Surveillance colonoscopy improves survival in a cohort of subjects with a single mismatch repair gene mutation

Incidence and prevalence of advanced colorectal neoplasia in Lynch syndrome

BACKGROUND AND AIMS

Lynch syndrome (LS) is the most common hereditary cause of colorectal cancer (CRC) and endometrial cancer (EC). Although colonoscopy reduces CRC in LS, the protection is variable. We assessed the prevalence and incidence of neoplasia in LS during surveillance colonoscopy in the United States and factors associated with advanced neoplasia.

METHODS

Patients with LS undergoing ≥1 surveillance colonoscopy and with no personal history of invasive CRC or colorectal surgery were included. Prevalent and incident neoplasia was defined as occurring <6 months before and ≥6 months after germline diagnosis of LS, respectively. We assessed advanced adenoma (AA), CRC, and the impact of mismatch repair pathogenic variant (PV) and typical LS cancer history (personal history of EC and/or family history of EC/CRC) on outcome.

RESULTS

A total of 132 patients (inclusive of 112 undergoing prevalent and incident surveillance) were included. The median examination interval and duration of prevalent and incident surveillance was .88 and 1.06 years and 3.1 and 4.6 years, respectively. Prevalent and incident AA were detected in 10.7% and 6.1% and invasive CRC in 0% and 2.3% of patients. All incident CRC occurred in MSH2 and MLH1 PV carriers and only 1 (.7%) while under surveillance in our center. AAs were detected in both LS cancer history cohorts and represented in all PVs.

CONCLUSIONS

In a U.S. cohort of LS, advanced neoplasia rarely occurred over annual surveillance. CRC was diagnosed only in MSH2/MLH1 PV carriers. AAs occurred regardless of PV or LS cancer history. Prospective studies are warranted to confirm our findings.

Challenges in the management of colorectal cancer in low- and middle-income countries

AIM

This narrative review aims to describe colorectal cancer (CRC) management landscape in low- and middle-income countries (LMICs), presenting the most recent and relevant papers on the topic. As a secondary aim, the authors suggest new ways of improving CRC patient care in LMICs.

BACKGROUND

Several studies show that the incidence of colon cancer in low- and middle-income countries (LMICs) is rising. In addition to the increasing incidence, lack of early detection and impeded access to optimal multidisciplinary treatment may worsen survival outcomes.

CONCLUSION

Developing quality diagnostic services in the proper health context is crucial for early diagnosis and successful therapy of CRC patients, and applying a resource-sensitive approach to prioritize essential treatments based on effectiveness and cost-effectiveness is key to overcoming barriers in LMICs, with clinical research collaborations between high-income countries (HICs) and LMICs being a helpful strategy to improve health indicators and prevent the burnout of health workers.

Immunogenomic Biomarkers and Validation in Lynch Syndrome

Lynch syndrome (LS) is an inherited disorder in which affected individuals have a significantly higher-than-average risk of developing colorectal and non-colorectal cancers, often before the age of 50 years. In LS, mutations in DNA repair genes lead to a dysfunctional post-replication repair system. As a result, the unrepaired errors in coding regions of the genome produce novel proteins, called neoantigens. Neoantigens are recognised by the immune system as foreign and trigger an immune response. Due to the invasive nature of cancer screening tests, universal cancer screening guidelines unique for LS (primarily colonoscopy) are poorly adhered to by LS variant heterozygotes (LSVH). Currently, it is unclear whether immunogenomic components produced as a result of neoantigen formation can be used as novel biomarkers in LS. We hypothesise that: (i) LSVH produce measurable and dynamic immunogenomic components in blood, and (ii) these quantifiable immunogenomic components correlate with cancer onset and stage. Here, we discuss the feasibility to: (a) identify personalised novel immunogenomic biomarkers and (b) validate these biomarkers in various clinical scenarios in LSVH.

A comparative cost analysis of two screening strategies for colorectal cancer in Lynch Syndrome in a South African tertiary hospital

AIM

Lynch Syndrome (LS) individuals have a 25-75% lifetime risk of developing colorectal cancer. Colonoscopy screening decreases this risk. This study compared the cost of Strategy 1: screening colonoscopy for 1st degree relatives of patients that met the Revised Bethesda Criteria (i.e., probands) to Strategy 2: screening colonoscopy for 1^st degree relatives of probands with genetic mutations for Lynch Syndrome based in a resource-constrained health care system.

METHOD

A comparative, health care provider perspective, cost analysis was conducted at a tertiary hospital, using a micro-costing, ingredient approach. Forty probands that underwent genetic testing between November 01, 2014 and October 30, 2015 and their first-degree relatives were costed according to Strategy 1 and Strategy 2. Unit costs of colonoscopy and genetic testing were estimated and used to calculate and compare the total costs per strategy in South African rand (R) converted to UK pounds (£). Sensitivity analyses were performed on colonoscopy adherence, relatives' positivity, and variable discount rates.

RESULTS

The cost for Strategy 1 amounted to £653 344/R6 161 035 compared to £49 327/R 465 155 for Strategy 2 (Discount rate 3%; Adherence 75%; and Positivity rate of relatives 45%). Base case analysis indicated a difference of 92% less in the total cost for Strategy 2 compared to Strategy 1. Sensitivity analyses showed that the difference in cost between the two strategies was not sensitive to variations in adherence, positivity or discount rates.

CONCLUSION

Colonoscopy screening for LS and at-risk family members was tenfold less costly when combined with genetic analysis. The logistics of rolling out this strategy nationally should be investigated.

Implementation of a Population-Based Cancer Family History Screening Program for Lynch Syndrome

OBJECTIVES

Lynch syndrome increases risks for colorectal and other cancers. Though published Lynch syndrome cancer risk-management guidelines are effective for risk-reduction, the condition remains under-recognized. The Cancer Genetics Program at an academic medical center implemented a population-based cancer family history screening program, Detecting Unaffected Individuals with Lynch syndrome, to aid in identification of individuals with Lynch syndrome.

METHODS

In this retrospective cohort study, simple cancer family history screening questionnaires were used to identify those at risk for Lynch syndrome. Program navigators triaged and educated those who screened positive about hereditary cancer, and genetic counseling and testing services, offering genetic counseling if eligible. Genetic counseling was provided primarily via telephone. Genetic counselors performed hereditary cancer risk assessment and offered genetic testing via hereditary cancer panels to those eligible. Remote service delivery models via telephone genetic counseling and at-home saliva testing were used to increase access to medical genetics services.

RESULTS

This program screened 212,827 individuals, over half of whom were considered underserved, and identified 133 clinically actionable genetic variants associated with hereditary cancer. Of these, 47 (35%) were associated with Lynch syndrome while notably, 70 (53%) were not associated with hereditary colorectal cancer. Of 3,344 patients offered genetic counseling after initial triage, 2,441 (73%) elected to schedule the appointment and 1,775 individuals (73%) completed genetic counseling. Among underserved patients, telephone genetic counseling completion rates were significantly higher than in-person appointment completion rates (P < .05). While remote service delivery improved appointment completion rates, challenges with genetic test completion using at-home saliva sample collection kits were observed, with 242 of 1592 individuals (15%) not completing testing.

CONCLUSION

Population-based cancer family history screening and navigation can help identify individuals with hereditary cancer syndromes across diverse patient populations, but logistics of certain downstream service delivery models can impact outcomes.

