Adherence to cancer prevention guidelines and risk of breast cancer.

Healthy eating patterns and keeping physically active are potentially more important for chronic disease prevention than intake or exclusion of specific food items or nutrients. To this end, many health organizations routinely publish dietary and lifestyle recommendations aimed at preventing chronic disease. Using data from the Canadian National Breast Screening Study, we investigated the association between breast cancer risk and adherence to two sets of guidelines specific for cancer prevention, namely the American Cancer Society (ACS) Guidelines and the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) Recommendations. At baseline, 49,613 women completed dietary and lifestyle questionnaires and height and weight measurements were taken. During a mean follow-up of 16.6 years, 2,503 incident cases of breast cancer were ascertained. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association of meeting each guideline, and number of guidelines met, with breast cancer risk. The two sets of guidelines yielded similar results. Specifically, adherence to all six ACS guidelines was associated with a 31% reduction in breast cancer risk when compared to subjects adhering to at most one guideline (HR=0.69; 95% CI=0.49-0.97); similarly, adherence to six or seven of the WCRF/AICR guidelines was also associated with a 31% reduction in breast cancer risk (HR=0.69; 95% CI=0.47-1.00). Under either classification, meeting each additional guideline was associated with a 4-6% reduction in breast cancer risk. These results suggest that adherence to cancer prevention guidelines is associated with a reduced risk of breast cancer.