Association between Dietary Inflammatory Potential and Breast Cancer Incidence and Mortality: Results from the Women's Health Initiative

Abstract

ObjectiveWe examined the association between the dietary inflammatory index (DII) and risk of invasive breast cancer (BC) incidence and mortality in postmenopausal women.MethodsThe DII was calculated from a baseline food frequency questionnaire administered to 117,510 women at risk of BC in the Women's Health Initiative (WHI) Observational Study and Clinical Trials, among whom 5,889 later developed BC and 406 died during an average of 12.3 years follow‐up. We used Cox regression to estimate hazard ratios and 95% CI by DII tertiles for invasive BC and its subtypes, and for BC mortality. The lowest tertile (representing the most anti‐inflammatory diet) was the referent.ResultsThe DII was not associated with incident BC overall, but was positively associated with risk of HER2+ BC (HRT3vsT1, 1.31; 95%CI, 1.06, 1.61;Ptrend=0.01). We observed a higher risk for BC mortality with intake of more pro‐inflammatory diets, controlling for age and total energy intake (HRT3vsT1, 1.48; 95%CI, 1.15, 1.91;Ptrend, 0.002), which was attenuated in fully‐adjusted models (HRT3vsT1, 1.30; 95%CI, 0.99, 1.71;Ptrend, 0.04).ConclusionFuture research is needed to confirm these differential findings by BC subtype and to examine whether reducing dietary inflammatory potential may improve BC survival. Funding: Prevent Cancer Foundation grant to SES & JZ, NCI grants to FKT & JRH. NHLBI funded the WHI.