Previous studies have shown that various dietary components may be implicated in the aetiology of prostate cancer, although the results remain equivocal. The possible relationship of inflammation derived from dietary exposures with prostate cancer risk has not been investigated. We examined the ability of a newly developed dietary inflammatory index (DII) to predict prostate cancer risk in a case-control study conducted in Italy between 1991 and 2002. A total of 1294 patients aged < 75 years with incident, histologically confirmed carcinoma of the prostate served as cases. A total of 1451 subjects aged < 75 years who were admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions served as controls. The DII was computed based on dietary intake assessed using a previously validated seventy-eight-item FFQ. Logistic regression models were used to estimate multivariable OR adjusted for age, study centre, years of education, social class, BMI, smoking status, family history of prostate cancer and total energy intake. Men with higher DII scores had a higher risk of prostate cancer when analysed using the DII as both continuous (OR 1.06, 95% CI 1.00, 1.13) and categorical, i.e., compared with men in the lowest quartile of the DII, men in the third and fourth quartiles were at elevated risk (OR(Quartile 3 v. 1) 1.32, 95% CI 1.03, 1.69 and OR(Quartile 4 v. 1) 1.33, 95% CI 1.01, 1.76; P trend= 0.04). These data suggest that a pro-inflammatory diet, as indicated by the increasing DII score, is a risk factor of prostate cancer in Italian men.
Keywords: Case–control studies; Diet; Dietary inflammatory index; Inflammation; Italy; Prostate cancer.