Yield of routine molecular analyses in colorectal cancer patients ≤70 years to detect underlying Lynch syndrome

A registry-based study on universal screening for defective mismatch repair in colorectal cancer in Denmark highlights disparities in screening uptake and counselling referrals

Universal screening for defective mismatch repair (dMMR) in colorectal cancer utilizes immunohistochemical staining for MLH1, MSH2, MSH6 and PSM2. Additionally, BRAF V600E mutations status and MLH1 hypermethylation should be performed to distinguish germline and somatic dMMR alterations. A decade of Danish population-based registries has been analysed regarding screening uptake, detection rate and referral to genetic counselling. MMR testing was performed in 71·8% (N = 34,664) of newly diagnosed colorectal cancers with an increasing trend to 88·8% coverage in the study's final year. The likelihood of undergoing MMR testing was reduced in males with 2% (95% CI 0·4-2·7, p = 0·008), with 4·1% in patients above age 70 years (95% CI 1·5-6·6, p = 0·003) compared in patients below age 51 years, with 16·3% in rectal cancers (95% CI 15·1-17·6, p < 0·001) and 1·4% left-sided colon cancers (95% CI 0·1-1·7, p = 0·03) compared to right-sided colon cancers. Tumour stage II and III increased the likelihood of being tested, with 3·7% for stage II (95% CI 2·2-5·6, p < 0·001) and 3·3% for stage III tumours (95% CI 1·8-4·8, p < 0·001) compared to stage I tumours, whereas the likelihood for stage IV tumours is reduced by 35·7% (95% CI 34·2-37·2, p < 0·001). Test rates significantly differed between the Danish health care regions. dMMR was identified in 15·1% (95% CI 14·8-15·6, p < 0·001) cases with somatic MMR inactivation in 6·7% of the cases. 8·3% tumours showed hereditary dMMR expression patterns, and 20·0% of those were referred to genetic counselling. Despite the high uptake rates, we found disparities between patient groups and missed opportunities for genetic diagnostics.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

PMS2-associated Lynch syndrome: Past, present and future

Carriers of any pathogenic variant in one of the MMR genes (path_MMR carriers) were traditionally thought to be at comparable risk of developing a range of different malignancies, foremost colorectal cancer (CRC) and endometrial cancer. However, it is now widely accepted that their cancer risk and cancer spectrum range notably depending on which MMR gene is affected. Moreover, there is increasing evidence that the MMR gene affected also influences the molecular pathogenesis of Lynch syndrome CRC. Although substantial progress has been made over the past decade in understanding these differences, many questions remain unanswered, especially pertaining to path_PMS2 carriers. Recent findings show that, while the cancer risk is relatively low, PMS2-deficient CRCs tend to show more aggressive behaviour and have a worse prognosis than other MMR-deficient CRCs. This, together with lower intratumoral immune infiltration, suggests that PMS2-deficient CRCs might have more in common biologically with sporadic MMR-proficient CRCs than with other MMR-deficient CRCs. These findings could have important consequences for surveillance, chemoprevention and therapeutic strategies (e.g. vaccines). In this review we discuss the current knowledge, current (clinical) challenges and knowledge gaps that should be targeted by future studies.

Somatic hits in mismatch repair genes in colorectal cancer among non-seminoma testicular cancer survivors

BACKGROUND

Non-seminoma testicular cancer survivors (TCS) have an increased risk of developing colorectal cancer (CRC) when they have been treated with platinum-based chemotherapy. Previously we demonstrated that among Hodgkin lymphoma survivors (HLS) there is enrichment of rare mismatch repair (MMR) deficient (MMRd) CRCs with somatic hits in MMR genes. We speculate that this phenomenon could also occur among other cancer survivors. We therefore aim to determine the MMR status and its underlying mechanism in CRC among TCS (TCS-CRC).

METHODS

Thirty TCS-CRC, identified through the Dutch pathology registry, were analysed for MMR proteins by immunohistochemistry. Next-generation sequencing was performed in MMRd CRCs without MLH1 promoter hypermethylation (n = 4). Data were compared with a male cohort with primary CRC (P-CRC, n = 629).

RESULTS

MMRd was found in 17% of TCS-CRCs vs. 9% in P-CRC (p = 0.13). MMRd was more often caused by somatic double or single hit in MMR genes by mutation or loss of heterozygosity in TCS-CRCs (3/30 (10%) vs. 11/629 (2%) in P-CRCs (p < 0.01)).

CONCLUSIONS

MMRd CRCs with somatic double or single hit are more frequent in this small cohort of TCS compared with P-CRC. Exposure to anticancer treatments appears to be associated with the development of these rare MMRd CRC among cancer survivors.

Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer

CONTEXT.—

The US Food and Drug Administration (FDA) approved immune checkpoint inhibitor therapy for patients with advanced solid tumors that have DNA mismatch repair defects or high levels of microsatellite instability; however, the FDA provided no guidance on which specific clinical assays should be used to determine mismatch repair status.

OBJECTIVE.—

To develop an evidence-based guideline to identify the optimal clinical laboratory test to identify defects in DNA mismatch repair in patients with solid tumor malignancies who are being considered for immune checkpoint inhibitor therapy.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Using the National Academy of Medicine-endorsed Grading of Recommendations Assessment, Development and Evaluation approach, the recommendations were derived from available evidence, strength of that evidence, open comment feedback, and expert panel consensus. Mismatch repair immunohistochemistry, microsatellite instability derived from both polymerase chain reaction and next-generation sequencing, and tumor mutation burden derived from large panel next-generation sequencing were within scope.

RESULTS.—

Six recommendations and 3 good practice statements were developed. More evidence and evidence of higher quality were identified for colorectal cancer and other cancers of the gastrointestinal (GI) tract than for cancers arising outside the GI tract.

CONCLUSIONS.—

An optimal assay depends on cancer type. For most cancer types outside of the GI tract and the endometrium, there was insufficient published evidence to recommend a specific clinical assay. Absent published evidence, immunohistochemistry is an acceptable approach readily available in most clinical laboratories.

Synonymous Variants: Necessary Nuance in our Understanding of Cancer Drivers and Treatment Outcomes

Once called "silent mutations" and assumed to have no effect on protein structure and function, synonymous variants are now recognized to be drivers for some cancers. There have been significant advances in our understanding of the numerous mechanisms by which synonymous single nucleotide variants (sSNVs) can affect protein structure and function by affecting pre-mRNA splicing, mRNA expression, stability, folding, miRNA binding, translation kinetics, and co-translational folding. This review highlights the need for considering sSNVs in cancer biology to gain a better understanding of the genetic determinants of human cancers and to improve their diagnosis and treatment. We surveyed the literature for reports of sSNVs in cancer and found numerous studies on the consequences of sSNVs on gene function with supporting in vitro evidence. We also found reports of sSNVs that have statistically significant associations with specific cancer types but for which in vitro studies are lacking to support the reported associations. Additionally, we found reports of germline and somatic sSNVs that were observed in numerous clinical studies and for which in silico analysis predicts possible effects on gene function. We provide a review of these investigations and discuss necessary future studies to elucidate the mechanisms by which sSNVs disrupt protein function and are play a role in tumorigeneses, cancer progression, and treatment efficacy. As splicing dysregulation is one of the most well recognized mechanisms by which sSNVs impact protein function, we also include our own in silico analysis for predicting which sSNVs may disrupt pre-mRNA splicing.