Genomic landscape of colorectal carcinoma in sub-Saharan Africa

Our understanding of the molecular classification of colorectal carcinoma (CRC) has evolved significantly over the past two decades. Tumours can be broadly categorised as microsatellite stable (MSS), microsatellite instability (MSI) or CpG island-methylator phenotype. Prognostic and predictive information is provided by these categories. The overwhelming majority of the data on which these categories are based have originated from Europe and North America. There is a dearth of information represented from Africa and indigenous African patients. However, some small studies and preliminary data have shown significant differences in all of these groups. The prevalence of MSI in Africa is consistently reported as almost double that of European and North American data. Interestingly, BRAF V600E mutations and MLH1 promotor hypermethylation seem to be uncommon in Africa. The high proportion of MSI tumours is only partly accounted for by germline mutations in mismatch repair genes (Lynch syndrome), suggesting that there are likely to be other mechanisms at play. Within the MSS group, preliminary data suggest that the typical molecular pathways (Wingless/Integrated pathway activation) may not be as dominant in Africa. The purpose of this review is to summarise the current state of the molecular genetic landscape of CRC in Africa and provide insights into areas for further study.

Lynch syndrome: from detection to treatment

Lynch syndrome (LS) is an inherited cancer predisposition syndrome associated with high lifetime risk of developing tumours, most notably colorectal and endometrial. It arises in the context of pathogenic germline variants in one of the mismatch repair genes, that are necessary to maintain genomic stability. LS remains underdiagnosed in the population despite national recommendations for empirical testing in all new colorectal and endometrial cancer cases. There are now well-established colorectal cancer surveillance programmes, but the high rate of interval cancers identified, coupled with a paucity of high-quality evidence for extra-colonic cancer surveillance, means there is still much that can be achieved in diagnosis, risk-stratification and management. The widespread adoption of preventative pharmacological measures is on the horizon and there are exciting advances in the role of immunotherapy and anti-cancer vaccines for treatment of these highly immunogenic LS-associated tumours. In this review, we explore the current landscape and future perspectives for the identification, risk stratification and optimised management of LS with a focus on the gastrointestinal system. We highlight the current guidelines on diagnosis, surveillance, prevention and treatment and link molecular disease mechanisms to clinical practice recommendations.

A Scoring Model and Protocol to Adapt Universal Screening for Lynch Syndrome to Identify Germline Pathogenic Variants by Next Generation Sequencing from Colorectal Cancer Patients and Cascade Screening

Simple Summary

Lynch syndrome (LS) is an autosomal-dominantly inherited form of cancer predisposition dominated by colorectal cancer (CRC). LS is caused by germline pathogenic variants (PV) occurring in known mismatch repair genes. For effective cascade screening, it is critical to identify PV for LS predisposition. When limited resources are available, next generation sequencing (NGS) of an entire cohort of colorectal cancer (CRC) patients, even those under 50 or 60 years of age, places a huge burden on the system. Here, we present an innovative LS ascertainment and follow-up program that includes LS molecular analysis, PV screening with NGS technology, and cascade screening. The goal is to improve LS ascertainment in light of the growing burden of early-onset CRC, particularly in low- and middle-income countries.

Abstract

Identification of germline pathogenic variants (PV) predisposing to Lynch syndrome (LS) is an important step for effective use of cascade screening of extended at-risk lineages, leading to reduced morbidity and mortality due to colorectal cancer (CRC). As a general rule, however, next generation sequencing (NGS, either of gene panels or whole exomes) is relatively expensive and unaffordable for general clinical use. In resource-poor settings, performing NGS testing on an entire cohort of CRC patients, even if limited to those under 50 or 60 years of age, still places an enormous burden on limited resources. Although family history can be a good indicator for LS testing, identifying at-risk family members and offering cascade screening may not benefit many patients/probands without an obvious family history. This article presents a novel program called Modified Ascertainment and follow-up Program (MAP) with a scoring model for LS ascertainment and molecular screening by NGS with diagnosis confirmation of PV and cascade screening. The goal is to improve LS ascertainment in light of the growing burden of early-onset CRC, particularly in low- and middle-income countries. Through MAP, judiciously applied molecular genetics will improve identification of PV predisposing to LS and cascade screening.

Endoscopy to Diagnose and Prevent Digestive Cancers in Lynch Syndrome

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

Prevalence of Mismatch Repair-Deficient Colorectal Adenoma/Polyp in Early-Onset, Advanced Cases: a Cross-Sectional Study Based on Iranian Hereditary Colorectal Cancer Registry

BACKGROUND

Lynch syndrome (LS) increases the risk of many types of cancer, mainly colorectal cancer (CRC). The purpose of this study was to assess the prevalence of mismatch repair (MMR) deficiency in patients under the age of 50 with advanced adenomatous polyps, aiming at an early diagnosis of LS.

METHODS

This retrospective, cross-sectional study included eligible patients with advanced adenomas diagnosed ≤ 50 years of age registered between April 2014 and February 2017 at three pathology centers in Mashhad. Pathological records were reviewed, and colon tissue specimens were analyzed by immunohistochemistry (IHC) staining to identify proteins which serve as markers for LS as they are related to loss of MMR gene (MLH1, MSH2, MSH6, and PMS2) expression.

RESULTS

Of 862 consecutive patients, a total of 50 adenomas (54% males, 46% females of mean age 41.24 ± 6.5) met the eligibility criteria. Of the adenomas examined, 20 (40%) had a tubulovillous component, 34 (68%) had high-grade dysplasia, and 30 (60%) had were larger than 10 mm protrusions. None of the patients had loss of MMR protein expression.

CONCLUSION

No individual with MMR genetic disorder was identified by IHC screening of early-onset advanced colorectal adenomas. This strategy is therefore not an effective strategy for detecting MMR mutation carriers.

Historical review of Lynch syndrome

Lynch syndrome was formerly known as Hereditary Nonpolyposis Colorectal Cancer. Currently, these two nomenclatures each have their unique definitions and are no longer used interchangeably. The history of hereditary nonpolyposis colorectal cancer was first recognized formally in the literature by Henry Lynch in 1967. With advances of molecular genetics, there has been a transformation from clinical phenotype to genotype diagnostics. This has led to the ability to diagnose affected patients before they manifest with cancer, and therefore allow preventative surveillance strategies. Genotype diagnostics has shown a difference in penetrance of different cancer risks dependent on the gene containing the mutation. Surgery is recommended as prevention for some cancers; for others they are reserved for once cancer is noted. Various surveillance strategies are recommended dependent on the relative risk of cancer and the ability to intervene with surgery to impact on survival. Risk reduction through aspirin has shown some recent promise, and continues to be studied.

The "unnatural" history of colorectal cancer in Lynch syndrome: Lessons from colonoscopy surveillance

Individuals with Lynch syndrome (LS), one of the most common inherited cancer syndromes, are at increased risk of developing malignancies, in particular colorectal cancer (CRC). Regular colonoscopy with polypectomy is recommended to reduce CRC risk in LS individuals. However, recent independent studies demonstrated that a substantial proportion of LS individuals develop CRC despite regular colonoscopy. The reasons for this surprising observation confirmed by large prospective studies are a matter of debate. In this review, we collect existing evidence from clinical, epidemiological and molecular studies and interpret them with regard to the origins and progression of LS-associated CRC. Alongside with hypotheses addressing colonoscopy quality and pace of progression from adenoma to cancer, we discuss the role of alternative precursors and immune system in LS-associated CRC. We also identify gaps in current knowledge and make suggestions for future studies aiming at improved CRC prevention for LS individuals.

Colorectal cancer incidence and mortality trends by sex and population group in South Africa: 2002-2014

BACKGROUND

South Africa (SA) has experienced a rapid transition in the Human Development Index (HDI) over the past decade, which had an effect on the incidence and mortality rates of colorectal cancer (CRC). This study aims to provide CRC incidence and mortality trends by population group and sex in SA from 2002 to 2014.

