Dietary inflammatory index before diagnosis and survival in an Italian cohort of women with breast cancer

The dietary inflammatory index(TM) (DII) has been shown to correlate with concentrations of several inflammatory markers and a variety of chronic disease endpoints, including cancers of various anatomic sites. We investigated whether the DII was associated with the risk for death among women with breast cancer (BrCa). This retrospective cohort study included 1453 women with BrCa, diagnosed between 1990 and 1994, and previously enrolled in a case-control study in northern Italy. With a median follow-up of 12.6 years, we observed 503 deaths, among which 398 were due to BrCa. The usual diet was assessed at BrCa diagnosis using a validated FFQ. DII scores were calculated using thirty-one foods/nutrients. Hazard ratios (HR) of death from all causes or from BrCa, with corresponding 95 % CI, were calculated using the Cox models, adjusted for age at diagnosis, tumour stage, oestrogen/progesterone receptor status and other potential confounders. The median DII score of the study women was -1.23, with a relatively narrow range (interquartile range -2.24 to -0.11), indicating a mainly anti-inflammatory diet. There was no difference in survival according to DII tertiles, neither considering all-cause mortality (HRtertile III v. I 1.00; 95 % CI 0.78, 1.28) nor BrCa-specific mortality (HRtertile III v. I 0.97; 95 % CI 0.73, 1.27). Study findings did not suggest an association between the inflammatory potential of diet, measured by the DII, and the survival of BrCa women. However, further studies are needed in populations reporting higher DII scores and a broader range of variability in the scores.