Diabetes risk reduction diet and the risk of breast cancer

Objective Diabetes and insulin levels may increase the risk of postmenopausal breast cancer. In the present investigation, we aimed at evaluating whether adherence to a diabetes risk reduction diet (DRRD) lowers the risk of breast cancer. Methods We used data from an Italian, multicentric case-control study (1991-1994) including 2569 incident histologically-confirmed breast cancer cases and 2588 hospital controls. A food frequency questionnaire collected subjects' usual diet. We derived a DRRD score on the basis of eight items: intake of cereal fiber, total fruit, coffee, polyunsaturated to saturated fats ratio and nuts (higher scores for higher intakes), and dietary glycemic index, red/processed meat and sugar-sweetened beverages/fruit juices (higher scores for lower intakes). The score theoretically ranged 8-37, with higher values indicating greater DRRD adherence. Odds ratios (ORs) of breast cancer according to the DRRD score were estimated using multiple logistic regression models. Results The DRRD score was inversely related to the risk of breast cancer. The ORs were 0.93 [95% confidence interval (CI), 0.89-0.98] for a three-point score increment and 0.76 (95% CI, 0.64-0.89) for the highest versus the lowest quartile (P for trend 0.001). Inverse associations were observed in subgroups of covariates. Conclusions Higher DRRD adherence may decrease the risk of breast cancer.