Report from the Jerusalem workshop on Lynch syndrome-hereditary nonpolyposis colorectal cancer

The implications for urological malignancies of non-coding RNAs in the the tumor microenvironment

Urological malignancies are a major global health issue because of their complexity and the wide range of ways they affect patients. There's a growing need for in-depth research into these cancers, especially at the molecular level. Recent studies have highlighted the importance of non-coding RNAs (ncRNAs) – these don't code for proteins but are crucial in controlling genes – and the tumor microenvironment (TME), which is no longer seen as just a background factor but as an active player in cancer progression. Understanding how ncRNAs and the TME interact is key for finding new ways to diagnose and predict outcomes in urological cancers, and for developing new treatments. This article reviews the basic features of ncRNAs and goes into detail about their various roles in the TME, focusing specifically on how different ncRNAs function and act in urological malignancies.

A locally advanced colon cancer patient with Muir-Torre syndrome obtains durable response to neoadjuvant and adjuvant immunotherapy

INTRODUCTION

Muir-Torre syndrome, presenting with cutaneous tumors and visceral malignancies, is a variant of Lynch syndrome. The development of immune checkpoint inhibitors provided novel effective treatment options for metastatic colorectal cancer patients with microsatellite instability and deficient mismatch repair. However, the use of immune checkpoint inhibitors in neoadjuvant and adjuvant settings for patients with locally advanced colorectal cancer remains undefined because of limited follow-ups in current studies.

CASE PRESENTATION

In the present study, we reported a 33-year-old Muri-Torre syndrome patient with stage ⅢC (c.T4N2M0) colorectal cancer and keratoacanthoma. Microsatellite instability / deficient mismatch repair, high tumor mutation burden, and MSH2 germline mutation were identified by next-generation sequencing. Pembrolizumab monotherapy was used as neoadjuvant treatment and the patient achieved a major pathological response. After surgical resection, pembrolizumab was continuously used in an adjuvant setting for 12 months. The patient remained disease-free with a durable disease-free survival for 44 months. To our knowledge, this is the first and longest follow-up study reporting pembrolizumab as a single-agent neoadjuvant therapy for locally advanced colon cancer.

CONCLUSIONS

The results demonstrate promising performance in neoadjuvant and adjuvant settings. Further studies are needed to confirm its potential usefulness as an outcome measure in clinical practice.

Diagnosis of patients with Lynch syndrome lacking the Amsterdam II or Bethesda criteria

BACKGROUND

Lynch Syndrome (LS) is an autosomal dominant inheritance disorder characterized by genetic predisposition to develop cancer, caused by pathogenic variants in the genes of the mismatch repair system. Cases are detected by implementing the Amsterdam II and the revised Bethesda criteria, which are based on family history.

MAIN BODY

Patients who meet the criteria undergo posterior tests, such as germline DNA sequencing, to confirm the diagnosis. However, these criteria have poor sensitivity, as more than one-quarter of patients with LS do not meet the criteria. It is very likely that the lack of sensitivity of the criteria is due to the incomplete penetrance of this syndrome. The penetrance and risk of developing a particular type of cancer are highly dependent on the affected gene and probably of the variant. Patients with variants in low-penetrance genes have a lower risk of developing a cancer associated with LS, leading to families with unaffected generations and showing fewer clear patterns. This study focuses on describing genetic aspects of LS cases that underlie the lack of sensitivity of the clinical criteria used for its diagnosis.

CONCLUSION

Universal screening could be an option to address the problem of underdiagnosis.

A Focused Clinical Review of Lynch Syndrome

Lynch syndrome (LS) is an autosomal dominant condition that increases an individual's risk of a constellation of cancers. LS is defined when an individual has inherited pathogenic variants in the mismatch repair genes. Currently, most people with LS are undiagnosed. Early detection of LS is vital as those with LS can be enrolled in cancer reduction strategies through chemoprophylaxis, risk reducing surgery and cancer surveillance. However, these interventions are often invasive and require refinement. Furthermore, not all LS associated cancers are currently amenable to surveillance. Historically only those with a strong family history suggestive of LS were offered testing; this has proved far too restrictive. New criteria for testing have recently been introduced including the universal screening for LS in associated cancers. This has increased the number of people being diagnosed with LS but has also brought about unique challenges such as when to consent for germline testing and questions over how and who should carry out the consent. The results of germline testing for LS can be complicated and the diagnostic pathway is not always clear. Furthermore, by testing only those with cancer for LS we fail to identify these individuals before they develop potentially fatal pathology. This review will outline these challenges and explore solutions. Furthermore, we consider the potential future of LS care and the related treatments and interventions which are the current focus of research.

Clinical prospects of WRN inhibition as a treatment for MSI tumours

The discovery of synthetic lethal interactions with genetic deficiencies in cancers has highlighted several candidate targets for drug development, with variable clinical success. Recent work has unveiled a promising synthetic lethal interaction between inactivation/inhibition of the WRN DNA helicase and tumours with microsatellite instability, a phenotype that arises from DNA mismatch repair deficiency. While these and further studies have highlighted the therapeutic potential of WRN inhibitors, compounds with properties suitable for clinical exploitation remain to be described. Furthermore, the complexities of MSI development and its relationship to cancer evolution pose challenges for clinical prospects. Here, we discuss possible paths of MSI tumour development, the viability of WRN inhibition as a strategy in different scenarios, and the necessary conditions to create a roadmap towards successful implementation of WRN inhibitors in the clinic.

Routine Immunohistochemical Analysis of Mismatch Repair Proteins in Colorectal Cancer—A Prospective Analysis

Simple Summary

Recognition of a hereditary colorectal cancer (CRC) syndrome is crucial. Our aim was to assess the value of routine immunohistochemistry screening for mismatch repair proteins deficiency in CRC patients under 70 years-old. In our cohort, this inclusive strategy allowed the identification of Lynch Syndrome patients that could otherwise be missed using a restrictive approach that relies only on Amsterdam and Bethesda criteria. This study strengthens current recommendations and highlights the role of universal CRC screening for MMR protein status.

