Although early detection of Lynch syndrome (LS) is important, a considerable proportion of patients with LS remains unrecognized. We aimed to study the yield of LS detection by routine molecular analyses in colorectal cancer (CRC) patients until 70 years of age. We prospectively included consecutive CRC patients ≤70 years. Tumour specimens were analysed for microsatellite instability (MSI), immunohistochemical mismatch-repair protein expression and MLH1-promoter methylation. Tumours were classified as either: (a) likely caused by LS; (b) sporadic microsatellite-unstable (MSI-H); or (c) microsatellite-stable (MSS). Predictors of LS were determined by multivariable logistic regression. A total of 1117 CRC patients (57% males, median age 61 years) were included. Fifty patients (4.5%, 95% CI 3.4-5.9) were likely to have LS, and 71 had a sporadic MSI-H tumour (6.4%, 95% CI 5.1-8.0). Thirty-five patients likely to have LS (70%) were aged > 50 years. A molecular profile compatible with LS was detected in 10% (15/144) of patients aged ≤50, in 4% (15/377) of those aged 51-60 and in 3% (20/596) of patients > 61 years. Compared to MSS cases, patients likely to have LS were significantly younger (OR 3.9, 95% CI 1.7-8.7) and more often had right-sided CRCs (OR 14, 95% CI 6.0-34). In conclusion, molecular screening for LS in CRC patients ≤70 years leads to identification of a molecular profile compatible with LS in 4.5% of patients, with most of them not fulfilling the age criterion (≤50 years) routinely used for LS assessment. Routine use of MSI testing may be considered in CRC patients up to the age of 70 years, with a central role for the pathologist in the selection of patients.

BackgroundLynch syndrome (LS) is associated with a high risk for colorectal cancer (CRC) and extracolonic malignancies, such as endometrial carcinoma (EC). The risk is dependent of the affected mismatch repair gene. The aim of the present study was to calculate the cumulative risk of LS related cancers in proven MLH1, MSH2 and MSH6 mutation carriers.MethodsThe studypopulation consisted out of 67 proven LS families. Clinical information including mutation status and tumour diagnosis was collected. Cumulative risks were calculated and compared using Kaplan Meier survival analysis.ResultsMSH6 mutation carriers, both males and females had the lowest risk for developing CRC at age 70 years, 54% and 30% respectively and the age of onset was delayed by 3-5 years in males. With respect to endometrial carcinoma, female MSH6 mutation carriers had the highest risk at age 70 years (61%) compared to MLH1 (25%) and MSH2 (49%). Also, the age of EC onset was delayed by 5-10 years in comparison with MLH1 and MSH2.ConclusionsAlthough the cumulative lifetime risk of LS related cancer is similar, MLH1, MSH2 and MSH6 mutations seem to cause distinguishable cancer risk profiles. Female MSH6 mutation carriers have a lower CRC risk and a higher risk for developing endometrial carcinoma. As a consequence, surveillance colonoscopy starting at age 30 years instead of 20-25 years is more suitable. Also, prophylactic hysterectomy may be more indicated in female MSH6 mutation carriers compared to MLH1 and MSH2 mutation carriers.

Objective To compare the sensitivity of autofluorescence endoscopy (AFE) and white light video endoscopy (WLE) for the detection of colorectal adenomas in high-risk patients belonging to Lynch syndrome (LS) or familial colorectal cancer (CRC) families. Methods This was a prospective single-centre study carried out in a tertiary referral centre. The subjects were 75 asymptomatic patients originating from LS or familial CRC families. Patients were examined with either WLE followed by AFE or AFE followed by WLE. Back-to-back colonoscopy was performed by two blinded endoscopists. All lesions were removed during the second endoscopic procedure. Lesions missed during the second procedure were identified and removed on third pass. The sensitivity calculations for colorectal adenomas were based on histology results. The main outcome measures were the difference in sensitivity between WLE and AFE for the detection of adenomas in patients with LS or familial CRC. Results At least one adenoma was detected in 41 (55%) patients. WLE identified adenomas in 28/41 patients and AFE in 37/41 patients, corresponding to a 32% increase. In total 95 adenomas were detected, 65 by WLE and 87 by AFE, resulting in a significantly higher sensitivity of AFE compared with WLE (92% vs 68%; p¼0.001). The additionally detected adenomas with AFE were significantly smaller than the adenomas detected by WLE (mean 3.0 mm vs 4.9 mm, p<0.01). Conclusions AFE improves the detection of colorectal adenomas in patients with LS or familial CRC. The results of this study suggest that AFE may be preferable for surveillance of these high-risk patients.

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There is a high incidence of MSH6 mutations in families tested for Lynch syndrome in a diagnostic setting. Many of these families remain underdiagnosed using the AC II. The rBG are more useful to select these families for further analysis. However, to optimise the detection of MSH6 families, MSI and IHC analysis should also be performed in families with clustering of late-onset endometrial carcinoma.