METHODS

Incidence data were extracted from the South African National Cancer Registry and mortality data obtained from Statistics South Africa (STATS SA), for the period 2002 to 2014. Age-standardised incidence rates (ASIR) and age-standardised mortality rates (ASMR) were calculated using the STATS SA mid-year population as the denominator and the Segi world standard population data for standardisation. A Joinpoint regression analysis was computed for the CRC ASIR and ASMR by population group and sex.

RESULTS

A total of 33,232 incident CRC cases and 26,836 CRC deaths were reported during the study period. Of the CRC cases reported, 54% were males and 46% were females, and among deaths reported, 47% were males and 53% were females. Overall, there was a 2.5% annual average percentage change (AAPC) increase in ASIR from 2002 to 2014 (95% CI: 0.6-4.5, p-value < 0.001). For ASMR overall, there was 1.3% increase from 2002 to 2014 (95% CI: 0.1-2.6, p-value < 0.001). The ASIR and ASMR among population groups were stable, with the exception of the Black population group. The ASIR increased consistently at 4.3% for black males (95% CI: 1.9-6.7, p-value < 0.001) and 3.4% for black females (95% CI: 1.5-5.3, p-value < 0.001) from 2002 to 2014, respectively. Similarly, ASMR for black males and females increased by 4.2% (95% CI: 2.0-6.5, p-value < 0.001) and 3.4% (, 95%CI: 2.0-4.8, p-value < 0.01) from 2002 to 2014, respectively.

CONCLUSIONS

The disparities in the CRC incidence and mortality trends may reflect socioeconomic inequalities across different population groups in SA. The rapid increase in CRC trends among the Black population group is concerning and requires further investigation and increased efforts for cancer prevention, early screening and diagnosis, as well as better access to cancer treatment.

Progress Report: New insights into the prevention of CRC by colonoscopic surveillance in Lynch syndrome

Lynch syndrome is the most frequent hereditary colorectal cancer (CRC) syndrome, affecting approximately 1 in 300 in the Western population. It is caused by pathogenic variants in the mismatch repair (MMR) genes including MLH1, MSH2 (EPCAM), MSH6 and PMS2, and is associated with high risks of CRC, endometrial cancer and other cancers. In view of these risks, carriers of such variants are encouraged to participate in colonoscopic surveillance programs that are known to substantially improve their prognosis. In the last decade several important studies have been published that provide detailed cancer risk estimates and prognoses based on large numbers of patients. These studies also provided new insights regarding the pathways of carcinogenesis in CRC, which appear to differ depending on the specific MMR gene defect. In this report, we will discuss the implications of these new findings for the development of new surveillance protocols.

Public support for healthcare-mediated disclosure of hereditary cancer risk information: Results from a population-based survey in Sweden

Background

Targeted surveillance of at-risk individuals in families with increased risk of hereditary cancer is an effective prevention strategy if relatives are identified, informed and enrolled in screening programs. Despite the potential benefits, many eligible at-risk relatives remain uninformed of their cancer risk. This study describes the general public's opinion on disclosure of hereditary colorectal cancer (CRC) risk information, as well as preferences on the source and the mode of information.

Methods

A random sample of the general public was assessed through a Swedish citizen web-panel. Respondents were presented with scenarios of being an at-risk relative in a family that had an estimated increased hereditary risk of CRC; either 10% (moderate) or 70% (high) lifetime risk. A colonoscopy was presented as a preventive measure. Results were analysed to identify significant differences between groups using the Pearson's chi-square (χ²) test.

Results

Of 1800 invited participants, 977 completed the survey (54%). In the moderate and high-risk scenarios, 89.2 and 90.6% respectively, would like to receive information about a potential hereditary risk of CRC (χ2, p = .755). The desire to be informed was higher among women (91.5%) than men (87.0%, χ2, p = .044). No significant differences were found when comparing different age groups, educational levels, place of residence and having children or not. The preferred source of risk information was a healthcare professional in both moderate and high-risk scenarios (80.1 and 75.5%). However, 18.1 and 20.1% respectively would prefer to be informed by a family member. Assuming that healthcare professionals disclosed the information, the favoured mode of information was letter and phone (38.4 and 33.2%).

Conclusions

In this study a majority of respondents wanted to be informed about a potential hereditary risk of CRC and preferred healthcare professionals to communicate this information. The two presented levels of CRC lifetime risk did not significantly affect the interest in being informed. Our data offer insights into the needs and preferences of the Swedish population, providing a rationale for developing complementary healthcare-assisted communication pathways to realise the full potential of targeted prevention of hereditary CRC.

Cost-effectiveness analysis of genetic diagnostic strategies for Lynch syndrome in Italy

Lynch syndrome (LS) is an autosomal dominant condition caused by pathogenic variants in mismatch repair (MMR) genes that predispose individuals to different malignancies, such as colorectal cancer (CRC) and endometrial cancer. Current guidelines recommended testing for LS in individuals with newly diagnosed CRC to reduce cancer morbidity and mortality in relatives. Economic evaluations in support of such approach, however, are not available in Italy. We developed a decision-analytic model to analyze the cost-effectiveness of LS screening from the perspective of the Italian National Health System. Three testing strategies: the sequencing of all MMR genes without prior tumor analysis (Strategy 1), a sequential IHC and MS-MLPA analysis (Strategy 2), and an age-targeted strategy with a revised Bethesda criteria assessment before IHC and methylation-specific MLPA for patients ≥ than 70 years old (Strategy 3) were analyzed and compared to the “no testing” strategy. Quality Adjusted Life Years (QALYs) in relatives after colonoscopy, aspirin prophylaxis and an intensive gynecological surveillance were estimated through a Markov model. Assuming a CRC incidence rate of 0.09% and a share of patients affected by LS equal to 2.81%, the number of detected pathogenic variants among CRC cases ranges, in a given year, between 910 and 1167 depending on the testing strategy employed. The testing strategies investigated, provided one-time to the entire eligible population (CRC patients), were associated with an overall cost ranging between €1,753,059.93-€10,388,000.00. The incremental cost-effectiveness ratios of the Markov model ranged from €941.24 /QALY to €1,681.93 /QALY, thus supporting that “universal testing” versus “no testing” is cost-effective, but not necessarily in comparison with age-targeted strategies. This is the first economic evaluation on different testing strategies for LS in Italy. The results might support the introduction of cost-effective recommendations for LS screening in Italy.

Yield of Lynch Syndrome Surveillance for Patients With Pathogenic Variants in DNA Mismatch Repair Genes

BACKGROUND & AIMS

Patients with Lynch syndrome are offered the same colorectal cancer (CRC) surveillance programs (colonoscopy every 2 years), regardless of the pathogenic DNA mismatch repair gene variant the patient carries. We aimed to assess the yield of surveillance for patients with these variants in MLH1, MSH2, MSH6, and PMS2.

METHODS

We analyzed data on colonoscopy surveillance, including histopathology analysis, from all patients diagnosed with Lynch syndrome (n = 264) at a single center. We compared the development of (advanced) adenomas and CRC among patients with pathogenic variants in the DNA mismatch repair genes MLH1 (n = 55), MSH2 (n = 44), MSH6 (n = 143), or PMS2 (n = 22) over 1836 years of follow-up (median follow-up of 6 years per patient).

