Adherence to the World Cancer Research Fund/American Institute for Cancer Research recommendations and breast cancer risk

The World Cancer Research Fund/American Association for Cancer Research (WCRF/AICR) has published eight nutrition‐related recommendations for the prevention of cancer. However, few prospective studies have examined these recommendations by breast cancer hormone receptor subtype and only one case–control study has included the dietary supplements recommendation in their evaluation. We investigated whether adherence to the WCRF/AICR cancer prevention recommendations was associated with breast cancer incidence, overall and by hormone receptor subtype, in the Swedish Mammography Cohort. Among 31,514 primarily postmenopausal women diet and lifestyle factors were assessed with a self‐administered food frequency questionnaire. A score was constructed based on adherence to the recommendations for body fatness, physical activity, energy density, plant foods, animal foods, alcoholic drinks and dietary supplements (score range 0–7). Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). During 15 years of follow‐up 1,388 cases of breast cancer were identified. Women who met six to seven recommendations had a 51% decreased risk of breast cancer compared to women meeting only zero to two recommendations (95% CI = 0.35–0.70). The association between each additional recommendation met and breast cancer risk was strongest for the ER‐positive/PR‐positive subtype (HR = 0.86; 95% CI = 0.79–0.94), while for the ER‐negative/PR‐negative subtype the individual recommendations regarding plant and animal foods were most strongly associated with reduced risk. Our findings support that adherence to the WCRF/AICR recommendations reduces breast cancer risk in a population of primarily postmenopausal women. Promoting these recommendations to the public could help reduce breast cancer incidence.