Universal Immunohistochemistry for Lynch Syndrome: A Systematic Review and Meta-analysis of 58,580 Colorectal Carcinomas

BACKGROUND & AIMS

Lynch syndrome is a form of hereditary colorectal cancer (CRC) caused by pathogenic germline variants (PV) in DNA mismatch repair (MMR) genes. Currently, many Western countries perform universal immunohistochemistry testing on CRC to increase the identification of Lynch syndrome patients and their relatives. For a clear understanding of health benefits and costs, data on its outcomes are required: proportions of Lynch syndrome, sporadic MMR-deficient (MMRd) cases, and unexplained MMRd cases.

METHODS

Ovid Medline, Embase, and Cochrane CENTRAL were searched for studies reporting on universal MMR immunohistochemistry, followed by MMR germline analysis, until March 20, 2020. Proportions were calculated, subgroup analyses were performed based on age and diagnostics used, and random effects meta-analyses were conducted. Quality was assessed using the Joanna Briggs Critical Appraisal Tool for Prevalence Studies.

RESULTS

Of 2723 identified articles, 56 studies covering 58,580 CRCs were included. In 6.22% (95% CI, 5.08%-7.61%; I² = 96%) MMRd was identified. MMR germline PV was present in 2.00% (95% CI, 1.59%-2.50%; I² = 92%), ranging from 1.80% to 7.27% based on completeness of diagnostics and age restriction. Immunohistochemistry outcomes were missing in 11.81%, and germline testing was performed in 76.30% of eligible patients. In 7 studies, including 6848 CRCs completing all diagnostic stages, germline PV and biallelic somatic MMR inactivation were found in 3.01% and 1.75%, respectively; 0.61% remained unexplained MMRd.

CONCLUSIONS

Age, completeness, and type of diagnostics affect the percentage of MMR PV and unexplained MMRd percentages. Complete diagnostics explain almost all MMRd CRCs, reducing the amount of subsequent multigene panel testing. This contributes to optimizing testing and surveillance in MMRd CRC patients and relatives.

Clinicopathological features and risk factors for developing colorectal neoplasia in Hodgkin's lymphoma survivors

BACKGROUND

Hodgkin's lymphoma (HL) survivors treated with abdominal radiotherapy and/or procarbazine have an increased risk of developing colorectal neoplasia.

AIMS

We evaluated the clinicopathological characteristics and risk factors for developing (advanced) neoplasia (AN) in HL survivors.

METHODS

In all, 101 HL survivors (median age 51 years, median age of HL diagnosis 25 years) underwent colonoscopy and 350 neoplasia and 44 AN (classified as advanced adenomas/serrated lesions or colorectal cancer), mostly right-sided, were detected, as published previously. An average-risk asymptomatic cohort who underwent screening colonoscopy were controls (median age 60 years). Clinicopathological characteristics of AN were evaluated in both groups. Mismatch repair (MMR) status was assessed using immunohistochemistry (MLH1/MSH2/MSH6/PMS2). Logistic regression analysis was performed to evaluate the risk factors for AN in HL survivors, including age at HL diagnosis and interval between HL and colonoscopy.

RESULTS

In 101 colonoscopies in HL survivors, AN was primarily classified based on polyp size ≥10 mm, whereas (high-grade)dysplasia was more often seen in AN in controls. An interval between HL diagnosis and colonoscopy >26 years was associated with more AN compared with an interval of <26 years, with an odds ratio for AN of 3.8 (95% confidence interval 1.4-9.1) (p < 0.01). All 39 AN that were assessed were MMR proficient.

CONCLUSIONS

Colorectal neoplasia in HL survivors differ from average-risk controls; classification AN was primarily based on polyp size (≥10 mm) in HL survivors. Longer follow-up between HL diagnosis and colonoscopy was associated with a higher prevalence of AN in HL survivors.

Genetic testing for assessment of lynch syndrome in young patients with polyps

BACKGROUND

Routine screening for establishing Lynch syndrome (LS) in young individuals diagnosed with adenomas is not recommended due to its low yield, and limited sensitivity of the employment of immunohistochemistry for DNA mismatch-repair proteins on polyps. Hence we aimed to evaluate the yield of germline mutational analysis in diagnosis of LS in a young Israeli cohort with colorectal adenomatous polyps.

METHODS

Data were retrospectively collected on consecutive patients, age ≤ 45 years, who underwent colonoscopy with removal of at least one adenoma during 2015-2020, and subsequently genetic testing by multigene panel or LS-Jewish founder mutation panel.

RESULTS

Overall, 92 patients were included (median age 35 years, range 23-45 years), of whom 79 (85.8%) underwent multigene panel genotyping, and 13 (14.2%) analysis for Jewish founder LS gene mutations. Altogether, 18 patients were identified with pathogenic mutations in actionable genes, including LS-associated genes in 6 (6.5%), BRCA2 in 2 (2.5%), GREM1 in 1(1.2%), and low-penetrance genes- APC I1307K and CHEK2- in 9 (11.4%) patients. Compared with non-LS patients, LS-carriers had a significantly higher median PREMM5 score (2.6 vs. 1.3; P = 0.04).

CONCLUSIONS

Young individuals diagnosed with adenomatous polyps should be offered genetic testing when fulfilling clinical guidelines for LS, but weight should also be given to adenoma characteristics in the PREMM5 score.

Comprehensive analysis of DNA mismatch repair-deficient gastric cancer in a Japanese hospital-based population

BACKGROUND

The attention on mismatch repair-deficient (dMMR) gastric cancer has increased in this era of anti-PD-1 blockade therapy; however, the prevalence and molecular genetics of patients with dMMR gastric cancer have not been completely investigated.

METHODS

Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary gastric cancers of 513 consecutive patients. Genetic and/or epigenetic alterations of the MMR genes were also investigated.

RESULTS

Loss of expression of one or more MMR proteins was observed in 58 patients (11.3%); 54 patients showed loss of MLH1/PMS2, 3 patients showed loss of MLH1/PMS2/MSH6 and 1 patient showed loss of PMS2 alone. Among these 58 patients, 55 showed hypermethylation of the promoter region of MLH1. Genetic testing revealed that the remaining three patients had Lynch syndrome (n = 1) or Lynch-like syndrome (n = 2). A total of 15 patients (25.9% of all patients with dMMR gastric cancer and 2.9% of all patients with gastric cancer), including 11 patients with stage I-III dMMR gastric cancer who had recurrence and 4 patients with stage IV dMMR gastric cancer, are potential candidates for the use of anti-PD-1 blockades.

CONCLUSIONS

This is the first study to investigate the frequency and molecular genetic mechanisms of dMMR gastric cancer comprehensively, focusing on the benefit of using PD-1 blockades. Our observations will be beneficial in the clinical practice of metastatic gastric cancer.

Compliance with mismatch repair testing in pT1 colorectal cancer diagnosed before the age of 70 years

Mismatch repair (MMR) testing is recommended in the Netherlands for all patients under 70 years of age with newly diagnosed colorectal cancer (CRC) in order to identify Lynch syndrome. T1 CRC can be removed by local excision or oncological surgical resection. We evaluated the frequency of MMR testing in pT1 lesions within the Dutch CRC screening cohort. pT1 CRC diagnosed within the Dutch population-based screening program from 2016-2018 were identified by the Dutch pathology registry (PALGA). Pathology reports were evaluated, including registration of MMR testing (by immunohistochemistry and/or microsatellite instability PCR). Frequency of MMR testing was compared between pT1 tumors that were treated by local (endoscopic or transanal) excision and oncological surgical resections. A total of 3.692 pT1 CRCs were diagnosed (median age 63 years, 61.4% males). MMR testing was performed in 83% and uptake increased over time (71% in 2016 to 92% in 2018, p<0.01). MMR testing was significantly more often performed in younger patients and in academic hospitals. When pT1 CRC was treated by oncological surgical resection (n=1.132), MMR testing was performed in 89% of cases and was known prior to oncological resection in 51% of cases. MMR testing occurred significantly less often in case of local excision (80% of n=2.560) compared to oncological surgical resection (p<0.01). MMR testing was performed in 83% of T1 CRCs and uptake increased over time. MMR testing was more frequently performed in pT1 CRC resected by oncological surgical resection compared with local excision.