RESULTS

At first colonoscopy, CRC was found in 8 patients. During 916 follow-up colonoscopies, CRC was found in 9 patients. No CRC was found in patients with variants in MSH6 or PMS2 over the entire follow-up period. There were no significant differences in the number of colonoscopies with adenomas or advanced adenomas among the groups. The median time of adenoma development was 3 years (IQR, 2-6 years). There were no significant differences in time to development of adenoma. However, patients with variants in MSH6 had a significant longer time to development of advanced neoplasia (advanced adenoma or CRC) than patients in the other groups. Six carriers died during follow up (5 from cancer, of which 3 from pancreatic cancer).

CONCLUSIONS

No CRC was found during follow-up of patients with Lynch syndrome carrying pathogenic variants in MSH6; advanced neoplasia developed over shorter follow-up time periods in patients with pathogenic variants in MLH1 or MSH2. The colonoscopy interval for patients with pathogenic variants in MSH6 might be increased to 3 years from the regular 2-year interval.

Benefit from extended surveillance interval on colorectal cancer risk in Lynch syndrome

AIM

Although patients with Lynch syndrome have an increased risk of developing colorectal cancer, surveillance can reduce morbidity and mortality. Whether or not affected individuals benefit from lifetime surveillance depends on individual factors and patient adherence, and these may vary, complicating risk modelling. The aim of this study was to identify individual factors which influence patient adherence to surveillance programmes and whether extended surveillance interval influenced their risk of developing colorectal cancer.

METHOD

Demographics and survival data were obtained from patients (n = 1223) with Lynch syndrome, identified by interrogating the Danish Hereditary Non-Polyposis Colorectal Cancer Register. These data were linked to patient surveillance interval data which had been divided into three subsets (< 27 months, adherent to the recommended biennial programme; > 27 months, extended surveillance interval; and no surveillance) to estimate the cumulative risks and hazard ratios (HRs) for colorectal cancer.

RESULTS

In all, 147 colorectal cancers (99 first; 48 metachronous) were identified in 1223 patients. Factors associated with adherence to surveillance were female sex, a previous history of cancer and age < 75 years. The cumulative incidence for colorectal cancer was 38% (95% CI 27%-50%) for surveillance intervals < 27 months, 48% (95% CI 29%-67%) for intervals > 27 months and 72% (95% CI 61%-83%) with no surveillance. Adjusted HRs were 0.22 for surveillance intervals < 27 months and 0.32 for surveillance intervals > 27 months. Extended surveillance intervals > 27 months had a non-significant benefit with an HR of 1.51 (95% CI 0.83-2.75) compared to surveillance intervals < 27 months.

CONCLUSION

This study demonstrates that adherence to colonoscopic surveillance in Lynch syndrome varies with age, sex and cancer history and demonstrates a consistent benefit from colorectal cancer surveillance, though it might be lower for individuals with extended intervals.

A Novel Germline MLH1 In-Frame Deletion in a Slovenian Lynch Syndrome Family Associated with Uncommon Isolated PMS2 Loss in Tumor Tissue

The diagnostics of Lynch syndrome (LS) is focused on the detection of DNA mismatch repair (MMR) system deficiency. MMR deficiency can be detected on tumor tissue by microsatellite instability (MSI) using molecular genetic test or by loss of expression of one of the four proteins (MLH1, MSH2, MSH6, and PMS2) involved in the MMR system using immunohistochemistry (IHC) staining. According to the National Comprehensive Cancer Network (NCCN) guidelines, definitive diagnosis of LS requires the identification of the germline pathogenic variant in one of the MMR genes. In the report, we are presenting interesting novel MLH1 in-frame deletion LRG_216t1:c.2236_2247delCTGCCTGATCTA p.(Leu746_Leu749del) associated with LS. The variant appears to be associated with uncommon isolated loss of PMS2 immunohistochemistry protein staining (expression) in tumor tissue instead of MLH1 and PMS2 protein loss, which is commonly seen with pathogenic variants in MLH1. The variant was classified as likely pathogenic, based on segregation analysis and molecular characterization of blood and tumor samples. According to the American College of Medical Genetics (ACMG) guidelines, the following evidence categories of PM1, PM2, PM4, and PP1 moderate have been used for classification of the novel variant. By detecting and classifying the novel MLH1 variant as likely pathogenic, we confirmed the LS in this family.

Microsatellite Instability assessment in Black South African Colorectal Cancer patients reveal an increased incidence of suspected Lynch syndrome

Microsatellite Instability (MSI) is a hallmark of colorectal cancer (CRC) and occurs in 15–16% of CRC. Molecular biological information of CRC in South Africa (SA) is largely unrecorded. This study was undertaken to determine the frequency of MSI, with particular reference to Lynch syndrome (LS) with a view to improve surveillance and prevention strategies. This was a retrospective study on CRC samples diagnosed between 2011–2015 at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). Samples diagnosed between 2011–2012 were screened for MSI by PCR and mismatch repair (MMR) immunohistochemistry (IHC), and additional BRAFV600E mutational analysis performed. T-tests, Fischer’s exact and Chi square statistical tests were applied. Twelve percent of patients displayed MSI, with increased frequency in black (15%) versus other ethnic group (OEG) (8%) patients. MSI patients were significantly younger than microsatellite stable (MSS) patients, however when stratified by ethnicity, black patients were predominantly younger (median age: 47), with increased MSH2/6 loss, and no BRAF mutations. These findings suggest a large proportion of young black SA CRC patients develop via the LS pathway due to earlier age onset and predominant MSH2/6 protein loss. SA patients of other ethnicities appear to follow the more well established sporadic MSI pathway.

Cost-effectiveness analysis of reflex testing for Lynch syndrome in women with endometrial cancer in the UK setting

Background

Lynch syndrome is a hereditary cancer syndrome caused by constitutional pathogenic variants in the DNA mismatch repair (MMR) system, leading to increased risk of colorectal, endometrial and other cancers. The study aimed to identify the incremental costs and consequences of strategies to identify Lynch syndrome in women with endometrial cancer.

Methods

A decision-analytic model was developed to evaluate the relative cost-effectiveness of reflex testing strategies for identifying Lynch syndrome in women with endometrial cancer taking the NHS perspective and a lifetime horizon. Model input parameters were sourced from various published sources. Consequences were measured using quality-adjusted life years (QALYs). A cost-effectiveness threshold of £20 000/QALY was used.

Results

Reflex testing for Lynch syndrome using MMR immunohistochemistry and MLH1 methylation testing was cost-effective versus no testing, costing £14 200 per QALY gained. There was uncertainty due to parameter imprecision, with an estimated 42% chance this strategy is not cost-effective compared with no testing. Age had a significant impact on cost-effectiveness, with testing not predicted to be cost-effective in patients aged 65 years and over.

Conclusions

Testing for Lynch syndrome in younger women with endometrial cancer using MMR immunohistochemistry and MLH1 methylation testing may be cost-effective. Age cut-offs may be controversial and adversely affect implementation.

Colorectal cancer incidence in path_MLH1 carriers subjected to different follow-up protocols: a Prospective Lynch Syndrome Database report

Background

We have previously reported a high incidence of colorectal cancer (CRC) in carriers of pathogenic MLH1 variants (path_MLH1) despite follow-up with colonoscopy including polypectomy.

Methods

The cohort included Finnish carriers enrolled in 3-yearly colonoscopy (n = 505; 4625 observation years) and carriers from other countries enrolled in colonoscopy 2-yearly or more frequently (n = 439; 3299 observation years). We examined whether the longer interval between colonoscopies in Finland could explain the high incidence of CRC and whether disease expression correlated with differences in population CRC incidence.

