Celine H. Leenen

Prospective evaluation of molecular screening for Lynch syndrome in patients with endometrial cancer ≤70 years

OBJECTIVE Lynch syndrome (LS) is a hereditary syndrome that predisposes to multiple malignancies including endometrial cancer (EC). We aimed to evaluate a diagnostic strategy for LS based on routine analysis of microsatellite instability (MSI) and immunohistochemical (IHC) staining for mismatch repair (MMR) proteins in tumour tissue of all newly diagnosed EC patients ≤ 70 years. METHODS Consecutive EC patients ≤ 70 years were included prospectively in eight Dutch centres. EC specimens were analysed for MSI, IHC of four MMR proteins, MMR gene methylation status and BRAF-mutations. tumours were classified as; 1) likely to be caused by LS, 2) sporadic MSI-H, or 3) microsatellite stable (MSS). RESULTS Tumour specimens of 179 patients (median age 61 years, IQR 57-66) were analysed. In our study 92% of included patients were over 50 years of age. Eleven EC patients were found likely to have LS (6%; 95% CI 3-11%), including 1 patient suspected of an MLH1, 2 of an MSH2, 6 of an MSH6 and 2 of a PMS2 gene defect. Germline mutation analyses revealed 7 MMR gene germline mutations. Ten patients likely to have LS (92%) were older than 50 years. In addition, 31 sporadic MSI-H tumours with MLH1 promoter hypermethylation (17%; 95% CI 13-24%) were identified. CONCLUSIONS Molecular screening for LS in patients with EC diagnosed ≤ 70 years, leads to identification of a profile likely to have LS in 6% of cases. New screening guidelines for LS are needed, including recommendations for EC patients older than 50 years of age.

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. Copyright

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

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. Copyright

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.

Su1818 Barriers to Genetic Testing for Lynch Syndrome

Background: The success of pancreatic cancer (PC) surveillance depends to a large extent on the commitment of participants to adhere to the repeated follow-up investigations. Though the results of our recently conducted retrospective study showed that the burden of PC surveillance is acceptable, a prospective assessment was warranted to document the mental and psychological impact of PC screening. We aimed to investigate possible changes in cancer worries and levels of anxiety and depression in high-risk individuals participating in a PC surveillance program. Methods Eligible for this prospective questionnaire study were high-risk individuals participating in our multicenter nationwide endoscopic ultrasound (EUS)-MRI-based PC-surveillance study. High-risk individuals were those with a strong family history of PC or carriers of PC-prone gene mutations. Questionnaires, administered both before (pretest) and after (posttest) the baseline PC screening investigations, assessed concerns about developing cancer (CancerWorry Scale), and levels of anxiety and depression (Hospital Anxiety and Depression scale). Results Of the 54 high-risk individuals, 47 (87%) completed both the pretest and posttest questionnaires (38% male, mean age= 52 yr., range 20-74 yrs.). Of these, 44 participated in the PC screening and 3 declined. All participants underwent both EUS and MRI. Prior to undergoing PC screening, 36% of the participants reported being fearful about undergoing EUS, whereas 5% was fearful about the MRI. After screening, 2.3% of all participants feared the next EUS (p<.001) and 2.3% the next MRI. The mean level of depression was significantly higher prior to screening as compared to after screening (p<.001). However, the number of participants with clinical levels of anxiety and/ or depression was low (n=5) and remained stable over time. Prior to, as well as after screening the most frequently reported worries were about the possibility of developing cancer themselves (29% at both time points) and the chance that relatives would develop cancer (19% and 21%, respectively). The 3 individuals who did not undergo screening indicated that they were not very fearful of the MRI or EUS. They also had low levels of anxiety, depression and cancer worries. Conclusion: The results of this prospective study indicate that: (1) the expected burden of EUS is higher than the actual experienced burden; and that (2) mean levels of anxiety, depression and cancer worries are not significantly influenced by participating in the PC screening program. This finding is of great importance for this group that is at high risk of developing pancreatic cancer and might benefit from participation in a life-long repeated PC surveillance program.