Inflammatory potential of diet and risk of laryngeal cancer in a case-control study from Italy

Besides tobacco and alcohol, diet and inflammation have been suggested to be important risk factors for laryngeal cancer. In this study, we examined the role of diet-associated inflammation, as estimated by dietary inflammatory index (DII) scores, in laryngeal cancer in a multicentre case-control study conducted between 1992 and 2000 in Italy. This study included 460 cases with incident, histologically confirmed laryngeal cancer, and 1,088 controls hospitalized for acute non-neoplastic diseases unrelated to tobacco and alcohol consumption. DII scores were computed from a reproducible and valid 78-item food-frequency questionnaire. Logistic regression models controlling for age, sex, study center, education, body mass index, tobacco smoking, alcohol drinking, and non-alcohol energy intake were used to estimate odds ratios (ORs) and the corresponding 95 % confidence intervals (CIs). Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of laryngeal cancer. The OR was 3.30 (95 % CI 2.06, 5.28; p for trend < 0.0001) for the highest versus the lowest DII quartile. When DII was considered as a continuous variable, the OR was 1.27 (95 % CI 1.15, 1.40) for a one-unit (9 % of the DII range) increase. Stratified analyses produced slightly stronger associations between DII and laryngeal cancer risk among Subjects < 60 years old (ORquartile4vs1 = 4.68), overweight subjects (ORQuartile4vs1 = 3.62), and among those with higher education (ORQuartile4vs1 = 3.92). We also observed a strong combined effect of higher DII and tobacco smoking or alcohol consumption on risk of laryngeal cancer. Compared with non-smokers having low DII scores, the OR was 6.64 for smokers with high DII scores. Likewise, compared with non/moderate drinkers with low DII, the OR was 5.82 for heavy drinkers with high DII. These results indicate that a pro-inflammatory diet is associated with increased risk of laryngeal cancer.