Initiatives to Scale Up and Expand Reach of Cancer Genomic Services Outside of Specialty Clinical Settings: A Systematic Review

CONTEXT

This systematic review aims to (1) characterize strategies used to identify individuals at increased risk for hereditary breast and ovarian cancer syndrome and Lynch syndrome outside of oncology and clinical genetic settings, (2) describe the extent to which these strategies have extended the reach of genetic services to underserved target populations, and (3) summarize indicators of the potential scalability of these strategies.

EVIDENCE ACQUISITION

Investigators searched PubMed, EMBASE, and PsycINFO for manuscripts published from October 2005 to August 2019. Eligible manuscripts were those published in English, those that described strategies to identify those at risk for hereditary breast and ovarian cancer syndrome or Lynch syndrome, those implemented outside of an oncology or genetic specialty clinic, and those that included measures of cancer genetic services uptake. This study assessed strategies used to increase the reach of genetic risk screening and counseling services. Each study was evaluated using the 16-item quality assessment tool, and results were reported according to the PRISMA guidelines.

EVIDENCE SYNTHESIS

Of the 16 eligible studies, 11 were conducted in clinical settings and 5 in public health settings. Regardless of setting, most (63%, 10/16) used brief screening tools to identify people with a family history suggestive of hereditary breast and ovarian cancer syndrome or Lynch syndrome. When reported, genetic risk screening reach (range =11%-100%) and genetic counseling reach (range =11%-100%) varied widely across studies. Strategies implemented in public health settings appeared to be more successful (median counseling reach=65%) than those implemented in clinical settings (median counseling reach=26%). Most studies did not describe fundamental components relevant for broad scalability.

CONCLUSIONS

Efforts to expand cancer genomic services are limited outside of traditional oncology and genetic clinics. This is a missed opportunity because evidence thus far suggests that these efforts can be successful in expanding the reach of genetic services with the potential to reduce health inequities in access. This review highlights the need for accelerating research that applies evidence-based implementation strategies and frameworks along with process evaluation to understand barriers and facilitators to scalability of strategies with high reach.

How Should We Test for Lynch Syndrome? A Review of Current Guidelines and Future Strategies

International guidelines for the diagnosis of Lynch syndrome (LS) recommend molecular screening of colorectal cancers (CRCs) to identify patients for germline mismatch repair (MMR) gene testing. As our understanding of the LS phenotype and diagnostic technologies have advanced, there is a need to review these guidelines and new screening opportunities. We discuss the barriers to implementation of current guidelines, as well as guideline limitations, and highlight new technologies and knowledge that may address these. We also discuss alternative screening strategies to increase the rate of LS diagnoses. In particular, the focus of current guidance on CRCs means that approximately half of Lynch-spectrum tumours occurring in unknown male LS carriers, and only one-third in female LS carriers, will trigger testing for LS. There is increasing pressure to expand guidelines to include molecular screening of endometrial cancers, the most frequent cancer in female LS carriers. Furthermore, we collate the evidence to support MMR deficiency testing of other Lynch-spectrum tumours to screen for LS. However, a reliance on tumour tissue limits preoperative testing and, therefore, diagnosis prior to malignancy. The recent successes of functional assays to detect microsatellite instability or MMR deficiency in non-neoplastic tissues suggest that future diagnostic pipelines could become independent of tumour tissue.

Cost-effectiveness of Active Identification and Subsequent Colonoscopy Surveillance of Lynch Syndrome Cases

BACKGROUND & AIMS

The province of Ontario, Canada is considering immunohistochemical followed by cascade analyses of all patients who received a diagnosis of colorectal cancer (CRC) at an age younger than 70 years to identify individuals with Lynch syndrome. We evaluated the costs and benefits of testing for Lynch syndrome and determined the optimal surveillance interval for first-degree relatives (FDRs) found to have Lynch syndrome.

METHODS

We developed a patient flow diagram to determine costs and yield of immunohistochemical testing for Lynch syndrome in CRC cases and, for those found to have Lynch syndrome, their FDRs, accounting for realistic uptake. Subsequently, we used the MISCAN-colon model to compare costs and benefits of annual, biennial, and triennial surveillance in FDRs identified with Lynch syndrome vs colonoscopy screening every 10 years (usual care for individuals without a diagnosis of Lynch syndrome).

RESULTS

Testing 1000 CRC cases was estimated to identify 20 CRC index cases and 29 FDRs with Lynch syndrome at a cost of $310,274. Despite the high cost of Lynch syndrome tests, offering the FDRs with Lynch syndrome biennial colonoscopy surveillance was cost-effective at $8785 per life-year gained compared with usual care because of a substantial increase in life-years gained (+122%) and cost savings in CRC care. Triennial surveillance was more costly and less effective, and annual surveillance showed limited additional benefit compared with biennial surveillance.

CONCLUSIONS

Immunohistochemical testing for Lynch syndrome in persons younger than 70 years who received a diagnosis of CRC and then testing FDRs of those found to have Lynch syndrome provide a good balance between costs and long-term benefits. Colonoscopy surveillance every 2 years is the optimal surveillance interval for patients with Lynch syndrome.

Complete Loss of EPCAM Immunoexpression Identifies EPCAM Deletion Carriers in MSH2-Negative Colorectal Neoplasia

Simple Summary

Colorectal carcinomas from patients with Lynch syndrome (LS) due to EPCAM deletions show loss of MSH2 expression. The aim of our study was to evaluate the usefulness of EPCAM expression in identifying carriers of EPCAM deletion among patients with MSH2-negative lesions. MSH2 and EPCAM immunohistochemistry was performed in a large series of lesions (190) composed of malignant and benign neoplasms as well as precursor lesions of different organs from 71 patients with suspected LS due to MSH2 alterations. Germ-line analysis confirmed LS in 68 patients due to MSH2 mutations (53) and EPCAM deletions (15). Among colorectal lesions with lack of MSH2 expression, only 17 were EPCAM-negative and belonged to patients with EPCAM deletions. We confirm that loss of EPCAM expression identifies EPCAM deletion carriers with 100% specificity and we recommend adding EPCAM IHC to the algorithm of MSH2-negative colorectal neoplasia.

Abstract

The use of epithelial cell adhesion molecule (EPCAM) immunohistochemistry (IHC) is not included in the colorectal cancer (CRC) screening algorithm to detect Lynch syndrome (LS) patients. The aim of the present study was to demonstrate that EPCAM IHC is a useful tool to guide the LS germ-line analysis when a loss of MSH2 expression was present. We retrospectively studied MSH2 and EPCAM IHC in a large series of 190 lesions composed of malignant neoplasms (102), precursor lesions of gastrointestinal (71) and extra-gastrointestinal origin (9), and benign neoplasms (8) from different organs of 71 patients suspicious of being LS due to MSH2 alterations. LS was confirmed in 68 patients, 53 with MSH2 mutations and 15 with EPCAM 3′-end deletions. Tissue microarrays were constructed with human normal tissues and their malignant counterparts to assist in the evaluation of EPCAM staining. Among 154 MSH2-negative lesions, 17 were EPCAM-negative, including 10 CRC and 7 colorectal polyps, and 5 of them showed only isolated negative glands. All lesions showing a lack of EPCAM expression belonged to patients with EPCAM 3′-end deletions. EPCAM IHC is a useful screening tool, with 100% specificity to identify LS patients due to EPCAM 3′-end deletions in MSH2-negative CRC and MSH2-negative colorectal polyps.

