline variants in DNA mismatch repair (MMR) genes, predisposing female carriers for endometrial cancer (EC) and ovarian cancer (OC). Since gynecological LS surveillance guidelines are based on little evidence, we assessed its outcomes. Data regarding gynecological tumors, surveillance, and (risk-reducing) surgery were collected from female LS carriers diagnosed in our center since 1993. Of 505 female carriers, 104 had a gynecological malignancy prior to genetic LS diagnosis. Of 264 carriers eligible for gynecological management, 164 carriers gave informed consent and had available surveillance data: 38 MLH1, 25 MSH2, 82 MSH6, and 19 PMS2 carriers (median follow-up 5.6 years). Surveillance intervals were within advised time in >80%. Transvaginal ultrasound, endometrial sampling, and CA125 measurements were performed in 76.8%, 35.9%, and 40.6%, respectively. Four symptomatic ECs, one symptomatic OC, and one asymptomatic EC were diagnosed. Endometrial hyperplasia was found in eight carriers, of whom three were symptomatic. Risk-reducing surgery was performed in 73 (45.5%) carriers (median age 51 years), revealing two asymptomatic ECs. All ECs were diagnosed in FIGO I. Gynecological management in LS carriers varied largely, stressing the need for uniform, evidence-based guidelines. Most ECs presented early and symptomatically, questioning the surveillance benefit in its current form.

Multi-trait GWAS using imputed high-density genotypes from whole-genome sequencing identifies genes associated with body traits in Nile tilapia

Background

Body traits are generally controlled by several genes in vertebrates (i.e. polygenes), which in turn make them difficult to identify through association mapping. Increasing the power of association studies by combining approaches such as genotype imputation and multi-trait analysis improves the ability to detect quantitative trait loci associated with polygenic traits, such as body traits.

Results

A multi-trait genome-wide association study (mtGWAS) was performed to identify quantitative trait loci (QTL) and genes associated with body traits in Nile tilapia (Oreochromis niloticus) using genotypes imputed to whole-genome sequences (WGS). To increase the statistical power of mtGWAS for the detection of genetic associations, summary statistics from single-trait genome-wide association studies (stGWAS) for eight different body traits recorded in 1309 animals were used. The mtGWAS increased the statistical power from the original sample size from 13 to 44%, depending on the trait analyzed. The better resolution of the WGS data, combined with the increased power of the mtGWAS approach, allowed the detection of significant markers which were not previously found in the stGWAS. Some of the lead single nucleotide polymorphisms (SNPs) were found within important functional candidate genes previously associated with growth-related traits in other terrestrial species. For instance, we identified SNP within the α1,6-fucosyltransferase (FUT8), solute carrier family 4 member 2 (SLC4A2), A disintegrin and metalloproteinase with thrombospondin motifs 9 (ADAMTS9) and heart development protein with EGF like domains 1 (HEG1) genes, which have been associated with average daily gain in sheep, osteopetrosis in cattle, chest size in goats, and growth and meat quality in sheep, respectively.

Conclusions

The high-resolution mtGWAS presented here allowed the identification of significant SNPs, linked to strong functional candidate genes, associated with body traits in Nile tilapia. These results provide further insights about the genetic variants and genes underlying body trait variation in cichlid fish with high accuracy and strong statistical support.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07341-z.

Inestabilidad microsatelital y cáncer gástrico

La inestabilidad microsatelital es causada por una alteración de los sistemas de reparación de apareamientoincorrecto, que puede afectar los microsatélites dentro de todo el genoma humano, produciendo errores en su replicación. Los estudios publicados, principalmente en la literatura inglesa, han encontrado que algunos tumores, como los gástricos, pueden expresar inestabilidad microsatelital. En la siguiente revisión de tema, se presenta una descripción de los sistemas de reparación de apareamientos incorrectos y su relación con la presencia de inestabilidad microsatelital en los tumores gástricos, así como su posible utilidad clínica, como factor asociado en la respuesta al tratamiento con inmunoterapia en los pacientes con dicha patología.