Results

Cumulative CRC incidences in carriers of path_MLH1 at 70-years of age were 41% for males and 36% for females in the Finnish series and 58% and 55% in the non-Finnish series, respectively (p > 0.05). Mean time from last colonoscopy to CRC was 32.7 months in the Finnish compared to 31.0 months in the non-Finnish (p > 0.05) and was therefore unaffected by the recommended colonoscopy interval. Differences in population incidence of CRC could not explain the lower point estimates for CRC in the Finnish series. Ten-year overall survival after CRC was similar for the Finnish and non-Finnish series (88% and 91%, respectively; p > 0.05).

Conclusions

The hypothesis that the high incidence of CRC in path_MLH1 carriers was caused by a higher incidence in the Finnish series was not valid. We discuss whether the results were influenced by methodological shortcomings in our study or whether the assumption that a shorter interval between colonoscopies leads to a lower CRC incidence may be wrong. This second possibility is intriguing, because it suggests the dogma that CRC in path_MLH1 carriers develops from polyps that can be detected at colonoscopy and removed to prevent CRC may be erroneous. In view of the excellent 10-year overall survival in the Finnish and non-Finnish series we remain strong advocates of current surveillance practices for those with LS pending studies that will inform new recommendations on the best surveillance interval.

Electronic supplementary material

The online version of this article (10.1186/s13053-017-0078-5) contains supplementary material, which is available to authorized users.

Decentralized colonoscopic surveillance with high patient compliance prevents hereditary and familial colorectal cancer

Although colonoscopic surveillance is recommended both for individuals with known hereditary colorectal cancer (HCRC) syndromes and those with a more moderate familial colorectal cancer (FCRC) history, the evidence for the benefits of surveillance is limited and surveillance practices vary. This study evaluates the preventive effect for individuals with a family history of CRC of decentralized colonoscopic surveillance with the guidance of a cancer prevention clinic. We performed a population based prospective study of 261 patients with HCRC or FCRC, recorded in the colonoscopic surveillance registry at the Cancer genetics clinic, University Hospital of Umeå, Sweden. Colonoscopic surveillance was conducted every second (HCRC) or fifth (FCRC) year at local hospitals in Northern Sweden. Main outcome measures were findings of high-risk adenomas (HRA) or CRC, and patient compliance to surveillance. Estimations of the expected numbers of CRC without surveillance were made. During a total of 1256 person years of follow-up, one case of CRC was found. The expected numbers of cancers in the absence of surveillance was between 9.5 and 10.5, resulting in a standardized incidence ratio, observed versus expected cases of CRC, between 0.10 (CI 95 % 0.0012-0.5299) and 0.11 (CI 95 % 0.0014-0.5857). No CRC mortality was reported, but three patients needed surgical intervention. HRA were found in 5.9 % (14/237) of the initial and in 3.4 % (12/356) of the follow-up colonoscopies. Patient compliance to the surveillance program was 90 % as 597 of the planned 662 colonoscopies were performed. The study concludes that colonoscopic surveillance with high patient compliance to the program is effective in preventing CRC when using a decentralized method for colonoscopy surveillance with the guidance of a cancer prevention clinic.

The shifting epidemiology of colorectal cancer in sub-Saharan Africa

The perception that colorectal cancer is rare in sub-Saharan Africa is widely held; however, it is unclear whether this is due to poor epidemiological data or to lower disease rates. The quality of epidemiological data has somewhat improved, and there is an ongoing transition to western dietary and lifestyle practices associated with colorectal cancer. The impact of these changes on the incidence of colorectal cancer is not as evident as it is with other non-communicable diseases such as diabetes. In this Viewpoint, we discuss the epidemiology of colorectal cancer in sub-Saharan Africa. Colorectal cancer in this region frequently occurs at an early age, often with distinctive histological characteristics. We detail the crucial need for hypothesis-driven research on the risk factors for colorectal cancer in this population and identify key research gaps. Should colorectal cancer occur more frequently than assumed, then commensurate allocation of resources will be needed for diagnosis and treatment.

Is there evidence that we should screen the general population for Lynch syndrome with genetic testing? A systematic review

BACKGROUND

The emerging dual imperatives of personalized medicine and technologic advances make population screening for preventable conditions resulting from genetic alterations a realistic possibility. Lynch syndrome is a potential screening target due to its prevalence, penetrance, and the availability of well-established, preventive interventions. However, while population screening may lower incidence of preventable conditions, implementation without evidence may lead to unintentional harms. We examined the literature to determine whether evidence exists that screening for Lynch-associated mismatch repair (MMR) gene mutations leads to improved overall survival, cancer-specific survival, or quality of life. Documenting evidence and gaps is critical to implementing genomic approaches in public health and guiding future research.

MATERIALS AND METHODS

Our 2014-2015 systematic review identified studies comparing screening with no screening in the general population, and controlled studies assessing analytic validity of targeted next-generation sequencing, and benefits or harms of interventions or screening. We conducted meta-analyses for the association between early or more frequent colonoscopies and health outcomes.

RESULTS

Twelve studies met our eligibility criteria. No adequate evidence directly addressed the main question or the harms of screening in the general population. Meta-analyses found relative reductions of 68% for colorectal cancer incidence (relative risk: 0.32, 95% confidence interval: 0.23-0.43, three cohort studies, 590 participants) and 78% for all-cause mortality (relative risk: 0.22, 95% confidence interval: 0.09-0.56, three cohort studies, 590 participants) for early or more frequent colonoscopies among family members of people with cancer who also had an associated MMR gene mutation.

CONCLUSION

Inadequate evidence exists examining harms and benefits of population-based screening for Lynch syndrome. Lack of evidence highlights the need for data that directly compare benefits and harms.

Cost-effectiveness of routine screening for Lynch syndrome in endometrial cancer patients up to 70years of age

PURPOSE

To assess cost-effectiveness of routine screening for Lynch Syndrome (LS) in endometrial cancer (EC) patients ≤70years of age.

METHODS

Consecutive EC patients ≤70years of age were screened for LS by analysis of microsatellite instability, immunohistochemistry and MLH1 hypermethylation. Costs and health benefit in life years gained (LYG) included surveillance for LS carriers among EC patients and relatives. We calculated incremental cost-effectiveness ratios (ICERs) comparing LS screening among EC patients ≤70years with ≤50years and the revised Bethesda guidelines.

RESULTS

Screening for LS in 179 EC patients identified 7 LS carriers; 1 was ≤50 and 6 were 51-70years. Per age category 18 and 9 relatives were identified as LS carrier. Screening resulted in 74,7 LYG (45,4 and 29,3 LYG per age category). The ICER for LS screening in EC patients ≤70 compared with ≤50years was €5,252/LYG. The revised Bethesda guidelines missed 4/7 (57%) LS carriers among EC patients. The ICER for LS screening in EC patients ≤70years of age compared with the revised Bethesda guidelines was €6,668/LYG. Both ICERs remained <€16,000/LYG in sensitivity analyses.

CONCLUSION

Routine LS screening in EC patients ≤70years is a cost-effective strategy, allowing colorectal cancer prevention in EC patients and their relatives.

The Impact of Receiving Predictive Genetic Information about Lynch Syndrome on Individual Colonoscopy and Smoking Behaviors

BACKGROUND

This study investigated whether receiving the results of predictive genetic testing for Lynch syndrome, indicating the presence or absence of an inherited predisposition to various cancers, including colorectal cancer, was associated with change in individual colonoscopy and smoking behaviors, which could prevent colorectal cancer.

METHODS

The study population included individuals with no previous diagnosis of colorectal cancer, whose families had already identified deleterious mutations in the mismatch repair or EPCAM genes. Hypotheses were generated from a simple health economics model and tested against individual-level panel data from the Australasian Colorectal Cancer Family Registry.