Molecular pathology of Lynch syndrome

Lynch syndrome (LS) is characterised by predisposition to colorectal, endometrial, and other cancers and is caused by inherited pathogenic variants affecting the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2. It is probably the most common predisposition to cancer, having an estimated prevalence of between 1/100 and 1/180. Resources such as the International Society for Gastrointestinal Hereditary Cancer's MMR gene variant database, the Prospective Lynch Syndrome Database (PLSD), and the Colon Cancer Family Register (CCFR), as well as pathological and immunological studies, are enabling advances in the understanding of LS. These include defined criteria by which to interpret gene variants, the function of MMR in the normal control of apoptosis, definition of the risks of the various cancers, and the mechanisms and pathways by which the colorectal and endometrial tumours develop, including the critical role of the immune system. Colorectal cancers in LS can develop along three pathways, including flat intramucosal lesions, which depend on the underlying affected MMR gene. This gives insights into the limitations of colonoscopic surveillance and highlights the need for other forms of anti-cancer prophylaxis in LS. Finally, it shows that the processes of autoimmunisation and immunoediting fundamentally constrain the development of tumours in LS and explain the efficacy of immune checkpoint blockade therapy in MMR-deficient tumours. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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

BACKGROUND

The prevalence of Lynch syndrome and the use of universal tumor screening to identify Lynch syndrome among unselected patients with upper urinary tract urothelial carcinoma, which is associated with Lynch syndrome, have not been closely investigated yet.

METHODS

A total of 166 tumors from 164 upper urinary tract urothelial carcinoma patients were tested for microsatellite instability and expression of mismatch repair proteins (MLH1, MHS2, MSH6 and PMS2) by immunohistochemistry. Genetic testing was performed for patients suspected of having Lynch syndrome. Clinicopathological factors, including familial and personal cancer history associated with mismatch repair deficiency, were evaluated.

RESULTS

The frequency of high-level microsatellite instability and loss of at least one mismatch repair protein was 2.4% (4/164); the microsatellite instability and immunohistochemistry results showed complete concordance. Of these four patients, three were genetically proven to have Lynch syndrome, while the remaining one was highly suggestive for Lynch syndrome based on their personal cancer history. Univariate analysis showed that age<70 years (P = 0.04), ureter as the tumor location (P = 0.052), previous history/synchronous diagnosis of colorectal cancer (P < 0.01) and fulfillment of the criteria per the revised Bethesda guideline (P < 0.01) tended to be or were significantly associated with high-level microsatellite instability/mismatch repair loss.

CONCLUSIONS

The prevalence of Lynch syndrome among unselected upper urinary tract urothelial carcinoma patients was at least 1.8% in our study population. The screening efficacies of the microsatellite instability test and immunohistochemistry appear equivalent. Universal tumor screening may be a valid approach; however, selective screening methods that consider factors associated with mismatch repair loss/high-level microsatellite instability tumors require further investigation.

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.

Microsatellite instability screening in colorectal adenomas to detect Lynch syndrome patients? A systematic review and meta-analysis

The colorectal cancer spectrum has changed due to population screening programs, with a shift toward adenomas and early cancers. Whether it would be a feasible option to test these adenomas for detection of Lynch syndrome (LS) patients is unclear. Through meta-analysis and systematic review, risk factors for DNA mismatch repair deficiency (dMMR) and microsatellite instability (MSI) in adenomas were identified in LS and unselected patient cohorts. Data were extracted for patient age and MMR variant together with adenoma type, grade, size, and location. A total of 41 studies were included, and contained more than 519 LS patients and 1698 unselected patients with 1142 and 2213 adenomas respectively. dMMR/MSI was present in 69.5% of conventional adenomas in LS patients, compared with 2.8% in unselected patients. In the LS cohort, dMMR/MSI was more frequently present in patients older than 60 years (82% versus 54%). dMMR/MSI was also more common in villous adenomas (84%), adenomas over 1 cm (81%), and adenomas with high grade dysplasia (88%). No significant differences were observed for dMMR/MSI in relation to MMR variants and location of adenomas. In the context of screening, we conclude that detection of dMMR/MSI in conventional adenomas of unselected patients is uncommon and might be considered as indication for LS testing. Within the LS cohort, 69.5% of LS patients could have been detected through dMMR/MSI screening of their conventional adenomas.

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

The prevalence of Lynch syndrome (LS) varies significantly in different populations, suggesting that ethnic features might play an important role. We enrolled 3330 consecutive Chinese patients who had surgical resection for newly diagnosed colorectal cancer. Universal screening for LS was implemented, including immunohistochemistry for mismatch repair (MMR) proteins, BRAF^V600E mutation test and germline sequencing. Among the 3250 eligible patients, MMR protein deficiency (dMMR) was detected in 330 (10.2%) patients. Ninety-three patients (2.9%) were diagnosed with LS. Nine (9.7%) patients with LS fulfilled Amsterdam criteria II and 76 (81.7%) met the revised Bethesda guidelines. Only 15 (9.7%) patients with absence of MLH1 on IHC had BRAF^V600E mutation. One third (33/99) of the MMR gene mutations have not been reported previously. The age of onset indicates risk of LS in patients with dMMR tumors. For patients older than 65 years, only 2 patients (5.7%) fulfilling revised Bethesda guidelines were diagnosed with LS. Selective sequencing of all cases with dMMR diagnosed at or below age 65 years and only of those dMMR cases older than 65 years who fulfill revised Bethesda guidelines results in 8.2% fewer cases requiring germline testing without missing any LS diagnoses. While the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of constitutional mutations and frequency of BRAF^V600E mutation is different. Patients older than 65 years who do not meet the revised Bethesda guidelines have a low risk of LS, suggesting germline sequencing might not be necessary in this population.

Worldwide Practice Patterns in Lynch Syndrome Diagnosis and Management, Based on Data From the International Mismatch Repair Consortium

BACKGROUND & AIMS

Families with a history of Lynch syndrome often do not adhere to guidelines for genetic testing and screening. We investigated practice patterns related to Lynch syndrome worldwide, to ascertain potential targets for research and public policy efforts.

METHODS

We collected data from the International Mismatch Repair Consortium (IMRC), which comprises major research and clinical groups engaged in the care of families with Lynch syndrome worldwide. IMRC institutions were invited to complete a questionnaire to characterize diagnoses of Lynch syndrome and management practice patterns.

RESULTS

Fifty-five providers, representing 63 of 128 member institutions (49%) in 21 countries, completed the questionnaire. For case finding, 55% of respondents reported participating in routine widespread population tumor testing among persons with newly diagnosed Lynch syndrome-associated cancers, whereas 27% reported relying on clinical criteria with selective tumor and/or germline analyses. Most respondents (64%) reported using multigene panels for germline analysis, and only 28% reported testing tumors for biallelic mutations for cases in which suspected pathogenic mutations were not confirmed by germline analysis. Respondents reported relying on passive dissemination of information to at-risk family members, and there was variation in follow through of genetic testing recommendations. Reported risk management practices varied-nearly all programs (98%) recommended colonoscopy every 1 to 2 years, but only 35% recommended chemoprevention with aspirin.

CONCLUSIONS

There is widespread heterogeneity in management practices for Lynch syndrome worldwide among IMRC member institutions. This may reflect the rapid pace of emerging technology, regional differences in resources, and the lack of definitive data for many clinical questions. Future efforts should focus on the large numbers of high-risk patients without access to state-of-the-art Lynch syndrome management.

