Inflammatory potential of diet and risk of oral and pharyngeal cancer in a large case-control study from Italy

Diet and inflammation have been suggested to be important risk factors for oral and pharyngeal cancer. We examined the association between dietary inflammatory index (DII) and oral and pharyngeal cancer in a large case-control study conducted between 1992 and 2009 in Italy. This study included 946 cases with incident, histologically confirmed oral and pharyngeal cancer, and 2492 controls hospitalized for acute non-neoplastic diseases. The DII was computed based on dietary intake assessed by a valid 78-item food frequency questionnaire and was adjusted for non-alcohol energy intake using the residual approach (E-DII). Logistic regression models were used to estimate odds ratios (ORs), and 95% confidence intervals (CIs), adjusted for age, sex, non-alcohol energy intake, study center, year of interview, education, body mass index, tobacco smoking, and alcohol drinking. Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of oral and pharyngeal cancer, the OR being 1.80 (95% CI 1.36-2.38) for the highest versus the lowest DII quartile and 1.17 (95% CI 1.10-1.25) for a one-unit increase (8% of the DII range). When stratified by selected covariates, a stronger association was observed among women (ORquartile4 v.1 3.30, 95% CI 1.95-5.57). We also observed stronger association for oral cancer subsite and a strong combined effect of higher DII and tobacco smoking or alcohol consumption on oral and pharyngeal cancer. These results indicate that the pro-inflammatory potential of the diet, as shown by higher DII scores, is associated with higher odds of oral and pharyngeal cancer.