RESULTS

The empirical analysis revealed evidence consistent with some of the hypotheses, with a higher likelihood of undergoing colonoscopy in those who discovered their genetic predisposition to colorectal cancer and a lower likelihood of quitting smoking in those who discovered their lack thereof.

CONCLUSIONS

Predictive genetic information about Lynch syndrome was associated with change in individual colonoscopy and smoking behaviors but not necessarily in ways to improve population health.

IMPACT

The study findings suggest that the impact of personalized medicine on disease prevention is intricate, warranting further analyses to determine the net benefits and costs. Cancer Epidemiol Biomarkers Prev; 25(11); 1524-33. ©2016 AACR.

Lynch syndrome risk management

Lynch syndrome has been known as hereditary non-polyposis colorectal cancer (HNPCC), and it is a dominantly inherited cancer syndrome caused by genetic mutations in cell mismatch repair genes, often leading to digestive system and female reproductive system tumors. At present, there is a high misdiagnosis rate for Lynch syndrome. This paper reviews the latest progress in Lynch syndrome risk management with regards to its monitoring, surgical treatment, pharmaceutical treatment, life style improvement and screening.

Universal Screening of Colorectal Cancers for Lynch Syndrome: Challenges and Opportunities

Lynch syndrome (LS) is the most common heritable colorectal cancer (CRC) syndrome, accounting for approximately 3 % of CRC cases in the USA each year. LS results from a genetic mutation in one of the four mismatch repair genes, and clinically LS is associated with CRC and other gastrointestinal and extra-gastrointestinal malignancies. In this review, we describe the various clinical criteria utilized for the identification of LS patients and the inherent flaws with these criteria. We discuss the concept of universal testing for LS in all cases of newly diagnosed CRC, along with the potential benefits and challenges of universal testing. Several studies have shown that universal tumor testing is cost-effective and identifies cases of LS that are missed using traditional clinical criteria, which may result in reduced cancer mortality for probands and their families. Yet the full benefits of universal tumor testing may be limited by the availability and patient acceptance of genetic testing, and by logistical obstacles affecting the implementation of universal testing programs. Lastly, we comment on developing technologies such as massively parallel next-generation sequencing, which permits simultaneous sequencing of multiple genes involved in LS and other inherited colon cancer syndromes.

Personalized Cancer Risk Assessments for Space Radiation Exposures

Individuals differ in their susceptibility to radiogenic cancers, and there is evidence that this inter-individual susceptibility extends to HZE ion-induced carcinogenesis. Three components of individual risk: sex, age at exposure, and prior tobacco use, are already incorporated into the NASA cancer risk model used to determine safe days in space for US astronauts. Here, we examine other risk factors that could potentially be included in risk calculations. These include personal and family medical history, the presence of pre-malignant cells that could undergo malignant transformation as a consequence of radiation exposure, the results from phenotypic assays of radiosensitivity, heritable genetic polymorphisms associated with radiosensitivity, and postflight monitoring. Inclusion of these additional risk or risk reduction factors has the potential to personalize risk estimates for individual astronauts and could influence the determination of safe days in space. We consider how this type of assessment could be used and explore how the provisions of the federal Genetic Information Non-discrimination Act could impact the collection, dissemination and use of this information by NASA.

Review: Clinical aspects of hereditary DNA Mismatch repair gene mutations

Inherited mutations of the DNA Mismatch repair genes MLH1, MSH2, MSH6 and PMS2 can result in two hereditary tumor syndromes: the adult-onset autosomal dominant Lynch syndrome, previously referred to as Hereditary Non-Polyposis Colorectal Cancer (HNPCC) and the childhood-onset autosomal recessive Constitutional Mismatch Repair Deficiency syndrome. Both conditions are important to recognize clinically as their identification has direct consequences for clinical management and allows targeted preventive actions in mutation carriers. Lynch syndrome is one of the more common adult-onset hereditary tumor syndromes, with thousands of patients reported to date. Its tumor spectrum is well established and includes colorectal cancer, endometrial cancer and a range of other cancer types. However, surveillance for cancers other than colorectal cancer is still of uncertain value. Prophylactic surgery, especially for the uterus and its adnexa is an option in female mutation carriers. Chemoprevention of colorectal cancer with aspirin is actively being investigated in this syndrome and shows promising results. In contrast, the Constitutional Mismatch Repair Deficiency syndrome is rare, features a wide spectrum of childhood onset cancers, many of which are brain tumors with high mortality rates. Future studies are very much needed to improve the care for patients with this severe disorder.

Long anticipation complicates identifying Lynch syndrome in monozygotic twins

Anticipation is a term used to express an earlier age of disease onset in successive generations. Patients with Lynch syndrome (LS) harbor mutations in MMR genes that appear to be associated with the phenomenon where disease is diagnosed 5–12 years earlier in mutation carrying children compared with their affected parent. This has the potential to complicate the recognition of LS as defined by the Amsterdam criteria (or iterations of it) in young probands affected by colorectal cancer. In this report, we describe a case of an LS family with an MLH1 mutation (c.1748 del T). The phenomenon of anticipation was observed in the son of a monozygotic twin who developed two colon cancers that were diagnosed at an age 20 years earlier than the first diagnosis of cancer in his mother. Both the mother and her twin went on to simultaneously develop a rectal carcinoma.

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.

Genetics, biomarkers, hereditary cancer syndrome diagnosis, heterogeneity and treatment: a review

OPINION STATEMENT

Molecular genetic pathways that drive the phenotypic and genotypic heterogeneity of hereditary colorectal cancer also can affect response to chemotherapy and chemoprevention. These mutations also can alter patients' response to therapy. Environmental differences can affect this highly complex conundrum. We will use Lynch syndrome as a model to explore this issue. However, to begin with, after more than a century of documentation, we must ask what is meant by the eponym "Lynch syndrome". Germline mutations may act as drivers of chemoprevention and chemotherapy and therein may act positively or conversely they may have a negative effect in terms of inhibiting the inactivation of cancer-causing germline mutations. A relatively new field of hereditary cancer therapeutics has significantly impacted cancer care, from the standpoint of the sensitivity or resistance to a particular form of chemotherapy and/or chemoprevention. The question for the diagnostician and therapist must always concern what is the best possible management approach for the patient, particularly when he or she harbors a cancer-causing germline mutation, which, in this case, causes Lynch syndrome. Continued molecular genetic research might yield a more tailored effective treatment for Lynch syndrome. The ultimate goal of such hereditary oncologic research is to better understand the mutation's therapeutic task, namely, its potential to benefit the patient in terms of its treatment goal, thereby fulfilling the essence of personalized medicine. However, this goal may be exceedingly complicated. For example, in the natural clinical and molecular genetic history of hereditary forms of cancer, there will be a predominance of early-onset cancers of multiple anatomic sites. In our Lynch syndrome model, these will be most commonly colorectal, endometrial, and ovarian cancer. Attention must initially be focused upon cancer's early age of onset coupled with the tendency to multiple primary cancers so that, in the case of CRC, colonoscopic screening must be initiated by age 20-25 years and repeated every other year until age 40 years and then annually thereafter. However, screening will be of limited efficacy in the gynecologic cancers (endometrial and ovarian) so that once the family is completed, particularly by age 35-40 years, careful attention must be given to the option of prophylactic hysterectomy and bilateral salpingo-oophorectomy. Given issues of tumor heterogeneity, selected Lynch syndrome families may show an excess of urologic cancers or cancers of the small bowel, and highly targeted screening should be given serious consideration for these as well as cancers of other anatomic sites in such high-risk, cancer-prone patients.