Routine Molecular Analysis for Lynch Syndrome Among Adenomas or Colorectal Cancer Within a National Screening Program

BACKGROUND & AIMS

It is important to identify individuals with Lynch syndrome because surveillance programs can reduce their morbidity and mortality from colorectal cancer (CRC). We assessed the diagnostic yield of immunohistochemistry to detect Lynch syndrome in patients with advanced and multiple adenomas within our national CRC screening program.

METHODS

We performed a prospective study of all participants (n = 1101; 55% male; median age, 66 years; interquartile range, 61-70 years) referred to the Erasmus MC in The Netherlands after a positive result from a fecal immunohistochemical test, from December 2013 to December 2016. Colon tissues were collected from patients with advanced adenomas, ≥4 nonadvanced adenomas, or CRC, and analyzed by immunohistochemistry to identify patients with loss of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, or PMS2): a marker of Lynch syndrome. Specimens from patients with loss of MLH1 were analyzed for MLH1 promoter hypermethylation. Patients with an MMR-deficient tumor or adenoma without MLH1 promoter hypermethylation were referred for genetic analysis.

RESULTS

At colonoscopy, 456 patients (41%) (65% male; mean age, 67 years; interquartile range, 63-71 years) were found to have CRC and/or an adenoma eligible for analysis by immunohistochemistry. Of 56 CRCs, 7 (13%) had lost an MMR protein and 5 had hypermethylation of the MLH1 promoter. Analyses of tumor DNA revealed that 2 patients without MLH1 promoter hypermethylation had developed sporadic tumors. In total, 400 patients with adenomas were analyzed. Of the examined adenomas, 208 (52%) had a villous component and/or high-grade dysplasia: 186 (47%) had a villous component and 41 (10%) had high-grade dysplasia. Only 1 adenoma had lost an MMR protein. This adenoma was found to have 2 somatic mutations in MSH6.

CONCLUSIONS

In a CRC screening program in The Netherlands for individuals aged 55 to 75 years, routine screening for Lynch syndrome by immunohistochemistry analysis of colon tissues from patients with advanced and multiple adenomas identified no individuals with this genetic disorder.

Double somatic mutations in mismatch repair genes are frequent in colorectal cancer after Hodgkin's lymphoma treatment

OBJECTIVE

Hodgkin's lymphoma survivors who were treated with infradiaphragmatic radiotherapy or procarbazine-containing chemotherapy have a fivefold increased risk of developing colorectal cancer (CRC). This study aims to provide insight into the development of therapy-related CRC (t-CRC) by evaluating histopathological and molecular characteristics.

DESIGN

54 t-CRCs diagnosed in a Hodgkin's lymphoma survivor cohort were analysed for mismatch repair (MMR) proteins by immunohistochemistry, microsatellite instability (MSI) and KRAS/BRAF mutations. MSI t-CRCs were evaluated for promoter methylation and mutations in MMR genes. Pathogenicity of MMR gene mutations was evaluated by in silico predictions and functional analyses. Frequencies were compared with a general population cohort of CRC (n=1111).

RESULTS

KRAS and BRAF mutations were present in 41% and 15% t-CRCs, respectively. Compared with CRCs in the general population, t-CRCs had a higher MSI frequency (24% vs 11%, p=0.003) and more frequent loss of MSH2/MSH6 staining (13% vs 1%, p<0.001). Loss of MLH1/PMS2 staining and MLH1 promoter methylation were equally common in t-CRCs and the general population. In MSI CRCs without MLH1 promoter methylation, double somatic MMR gene mutations (or loss of heterozygosity as second hit) were detected in 7/10 (70%) t-CRCs and 8/36 (22%) CRCs in the general population (p=0.008). These MMR gene mutations in t-CRCs were classified as pathogenic. MSI t-CRC cases could not be ascribed to Lynch syndrome.

CONCLUSIONS

We have demonstrated a higher frequency of MSI among t-CRCs, which results from somatic MMR gene mutations. This suggests a novel association of somatic MMR gene mutations with prior anticancer treatment.

Evaluation of universal immunohistochemical screening of sebaceous neoplasms in a service setting

BACKGROUND

Muir-Torre syndrome (MTS) is a subtype of Lynch syndrome, which encompasses the combination of sebaceous skin tumours or keratoacanthomas and internal malignancy, due to mutations in DNA mismatch repair genes. Sebaceous neoplasms (SNs) may occur before other malignancies, and may lead to the diagnosis, which allows testing of other family members, cancer surveillance, risk-reducing surgery or prevention therapies.

AIM

To evaluate the efficacy of universal immunohistochemistry (IHC) screening of SNs in a service setting.

METHODS

Patients with SNs were ascertained by a regional clinical pathology service over a 3-year period. Results of tumour IHC, clinical genetics notes and germline genetic testing were retrospectively reviewed.

RESULTS

In total, 62 patients presented with 71 SNs; 9 (15%) of these patients had previously diagnosed MTS. Tumour IHC was performed for 50 of the 53 remaining patients (94%); 26 (52%) had loss of staining of one or more mismatch repair proteins. Fifteen patients were referred to the Clinical Genetics department, and 10 patients underwent germline genetic testing. Two had a new diagnosis of MTS confirmed, with heterozygous pathogenic mutations detected in the MSH2 and PMS2 genes (diagnostic yield 20%). The PMS2 mutation was identified in a 57-year-old woman with a sebaceous adenoma and history of endometrial cancer; to our knowledge, this is the first time a PMS2 mutation has been reported in MTS.

CONCLUSIONS

Universal IHC screening of SNs is an effective method to identify cases for further genetic evaluation. Rates of referral to clinical genetics were only moderate (58%). Increased awareness of MTS could help improve the rate of onward referral.

A systematic review of test accuracy studies evaluating molecular micro-satellite instability testing for the detection of individuals with lynch syndrome

BACKGROUND

A systematic review was conducted to assess the diagnostic test accuracy of polymerase chain reaction (PCR)-based microsatellite instability (MSI) testing for identifying Lynch syndrome in patients with colorectal cancer (CRC). Unlike previous reviews, this was based on assessing MSI testing against best practice for the reference standard, and included CRC populations that were unselected, age-limited or high-risk for Lynch syndrome.

METHODS

Single- and two-gate diagnostic test accuracy studies, or similar, were identified, assessed for inclusion, data extracted and quality appraised by two reviewers according to a pre-specified protocol. Sensitivity of MSI testing was estimated for all included studies. Specificity, likelihood ratios and predictive values were estimated for studies that were not based on high-risk samples. Narrative synthesis was conducted.

RESULTS

Nine study samples were included. When MSI-Low results were considered to be negative, sensitivity estimates ranged from 67% (95% CI 47, 83) to 100% (95% CI 94, 100). Three studies contributed to estimates of both sensitivity and specificity, with specificity ranging from 61% (95% CI 57, 65), to 93% (95% CI 89, 95). Good sensitivity was achieved at the expense of specificity. When MSI-L was considered to be positive (effectively lowering the threshold for a positive index test result) sensitivity increased and specificity decreased. Between-study heterogeneity in both the MSI and reference standard testing, combined with the low number of studies contributing to both sensitivity and specificity estimates, precluded pooling by meta-analysis.

CONCLUSIONS

MSI testing is an effective screening test for Lynch syndrome. However, there is significant uncertainty surrounding what balance of sensitivity and specificity will be achieved in clinical practice and how this relates to specific characteristics of the test (such as the panel of markers used or the thresholds used to denote a positive test).

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.

Universal molecular screening does not effectively detect Lynch syndrome in clinical practice

BACKGROUND

Lynch syndrome (LS) due to an inherited damaging mutation in mismatch repair (MMR) genes comprises 3% of all incident colorectal cancer (CRC). Molecular testing using immunohistochemistry (IHC) for MMR proteins is a recommended screening tool to identify LS in incident CRC. This study assessed outcomes of population-based routine molecular screening for diagnosis of LS in a regional center.

