Dietary inflammatory index and cancer risk in the elderly: A pooled-analysis of Italian case-control studies

The aim of this study was to evaluate whether the association between the inflammatory potential of one's diet and cancer risk varies across age groups in a population characterized by widespread use of the Mediterranean diet.

We analyzed data from a network of case-control studies conducted in Italy between 1991 and 2014. The studies included cancers of the oral cavity (n = 509), pharynx (n = 436), nasopharynx (n = 198), larynx (n = 459), esophagus (n = 304), stomach (n = 230), colon (n = 1225), rectum (n = 728), liver (n = 184), pancreas (n = 326), breast (n = 2569), endometrium (n = 454), ovary (n = 1031), prostate (n = 1294), kidney (n = 767), and bladder (n = 690). Controls were 13 563 patients hospitalized for acute, non-neoplastic conditions. Dietary inflammatory index (DII) scores were computed based on 31 food parameters assessed using a reproducible and validated food frequency questionnaire. Odds ratios were estimated through logistic regression models adjusting for recognized confounding factors.

The DII increased with age, with lower scores among men than women, in individuals located in northern rather than in central or southern Italy, and in controls more than in cancer cases. After adjustment for cancer-specific potential confounders, an increasing DII score was directly associated with cancer risk for all considered cancer sites, except for liver and endometrium. Although the DII level varied across age groups, no heterogeneity in cancer risk emerged for any of the considered cancer sites.

In the Italian population, DII scores were higher in elderly than in middle-aged individuals. Although not directly affecting cancer risk, this finding may have important implications for the older population because elevated DII scores, indicating a proinflammatory diet, also have been associated with frailty.