Micronutrients and laryngeal cancer risk in Italy and Switzerland: a case-control study

Objective: To investigate the relation between various micronutrients and laryngeal cancer risk. Methods: A case-control study was conducted in Italy and Switzerland between 1992 and 2000. Cases were 527 patients with incident cancer of larynx, admitted to the major teaching and general hospitals of the study areas. Controls were 1297 subjects admitted for acute, non-neoplastic diseases to the same network of hospitals. Dietary habits were assessed using a validated food-frequency questionnaire. Odds ratios (OR) and their corresponding 95% confidence intervals (CI) were computed using multiple logistic regression. Results: Significant inverse relations emerged between laryngeal cancer risk and intake of vitamin C (OR = 0.2, for the highest versus the lowest intake quintile; 95% CI: 0.2-0.4), beta-carotene (OR = 0.2; 95% CI: 0.2-0.4), alpha-carotene (OR = 0.3; 95% CI: 0.2-0.5), lutein/zeaxanthin (OR = 0.4; 95% CI: 0.3 - 0.6), vitamin E (OR = 0.4; 95% CI: 0.3 0.6), beta-criptoxanthin (OR = 0.4; 95% CI: 0.2-0.5), folic acid (OR = 0.4; 95% CI: 0.2 - 0.6), thiamin (OR = 0.4; 95% CI: 0.3 - 0.6), glutathione (OR = 0.5; 95% CI: 0.4-0.8), reduced glutathione (OR = 0.6; 95% CI: 0.4-0.8), vitamin B6 (OR = 0.6; 95% CI: 0.4 - 0.9) and potassium(OR = 0.6; 95% CI: 0.4-0.9). Direct associations were found with zinc (OR = 1.5; 95% CI: 1.0 - 2.2) and vitamin D (OR = 1.8; 95% CI: 1.2-2.6). Combining low intakes of vitamin C, carotene, vitamin E, and folate with heavy smoking and drinking led to ORs between 80 and 170. Conclusions: This study provides further support that, independently from smoking and alcohol consumption, the intake of several micronutrients, including selected antioxidants, is inversely related to laryngeal cancer risk.