METHODS

We conducted a prospective, consecutive case series study of universal IHC testing on cases of resected CRC from September 2004-December 2013. Referred cases with abnormal IHC results that attended a familial cancer clinic were assessed according to modified Bethesda criteria (until 2009) or molecular criteria (from 2009).

RESULTS

1612 individuals underwent resection for CRC in the study period and had MMR testing by IHC. Of these, 274 cases (16.9%) exhibited loss of expression of MMR genes. The mean age at CRC diagnosis was 68.1 years (± standard deviation 12.7) and the mean age of those with an IHC abnormality was 71.6 (± 11.8). A total of 82 (29.9%) patients with an abnormal result were seen in a subspecialty familial cancer clinic. Patients aged under 50 (p = 0.009) and those with loss of MSH6 staining (p = 0.027) were more likely to be referred and to attend. After germ-line sequencing, 0.6% (10 of 82) were identified as having a clinically significant abnormality. A further eight probands with pathogenic germ-line mutations were identified from other referrals to the service over the same time period.

CONCLUSIONS

While technically accurate, the yield of 'universal' IHC in detecting new Lynch probands is limited by real-world factors that reduce referrals and genetic testing. We propose an alternative approach for universal, incident case detection of Lynch syndrome with 'one-stop' MMR testing and sequencing.

Colorectal cancer surveillance in Hodgkin lymphoma survivors at increased risk of therapy-related colorectal cancer: study design

Background

Second primary malignancies are a major cause of excess morbidity and mortality in cancer survivors. Hodgkin lymphoma survivors who were treated with infradiaphragmatic radiotherapy and/or high-dose procarbazine have an increased risk to develop colorectal cancer.

Colonoscopy surveillance plays an important role in colorectal cancer prevention by removal of the precursor lesions (adenomas) and early detection of cancer, resulting in improved survival rates. Therefore, Hodgkin lymphoma survivors treated with infradiaphragmatic radiotherapy and/or high-dose procarbazine could benefit from colonoscopy, or other surveillance modalities, which are expected to reduce colorectal cancer incidence and mortality. Current knowledge on clinicopathological and molecular characteristics of therapy-related colorectal cancer is limited. The pathogenesis of such colorectal cancers might be different from the pathogenesis in the general population and therefore these patients might require a different clinical approach.

We designed a study with the primary aim to assess the diagnostic yield of a first surveillance colonoscopy among Hodgkin lymphoma survivors at increased risk of colorectal cancer and to compare these results with different screening modalities in the general population. Secondary aims include assessment of the test characteristics of stool tests and evaluation of burden, acceptance and satisfaction of CRC surveillance through two questionnaires.

Methods/Design

This prospective multicenter cohort study will include Hodgkin lymphoma survivors who survived ≥8 years after treatment with infradiaphragmatic radiotherapy and/or procarbazine (planned inclusion of 259 participants). Study procedures will consist of a surveillance colonoscopy with removal of precursor lesions (adenomas) and 6–8 normal colonic tissue biopsies, a fecal immunochemical test and a stool DNA test. All neoplastic lesions encountered will be classified using relevant histomorphological, immunohistochemical and molecular analyses in order to obtain more insight into colorectal carcinogenesis in Hodgkin lymphoma survivors. The Miscan-model will be used for cost-effectiveness analyses.

Discussion

Evaluation of the diagnostic performance, patient acceptance and burden of colorectal cancer surveillance is necessary for future implementation of an individualized colorectal cancer surveillance program for Hodgkin lymphoma survivors. In addition, more insight into treatment-induced colorectal carcinogenesis will provide the first step towards prevention and personalized treatment. This information may be extrapolated to other groups of cancer survivors.

Trial registration

Registered at the Dutch Trial Registry (NTR): NTR4961.

The Influence of BRAF and KRAS Mutation Status on the Association between Aspirin Use and Survival after Colon Cancer Diagnosis

Background

Use of aspirin after diagnosis of colon cancer has been associated with improved survival. Identification of cancer subtypes that respond to aspirin treatment may help develop personalized treatment regimens. The aim of this study was to investigate the influence of BRAF and KRAS mutation status on the association between aspirin use and overall survival after colon cancer diagnosis.

Methods

A random selection of 599 patients with colon cancer were analyzed, selected from the Eindhoven Cancer Registry, and BRAF and KRAS mutation status was determined. Data on aspirin use (80 mg) were obtained from the PHARMO Database Network. Parametric survival models with exponential (Poisson) distribution were used.

Results

Aspirin use after colon cancer diagnosis was associated with improved overall survival in wild-type BRAF tumors, adjusted rate ratio (RR) of 0.60 (95% CI 0.44–0.83). In contrast, aspirin use in BRAF mutated tumors was not associated with an improved survival (RR 1.11, 95% CI 0.57–2.16). P-value for interaction was non-significant. KRAS mutational status did not differentiate in the association between aspirin use and survival.

Conclusion

Low-dose aspirin use after colon cancer diagnosis was associated with improved survival in BRAF wild-type tumors only. However, the large confidence interval of the rate ratio for the use of aspirin in patients with BRAF mutation does not rule out a possible benefit. These results preclude BRAF and KRAS mutation status to be used as a marker for individualized treatment with aspirin, if aspirin becomes regular adjuvant treatment for colon cancer patients in the future.

Surveillance after endoscopic and surgical resection of colorectal cancer

With the increase in colorectal cancer burden, surveillance following endoscopic and surgical resection is an essential issue. The aim of surveillance programs is improvement of patient survival by early detection of residual tumor tissue or local recurrence, metachronous colorectal tumors, and metastases. Appropriate surveillance should be determined according to this risk of factors. In current guidelines, only surveillance colonoscopy is recommended after endoscopic resection of polyps with high-grade dysplasia, whereas intensive, multimodality surveillance using colonoscopy, radiological imaging and tumor marker measurements is recommended following surgical resection of invasive colorectal cancer. Detailed recommendations, including the timing of surveillance, are described based on high-quality evidence. However, there are still many unresolved issues for which more high-quality evidence is required.

Universal tumor screening for Lynch syndrome: health-care providers' perspectives

PURPOSE

Population-based reflex testing of colorectal tumors can identify individuals with Lynch syndrome (LS), but there is debate regarding the type of patient discretion such a program warrants. We examined health-care providers' views and experiences to inform the design of a reflex-testing program and their perspectives regarding an opt-out option.

METHODS

We interviewed providers managing LS or colorectal cancer patients, including surgeons, genetic counselors, oncologists, primary-care physicians, and gastroenterologists. Qualitative data were analyzed thematically using constant comparison techniques.

RESULTS

Providers supported a reflex-testing program because of the current lack of coordinated immunohistochemistry (IHC) testing and underascertainment of LS patients as well as the opportunity to standardize the increasing use of genomic tests in practice. Most supported an opt-out after reflex testing because they felt that IHC is akin to other pathology tests, which are not optional. Some favored an opt-out before testing because of concern for patients experiencing distress, insurance discrimination, or a diagnostic odyssey that may be inconclusive.

CONCLUSION

Providers support a reflex-testing program to improve the identification and management of suspected LS patients. However, how to support meaningful information provision to enable an opt-out without jeopardizing testing uptake and the anticipated public health benefits remains a policy challenge.Genet Med advance online publication 06 October 2016.

Universal Versus Targeted Screening for Lynch Syndrome: Comparing Ascertainment and Costs Based on Clinical Experience

BACKGROUND

Strategies to screen colorectal cancers (CRCs) for Lynch syndrome are evolving rapidly; the optimal strategy remains uncertain.

