Adherence to the World Cancer Research Fund/American Institute for Cancer Research 2018 Recommendations for Cancer Prevention and Risk of Colorectal Cancer

Background: The World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) 2018 diet, nutrition, and physical activity recommendations aim to reduce cancer risk. We examined adherence to the WCRF/AICR recommendations and colorectal cancer risk in two prospective cohorts. Methods: We followed 68,977 women in the Nurses' Health Study and 45,442 men in the Health Professionals Follow-up Study from 1986 until 2012. We created cumulatively averaged WCRF/AICR scores using updated diet, adiposity, and physical activity data from questionnaires, and used Cox regression to estimate sex-specific HRs and 95% confidence intervals (CI) for incident colorectal cancer. Results: We documented 2,449 colorectal cancer cases. Men in the highest quintile of the WCRF/AICR lifestyle score had a lower risk of colorectal cancer compared with those in the lowest quintile (HRQ5vsQ1 = 0,64; 95% CI, 0.52-0.77). The result was weaker in women (HRQ5vsQ1 = 0.86; 95% CI, 0.72-1.02; P-heterogeneity by sex = 0.006). When analyzing the diet recommendations alone, we similarly observed stronger inverse associations in men (HRQ5vsQ1 = 0.74; 95% CI, 0.61-0.90) compared with women (HRQ5vsQ1- 0.93; 95% CI, 0.77-1.12; P-heterogeneity by sex = 0.06). In men, the lifestyle score was more strongly inversely associated with risk of distal colon cancer compared with proximal colon or rectal cancer (P-common effects = 0.03); we did not observe significant differences between anatomic locations in women. Conclusions: The 2018 WCRF/AICR cancer prevention recommendations are associated with lower colorectal cancer risk in men, with weaker results in women. Impact: Consideration of adiposity and physical activity in conjunction with diet is important for colorectal cancer prevention.