Dietary Inflammatory Index and Odds of Breast Cancer in a Case-Control Study from Iran

Chronic inflammation is implicated in breast cancer (BrCa) development; however, studies on the association of the inflammatory potential of diet and breast cancer have produced conflicting results. With this as background, we investigated the association between dietary inflammatory index (DII (R)) scores and BrCa risk in an Iranian case-control study. In this study, 136 newly diagnosed breast cancer patients and 272 hospitalized controls were recruited using convenience sampling. DII scores were computed from dietary intake data collected through a validated food frequency questionnaire (FFQ). Adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between the DII and BrCa risk were estimated by logistic regression. After controlling for multiple potential confounders, a significantly increased BrCa odds was observed in the highest quartile of DII score compared to the lowest quartile (ORquartile 4 vs. 1=2.64, 95% CI: 1.12-6.25; P-trend=0.01). In subanalysis based on menopausal status, a positive association was observed between the DII and BrCa risk among premenopausal women (ORquartile 4 vs. 1=5.51, 95% CI: 1.45-20.93; P-trend=0.005); however, no association was detected in postmenopausal women. Our findings suggest that more proinflammatory diets, indicated by higher DII scores, may increase the odds of BrCa, especially among premenopausal women.