Prospective study of dietary inflammatory index and risk of breast cancer in Swedish women

BACKGROUND: The role of diet in breast cancer (BrCa) aetiology has been studied widely. Although the results are inconsistent, dietary components have been implicated through their effects on inflammation. We examined the association between a dietary inflammatory index (DII) and BrCa incidence in the Swedish Women's Lifestyle Study. METHODS: The DII was computed at baseline from a validated 80-item food frequency questionnaire in a cohort of 49 258 women, among whom 1895 incident BrCa cases were identified through linkage with the National Cancer Registry through 2011. We used multivariable Cox proportional models to estimate hazard ratios (HR). RESULTS: Positive associations were observed between DII and BrCa (HR(DII quartile 4 vs 1)=1.18; 95% CI: 1.00, 1.39), with somewhat stronger associations in postmenopausal women (HR(DII quartile 4 vs 1)=1.22; 95% CI: 1.01, 1.46). CONCLUSIONS: A proinflammatory diet appears to increase the risk of developing BrCa, especially in postmenopausal women.