Clinicopathological features of mismatch repair protein expression patterns in colorectal cancer

Microsatellite instability (MSI) is reflective of a deficient mismatch repair (dMMR) system, which is mostly associated with the methylation of mismatch repair (MMR) genes and BRAF mutations in sporadic colorectal cancers (CRCs). We performed a retrospective study to analyze the clinicopathological features of dMMR CRCs and their association with the BRAF V600E mutation. The incidence of dMMR CRCs in our cohort was 7.4 % (118/1603). Immunohistochemistry (IHC) revealed four common dMMR IHC patterns in 116 dMMR CRCs from 110 patients. dMMR type 1 (MLH1-/PMS2-) CRCs were the most frequent pattern, usually showing typical proximal location and MSI histology. The BRAF V600E mutation was almost exclusively observed in dMMR type 1 (32 of 72) and dMMR type 2 (PMS- only, 7 of 18) CRCs (p = 0.001). Patients with dMMR type 3 (MSH2-/MSH6-) CRCs were usually diagnosed at younger ages (p < 0.001) and had the strongest family history of Lynch syndrome-associated tumors (p = 0.002). dMMR type 3 CRCs frequently presented at advanced stages (p = 0.005) with perineural invasion (p = 0.021). We also found a significant positive association of dMMR type 1 and type 3 with advanced stages of CRC, whereas dMMR types 2 and 4 (MSH6- only) were usually diagnosed at early stages of CRC (p < 0.001). In conclusion, BRAF V600E mutations almost exclusively occurred in dMMR type 1 and 2 CRCs. Patterns of MMR protein expression display distinct associations with tumor staging and age at diagnosis.

Precision Prevention: The Current State and Future of Genomically Guided Cancer Prevention

The identification of cancer-predisposing germline variants has potentially substantial clinical impact for patients and their families. Although management guidelines have been proposed for some genes, guidelines for other genes are lacking. This review focuses on the current surveillance and management guidelines for the most common hereditary cancer syndromes and discusses some of the most pivotal studies supporting the available guidelines. We also highlight the gaps in the identification of germline carriers, the cascade testing of at-risk relatives, and the challenges impeding the proper follow-up and optimal management of pathogenic germline carriers. The anticipated surge in the number of identified germline carriers, deficient management guidelines, poor cascade testing uptake, and long-term follow-up necessitate the development of multidisciplinary clinics as an obligatory step toward the improvement of cancer prevention.

Associations Between Mutations in MSH6 and PMS2 and Risk of Surveillance-detected Colorectal Cancer

BACKGROUND & AIMS

Lynch syndrome is the most common inherited cause of colorectal cancer (CRC). Contemporary and mutation-specific estimates of CRC-risk in patients undergoing colonoscopy would optimize surveillance strategies. We performed a prospective national cohort study, using data from New Zealand, to assess overall and mutation-specific risk of CRC in patients with Lynch syndrome undergoing surveillance.

METHODS

We performed a prospective study of 381 persons with Lynch syndrome in New Zealand (98 with Lynch-syndrome associated variants in MLH1, 159 in MSH2, 103 in MSH6, and 21 in PMS2). Participants were offered annual colonoscopy starting at age 25 y, and those who underwent 2 or more colonoscopies before December 31, 2017 were included in the final analysis. Patients with previous colonic resection, history of CRC or diagnosis of CRC at index colonoscopy were excluded.

RESULTS

Study participants underwent 2061 colonoscopies during 2296 person-y; the median observation-period was 4.43 y and mean-age at enrollment was 43 y. Eighteen patients developed CRC (8 with variants in MLH1, 8 in MSH2, and 2 in MSH6) after a median follow-up period of 6.5 y (range 1-16 y). Eighty-three percent of patients had a surveillance colonoscopy in preceding 24 months before diagnosis of CRC; 94% were diagnosed with stage 0-II CRC and there was no CRC-related mortality. The overall-risk of developing CRC in the 5 y after first surveillance colonoscopy was 2.49% (95% CI, 1.18-5.23); cumulative risks for CRC in patients with Lynch syndrome-associated variants in MLH1, MSH2, or MSH6 by age 70 y were 17.7%, 17.8%, and 8.5%, respectively. Age-adjusted CRC-risk in patients with variants in MSH6 was lower than in MLH1 (hazard ratio, 0.2; 95% CI, 0.04-0.94; P = .02). Of patients with CRC, 33% had an adenomatous polyp resected from same segment in which a colorectal tumor later developed.

CONCLUSIONS

The risk of CRC in patients with Lynch syndrome-associated mutations in MSH6 or PMS2 was significantly lower than in patients with mutations in MLH1. Incomplete adenomatous polyp resection might be responsible for one third of surveillance-detected CRCs.

Frequency and spectrum of actionable pathogenic secondary findings in Taiwanese exomes

Background

Exome sequencing has recently become more readily available, and more information about incidental findings has been disclosed. However, data from East Asia are scarce. We studied the application of exome sequencing to the identification of pathogenic/likely pathogenic variants in the ACMG 59 gene list and the frequency of these variants in the Taiwanese population.