No evidence of genetic anticipation in a large family with Lynch syndrome

Lynch syndrome is the commonest inherited cause of colorectal cancer (CRC). Genetic anticipation occurs when the age of onset of a disorder decreases in successive generations. It is controversial whether this occurs in Lynch syndrome. Previous studies have included heterogenous groups of subjects from multiple families, including subjects with a clinical diagnosis (based on family history) as well as those with proven germline mismatch repair gene mutations. The purpose of this study was to determine whether genetic anticipation occurs in mismatch repair gene carriers from a single Lynch syndrome family. This study includes members of a single family known to carry an MLH1 gene mutation who are proven germline mutation carriers or obligate carriers (based on their offspring's mutation status). Evidence of genetic anticipation (determined by age of onset of first CRC) was sought in two ways: Firstly, subjects were grouped as parent-child pairs and individuals were compared with their own offspring; secondly they were grouped by generation within the family tree. The Kaplan-Meier technique was used to adjust for variable follow up times. The family tree consisted of 714 subjects. Ninety-two subjects over five generations were included in the study. There was no evidence of genetic anticipation over the generations. (P = 0.37). Similarly, in the 75 parent-child pairs identified, age of onset of CRC was similar for parents and children (P = 0.51). We could not identify any evidence of genetic anticipation in mutation carriers from a single family with Lynch syndrome.

Endometrial tumour BRAF mutations and MLH1 promoter methylation as predictors of germline mismatch repair gene mutation status: a literature review

Colorectal cancer (CRC) that displays high microsatellite instability (MSI-H) can be caused by either germline mutations in mismatch repair (MMR) genes, or non-inherited transcriptional silencing of the MLH1 promoter. A correlation between MLH1 promoter methylation, specifically the 'C' region, and BRAF V600E status has been reported in CRC studies. Germline MMR mutations also greatly increase risk of endometrial cancer (EC), but no systematic review has been undertaken to determine if these tumour markers may be useful predictors of MMR mutation status in EC patients. Endometrial cancer cohorts meeting review inclusion criteria encompassed 2675 tumours from 20 studies for BRAF V600E, and 447 tumours from 11 studies for MLH1 methylation testing. BRAF V600E mutations were reported in 4/2675 (0.1%) endometrial tumours of unknown MMR mutation status, and there were 7/823 (0.9%) total sequence variants in exon 11 and 27/1012 (2.7%) in exon 15. Promoter MLH1 methylation was not observed in tumours from 32 MLH1 mutation carriers, or for 13 MSH2 or MSH6 mutation carriers. MMR mutation-negative individuals with tumour MLH1 and PMS2 IHC loss displayed MLH1 methylation in 48/51 (94%) of tumours. We have also detailed specific examples that show the importance of MLH1 promoter region, assay design, and quantification of methylation. This review shows that BRAF mutations occurs so infrequently in endometrial tumours they can be discounted as a useful marker for predicting MMR-negative mutation status, and further studies of endometrial cohorts with known MMR mutation status are necessary to quantify the utility of tumour MLH1 promoter methylation as a marker of negative germline MMR mutation status in EC patients.

Hereditary and common familial colorectal cancer: evidence for colorectal screening

Colorectal cancer (CRC) is the fourth most common cancer among men and women. Between 3 and 6% of all CRCs are attributed to well-defined inherited syndromes, including Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis and several hamartomatous conditions. Up to 30% of CRC cases exhibit common familial risk, likely related to a combination of inherited factors and environment. Identification of these patients through family history and appropriate genetic testing can provide estimates of cancer risk that inform appropriate cancer screening, surveillance and/or preventative interventions. This article examines the colon cancer syndromes, their genetic basis, clinical management and evidence supporting colorectal screening. It also deals with the category of common (non-syndromic) familial risk including risk determination and screening guidelines.

Prevalence of Lynch syndrome in a Middle Eastern population with colorectal cancer

BACKGROUND

Lynch syndrome (LS; hereditary nonpolyposis colorectal cancer) is a common cause of hereditary colorectal cancer (CRC). CRC is the most common cancer diagnosed among males in Saudi Arabia but to the authors' knowledge there is a lack of data regarding the prevalence of LS in patients with CRC. There currently are no clear guidelines for the selection criteria for these patients to screen for LS.

METHODS

A comprehensive molecular characterization was performed in a cohort of 807 CRC cases by immunohistochemical and microsatellite analysis using polymerase chain reaction. BRAF mutation screening, high CpG island methylator phenotype, and analysis for germline mutations were performed in 425 CRC samples. These were all high microsatellite instability (MSI-H) samples (91 cases), all low MSI samples (143 cases), and selected cases from the microsatellite stable group (191 cases) that met revised Bethesda guidelines.

RESULTS

Polymerase chain reaction identified 91 MSI-H cases (11.3%) and sequencing revealed mismatch repair germline mutations in 8 CRC cases only. Of the total of 807 CRC cases, these 8 cases (0.99%) were MSI-H, met the revised Bethesda guidelines, and did not harbor BRAF mutations.

CONCLUSIONS

The results of the current study confirmed cases of LS in approximately 1.0% of CRC samples and reflects the efficacy of screening among MSI-H cases that lack BRAF mutations. This comprehensive study from Saudi Arabia will help in implementing a universal screening/reflex testing strategy in a clinical setting in Saudi Arabia and in conducting a national screening program that benefits both patients and their relatives.

Advanced colorectal adenomas in patients under 45 years of age are mostly sporadic

BACKGROUND

The presence of advanced adenomas in younger individuals is a criterion for Lynch syndrome (LS). However, the utility of screening advanced adenomas for loss of mismatch repair (MMR) protein expression to identify suspected LS remains unclear.

AIMS

Determine the prevalence of MMR defects to understand whether these patients harbor a defined genetic risk for CRC.

METHODS

The study cohort included adult patients ≤45 years of age with advanced adenomas (villous histology, ≥1 cm in diameter, ≥3 polyps of any size) endoscopically removed between 2001 and 2011. Clinical records were reviewed along with detailed pathological review and immunohistochemical MMR analysis.

RESULTS

A total of 76 (40.1 % male, age 40.6 ± 5.4 years) patients met inclusion and exclusion criteria. Indications for colonoscopy were gastrointestinal (GI) bleeding 39 (51.3 %), CRC in a first-degree relative 17 (22.4 %) and somatic GI symptoms 20 (26.3 %). Index colonoscopy revealed a median of 1 adenoma (range 1-4), mean diameter of 12.9 ± 7.1 mm, 40 (52.6 %) with villous histology. The mean follow-up duration was 3.3 ± 2 years. Recurrent adenomas developed in 24 (31.6 %), of which 8 (10.5 %) were advanced adenomas; none of these patients developed CRC. One of 66 (1.5 %) adenomas available for immunohistochemical (IHC) testing revealed loss of MLH1 and PMS2.

CONCLUSIONS

IHC screening of advanced adenomas from patients younger than 45 years of age identified potential LS in one of 64 patients. The low yield of IHC screening in this population suggests that universal IHC screening of advanced adenomas from patients younger than 45 years of age for MMR defects is not an efficient strategy for identifying LS subjects.

Mismatch repair gone awry: Management of Lynch syndrome

The hallmark of Lynch syndrome involves germline mutations of genes important in DNA mismatch repair. Affected family kindreds will have multiple associated malignancies, the most common of which is colorectal adenocarcinoma. Recently, evidence has shown that clinical diagnostic criteria provided by the Amsterdam Criteria and the Bethesda Guidelines must be linked with microsatellite instability testing to correctly diagnose Lynch syndrome. We present a case of metachronous colorectal adenocarcinomas in a patient less than 50 years of age, followed by a discussion of Lynch syndrome, with an emphasis on surveillance and prevention of malignancies.

