The power of a healthy lifestyle for cancer prevention:the example of colorectal cancer

Objective:We aimed to directly compare the estimated effects of adherence to a healthy lifestyle with those of risk predisposition according to known genetic variants affecting colorectal cancer(CRC)risk,to support effective risk communication for cancer prevention.Methods:A healthy lifestyle score(HLS)was derived from 5 lifestyle factors:smoking,alcohol consumption,diet,physical activity,and body adiposity.The association of lifestyle and polygenic risk score(PRS)(based on 140 CRC-associated risk loci)with CRC risk was assessed with multiple logistic regression and compared through the genetic risk equivalent(GRE),a novel approach providing an estimate of the effects of adherence to a healthy lifestyle in terms of percentile differences in PRS.Results:A higher HLS was associated with lower CRC risk(4,844 cases,3,964 controls).Those adhering to all 5 healthy lifestyle factors had a 62%(95%CI 54%-68%)lower CRC risk than those adhering to≤2 healthy lifestyle factors.The estimated effect of adherence to all 5 compared with≤2 healthy lifestyle factors was as strong as the effect of having a 79 percentile(GRE 79,95%CI 61-97)lower PRS.The association between a healthy lifestyle and CRC risk was independent of PRS level but was particularly pronounced among those with a family history of CRC in≥1 first-degree relative(P-interaction=0.0013).Conclusions:A healthy lifestyle was strongly inversely associated with CRC risk.The large GRE indicated that CRC risk determined by polygenic risk may be offset to a substantial extent by adherence to a healthy lifestyle.