Methods

This study screened 161 Taiwanese exomes for variants from the ACMG 59 gene list. The identified variants were reviewed based on information from different databases and the available literature and classified according to the ACMG standard guidelines.

Results

We identified seven pathogenic/likely pathogenic variants in eight individuals, with five participants with autosomal recessive variants in one allele and three participants with autosomal dominant variants. Approximately 1.86% (3/161) of the Taiwanese individuals had a reportable pathogenic/likely pathogenic variant as determined by whole‐exome sequencing (WES), which was comparable to the proportions published previously in other countries. We further investigated the high carrier rate of rare variants in the ATP7B gene, which might indicate a founder effect in our population.

Conclusion

This study was the first to provide Taiwanese population data of incidental findings and emphasized a high carrier rate of candidate pathogenic/likely pathogenic variants in the ATP7B gene.

SWI/SNF Complex Mutations in Gynecologic Cancers: Molecular Mechanisms and Models

The SWI/SNF (mating type SWItch/Sucrose NonFermentable) chromatin remodeling complexes interact with histones and transcription factors to modulate chromatin structure and control gene expression. These evolutionarily conserved multisubunit protein complexes are involved in regulating many biological functions, such as differentiation and cell proliferation. Genomic studies have revealed frequent mutations of genes encoding multiple subunits of the SWI/SNF complexes in a wide spectrum of cancer types, including gynecologic cancers. These SWI/SNF mutations occur at different stages of tumor development and are restricted to unique histologic types of gynecologic cancers. Thus, SWI/SNF mutations have to function in the appropriate tissue and cell context to promote gynecologic cancer initiation and progression. In this review, we summarize the current knowledge of SWI/SNF mutations in the development of gynecologic cancers to provide insights into both molecular pathogenesis and possible treatment implications for these diseases.

Guidelines for the management of hereditary colorectal cancer from the British Society of Gastroenterology (BSG)/Association of Coloproctology of Great Britain and Ireland (ACPGBI)/United Kingdom Cancer Genetics Group (UKCGG)

Heritable factors account for approximately 35% of colorectal cancer (CRC) risk, and almost 30% of the population in the UK have a family history of CRC. The quantification of an individual's lifetime risk of gastrointestinal cancer may incorporate clinical and molecular data, and depends on accurate phenotypic assessment and genetic diagnosis. In turn this may facilitate targeted risk-reducing interventions, including endoscopic surveillance, preventative surgery and chemoprophylaxis, which provide opportunities for cancer prevention. This guideline is an update from the 2010 British Society of Gastroenterology/Association of Coloproctology of Great Britain and Ireland (BSG/ACPGBI) guidelines for colorectal screening and surveillance in moderate and high-risk groups; however, this guideline is concerned specifically with people who have increased lifetime risk of CRC due to hereditary factors, including those with Lynch syndrome, polyposis or a family history of CRC. On this occasion we invited the UK Cancer Genetics Group (UKCGG), a subgroup within the British Society of Genetic Medicine (BSGM), as a partner to BSG and ACPGBI in the multidisciplinary guideline development process. We also invited external review through the Delphi process by members of the public as well as the steering committees of the European Hereditary Tumour Group (EHTG) and the European Society of Gastrointestinal Endoscopy (ESGE). A systematic review of 10 189 publications was undertaken to develop 67 evidence and expert opinion-based recommendations for the management of hereditary CRC risk. Ten research recommendations are also prioritised to inform clinical management of people at hereditary CRC risk.

Genetics and the Gynecologic Patient

Background: The field of hereditary cancer syndromes and genetic testing for patients and families is a rapidly evolving discipline, with an emphasis on cancer prevention. Methods: We review the literature regarding the most common genetic syndromes associated with gynecologic malignancies and discuss the management of these conditions. We also examine the logistic process surrounding cancer genetic testing and identify some perceived barriers. Results: Five genetic syndromes are known to be associated with gynecologic malignancies: hereditary breast and ovarian cancer, Lynch, Cowden, Peutz-Jeghers, and Li-Fraumeni. Each is associated with varying risks of breast, ovarian, and uterine malignancies. The National Comprehensive Cancer Network guidelines regarding the management of these syndromes are focused primarily on reducing the risk of developing gynecologic malignancies. However, great complexity is involved with genetic testing for patients and their families, and barriers exist for the widespread use and implementation of such testing. Conclusion: Genetic testing is fundamental to primary cancer prevention and to oncologic care. Physicians, payers, and institutions must work collaboratively to maximize genetic testing with the goals of primary cancer prevention and treatment.

