Inflammatory Potential of the Diet and Risk of Breast Cancer in the European Investigation Into Cancer and Nutrition (EPIC) Study

We aimed to evaluate the association between the inflammatory potential of the diet and the risk of breast cancer overall, by tumour subtypes and according to menopausal status. A total of 318,686 women from the European Prospective Investigation into Cancer and Nutrition (EPIC) were followed for 14 years, among whom 13,246 incident breast cancer cases were identified. Dietary inflammatory potential was characterized by an inflammatory score of the diet (ISD). Multivariable Cox regression models were used to assess the potential effect of the ISD on the risk of overall breast cancer and by tumour subtypes by means of the hazard ratio (HR) and 95% confidence interval (95% CI). ISD was positively associated with breast cancer risk. Adjusted for relevant confounders, each increase of one standard deviation (1-SD) of the score increased by 4% the risk of breast cancer (HR 1.04; 95% CI: 1.01–1.07). Women in the highest quintile of the ISD (indicating most pro-inflammatory diet) had a 12% increase in risk compared with those in the lowest quintile (HR 1.12; 95% CI: 1.04–1.21) with a significant trend. The association was more pronounced among premenopausal women, with increased risk of 8% for 1-SD increase of the score (HR 1.08; 95% CI: 1.01–1.14). The pattern of the association was quite homogeneous by tumour subtypes based on hormone receptor status. There were no significant interactions between ISD and body mass index, physical activity or alcohol consumption. Women consuming more pro-inflammatory diets as measured by ISD are at increased risk for breast cancer, especially premenopausal women. Instituto de Salud Carlos III (Co-funded by European Regional Development Fund [ERDF], a way to build Europe). Instituto de Salud Carlos III (Co-funded by European Social Fund. ESF investing in your future). The coordination of EPIC is financially supported by International Agency for Research on Cancer (IARC) and also by the Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London which has additional infrastructure support provided by the NIHR Imperial Biomedical Research Centre (BRC).