Cancer risks for MSH6 pathogenic variant carriers

IntroductionLynch syndrome (LS) is a hereditary cancer syndrome caused by (likely) pathogenic variants (LP/P) in DNA mismatch repair genes, including MSH6. It is associated with elevated lifetime risks for colorectal cancer (CRC), endometrial cancer (EC), and other malignancies. However, cancer risks specific to MSH6-associated LS, particularly for non-colorectal cancers, remain poorly defined. This study aims to provide refined cancer risk estimates for individuals with MSH6 LP/P. MethodsWe conducted a retrospective cohort study of 360 families with 1117 known MSH6 LP/P carriers identified in the Netherlands between 1995 and 2020. Pedigree data were collected from multiple clinical centers, and cancer diagnoses were confirmed through medical records. Age- and sex-specific hazard ratios (HRs) and cumulative risks (CRs) were estimated using segregation analysis, appropriately adjusted for ascertainment. ResultsCR by age 80 for MSH6 LP/P carriers were 36% in males (95% CI:25-48%) and 21% in females (95% CI 13-32%) for CRC, and 23% in females (95% CI:15-43%) for EC. Elevated risks were observed for ovarian cancer (OC) (6.4%, 95% CI:3-14.8%; HR 5.58, p=0.00037), urinary tract cancers (10.1% in males, 4.1% in females; HR 2.52, p=0.012), and biliary tract cancers (4.9% in males, 4.2% in females; HR 2.76, p=0.031). No increased risks were identified for prostate or breast cancer. ConclusionThis study refines cancer risk estimates for MSH6 LP/P carriers, suggesting the need for delayed CRC screening in males and females and proactive discussions regarding prophylactic surgery for females to address elevated risks for EC and OC.