Nutrient-based dietary patterns and the risk of oral and pharyngeal cancer

The relationship between diet and oral and pharyngeal cancer has been rarely addressed considering dietary patterns. We examined this issue using data from a case-control study carried out between 1992 and 2005. Cases were 804 incident oral cancers hospitalized in 3 Italian areas. Controls were 2080 subjects hospitalized for non-neoplastic diseases. Dietary habits were investigated through a validated 78-item food-frequency questionnaire. Overall and individual measures of sampling adequacy were calculated to assess if applying a factor analysis or not. A posteriori dietary patterns were identified through a principal component factor analysis performed on a selected set of 29 nutrients. The internal reproducibility, robustness and reliability of the identified patterns were evaluated. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional multiple logistic regression models on quintiles of factor scores. The measures of sampling adequacy were generally satisfactory. We identified five major dietary patterns named Animal products, Starch-rich, Vitamins and fiber, Unsaturated fats and Retinol and niacin. The Animal products pattern was positively associated with oral cancer (OR=1.56, 95% CI: 1.13-2.15 for the highest vs. the lowest score quintile), whereas the Starch-rich pattern (OR=0.71, 95% CI: 0.50-0.99), the Vitamins and fiber pattern (OR=0.47, 95% CI: 0.34-0.65) and the Unsaturated fats pattern (OR=0.63, 95% CI: 0.45-0.86) were inversely associated with it. These findings confirm that diets rich in animal origin and animal fats are positively, and those rich in fruit and vegetables, and vegetable fats inversely related to oral and pharyngeal cancer risk.