Dietary Inflammatory Index and Risk of Bladder Cancer in a Large Italian Case-Control Study

To evaluate the association between diet in relation to its inflammatory property and bladder cancer (BC) risk . METHODS:In this study we explored the association between the dietary inflammatory index (DII) and BC risk in an Italian case-control study conducted between 2003 and 2014. Cases were 690 patients with incident, histologically confirmed cases of BC from 4 areas in Italy. Controls were 665 cancer free subjects admitted to the same network of hospitals as cases for a wide spectrum of acute, non-neoplastic conditions. The DII was computed based on dietary intake assessed using a reproducible and valid 80-item food frequency questionnaire. Odds ratios (OR) were estimated through logistic regression models adjusting for age, sex, total energy intake, and other recognised confounding factors. RESULTS:Quartile 4 (DII=0.41, 4.58; cases=207) had higher number of participants compared to quartile1 (DII=-5.94, -2.41; cases=124) Subjects in the highest quartile of DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of BC compared to subjects in the lowest quartile (i.e., with an anti-inflammatory diet) (ORQuartile4vs1= 1.97, 95% confidence interval, 1.28, 3.03; p-trend=0.003). Stratified analyses produced stronger associations between DII and BC risk among females (ORQuartile4vs1= 5.73; 95%CI=1.46, 22.44), older ≥65 years (ORQuartile4vs1= 2.45; 95%CI=1.38, 4.34), subjects with higher education ≥7 years (ORQuartile4vs1= 2.22; 95%CI=1.27, 3.88) and never smokers (ORQuartile4vs1= 4.04;95%CI=1.51, 10.80). CONCLUSION:A pro-inflammatory diet as indicated by higher DII scores is associated with increased BC risk.