Abstract

Recognition of a hereditary colorectal cancer (CRC) syndrome is crucial and Lynch Syndrome (LS) is the most frequent immunohistochemistry (IHC)—screening for mismatch repair proteins (MMR) deficiency in CRC is therefore advocated. An unicentric cohort study was conducted in a central Oncological Hospital to assess its results. All patients under 70 years-old admitted between July 2017–June 2019 and submitted to surgery for CRC were included. Of 275 patients, 56.0% were male, median age 61.0 (IQR:54.5–65.0), with synchronous tumors in six. Histology revealed high grade adenocarcinoma in 8.4%; mucinous and/or signet ring differentiation in 11.3%; and lymphocytic infiltration in 29.8%. Amsterdam (AC) and Bethesda (BC) Criteria were fulfilled in 11 and 74 patients, respectively. IHC revealed loss of expression of MMR proteins in 24 (8.7%), mostly MLH1 and PMS2 (n = 15) and PMS2 (n = 4). Among these, no patients fulfilled AC and 13 fulfilled BC. BRAF mutation or MLH1 promoter hypermethylation was found in four patients with MLH1 loss of expression. Genetic diagnosis was performed in 51 patients, 11 of them with altered IHC. LS was diagnosed in four, and BC was present in three. One patient would not have been diagnosed without routine IHC screening. These results strengthen the important role of IHC screening for MMR proteins loss of expression in CRC.

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.

Lynch-like Syndrome: Potential Mechanisms and Management

Simple Summary

Lynch-like syndrome (LLS) is defined as colorectal cancer cases with microsatellite instability (MSI) and loss of expression of MLH1, MSH2, MSH6, or PMS2 by immunohistochemistry (IHC) in the absence of a germline mutation in these genes that cannot be explained by BRAF mutation or MLH1 hypermethylation. The application of the universal strategy for the diagnosis of Lynch syndrome (LS) in all CRCs is leading to an increase in the incidence of cases of LLS. It has been described that risk of cancer in relatives of LLS patients is in between of that found in Lynch syndrome families and sporadic cases. That makes LLS patients and their families a challenging group for which the origin of CRC is unknown, being a mixture between unidentified hereditary CRC and sporadic cases. The potential causes of LLS are discussed in this review, as well as methods for identification of truly hereditary cases.

Abstract

Lynch syndrome is an autosomal dominant disorder caused by germline mutations in DNA mismatch repair (MMR) system genes, such as MLH1, MSH2, MSH6, or PMS2. It is the most common hereditary colorectal cancer syndrome. Screening is regularly performed by using microsatellite instability (MSI) or immunohistochemistry for the MMR proteins in tumor samples. However, in a proportion of cases, MSI is found or MMR immunohistochemistry is impaired in the absence of a germline mutation in MMR genes, BRAF mutation, or MLH1 hypermethylation. These cases are defined as Lynch-like syndrome. Patients with Lynch-like syndrome represent a mixture of truly hereditary and sporadic cases, with a risk of colorectal cancer in first-degree relatives that is between the risk of Lynch syndrome in families and relatives of sporadic colon cancer cases. Although multiple approaches have been suggested to distinguish between hereditary and sporadic cases, a homogeneous testing protocol and consensus on the adequate classification of these patients is still lacking. For this reason, management of Lynch-like syndrome and prevention of cancer in these families is clinically challenging. This review explains the concept of Lynch-like syndrome, potential mechanisms for its development, and methods for adequately distinguishing between sporadic and hereditary cases of this entity.

Case Report: A New Subtype of Lynch Syndrome Associated With MSH2 c.1024_1026 Identified in a Chinese Family

Background

Lynch syndrome is an autosomal dominant disorder associated with a high incidence of various cancer types. Multiple variants of mismatch repair genes have been reported for Lynch syndrome. However, the diagnosis in patients with atypical cancer types remains challenging. Specifically, little is known about the genetic background of Lynch syndrome-related renal carcinoma. We present a case wherein a renal carcinoma patient with multiple primary skin tumors harbored a variant that has not been previously shown to be associated with Lynch syndrome.

Case Presentation

The proband was a 60-year-old Chinese man with a history of Lynch syndrome-related renal carcinoma and recurrent primary skin tumors. Immunohistochemistry revealed loss of MSH2 and MSH6. Sequencing of mismatch repair genes revealed a previously unknown germline MSH2 mutation (c.1024_1026), which results in an amino acid deletion (p.V342). This variant was co-segregated among the carcinoma-affected family members. After six cycles of immunotherapy, a marked regression of the skin tumors was observed.

Conclusions

We clarify the pathogenic significance of this newly described mutation and suggest immunotherapy for patients with this subtype of Lynch syndrome.

Mismatch repair deficiency: The what, how and why it is important

The mismatch repair system is a major pathway that functions in the maintenance of genomic integrity. It is involved in mitotic and meiotic recombination, apoptosis, immunoglobulin gene rearrangement, somatic hypermutation, and other processes. Deficiencies in mismatch repair give rise to hypermutability and the phenomenon called microsatellite instability. Detection of deficient mismatch repair function or microsatellite instability is used diagnostically, predictively, and prognostically. Specifically, deficient mismatch repair function is used for screening of Lynch syndrome, determining patients who are likely to respond to immune checkpoint inhibition, and to contributes to an understanding of which cancer patients may pursue a more aggressive clinical course. Microsatellite instability can be evaluated directly by polymerase chain reaction (PCR) or indirectly by assessment of mismatch repair protein expression using immunohistochemistry (IHC), and mismatch repair function using next-generation sequencing assays which evaluates homopolymer indels. In this article, we provide a concise practical review on mismatch repair deficiency (MMR-d)/microsatellite instability (MSI), focusing on clinical testing, different testing methods, interpretation of findings, the predictive, and prognostic utility of MSI.

General insight into cancer: An overview of colorectal cancer (Review)

Cancer is currently among the leading causes of mortality globally. Colorectal cancer (CRC) ranks second among the most common types of cancer in terms of mortality worldwide. This type of cancer arises from mutations in the colonic and rectal epithelial tissues that target oncogenes, tumor suppressor genes and genes related to DNA repair mechanisms. The aim of the present review was to provide an explanation of CRC classification, which is carried out according to the histological subtype, location and molecular pathways implicated in its development. The pathogenic mechanisms implicated in CRC may involve one of three different molecular pathways: Chromosomal instability, microsatellite instability and cytosine preceding guanine island methylator phenotype. In addition, a variety of mutated genes associated with CRC, which affect certain signaling pathways, including DNA mismatch repair, cell cycle checkpoints and apoptotic pathways, were discussed. Moreover, a brief description of the risk factors and the symptoms associated with CRC was also provided. Finally, the treatment approaches to CRC were outlined.