AIM

We compared targeted versus universal screening of CRCs for Lynch syndrome.

METHODS

In 2010-2011, we employed targeted screening (age < 60 and/or Bethesda criteria). From 2012 to 2014, we screened all CRCs. Immunohistochemistry for the four mismatch repair proteins was done in all cases, followed by other diagnostic studies as indicated. We modeled the diagnostic costs of detecting Lynch syndrome and estimated the 5-year costs of preventing CRC by colonoscopy screening, using a system dynamics model.

RESULTS

Using targeted screening, 51/175 (29 %) cancers fit criteria and were tested by immunohistochemistry; 15/51 (29 %, or 8.6 % of all CRCs) showed suspicious loss of ≥1 mismatch repair protein. Germline mismatch repair gene mutations were found in 4/4 cases sequenced (11 suspected cases did not have germline testing). Using universal screening, 17/292 (5.8 %) screened cancers had abnormal immunohistochemistry suspicious for Lynch syndrome. Germline mismatch repair mutations were found in only 3/10 cases sequenced (7 suspected cases did not have germline testing). The mean cost to identify Lynch syndrome probands was ~$23,333/case for targeted screening and ~$175,916/case for universal screening at our institution. Estimated costs to identify and screen probands and relatives were: targeted, $9798/case and universal, $38,452/case.

CONCLUSIONS

In real-world Lynch syndrome management, incomplete clinical follow-up was the major barrier to do genetic testing. Targeted screening costs 2- to 7.5-fold less than universal and rarely misses Lynch syndrome cases. Future changes in testing costs will likely change the optimal algorithm.

Autophagy is upregulated during colorectal carcinogenesis, and in DNA microsatellite stable carcinomas

Cancer cells are exposed to a wide range of stress sources, such as nutrient deprivation and hypoxia, as well as cytotoxic chemotherapy and radiotherapy. Certain forms of stress can also promote survival activating the metabolic autophagy pathway in cancer cells. Autophagy is dramatically increased in cancer cells. In these conditions, it is becoming evident that autophagy protects cells, by providing an alternative energy source and by eliminating dysfunctional organelles or proteins. Its role in tumorigenesis is more controversial and both the presence and the absence of autophagy have been implicated. Autophagy is known to be associated with the poor outcome of patients with various types of cancers, and its effectiveness as a prognostic marker in colorectal cancer was demonstrated by several studies. The inhibition of autophagy may be a potential therapeutic target in colorectal cancer. In vitro experiments have shown that the inhibition of autophagy increases 5-FU-induced apoptosis. There are two trials currently investigating the addition of chloroquine to 5-FU-based chemotherapy and bevacizumab. In the present study, we evaluated the expression of LC3B-II in samples of human colorectal microadenomas (i.e., dysplastic aberrant crypt foci) and carcinomas compared to normal mucosa. Furthermore, the expression pattern of LC3B-II was assessed in carcinomas classified as DNA microsatellite stable (MSS) and unstable (MSI). Thus, immunofluorescence techniques coupled with confocal microscopy and immunoblot experiments were performed. The results clearly showed a significant increase in expression of the autophagic key factor in microadenomas and carcinomas with respect to normal mucosa. In MSS carcinomas, the level of LC3B-II expression was higher than that in the MSI carcinomas.

Comparison of Prediction Models for Lynch Syndrome Among Individuals With Colorectal Cancer

BACKGROUND

Recent guidelines recommend the Lynch Syndrome prediction models MMRPredict, MMRPro, and PREMM1,2,6 for the identification of MMR gene mutation carriers. We compared the predictive performance and clinical usefulness of these prediction models to identify mutation carriers.

METHODS

Pedigree data from CRC patients in 11 North American, European, and Australian cohorts (6 clinic- and 5 population-based sites) were used to calculate predicted probabilities of pathogenic MLH1, MSH2, or MSH6 gene mutations by each model and gene-specific predictions by MMRPro and PREMM1,2,6. We examined discrimination with area under the receiver operating characteristic curve (AUC), calibration with observed to expected (O/E) ratio, and clinical usefulness using decision curve analysis to select patients for further evaluation. All statistical tests were two-sided.

RESULTS

Mutations were detected in 539 of 2304 (23%) individuals from the clinic-based cohorts (237 MLH1, 251 MSH2, 51 MSH6) and 150 of 3451 (4.4%) individuals from the population-based cohorts (47 MLH1, 71 MSH2, 32 MSH6). Discrimination was similar for clinic- and population-based cohorts: AUCs of 0.76 vs 0.77 for MMRPredict, 0.82 vs 0.85 for MMRPro, and 0.85 vs 0.88 for PREMM1,2,6. For clinic- and population-based cohorts, O/E deviated from 1 for MMRPredict (0.38 and 0.31, respectively) and MMRPro (0.62 and 0.36) but were more satisfactory for PREMM1,2,6 (1.0 and 0.70). MMRPro or PREMM1,2,6 predictions were clinically useful at thresholds of 5% or greater and in particular at greater than 15%.

CONCLUSIONS

MMRPro and PREMM1,2,6 can well be used to select CRC patients from genetics clinics or population-based settings for tumor and/or germline testing at a 5% or higher risk. If no MMR deficiency is detected and risk exceeds 15%, we suggest considering additional genetic etiologies for the cause of cancer in the family.

Colorectal cancer

Colorectal cancer had a low incidence several decades ago. However, it has become a predominant cancer and now accounts for approximately 10% of cancer-related mortality in western countries. The 'rise' of colorectal cancer in developed countries can be attributed to the increasingly ageing population, unfavourable modern dietary habits and an increase in risk factors, such as smoking, low physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged, providing additional options for patients; these treatments include laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies. However, these new treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have gained momentum. This Primer provides an overview of the current state of the art of knowledge on the epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.

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.

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

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

Limited diagnostic value of microsatellite instability associated pathology features in colorectal cancer

To determine the diagnostic test characteristics and inter-observer variation of pathology features for identifying high microsatellite instability (MSI-H) colorectal cancer (CRC). Six pathologists blindly evaluated 177 CRC for the presence of MSI-H associated pathology features. Inter-observer agreement was determined by using Kappa-statistics. In the first random 88/177 cases, mucinous carcinoma, tumor-infiltrating lymphocytes (TIL) and Crohns-like infiltrate (CLI) were the best discriminators between MSI-H and microsatellite stable CRC [OR 5.6 (95 % CI 1.7-19), 5.4 (1.8-17) and 3.5 (1.1-11), respectively], with high specificity (89-91 %). The sensitivities for MSI-H, however, were low (31-41 %). In addition, inter-observer agreement was moderate for TIL and CLI (κ 0.38 and 0.48, respectively), but very good for mucinous carcinoma (κ 0.86). Interpretation of overall histopathology as suggestive for MSI-H performed better than any individual feature; OR 15 (5.2-44), and area under the curve 0.79. However, inter-observer agreement was moderate (κ 0.53). In the second set, TIL and CLI were scored according to updated scoring systems. Although both remained the best individual discriminators, test characteristics and inter-observer agreement did not improve. MSI-H pathology features have moderate accuracy for identifying MSI-H CRC, and are identified with moderate inter-observer agreement. These findings highlight the limitations of clinical strategies, such as the revised Bethesda guidelines, which incorporate the MSI-H associated pathology features in their strategy to identify persons with lynch syndrome.

Lynch syndrome caused by germline PMS2 mutations: delineating the cancer risk

PURPOSE

The clinical consequences of PMS2 germline mutations are poorly understood compared with other Lynch-associated mismatch repair gene (MMR) mutations. The aim of this European cohort study was to define the cancer risk faced by PMS2 mutation carriers.