Use of Family History and Genetic Testing to Determine Risk of Colorectal Cancer

Approximately 35% of patients with colorectal cancer (CRC) have a family history of the disease attributed to genetic factors, common exposures, or both. Some families with a history of CRC carry genetic variants that cause CRC with high or moderate penetrance, but these account for only 5% to 10% of CRC cases. Most families with a history of CRC and/or adenomas do not carry genetic variants associated with cancer syndromes; this is called common familial CRC. Our understanding of familial predisposition to CRC and cancer syndromes has increased rapidly due to advances in next-generation sequencing technologies. As a result, there has been a shift from genetic testing for specific inherited cancer syndromes based on clinical criteria alone, to simultaneous testing of multiple genes for cancer-associated variants. We summarize current knowledge of common familial CRC, provide an update on syndromes associated with CRC (including the nonpolyposis and polyposis types), and review current recommendations for CRC screening and surveillance. We also provide an approach to genetic evaluation and testing in clinical practice. Determination of CRC risk based on family cancer history and results of genetic testing can provide a personalized approach to cancer screening and prevention, with optimal use of colonoscopy to effectively decrease CRC incidence and mortality.

Noninvasive Detection of Microsatellite Instability and High Tumor Mutation Burden in Cancer Patients Treated with PD-1 Blockade

PURPOSE

Microsatellite instability (MSI) and high tumor mutation burden (TMB-High) are promising pan-tumor biomarkers used to select patients for treatment with immune checkpoint blockade; however, real-time sequencing of unresectable or metastatic solid tumors is often challenging. We report a noninvasive approach for detection of MSI and TMB-High in the circulation of patients.

EXPERIMENTAL DESIGN

We developed an approach that utilized a hybrid-capture-based 98-kb pan-cancer gene panel, including targeted microsatellite regions. A multifactorial error correction method and a novel peak-finding algorithm were established to identify rare MSI frameshift alleles in cell-free DNA (cfDNA).

RESULTS

Through analysis of cfDNA derived from a combination of healthy donors and patients with metastatic cancer, the error correction and peak-finding approaches produced a specificity of >99% (n = 163) and sensitivities of 78% (n = 23) and 67% (n = 15), respectively, for MSI and TMB-High. For patients treated with PD-1 blockade, we demonstrated that MSI and TMB-High in pretreatment plasma predicted progression-free survival (hazard ratios: 0.21 and 0.23, P = 0.001 and 0.003, respectively). In addition, we analyzed cfDNA from longitudinally collected plasma samples obtained during therapy to identify patients who achieved durable response to PD-1 blockade.

CONCLUSIONS

These analyses demonstrate the feasibility of noninvasive pan-cancer screening and monitoring of patients who exhibit MSI or TMB-High and have a high likelihood of responding to immune checkpoint blockade.See related commentary by Wang and Ajani, p. 6887.

Microsatellite Instability in Endometrial Carcinoma by Immunohistochemistry, Association with Clinical and Histopathologic Parameters

Objective: We aimed to investigate the frequency of microsatellite instability (MSI) in endometrial carcinoma in our population and its association with clinico-pathologic features. Methods: A total of 126 cases of primary endometrial carcinoma were included in the study that underwent surgical resections. All slides of these cases were reviewed and representative paraffin fixed tissue blocks were selected for MLH1, MSH2, MSH6 and PMS2 IHC staining. IHC expression was categorized into five groups: no loss of expression; loss of expression of all four antibodies; combined loss of MLH1/PMS2; combined loss of MSH2/MSH6; and isolated loss of MLH1. Pathological records of all cases were retrieved from patient files. Result: Abnormal expression of MSI was noted in 56 cases (44.4%) among which 16 cases showed loss of nuclear expression of all markers, 34 cases showed loss of MLH1/PMS2 expression, 4 cases showed loss of MSH2/MSH6 while only 2 cases revealed isolated loss of MLH. Personal and family history suggestive of inherited cancer susceptibility was revealed in 11 cases most of which were associated with MSH2/MSH6 loss. Significant association of MSI expression was found with tumor stage and personal/family history of endometrial/ colon cancer. Conclusion: A high frequency of endometrioid cancers in our study showed abnormal expression of MSI markers, most of which depicted MLH1/PMS2 loss and were not associated with inherited cancer susceptibility. On the other hand, a minority of cases showed loss of all MSI markers or MSH2/MSH6 loss and were significantly associated with family/personal history of cancer. Therefore, we suggest that epigenetic changes in MLH1 locus may be a predominant pathway of tumorigenesis in our population rather than inherited mutation of MSI genes; however more large scale studies with genetic testing are required to validate this observation.

