Energy balance-related factors and risk of colorectal cancer based on KRAS , PIK3CA , and BRAF mutations and MMR status

Introduction KRAS mutations ( KRAS mut ), PIK3CA mut , BRAF mut , and mismatch repair deficiency (dMMR) have been associated with the Warburg-effect. We previously observed differential associations between energy balance-related factors (BMI, clothing-size, physical activity) and colorectal cancer (CRC) subtypes based on the Warburg-effect. We now investigated whether associations between energy balance-related factors and risk of CRC differ between subgroups based on mutation and MMR status. Methods Information on molecular features was available for 2349 incident CRC cases within the Netherlands Cohort Study (NLCS), with complete covariate data available for 1934 cases and 3911 subcohort members. Multivariable-adjusted Cox-regression was used to estimate associations of energy balance-related factors with risk of CRC based on individual molecular features ( KRAS mut ; PIK3CA mut ; BRAF mut ; dMMR) and combinations thereof (all-wild-type + MMR-proficient (pMMR); any-mutation/dMMR). Results In men, BMI and clothing-size were positively associated with risk of colon, but not rectal cancer, regardless of molecular features subgroups; the strongest associations were observed for PIK3CA mut colon cancer. In women, however, BMI and clothing-size were only associated with risk of KRAS mut colon cancer ( p -heterogeneity KRAS mut versus all-wild-type+pMMR = 0.008). Inverse associations of non-occupational physical activity with risk of colon cancer were strongest for any-mutation/dMMR tumors in men and women, and specifically for PIK3CA mut tumors in women. Occupational physical activity was inversely associated with both combination subgroups of colon cancer in men. Conclusion In men, associations did not vary according to molecular features. In women, a role of KRAS mutations in the etiological pathway between adiposity and colon cancer is suggested, and of PIK3CA mutations between physical activity and colon cancer.