METHODS

Data were collected from 98 PMS2 families ascertained from family cancer clinics that included a total of 2,548 family members and 377 proven mutation carriers. To adjust for potential ascertainment bias, a modified segregation analysis model was used to calculate colorectal cancer (CRC) and endometrial cancer (EC) risks. Standardized incidence ratios (SIRs) were calculated to estimate risks for other Lynch syndrome-associated cancers.

RESULTS

The cumulative risk (CR) of CRC for male mutation carriers by age 70 years was 19%. The CR among female carriers was 11% for CRC and 12% for EC. The mean age of CRC development was 52 years, and there was a significant difference in mean age of CRC between the probands (mean, 47 years; range, 26 to 68 years) and other family members with a PMS2 mutation (mean, 58 years; range, 31 to 86 years; P < .001). Significant SIRs were observed for cancers of the small bowel, ovaries, breast, and renal pelvis.

CONCLUSION

CRC and EC risks were found to be markedly lower than those previously reported for the other MMR. However, these risks embody the isolated risk of carrying a PMS2 mutation, and it should be noted that we observed a substantial variation in cancer phenotype within and between families, suggesting the influence of genetic modifiers and lifestyle factors on cancer risks.

Applying public health screening criteria: how does universal newborn screening compare to universal tumor screening for Lynch syndrome in adults with colorectal cancer?

Institutions have increasingly begun to adopt universal tumor screening (UTS) programs whereby tumors from all newly diagnosed patients with colorectal cancer (CRC) are screened to identify who should be offered germline testing for Lynch syndrome (the most common cause of hereditary CRC). Given limited information about the impact of universal screening programs to detect hereditary disease in adults, we apply criteria used to evaluate public health screening programs and compare and contrast UTS with universal newborn screening (NBS) for the purpose of examining ethical implications and anticipating potential outcomes of UTS. Both UTS and a core set of NBS conditions clearly meet most of the Wilson and Jungner screening criteria. However, many state NBS panels include additional conditions that do not meet several of these criteria, and there is currently insufficient data to confirm that UTS meets some of these criteria. Comparing UTS and NBS with regard to newer screening criteria raises additional issues that require attention for both UTS and NBS. Comparisons also highlight the importance of evaluating the implementation of genomic tests to ensure or improve their effectiveness at reducing morbidity and mortality while minimizing potential harms.

Comparing universal Lynch syndrome tumor-screening programs to evaluate associations between implementation strategies and patient follow-through

PURPOSE

Universal tumor screening (UTS) for all colorectal cancer patients can improve the identification of Lynch syndrome, the most common cause of hereditary colorectal cancer. This multiple-case study explored how variability in UTS procedures influenced patient follow-through (PF) with germ-line testing after a screen-positive result.

METHODS

Data were obtained through Web-based surveys and telephone interviews with institutional informants. Institutions were categorized as Low-PF (≤10% underwent germ-line testing), Medium-PF (11-40%), or High-PF (>40%). To identify implementation procedures (i.e., conditions) unique to High-PF institutions, qualitative comparative analysis was performed.

RESULTS

Twenty-one informants from 15 institutions completed surveys and/or interviews. Conditions present among all five High-PF institutions included the following: (i) disclosure of screen-positive results to patients by genetic counselors; and (ii) genetic counselors either facilitate physician referrals to genetics professionals or eliminate the need for referrals. Although both of these High-PF conditions were present among two Medium-PF institutions, automatic reflex testing was lacking and difficulty contacting screen-positive patients was a barrier. The three remaining Medium-PF and five Low-PF institutions lacked the conditions found in High-PF institutions.

CONCLUSION

METHODS for streamlining UTS procedures, incorporating a high level of involvement of genetic counselors in tracking and communication of results and in reducing barriers to patient contact, are reviewed within a broader discussion on maximizing the effectiveness and public health impact of UTS.

Somatic aberrations of mismatch repair genes as a cause of microsatellite-unstable cancers

Lynch syndrome (LS) is caused by germline mutations in mismatch repair (MMR) genes, resulting in microsatellite-unstable tumours. Approximately 35% of suspected LS (sLS) patients test negative for germline MMR gene mutations, hampering conclusive LS diagnosis. The aim of this study was to investigate somatic MMR gene aberrations in microsatellite-unstable colorectal and endometrial cancers of sLS patients negative for germline MMR gene mutations. Suspected LS cases were selected from a retrospective Clinical Genetics Department diagnostic cohort and from a prospective multicentre population-based study on LS in The Netherlands. In total, microsatellite-unstable tumours of 40 sLS patients (male/female 20/20, median age 57 years) were screened for somatic MMR gene mutations by next-generation sequencing. In addition, loss of heterozygosity (LOH) of the affected MMR genes in these tumours as well as in 68 LS-associated tumours and 27 microsatellite-unstable tumours with MLH1 promoter hypermethylation was studied. Of the sLS cases, 5/40 (13%) tumours had two pathogenic somatic mutations and 16/40 (40%) tumours had a (likely) pathogenic mutation and LOH. Overall, LOH of the affected MMR gene locus was observed in 24/39 (62%) tumours with informative LOH markers. Of the LS cases and the tumours with MLH1 promoter hypermethylation, 39/61 (64%) and 2/21 (10%) tumours, respectively, demonstrated LOH. Half of microsatellite-unstable tumours of sLS patients without germline MMR gene mutations had two (likely) deleterious somatic MMR gene aberrations, indicating their sporadic origin. Therefore, we advocate adding somatic mutation and LOH analysis of the MMR genes to the molecular diagnostic workflow of LS.

Aberrant SOX2 expression in colorectal cancers does not correlate with mucinous differentiation and gastric mucin MUC5AC expression

Colorectal cancer (CRC) can be divided into non-mucinous and mucinous subtypes, of which the latter portends to have a worse clinical prognosis. A previous study suggested a putative link between SOX2 expression observed selectively in mucinous CRC and the induction of the gastric mucin MUC5AC. In this study, we re-evaluated the expression behavior of SOX2, MUC5AC, and CDX2 in both types of CRC. We performed immunohistochemical analysis on 90 cases of non-mucinous CRCs, 57 cases of mucinous CRCs, and 15 case-matched normal intestinal mucosa. In contrast to the previously suggested link between SOX2 and mucinous CRC, we observe aberrant expression of SOX2 at equal levels in both subtypes. Fluorescence in situ hybridization (FISH) analysis shows that expression is not attributed to genomic amplification. While SOX2 and CDX2 are normally expressed in a reciprocal manner, SOX2-positive tumor cells co-express CDX2. Furthermore, we show that MUC5AC is expressed independently of SOX2. In conclusion, we show that aberrant SOX2 expression is specifically linked neither to mucinous CRCs nor to the induction of MUC5AC, in contrast to previous suggestions.

Guidelines on genetic evaluation and management of Lynch syndrome: a consensus statement by the US Multi-Society Task Force on colorectal cancer

The Multi-Society Task Force, in collaboration with invited experts, developed guidelines to assist health care providers with the appropriate provision of genetic testing and management of patients at risk for and affected with Lynch syndrome as follows: Figure 1 provides a colorectal cancer risk assessment tool to screen individuals in the office or endoscopy setting; Figure 2 illustrates a strategy for universal screening for Lynch syndrome by tumor testing of patients diagnosed with colorectal cancer; Figures 3-6 provide algorithms for genetic evaluation of affected and at-risk family members of pedigrees with Lynch syndrome; Table 10 provides guidelines for screening at-risk and affected persons with Lynch syndrome; and Table 12 lists the guidelines for the management of patients with Lynch syndrome. A detailed explanation of Lynch syndrome and the methodology utilized to derive these guidelines, as well as an explanation of, and supporting literature for, these guidelines are provided.