Next Generation Sequencing in Molecular Diagnosis of Lynch Syndrome - a Pilot Study Using New Stratification Criteria

The development of the new technologies such as the next-generation sequencing (NGS) makes more accessible the diagnosis of genetically heterogeneous diseases such as Lynch syndrome (LS). LS is one of the most common hereditary form of colorectal cancer. This autosomal dominant inherited disorder is caused by deleterious germline mutations in one of the mismatch repair (MMR) genes - MLH1, MSH2, MSH6 or PMS2, or the deletion in the EPCAM gene. These mutations eventually result in microsatellite instability (MSI), which can be easily tested in tumor tissue. According to the actual recommendations, all patients with CRC that are suspect to have LS, should be offered the MSI testing. When the MSI is positive, these patients should be recommended to genetic counseling. Here we report a pilot study about the application of NGS in the LS diagnosis in patients considered to have sporadic colorectal cancer. The inclusion criteria for the NGS testing were MSI positivity, BRAF V600E and MHL1 methylation negativity. We have used 5 gene amplicon based massive parallel sequencing on MiSeq platform. In one patient, we have identified a new pathogenic mutation in the exon 4 of the MSH6 gene that was previously not described in ClinVar, Human Gene Mutation Database, Ensembl and InSight databases. This mutation was confirmed by the Sanger method. We have shown that the implementation of new criteria for colorectal patients screening are important in clinical praxis and the NGS gene panel testing is suitable for routine laboratory settings.

A new mutL homolog 1 c.1896+5G>A germline mutation detected in a Lynch syndrome-associated lung and gastric double primary cancer patient

BACKGROUND

Mismatch-repair genes (MMRs) ensure high fidelity in genome editing. Loss of function mutation of MMRs will lead to instability of the genome and increase the incidence of cancers. Human mutL homolog 1 (MLH1) is a member of the MMRs, and its mutation is found in Lynch syndrome (LS). In addition to the high incidence of colorectal cancer, LS patients often have other primary cancers. Here, a case of LS-associated lung and gastric double primary cancer was reported.

METHODS

Diagnosis of lung and gastric double primary cancer was mainly based on clinical findings, imaging examination, and histopathological data. The tumor tissues and blood samples were collected, and then genomic DNA was extracted and 450 cancer-related gene alteration screening was conducted by next-generation sequencing and the functional verification of a mutant gene was carried out using the PCR method.

RESULTS

We detected the epidermal growth factor receptor L858R, MSH2 R929* and telomerase reverse transcriptase amplification in the lung cancer specimen; CDH1 c.1320+1G>T mutation in the gastric cancer (GC) specimen; and MLH1 c.1896+5G>A germline mutation in the lung and GC specimens by 450 cancer-related gene mutations detection using next-generation sequencing technology. MLH1c.1896+5G>A is a novel germline mutation, and it was verified by the PCR subsequently. It was found that it could affect the splicing of intron 16. Nine relatives of three-generation of the patient were examined and the MLH1 c.1896+5G>A mutation and pedigree analysis were performed. The father's sister without cancer also carries this mutation.

CONCLUSION

Diagnosis of LS was mainly depended on the following: the cancer histories of his relatives, multi-primary cancers of lung and stomach in his own body, MLH1 and MSH2 gene mutations detected in the cancer tissues. The clinical significance of this new MLH1 c.1896+5G>A germline mutation detected in the LS-associated double primary cancer patient needed further study.

Additional loss of MSH2 and MSH6 expression in sporadic deficient mismatch repair colorectal cancer due to MLH1 promoter hypermethylation

Colorectal cancer (CRC) is common with 3% of cases associated with germline mutations in the mismatch repair pathway characteristic of Lynch syndrome (LS). The UK National Institute for Health and Care Excellence recommends screening for LS in all patients newly diagnosed with CRC, irrespective of age. The Yorkshire Cancer Research Bowel Cancer Improvement Programme includes a regional LS screening service for all new diagnoses of CRC. In the first 829 cases screened, 80 cases showed deficient mismatch repair (dMMR) including four cases showing areas with loss of expression of all four mismatch repair proteins by immunohistochemistry. The cases demonstrated diffuse MLH1 loss associated with BRAF mutations and MLH1 promoter hypermethylation in keeping with sporadic dMMR, with presumed additional double hit mutations in MSH2+/-MSH6 rather than underlying LS. Recognition and accurate interpretation of this unusual phenotype is important to prevent unnecessary referrals to clinical genetics and associated patient anxiety.