Adherence to the World Cancer Research Fund/American Institute for Cancer Research Cancer Prevention Recommendations and Colorectal Cancer Survival

Background: Patients with cancer are recommended to follow cancer prevention guidelines due to inadequate evidence for specific recommendations for cancer survivors. Methods: We examined whether diet and lifestyle scores measuring adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention guidelines were associated with colorectal cancer-specific and overall mortality among 1,491 patients with colorectal cancer in two prospective cohorts. Cox proportional hazards regression models were used to calculate the multivariable-adjusted HRs and 95% confidence intervals (CI). Results: During a median follow-up of 7.92 years, there were 641 deaths (179 colorectal cancer-specific deaths). Patients in the highest quartile of the post-diagnostic WCRF/AICR lifestyle score including diet, body mass index (BMI), and physical activity had a 24% lower risk (HR = 0.76, 95% CI: 0.49-1.18) of colorectal cancer-specific mortality and a 37% lower risk (HR = 0.63, 95% CI: 0.50-0.78) of overall mortality compared with the lowest quartile. When BMI was not included in the lifestyle score due to potential disease-related weight loss, stronger inverse associations were observed for both colorectal cancer-specific and overall mortality for the same comparison (colorectal cancer-specific: HR = 0.50, 95% CI: 0.32-0.79; overall: HR = 0.59, 95% CI: 0.47-0.75). The post-diagnostic WCRF/AICR diet score was not statistically significantly associated with either colorectal cancer-specific or overall mortality. Conclusions: Greater adherence to the WCRF/AICR cancer prevention recommendations was associated with improved survival in patients with colorectal cancer. Impact: This study provides support for patients with colorectal cancer to follow cancer prevention recommendations after diagnosis. Future studies on cancer survivors will continue to contribute to evidence-based diet and lifestyle recommendations for patients with cancer.