When guidelines face reality - Lynch syndrome screening in the setting of public health system in a developing country

Lynch syndrome (LS) is the most common cause of hereditary colorectal cancer (CRC); however, it is still underrecognized and underdiagnosed. While international guidelines gravitate towards universal screening, the underuse of screening methods has been reported in real-world scenarios. This study aims to evaluate screening for LS among patients diagnosed with CRC in a public cancer center in Brazil and evaluate access to genetic counseling and testing for abnormal screens. For that purpose, all patients with CRC registered in our institution from July 2012 to December 2018 had their charts reviewed. Demographic and clinical characteristics were noted, as well as immunohistochemistry and microsatellite instability analysis results, when available. After applying exclusion criteria, a total of 1234 charts were reviewed. Among these, 257 patients were screened for LS, making up a 20.8% screening rate; when considering Jerusalem criteria, screening rate was 24.5%; for Bethesda criteria, it was 35.1%. Almost 80% of patients fulfilling Amsterdam criteria I/II were screened. There were 64 abnormal screens, from which 40 (62.5%) underwent genetic counseling and 12 (18.7%) underwent genetic testing. We concluded that overall screening rates for LS among CRC patients in a public cancer center in Brazil are low, and still very guided by stringent clinical criteria. Referral to genetic counseling and access to testing is limited, calling the whole process into question. Public policies aiming to raise awareness on hereditary cancer and include genetic testing in the public health system could help improve this scenario.

Screening and prevention of colorectal cancer

Mortality from colorectal cancer is reduced through screening and early detection; moreover, removal of neoplastic lesions can reduce cancer incidence. While understanding of the risk factors, pathogenesis, and precursor lesions of colorectal cancer has advanced, the cause of the recent increase in cancer among young adults is largely unknown. Multiple invasive, semi- and non-invasive screening modalities have emerged over the past decade. The current emphasis on quality of colonoscopy has improved the effectiveness of screening and prevention, and the role of new technologies in detection of neoplasia, such as artificial intelligence, is rapidly emerging. The overall screening rates in the US, however, are suboptimal, and few interventions have been shown to increase screening uptake. This review provides an overview of colorectal cancer, the current status of screening efforts, and the tools available to reduce mortality from colorectal cancer.

Cost-effectiveness of prophylactic hysterectomy in first-degree female relatives with Lynch syndrome of patients diagnosed with colorectal cancer in the United States: a microsimulation study

Background

To evaluate the cost‐effectiveness of prophylactic hysterectomy (PH) in women with Lynch syndrome (LS).

Methods

We developed a microsimulation model incorporating the natural history for the development of hyperplasia with and without atypia into endometrial cancer (EC) based on the MISCAN‐framework. We simulated women identified as first‐degree relatives (FDR) with LS of colorectal cancer patients after universal testing for LS. We estimated costs and benefits of offering this cohort PH, accounting for reduced quality of life after PH and for having EC. Three minimum ages (30/35/40) and three maximum ages (70/75/80) were compared to no PH.

Results

In the absence of PH, the estimated number of EC cases was 300 per 1,000 women with LS. Total associated costs for treatment of EC were $5.9 million. Offering PH to FDRs aged 40–80 years was considered optimal. This strategy reduced the number of endometrial cancer cases to 5.4 (−98%), resulting in 516 quality‐adjusted life years (QALY) gained and increasing the costs (treatment of endometrial cancer and PH) to $15.0 million (+154%) per 1,000 women. PH from earlier ages was more costly and resulted in fewer QALYs, although this finding was sensitive to disutility for PH.

Conclusions

Offering PH to 40‐ to 80‐year‐old women with LS is expected to add 0.5 QALY per person at acceptable costs. Women may decide to have PH at a younger age, depending on their individual disutility for PH and premature menopause.

Genetic Gastric Cancer Risk Syndromes

Purpose of review

Gastric cancer is a leading cause of cancer death in the world. Between 1% and 3% of cases are associated with specific genetic cancer risk syndromes. The purpose of this article is to review the latest insights, as well as gaps in knowledge, regarding some of the most common hereditary gastric cancer syndromes: hereditary diffuse gastric cancer (HDGC), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Lynch syndrome, the adenomatous polyposis syndromes, and the hamartomatous polyposis syndromes.

Recent findings

Patients carrying pathogenic variants in CDH1, but not meeting clinical criteria for HDGC, are increasingly being identified thanks to multigene panel testing; their absence from previous analyses overestimated gastric cancer penetrance. GAPPS is a recently described hereditary gastric cancer syndrome associated with specific point mutations in the promoter 1B region of the APC gene.

Summary

Risk of gastric cancer is highest among carriers of pathogenic variants in CDH1, with cumulative incidences approximately 40% and 30% for men and women, respectively. Mutations associated with Lynch syndrome and adenomatous polyposis syndromes confer greatest risk for gastric cancer in East Asian populations. Risk of gastric cancer in GAPPS and hamartomatous polyposis syndromes is difficult to estimate due to their rarity, but mutation status likely determines risk. Future research is needed to more precisely define risk of gastric cancer in these syndromes, so strategies for screening and prophylactic gastrectomy can be optimized.

Quadruple gastrointestinal cancer with discordance of mismatch repair protein deficiency and microsatellite instability suggesting Lynch syndrome

A 65-year-old woman with prior personal and family histories of cancer was admitted to our hospital for quadruple cancer. Preoperative endoscopy revealed a type 0-II gastric cancer (GC; gastric body), advanced type-II colon cancer (ascending colon), and early-stage recto-sigmoid colon cancers. We diagnosed her with Lynch syndrome (LS) per Amsterdam criteria, and performed distal gastrectomy, ileocecal resection and high anterior resection. Her pathological diagnoses were GC: well-to-poorly differentiated adenocarcinoma (AD, por2 > tub2) with signet-ring cells, ypT1b SM2; ascending colon cancer: AD with focal mucin products (tub2 > muc), SS; sigmoid colon cancer: AD (tub1), M; recto-sigmoid cancer: AD (tub1 > tub2), SM. Immunohistochemical tests revealed that all cancers lacked the MLH1/PMS2 protein. However, the three colon cancers were found to have high microsatellite instability (MSI); the GC was microsatellite stable (MSS). No recurrence or other cancers were observed for 30 months after surgery without adjuvant chemotherapy. As patients with LS may also develop MSS cancers, we should check for MSI in all LS cancers for proper treatment.

Assessing Effectiveness of Colonic and Gynecological Risk Reducing Surgery in Lynch Syndrome Individuals

Simple Summary

Colorectal and endometrial cancers are the most important life-threating risk in Lynch syndrome subjects, with incidences at 75 years as high as 40–60%. However, surveillance has shown to be ineffective. Risk reducing surgeries are an option in Lynch Syndrome (LS) individuals to decrease incidence of this type of cancers. In this manuscript, we have analyzed the rates of colorectal and gynecological cancer in 976 LS individuals after a mean follow-up of 10.2 years (patients under regular surveillance or after a risk reducing surgery). We can confirm in the largest study published up to the present in a single-institution that risk reducing surgeries are effective in decreasing incidence of colorectal and gynecological cancer in all LS carriers. Moreover, is the first report showing a decrease in all-cause mortality cumulative incidence in females with Lynch syndrome that undergo gynecological risk reducing surgery.

