Diet Quality as Measured by the Healthy Eating Index 2015 and Oral and Pharyngeal Cancer Risk.

BACKGROUND: Alcohol and tobacco are the major risk factors for oral and pharyngeal cancer, but diet is likely to have a role, too. OBJECTIVE: The objective was to analyze the relationship between adherence to the 2015-2020 Dietary Guidelines for Americans (DGA), as measured by the Healthy Eating Index 2015 (HEI-2015), and oral and pharyngeal cancer risk. Moreover, this work aimed to quantify the number of avoidable cases under different scenarios of increased adherence to the DGA, with the use of the potential impact fraction. This estimates the proportion of cases that would occur if the distribution of the risk factor in the population followed an alternative distribution. DESIGN: A multicenter, case-control study was conducted in Italy between 1991 and 2009. Participants' usual diet for the 2 years preceding study enrolment was assessed using a food frequency questionnaire. PARTICIPANTS AND SETTING: Cases were 946 patients admitted to major hospitals with incident, histologically confirmed oral and pharyngeal cancer. Controls were 2,492 patients admitted to the same hospitals for acute non neoplastic conditions. MAIN OUTCOME MEASURES: The adherence to the DGA was assessed using the HEI-2015 score (range = 0 to 100), based on 13 components. The outcome was oral and pharyngeal cancer. STATISTICAL ANALYSES PERFORMED: Odds ratios and the corresponding 95% CIs were estimated using multiple logistic regression models adjusted for tobacco, alcohol, and other relevant covariates. The potential impact fraction was estimated under different scenarios of adherence to the DGA. RESULTS: In this Italian population the HEI-2015 score ranged from 33.4 to 97.5. A higher HEI-2015 score was associated with a lower risk of oral and pharyngeal cancer, with an odds ratio of 0.70 (95% CI 0.62 to 0.79) for a 10-point increment of the score. The estimated potential impact fraction was 64.8% under the maximum achievable reduction scenario, and it ranged from 9% to 27% following other more feasible scenarios. CONCLUSIONS: The HEI-2015 score was inversely related to oral and pharyngeal cancer risk in this Italian population. This analysis allowed for the estimation of the fraction of preventable cases, under different feasible scenarios. A share of 9% to 27% of avoidable cases of oral and pharyngeal cancer might be obtained across real-world scenarios of adherence to the DGA as measured by the HEI-2015 score.