Alcohol and colorectal cancer risk subclassified by mutational signatures of DNA mismatch repair deficiency

Background We examined whether the association between alcohol consumption and CRC incidence was stronger for tumors with higher contributions of defective MMR (dMMR)-related tumor mutational signatures (TMSs). Methods We used data from 227,916 men and women who participated in the Nurses’ Health Study (1980-2016), the Nurses’ Health Study II (1991-2017), and the Health Professionals Follow-up Study (1986-2016). Dietary data was collected every 4 years through validated food frequency questionnaires. Relative contributions of two dMMR-related TMSs (c-dMMRa/SBS15 and c-dMMRb/SBS26) were quantified using whole-exome sequencing data in a subset of incident CRC cases. Duplication-method Cox proportional hazards regression models were used to assess the association between alcohol consumption and the risk of CRC subtypes according to different contributions of the TMSs. All statistical tests were 2-sided. Results We documented 825 incident CRC cases with available TMS data over 26-36 years of follow-up. The association between alcohol consumption and CRC incidence was stronger for tumors with higher contributions of c-dMMRb/SBS26 (P-heterogeneitytrend = 0.02) compared to tumors with lower contributions of this TMS. Compared with nondrinkers, drinkers with ≥15 g/d of alcohol had a high risk of c-dMMRb/SBS26-high CRC [multivariable-adjusted HR: 2.43 (95% CI: 1.55-3.82)], but not c-dMMRb/SBS26-low CRC [0.86 (95% CI: 0.57-1.28)] or c-dMMRb/SBS26-moderate CRC [1.14 (95% CI: 0.76-1.71)]. No significant differential associations were observed for c-dMMRa/SBS15 (P-heterogeneitytrend = 0.41). Conclusions High alcohol consumption was associated with an increased incidence of CRC containing higher contributions of c-dMMRb/SBS26, suggesting that alcohol consumption may be involved in colorectal carcinogenesis through the DNA mismatch repair pathway.