Abstract

Background: Colorectal (CRC) and endometrial cancer (EC) are the most common types of cancer in Lynch syndrome (LS). Risk reducing surgeries (RRS) might impact cancer incidence and mortality. Our objectives were to evaluate cumulative incidences of CRC, gynecological cancer and all-cause mortality after RRS in LS individuals. Methods: Retrospective analysis of 976 LS carriers from a single-institution registry. Primary endpoints were cumulative incidence at 75 years of cancer (metachronous CRC in 425 individuals; EC and ovarian cancer (OC) in 531 individuals) and all-cause mortality cumulative incidence, comparing extended (ES) vs. segmental surgery (SS) in the CRC cohort and risk reducing gynecological surgery (RRGS) vs. surveillance in the gynecological cohort. Results: Cumulative incidence at 75 years of metachronous CRC was 12.5% vs. 44.7% (p = 0.04) and all-cause mortality cumulative incidence was 38.6% vs. 55.3% (p = 0.31), for ES and SS, respectively. Cumulative, incidence at 75 years was 11.2% vs. 46.3% for EC (p = 0.001) and 0% vs. 12.7% for OC (p N/A) and all-cause mortality cumulative incidence was 0% vs. 52.7% (p N/A), for RRGS vs. surveillance, respectively. Conclusions: RRS in LS reduces the incidence of metachronous CRC and gynecological neoplasms, also indicating a reduction in all-cause mortality cumulative incidence in females undergoing RRGS.

Risk of Cancer in Family Members of Patients with Lynch-Like Syndrome

Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC patients develop mismatch repair deficiency without germline pathogenic mutation, known as Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6, and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients. In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56–2.71), which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67–4.90; p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR of LLS patients (SIR, 2.04; 95% CI, 1.44–2.80) but was lower than that among FDR of patients with LS (SIR, 5.01, 95% CI, 4.26–5.84; p < 0.001). FDRs with LLS have an increased risk of developing CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus, their management should take into account this increased risk.

ESMO recommendations on microsatellite instability testing for immunotherapy in cancer, and its relationship with PD-1/PD-L1 expression and tumour mutational burden: a systematic review-based approach

BACKGROUND

Cancers with a defective DNA mismatch repair (dMMR) system contain thousands of mutations most frequently located in monomorphic microsatellites and are thereby defined as having microsatellite instability (MSI). Therefore, MSI is a marker of dMMR. MSI/dMMR can be identified using immunohistochemistry to detect loss of MMR proteins and/or molecular tests to show microsatellite alterations. Together with tumour mutational burden (TMB) and PD-1/PD-L1 expression, it plays a role as a predictive biomarker for immunotherapy.

METHODS

To define best practices to implement the detection of dMMR tumours in clinical practice, the ESMO Translational Research and Precision Medicine Working Group launched a collaborative project, based on a systematic review-approach, to generate consensus recommendations on the: (i) definitions related to the concept of MSI/dMMR; (ii) methods of MSI/dMMR testing and (iii) relationships between MSI, TMB and PD-1/PD-L1 expression.

RESULTS

The MSI-related definitions, for which a consensus frame-work was used to establish definitions, included: 'microsatellites', 'MSI', 'DNA mismatch repair' and 'features of MSI tumour'. This consensus also provides recommendations on MSI testing; immunohistochemistry for the mismatch repair proteins MLH1, MSH2, MSH6 and PMS2 represents the first action to assess MSI/dMMR (consensus with strong agreement); the second method of MSI/dMMR testing is represented by polymerase chain reaction (PCR)-based assessment of microsatellite alterations using five microsatellite markers including at least BAT-25 and BAT-26 (strong agreement). Next-generation sequencing, coupling MSI and TMB analysis, may represent a decisive tool for selecting patients for immunotherapy, for common or rare cancers not belonging to the spectrum of Lynch syndrome (very strong agreement). The relationships between MSI, TMB and PD-1/PD-L1 expression are complex, and differ according to tumour types.

CONCLUSIONS

This ESMO initiative is a response to the urgent questions raised by the growing success of immunotherapy and provides also important insights on the relationships between MSI, TMB and PD-1/PD-L1.

Post-operative and oncological 3-year follow-up outcomes in stage 2 colonic cancer in the emergency and elective setting: a cohort study

BACKGROUND

Stage 2 colonic cancer comprises a heterogeneous group of patients with a spectrum of disease, from invasion of the sub-serosa to tumour perforation into visceral peritoneum/adjacent organs. This study evaluates the post-operative outcomes and prognostic factors of patients with both emergency and elective presentations of stage 2 colonic cancer treated with curative intent.

METHODS

Retrospective analysis of a prospectively maintained database of adult patients (emergency and elective) who underwent curative surgery for stage 2 colonic cancer in a single tertiary referral centre between 2007 and 2016 was conducted. Multivariate analysis was performed to identify prognostic factors. Measured variables included demographics, complications, histology, disease-free survival and overall survival (OS).

RESULTS

A total of 428 patients with stage 2 colonic cancer received curative surgical resection, and negative resection margins were achieved in all cases: T3 group (stage 2A): 316 (73.8%); T4a group (stage 2B): 78 patients (18.2%); and T4b group (stage 2C): 34 (8%). There were 187 (45.7%) post-operative complications, 32 (7.5%) anastomotic leaks and eight (1.9%) 30-day mortalities. Eighty patients (19.3%) died during the follow-up. During the follow-up period, 45 patients developed recurrence (all distant). Multivariate analysis identified age >70 years, American Society of Anesthesiologists grades III-IV and male gender as factors associated with poor OS, while recurrence was higher in those aged over 70 years and with stages 2B-2C disease.

CONCLUSION

Surgical morbidity in patients with stage 2 colonic cancer who have undergone curative surgery is high. Older and more co-morbid patients have poorer OS. Stages 2B and 2C colon cancer patients have worse prognosis than those with stage 2A regarding recurrence. Future larger data sets are required to determine the role of transmural spread as a prognostic factor.

Clinical and Pathological Characterization of Lynch-Like Syndrome

BACKGROUND & AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Patients with LLS have homogeneous clinical, demographic, and pathology characteristics, regardless of family history of CRC.

The Current Practice of Lynch Syndrome Diagnosis and Management in Italy: A Qualitative Assessment

BACKGROUND

Lynch syndrome (LS) is the most frequent form of hereditary colorectal cancer (CRC; up to 3-5% of the total CRC burden) and predisposes to the development of other cancers. Multidisciplinary diagnostic strategies are relevant both to the index cases and to their at-risk relatives, but their implementation is still limited. Our study aimed to explore LS testing practices in Italy.

METHODS

In order to ascertain the current practice of LS diagnosis and management, we conducted a qualitative assessment by sending a questionnaire to health care professionals at 4 Italian hospitals selected as "models" representing different hospital settings. Based on the surveys, we reconstructed the management pathways for CRC patients in terms of diagnostic strategies and health professionals involved.