Tumour MLH1 promoter region methylation testing is an effective prescreen for Lynch Syndrome (HNPCC)

BACKGROUND AND AIMS

Lynch syndrome (LS) patients have DNA mismatch repair deficiency and up to 80% lifetime risk of colorectal cancer (CRC). Screening of mutation carriers reduces CRC incidence and mortality. Selection for constitutional mutation testing relies on family history (Amsterdam and Bethesda Guidelines) and tumour-derived biomarkers. Initial biomarker analysis uses mismatch repair protein immunohistochemistry and microsatellite instability. Abnormalities in either identify mismatch repair deficiency but do not differentiate sporadic epigenetic defects, due to MLH1 promoter region methylation (13% of CRCs) from LS (4% of CRCs). A diagnostic biomarker capable of making this distinction would be valuable. This study compared two biomarkers in tumours with mismatch repair deficiency; quantification of methylation of the MLH1 promoter region using a novel assay and BRAF c.1799T>A, p.(Val600Glu) mutation status in the identification of constitutional mutations.

METHODS

Tumour DNA was extracted (formalin fixed, paraffin embedded, FFPE tissue) and pyrosequencing used to test for MLH1 promoter methylation and presence of the BRAF c.1799T>A, p.(Val600Glu) mutation 71 CRCs from individuals with pathogenic MLH1 mutations and 73 CRCs with sporadic MLH1 loss. Specificity and sensitivity was compared.

FINDINGSS

Unmethylated MLH1 promoter: sensitivity 94.4% (95% CI 86.2% to 98.4%), specificity 87.7% (95% CI 77.9% to 94.2%), Wild-type BRAF (codon 600): sensitivity 65.8% (95% CI 53.7% to 76.5%), specificity 98.6% (95% CI 92.4% to 100.0%) for the identification of those with pathogenic MLH1 mutations.

CONCLUSIONS

Quantitative MLH1 promoter region methylation using pyrosequencing is superior to BRAF codon 600 mutation status in identifying constitutional mutations in mismatch repair deficient tumours.

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.

Genetic predisposition to colorectal cancer: Where we stand and future perspectives

The development of colorectal cancer (CRC) can be influenced by genetic factors in both familial cases and sporadic cases. Familial CRC has been associated with genetic changes in high-, moderate- and low-penetrance susceptibility genes. However, despite the availability of current gene-identification techniques, the genetic causes of a considerable proportion of hereditary cases remain unknown. Genome-wide association studies of CRC have identified a number of common low-penetrance alleles associated with a slightly increased or decreased risk of CRC. The accumulation of low-risk variants may partly explain the familial risk of CRC, and some of these variants may modify the risk of cancer in patients with mutations in high-penetrance genes. Understanding the predisposition to develop CRC will require investigators to address the following challenges: the identification of genes that cause uncharacterized hereditary cases of CRC such as familial CRC type X and serrated polyposis; the classification of variants of unknown significance in known CRC-predisposing genes; and the identification of additional cancer risk modifiers that can be used to perform risk assessments for individual mutation carriers. We performed a comprehensive review of the genetically characterized and uncharacterized hereditary CRC syndromes and of low- and moderate-penetrance loci and variants identified through genome-wide association studies and candidate-gene approaches. Current challenges and future perspectives in the field of CRC predisposition are also discussed.

The genetic basis of Lynch syndrome and its implications for clinical practice and risk management

Lynch syndrome is the most common cause of hereditary colon cancer, and accounts for as much as 3% of all colon and endometrial cancers. The identification and management of individuals with Lynch syndrome have evolved over the past 20 years, yet the syndrome remains vastly underdiagnosed. It is important for clinicians to recognize individuals and families who are at risk in order to be able to manage them appropriately and reduce their morbidity and mortality from this condition. This review will touch on the history of Lynch syndrome, the current knowledge of genotype–phenotype correlations, the cancers associated with Lynch syndrome, and management of individuals who are gene carriers.

Cancer risk in Lynch Syndrome

Lynch Syndrome, or hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant cancer predisposition syndrome caused by inactivating mutations in DNA mismatch repair genes. It accounts for 2-4 % of all incident colorectal cancers. Mutation carriers are at risk of early onset colorectal cancer, endometrial cancer, and a spectrum of other tumours. Accurate estimation of cancer risk for mutation carriers is essential for counselling, and establishing appropriate screening guidelines. This study reviews the current data on cancer risk, and emerging risk reduction strategies.

Systematic review of the impact of registration and screening on colorectal cancer incidence and mortality in familial adenomatous polyposis and Lynch syndrome

BACKGROUND

The British Society of Gastroenterology recommends that all familial adenomatous polyposis (FAP) and Lynch syndrome (LS) families are screened in the context of a registry. This systematic review was performed to appraise the published evidence for registration and screening in relation to colorectal cancer (CRC) incidence and mortality.

METHODS

Five electronic databases were searched using a combination of medical subject heading terms and free-text keywords. Titles and abstracts were scrutinized by two independent reviewers. Inclusion criteria were English-language studies describing CRC incidence and/or mortality in patients with FAP or LS, with comparison of either: screened and unscreened patients, or time periods before and after establishment of the registry.

RESULTS

Of 4668 abstracts identified, 185 full-text articles were selected; 43 studies fulfilled the inclusion criteria. No randomized clinical trial evidence was identified. For FAP, 33 of 33 studies described a significant reduction of CRC incidence and mortality with registration and screening. For LS, nine of ten studies described a reduction of CRC incidence and mortality with registration and screening. Five studies (FAP, 2; LS, 3) provided evidence for complete prevention of CRC-related deaths during surveillance. Clinical and statistical heterogeneity prevented pooling of data for meta-analysis.

CONCLUSION

Studies consistently report that registration and screening result in a reduction of CRC incidence and mortality in patients with FAP and LS (level 2a evidence, grade B recommendation). Funding and managerial support for hereditary CRC registries should be made available.

Communication and technology in genetic counseling for familial cancer

When a cancer predisposing germline mutation is detected in an index case, the presence of the underlying syndrome is confirmed and the potential for predictive testing of at-risk relatives is established. However, the reporting of a positive family history does not routinely lead to communication of information about risk to close, much less distant relatives. This review summarizes information technology utilized to address penetration or 'reach' of knowledge of risk within extended families, including the use of telephone and video counseling to reach distant patients, and anticipate novel internet-based processes for communication between investigators and relatives.

BRAF V600E mutation analysis simplifies the testing algorithm for Lynch syndrome

OBJECTIVES

To evaluate our experience of adding reflex BRAF mutation analysis following mismatch repair (MMR) protein staining in the test algorithm for Lynch syndrome (LS), the most common inherited predisposition to colorectal cancer (CRC).

METHODS

Since January 1, 2009, BRAF V600E mutation analysis has been performed at our institution for all newly diagnosed CRCs with absent MLH1 and PMS2 proteins.

RESULTS

Ninety (22%) of 412 patients with CRC had at least 1 MMR absent (65 had MLH1 and PMS2 absent and 25 had other stain(s) absent). BRAF mutation was found in 36 (55%) of 65. Fifty-four (13%) of 412 patients required follow-up after addition of BRAF analysis compared with 90 who would have required follow-up without BRAF analysis.

CONCLUSIONS

The addition of reflex BRAF mutation testing in CRCs with absent MLH1 and PMS2 reduced the number of patient contacts by 40% and simplified the genetic testing for LS, leading to cost and time savings.