BACKGROUND & AIMS:
The combined effects of healthy lifestyle factors on colorectal cancer (CRC) risk are unclear. We aimed to develop a healthy lifestyle score, to investigate the joint effects of modifiable lifestyle factors on reduction of CRC risk and determine whether associations differ with genetic risk.
We collected data from a large population-based case-control study in Germany and used multiple logistic regression analyses to examine associations between the healthy lifestyle score (derived from 5 modifiable lifestyle factors: smoking, alcohol consumption, diet, physical activity, and body fatness) and CRC risk. We created a genetic risk score, based on 53 risk variants, to investigate the association of the healthy lifestyle score and risk of CRC, stratified by genetic risk.
We included 4092 patients with CRC and 3032 individuals without CRC (controls) in our analysis. In adjusted models, compared with participants with 0 or 1 healthy lifestyle factor, participants with 2 (odds ratio [OR] 0.85; 95% confidence interval [CI] 0.67-1.06), 3 (OR 0.62; 95% CI 0.50-0.77), 4 (OR 0.53; 95% CI 0.42-0.66), or 5 (OR 0.33; 95% CI 0.26-0.43) healthy lifestyle factors had increasingly lower risks of CRC (P trend <.0001). We found no differences among subgroups stratified by genetic risk score, history of colonoscopy, or family history of CRC. Overall, 45% of CRC cases (95% CI 34%-53%) could be attributed to nonadherence to all 5 healthy lifestyle behaviors.
In a large population-based case-control study, we identified a combination of lifestyle factors that appears to reduce risk of CRC, regardless of the patient's genetic profile. These results reinforce the importance of primary prevention of CRC.