RESULTS

Seven of the 8 invited professionals filled in the questionnaire. Noncompliance with the latest guidelines was reported, as no tumor "screening" was performed on CRC cases. The lack of a structured multidisciplinary team who manages CRC patients from risk assessment to diagnosis and follow-up was reported. The availability of professionals and laboratory technologies differ widely between hospitals. As for cascade testing of at-risk relatives, a systematic and active approach was absent in all the considered hospitals.

CONCLUSIONS

Our study shows that no structured and standardized pathways for the diagnosis and management of LS patients are currently in place in Italy. We envisage that by extending our research to further experiences and countries, an increasing awareness of the topic can be translated into a health gain for hereditary CRC patients and their at-risk relatives.

Phenotypic and genotypic heterogeneity of Lynch syndrome: a complex diagnostic challenge

Lynch syndrome is the hereditary disorder that most frequently predisposes to colorectal cancer as well as predisposing to a number of extracolonic cancers, most prominently endometrial cancer. It is caused by germline mutations in the mismatch repair genes. Both its phenotype and genotype show marked heterogeneity. This review gives a historical overview of the syndrome, its heterogeneity, its genomic landscape, and its implications for complex diagnosis, genetic counseling and putative implications for immunotherapy.

Muir-Torre Syndrome: A Case Report in a Woman Without Personal Cancer History

We report a case of a 68-year-old white woman presenting with 5 sebaceous neoplasms, ranging from sebaceous adenoma to sebaceoma on histopathology. Despite the lack of a personal cancer history, her multiple sebaceous neoplasms and a paternal history of colon cancer prompted testing her sebaceous adenomas for microsatellite instability (MSI) by immunohistochemistry. The results showed retained nuclear expressions of MLH1 and PMS2 while MSH2 and MSH6 proteins were absent. The tumor infiltrating lymphocytes expressed both MSH2 and MSH6, providing reliable internal positive controls. Having a high probability for MSI, she was found to be heterozygous for a germline point mutation in MSH2 gene, where a pathologic variant, c.1165C > T (p.Arg389*), determined by sequencing confirmed Muir-Torre syndrome (MTS). On further genetic counseling recommendations, one of her 2 sons was found to have colon cancer in the context of his MTS. In this article, we highlight and review the implications of MSI testing by both immunohistochemistry and sequencing as they relate to confirming the diagnosis of a suspected case of MTS.

Constitutional mismatch repair deficiency as a differential diagnosis of neurofibromatosis type 1: consensus guidelines for testing a child without malignancy

Constitutional mismatch repair deficiency (CMMRD) is a rare childhood cancer predisposition syndrome caused by biallelic germline mutations in one of four mismatch-repair genes. Besides very high tumour risks, CMMRD phenotypes are often characterised by the presence of signs reminiscent of neurofibromatosis type 1 (NF1). Because NF1 signs may be present prior to tumour onset, CMMRD is a legitimate differential diagnosis in an otherwise healthy child suspected to have NF1/Legius syndrome without a detectable underlying NF1/SPRED1 germline mutation. However, no guidelines indicate when to counsel and test for CMMRD in this setting. Assuming that CMMRD is rare in these patients and that expected benefits of identifying CMMRD prior to tumour onset should outweigh potential harms associated with CMMRD counselling and testing in this setting, we aimed at elaborating a strategy to preselect, among children suspected to have NF1/Legius syndrome without a causative NF1/SPRED1 mutation and no overt malignancy, those children who have a higher probability of having CMMRD. At an interdisciplinary workshop, we discussed estimations of the frequency of CMMRD as a differential diagnosis of NF1 and potential benefits and harms of CMMRD counselling and testing in a healthy child with no malignancy. Preselection criteria and strategies for counselling and testing were developed and reviewed in two rounds of critical revisions. Existing diagnostic CMMRD criteria were adapted to serve as a guideline as to when to consider CMMRD as differential diagnosis of NF1/Legius syndrome. In addition, counselling and testing strategies are suggested to minimise potential harms.

Hereditary Nonpolyposis Colorectal Cancer and Cancer Syndromes: Recent Basic and Clinical Discoveries

Approximately one-third of individuals diagnosed with colorectal cancer have a family history of cancer, suggesting that CRCs may result from a heritable component. Despite the availability of current gene-identification techniques, only 5% of all CRCs emerge from well-identifiable inherited causes for predisposition, including polyposis and nonpolyposis syndromes. Hereditary nonpolyposis colorectal cancer represents a large proportion of cases, and robustly affected patients are at increased risk for early onset, synchronous, and metachronous colorectal malignancies and extracolonic malignancies. HNPCC encompasses several cancer syndromes, such as Lynch syndrome, Lynch-like syndrome, and familial colorectal cancer type X, which have remarkable clinical presentations and overlapping genetic profiles that make clinical diagnosis a challenging task. Therefore, distinguishing between the HNPCC disorders is crucial for physicians as an approach to tailor different recommendations for patients and their at-risk family members according to the risks for colonic and extracolonic cancer associated with each syndrome. Identification of these potential patients through epidemiological characteristics and new genetic testing can estimate the individual risk, which informs appropriate cancer screening, surveillance, and/or treatment strategies. In the past three years, many appealing and important advances have been made in our understanding of the relationship between HNPCC and CRC-associated syndromes. The knowledge from the genetic profile of cancer syndromes and unique genotype-phenotype profiles in the different syndromes has changed our cognition. Therefore, this review presents and discusses HNPCC and several common nonpolyposis syndromes with respect to molecular phenotype, histopathologic features, and clinical presentation.

Microsatellite instability in colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease that is caused by the interaction of genetic and environmental factors. Although it is one of the most common cancers worldwide, CRC would be one of the most curable cancers if it is detected in the early stages. Molecular changes that occur in colorectal cancer may be categorized into three main groups: 1) Chromosomal Instability (CIN), 2) Microsatellite Instability (MSI), and 3) CpG Island Methylator phenotype (CIMP). Microsatellites, also known as Short Tandem Repeats (STRs) are small (1-6 base pairs) repeating stretches of DNA scattered throughout the entire genome and account for approximately 3 % of the human genome. Due to their repeated structure, microsatellites are prone to high mutation rate. Microsatellite instability (MSI) is a unique molecular alteration and hyper-mutable phenotype, which is the result of a defective DNA mismatch repair (MMR) system, and can be defined as the presence of alternate sized repetitive DNA sequences which are not present in the corresponding germ line DNA. The presence of MSI is found in sporadic colon, gastric, sporadic endometrial and the majority of other cancers. Approximately, 15-20 % of colorectal cancers display MSI. Determination of MSI status in CRC has prognostic and therapeutic implications. As well, detecting MSI is used diagnostically for tumor detection and classification. For these reasons, microsatellite instability analysis is becoming more and more important in colorectal cancer patients. The objective of this review is to provide the comprehensive summary of the update knowledge of colorectal cancer classification and diagnostic features of microsatellite instability.

Community Practice Implementation of a Self-administered Version of PREMM1,2,6 to Assess Risk for Lynch Syndrome

BACKGROUND & AIMS

Lynch syndrome is a genetic disorder that greatly increases risk for colorectal and other cancers, although it is underdiagnosed. Prediction of MLH1, MSH2, and MSH6 (PREMM_1,2,6) is a web-based tool that analyzes individuals' personal/family histories of cancer to quantify their likelihood of carrying a germline mutation associated with Lynch syndrome. We investigated the feasibility of systematic risk assessment for Lynch syndrome in a community gastroenterology practice using a patient-completed version of PREMM_1,2,6.

METHODS

PREMM_1,2,6 was adapted into a computer tablet version designed for self-administration by patients. Individuals presenting to a community gastroenterology office and endoscopy facility in California completed the PREMM_1,2,6 assessment before their visit (n = 3134). The total study duration (8 months) comprised a 2-month initiation period (May 1-June 30, 2013) and a 6-month study period (July 1-December 31, 2013). Genetic counseling and germline analysis for mutations in genes associated with Lynch syndrome (MLH1, MSH2, MSH6, PMS2, and EPCAM) were offered to individuals with PREMM_1,2,6 scores of 5% or higher. Patients and providers completed surveys to evaluate the feasibility and satisfaction with the process.

RESULTS

Of the 3134 individuals assessed by PREMM_1,2,6 during the 6-month study period, 177 individuals (5.6%) had scores of 5% or higher. Of these, 146 individuals underwent genetic testing, along with 28 additional participants recruited nonconsecutively during the initiation period. Mutations associated with Lynch syndrome were detected in 3 of the 146 individuals (2.1%) with PREMM_1,2,6 scores of 5% or higher who underwent germline testing, and 3 of the 28 patients (10.7%) recruited during study initiation with PREMM_1,2,6 scores of 5% or higher. Of the participants who underwent genetic analysis, 98.6% stated that they understood the information provided to them. All of the surveyed providers stated that they were satisfied with the incorporation of PREMM_1,2,6 into their clinical practice, and that they would continue using it to assess risk for Lynch syndrome.

CONCLUSIONS

A patient self-administered version of the PREMM_1,2,6 Lynch syndrome risk assessment model can be used systematically in community-based gastroenterology and endoscopy practices.

Hereditary Colorectal Cancer Syndromes

Awareness of hereditary colorectal cancer syndromes is important to facilitate their identification because affected patients are at increased risk for early onset, synchronous, and metachronous colorectal malignancies, and certain extracolonic malignancies depending on the syndrome. Identification of an affected individual allows for screening and early interventions for patients and their at-risk kindred. Genetic counseling and testing is important to the care of these patients. As knowledge of the genetic basis of these syndromes grows, unique genotype-phenotype profiles allow clinicians to tailor surveillance and treatment strategies based on individual risk.

The current value of determining the mismatch repair status of colorectal cancer: A rationale for routine testing

Colorectal Cancer (CRC) is the third most prevalent cancer in men and women. Up to 15% of CRCs display microsatellite instability (MSI). MSI is reflective of a deficient mismatch repair (MMR) system and is most commonly caused by hypermethylation of the MLH1 promoter. However, it may also be due to autosomal dominant constitutional mutations in DNA MMR, termed Lynch Syndrome. MSI may be diagnosed via polymerase chain reaction (PCR) or alternatively, immunohistochemistry (IHC) can identify MMR deficiency (dMMR). Many institutions now advocate universal tumor screening of CRC via either PCR for MSI or IHC for dMMR to guide Lynch Syndrome testing. The association of sporadic MSI with methylation of the MLH1 promoter and an activating BRAF mutation may offer further exclusion criteria for genetic testing. Aside from screening for Lynch syndrome, MMR testing is important because of its prognostic and therapeutic implications. Several studies have shown MSI CRCs exhibit different clinicopathological features and prognosis compared to microsatellite-stable (MSS) CRCs. For example, response to conventional chemotherapy has been reported to be less in MSI tumours. More recently, MSI tumours have been shown to be responsive to immune-checkpoint inhibition providing a novel therapeutic strategy. This provides a rationale for routine testing for MSI or dMMR in CRC.

Screening for mismatch repair deficiency in colorectal cancer: data from three academic medical centers

Reflex immunohistochemistry (rIHC) for mismatch repair (MMR) protein expression can be used as a screening tool to detect Lynch Syndrome (LS). Increasingly the mismatch repair-deficient (dMMR) phenotype has therapeutic implications. We investigated the pattern and consequence of testing for dMMR in three Irish Cancer Centres (CCs). CRC databases were analyzed from January 2005-December 2013. CC1 performs IHC upon physician request, CC2 implemented rIHC in November 2008, and CC3 has been performing rIHC since 2004. The number of eligible patients referred to clinical genetic services (CGS), and the number of LS patients per center was determined. 3906 patients were included over a 9-year period. dMMR CRCs were found in 32/153 (21%) of patients at CC1 and 55/536 (10%) at CC2, accounting for 3% and 5% of the CRC population, respectively. At CC3, 182/1737 patients (10%) had dMMR CRCs (P < 0.001). Additional testing for the BRAF V600E mutation, was performed in 49 patients at CC3 prior to CGS referral, of which 29 were positive and considered sporadic CRC. Referrals to CGS were made in 66%, 33%, and 30% of eligible patients at CC1, CC2, and CC3, respectively. LS accounted for CRC in eight patients (0.8%) at CC1, eight patients (0.7%) at CC2, and 20 patients (1.2%) at CC3. Cascade testing of patients with dMMR CRC was not completed in 56%. Universal screening increases the detection of dMMR tumors and LS kindreds. Successful implementation of this approach requires adequate resources for appropriate downstream management of these patients.

Alcohol Consumption and the Risk of Colorectal Cancer for Mismatch Repair Gene Mutation Carriers

Background: People with germline mutation in one of the DNA mismatch repair (MMR) genes have increased colorectal cancer risk. For these high-risk people, study findings of the relationship between alcohol consumption and colorectal cancer risk have been inconclusive.Methods: 1,925 MMR gene mutations carriers recruited into the Colon Cancer Family Registry who had completed a questionnaire on lifestyle factors were included. Weighted Cox proportional hazard regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between alcohol consumption and colorectal cancer.Results: Colorectal cancer was diagnosed in 769 carriers (40%) at a mean (SD) age of 42.6 (10.3) years. Compared with abstention, ethanol consumption from any alcoholic beverage up to 14 g/day and >28 g/day was associated with increased colorectal cancer risk (HR, 1.50; 95% CI, 1.09-2.07 and 1.69; 95% CI, 1.07-2.65, respectively; Ptrend = 0.05), and colon cancer risk (HR, 1.78; 95% CI, 1.27-2.49 and 1.94; 95% CI, 1.19-3.18, respectively; Ptrend = 0.02). However, there was no clear evidence for an association with rectal cancer risk. Also, there was no evidence for associations between consumption of individual alcoholic beverage types (beer, wine, spirits) and colorectal, colon, or rectal cancer risk.Conclusions: Our data suggest that alcohol consumption, particularly more than 28 g/day of ethanol (∼2 standard drinks of alcohol in the United States), is associated with increased colorectal cancer risk for MMR gene mutation carriers.Impact: Although these data suggested that alcohol consumption in MMR carriers was associated with increased colorectal cancer risk, there was no evidence of a dose-response, and not all types of alcohol consumption were associated with increased risk. Cancer Epidemiol Biomarkers Prev; 26(3); 366-75. ©2016 AACR.

Prevalence and Penetrance of Major Genes and Polygenes for Colorectal Cancer

Background: Although high-risk mutations in identified major susceptibility genes (DNA mismatch repair genes and MUTYH) account for some familial aggregation of colorectal cancer, their population prevalence and the causes of the remaining familial aggregation are not known.Methods: We studied the families of 5,744 colorectal cancer cases (probands) recruited from population cancer registries in the United States, Canada, and Australia and screened probands for mutations in mismatch repair genes and MUTYH We conducted modified segregation analyses using the cancer history of first-degree relatives, conditional on the proband's age at diagnosis. We estimated the prevalence of mutations in the identified genes, the prevalence of HR for unidentified major gene mutations, and the variance of the residual polygenic component.Results: We estimated that 1 in 279 of the population carry mutations in mismatch repair genes (MLH1 = 1 in 1,946, MSH2 = 1 in 2,841, MSH6 = 1 in 758, PMS2 = 1 in 714), 1 in 45 carry mutations in MUTYH, and 1 in 504 carry mutations associated with an average 31-fold increased risk of colorectal cancer in unidentified major genes. The estimated polygenic variance was reduced by 30% to 50% after allowing for unidentified major genes and decreased from 3.3 for age <40 years to 0.5 for age ≥70 years (equivalent to sibling relative risks of 5.1 to 1.3, respectively).Conclusions: Unidentified major genes might explain one third to one half of the missing heritability of colorectal cancer.Impact: Our findings could aid gene discovery and development of better colorectal cancer risk prediction models. Cancer Epidemiol Biomarkers Prev; 26(3); 404-12. ©2016 AACR.

Historical Perspective on Familial Gastric Cancer

Gastric cancer is a common disease worldwide, typically associated with acquired chronic inflammation in the stomach, related in most instances to infection by Helicobacter pylori. A small percentage of cases occurs in familial clusters, and some of these can be linked to specific germline mutations. This article reviews the historical background to the current understanding of familial gastric cancer, focuses on the entity of hereditary diffuse gastric cancer, and also reviews the risks for gastric cancer related to a number of other familial genetic diseases.

Muir-Torre syndrome (MTS): An update and approach to diagnosis and management

Muir-Torre syndrome (MTS) is a rare genetic condition that predisposes individuals to skin tumors and visceral malignancies. Because of the potentially aggressive nature of internal malignancies and sebaceous carcinoma, and the tendency to have multiple low-grade visceral cancers, close cancer surveillance is required in individuals and their families with this usually autosomal dominant disorder. Although the majority of MTS is caused by mutations in DNA mismatch repair genes resulting in microsatellite instability, a newly described subtype of MTS does not demonstrate microsatellite instability and may be inherited in an autosomal recessive pattern. In addition, MTS may be unmasked in transplant recipients taking specific immunosuppressant drugs or other immunosuppressed patients. Neoplasms may be subject to immunohistochemistry or both immunohistochemistry and genetic testing to confirm the diagnosis of MTS. Here, we offer an update and an approach to the diagnosis and management of MTS with a particular emphasis on the role of immunohistochemistry and genetic testing.

Mismatch repair deficiency testing in clinical practice

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

Defective DNA mismatch repair activity is common in sebaceous neoplasms, and may be an ineffective approach to screen for Lynch syndrome

A subset of individuals with Lynch syndrome (LS) has a variant called Muir-Torre syndrome (MTS) where patients develop multiple sebaceous neoplasms. Absence of gene expression and microsatellite instability (MSI) have been welldocumented in LS neoplasms. It is unclear whether the presence of these abnormalities in isolated sebaceous neoplasms would indicate the likely presence of otherwise unsuspected LS or MTS. 164 specimens of sporadic cutaneous sebaceous neoplasms were obtained. IHC was performed for expression of the DNA mismatch repair (MMR) genes MSH2 and MLH1. A 5-marker mononucleotide repeat microsatellite panel was analyzed to detect MSI, and two or more mutated markers were required for MSI. 164 sebaceous neoplasms were obtained from 162 patients. IHC data was successfully obtained from 162 samples and MSI data was obtained from 138 samples. 50/162 (31%) had abnormal IHC with loss of staining for either MSH2 (37/162, 23%), MLH1 (9/162, 5%) or both (4/162, 2%). 37% (52/138) of the tumors had MSI. 82% (111/136) of those with both IHC and MSI results correlated as expected. 18% (25/136) showed discordance between IHC and MSI. 69/163 (42%) had either abnormal IHC or MSI, indicating deficient DNA MMR activity. Given the substantial proportion of DNA MMR deficiency in these sebaceous neoplasms, screening for DNA MMR defects in sebaceous neoplasms would not appear to be an effective way to distinguish patients with LS or MTS from those with sporadic skin lesions and an ordinary risk of cancer.

Hereditary cancer syndromes as model systems for chemopreventive agent development

Research in chemoprevention has undergone a shift in emphasis for pragmatic reasons from large, phase III randomized studies to earlier phase studies focused on safety, mechanisms, and utilization of surrogate endpoints such as biomarkers instead of cancer incidence. This transition permits trials to be conducted in smaller populations and at substantially reduced costs while still yielding valuable information. This article will summarize some of the current chemoprevention challenges and the justification for the use of animal models to facilitate identification and testing of chemopreventive agents as illustrated though four inherited cancer syndromes. Preclinical models of inherited cancer syndromes serve as prototypical systems in which chemopreventive agents can be developed for ultimate application to both the sporadic and inherited cancer settings.

Observational Study: Familial Relevance and Oncological Significance of Revised Bethesda Guidelines in Colorectal Patients That Have Undergone Curative Resection

Amsterdam criteria for the hereditary nonpolyposis colorectal cancer (HNPCC) exclude most suspect cases of possible hereditary colorectal cancer (CRC). By contrast, revised Bethesda guidelines excessively broaden the disease spectrum. The aim of this study is to retrospectively evaluate the cliniciopathilogical characteristics of patients fulfilling the revised Bethesda guidelines and to review the efficacy and limitations of the revised guidelines.This retrospective study enrolled 3609 patients who underwent curative surgery for primary CRC. Patients were classified into the Bethesda group or the control group according to whether they fulfilled the revised Bethesda guidelines. Patients were further categorized when they fulfilled a minimum of 2 items of the revised guidelines. Individual items were analyzed for deficient mismatch repair (d-MMR).The median follow-up was 82.9 (interquartile range, 72-101) months. Patients in the Bethesda group were younger and had a higher rate of reduced mismatch repair (MMR) protein expression, microsatellite instability, and right colonic involvement (all P < 0.001) than the control group. As a predictor of d-MMR, the revised Bethesda guidelines showed a sensitivity of 63.0% and a specificity of 72.6%. Items 1 and 2, respectively, or the item pair 1 and 2, were independent predictors of d-MMR (all P < 0.001). Patients fulfilling the Bethesda guidelines showed clinicopathological features of HNPCC.The revised Bethesda guidelines appear to be a competent predictor of d-MMR. Specifically, items 1 and 2 are significant predictors of d-MMR and may be relevant to the application of the revised Bethesda guidelines.

Approaches to diagnose DNA mismatch repair gene defects in cancer

The DNA repair pathway mismatch repair (MMR) is responsible for the recognition and correction of DNA biosynthetic errors caused by inaccurate nucleotide incorporation during replication. Faulty MMR leads to failure to address the mispairs or insertion deletion loops (IDLs) left behind by the replicative polymerases and results in increased mutation load at the genome. The realization that defective MMR leads to a hypermutation phenotype and increased risk of tumorigenesis highlights the relevance of this pathway for human disease. The association of MMR defects with increased risk of cancer development was first observed in colorectal cancer patients that carried inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Currently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome (LS) partly to include the associated risk of developing extra-colonic cancers. In addition, a number of non-hereditary, mostly epigenetic, alterations of MMR genes have been described in sporadic tumors. Besides conferring a strong cancer predisposition, genetic or epigenetic inactivation of MMR genes also renders cells resistant to some chemotherapeutic agents. Therefore, diagnosis of MMR deficiency has important implications for the management of the patients, the surveillance of their relatives in the case of LS and for the choice of treatment. Some of the alterations found in MMR genes have already been well defined and their pathogenicity assessed. Despite this substantial wealth of knowledge, the effects of a large number of alterations remain uncharacterized (variants of uncertain significance, VUSs). The advent of personalized genomics is likely to increase the list of VUSs found in MMR genes and anticipates the need of diagnostic tools for rapid assessment of their pathogenicity. This review describes current tools and future strategies for addressing the relevance of MMR gene alterations in human disease.

Detection of DNA repair protein in colorectal cancer of patients up to 50 years old can increase the identification of Lynch syndrome?

The aim of this study was to compare the results of protein level of the DNA mismatch repair genes with the clinical diagnosis of Lynch syndrome according to the Amsterdam II criteria in patients 50 years and younger who underwent surgery for colorectal cancer. The subjects of analysis were 48 patients 50 years old and younger. Immunohistochemistry assays were performed to detect proteins from the DNA mismatch repair genes. Clinicopathological data and Amsterdam II criteria for the diagnosis of hereditary nonpolyposis colorectal cancer were obtained by analyzing medical records. Two (4 %) patients satisfied the Amsterdam II criteria for Lynch syndrome, and both presented levels of all of the studied mismatch repair proteins. A total of 13 (27 %) patients exhibited the absence of protein levels of the studied mismatch repair genes. None of these patients were considered suspicious for Lynch syndrome according to the Amsterdam II criteria. Screening for the level of proteins of the mismatch repair system in all colorectal cancer patients 50 years and younger can increase the identification of patients with suspicion of Lynch syndrome.

Lynch Syndrome Patients with Limited Family History Identified in a Laboratory Setting: A Descriptive Study

OBJECTIVE

Patients diagnosed with colorectal cancer before the age of 50 years are recommended for Lynch syndrome (LS) testing according to current clinical guidelines. However, many patients are not identified because of the stringent guidelines on existing diagnostic criteria. The aim of this analysis was to evaluate the ability of existing criteria to adequately ascertain patients appropriate for LS genetic testing.

METHOD

To determine whether existing clinical diagnostic criteria underascertain individuals who would be appropriate candidates for hereditary cancer risk assessment, we stratified the detection rate of deleterious mismatch repair (MMR) mutations in 9,109 patients with a personal history of colorectal cancer who were diagnosed between the ages of 30 and 74 years with little or no family history suggestive of LS by 5-year age-at-detection intervals.

RESULTS

There was little difference in the aggregate positive mutation rate in individuals diagnosed between the ages of 50 and 59 years compared to the positive mutation rate in patients diagnosed before the age of 50 years.

CONCLUSION

These results suggest that cancer diagnosis under the age of 50 years is an insufficiently sensitive predictor of hereditary cancer susceptibility.

When is Genomic Testing Cost-Effective? Testing for Lynch Syndrome in Patients with Newly-Diagnosed Colorectal Cancer and Their Relatives

Varying estimates of the cost-effectiveness of genomic testing applications can reflect differences in study questions, settings, methods and assumptions. This review compares recently published cost-effectiveness analyses of testing strategies for Lynch Syndrome (LS) in tumors from patients newly diagnosed with colorectal cancer (CRC) for either all adult patients or patients up to age 70 along with cascade testing of relatives of probands. Seven studies published from 2010 through 2015 were identified and summarized. Five studies analyzed the universal offer of testing to adult patients with CRC and two others analyzed testing patients up to age 70; all except one reported incremental cost-effectiveness ratios (ICERs) < $ 100,000 per life-year or quality-adjusted life-year gained. Three studies found lower ICERs for selective testing strategies using family history-based predictive models compared with universal testing. However, those calculations were based on estimates of sensitivity of predictive models derived from research studies, and it is unclear how sensitive such models are in routine clinical practice. Key model parameters that are influential in ICER estimates included 1) the number of first-degree relatives tested per proband identified with LS and 2) the cost of gene sequencing. Others include the frequency of intensive colonoscopic surveillance, the cost of colonoscopy, and the inclusion of extracolonic surveillance and prevention options.