Selected micronutrients and oral and pharyngeal cancer

The relation between selected micronutrients and oral and pharyngeal cancer risk was investigated using data from a case-control study conducted betwe en January 1992 and November 1997 in Italy and Switzerland. Cases were 754 incident, histologically confirmed oral cancers (344 of the oral cavity and 410 of the pharynx) admitted to the major teaching and general hospitals i n the study areas. Controls were 1,775 subjects with no history of cancer a dmitted to hospitals in the same catchment areas for acute, non-neoplastic diseases. Dietary habits were investigated using a validated food-frequency questionnaire. Odds ratios (ORs) were computed after allowance for age, se x, center, education, occupation, body mass index, smoking and drinking hab its and non-alcohol energy intake. Micronutrients were analyzed both as con tinuous variables and in quintiles. in the former case, the unit was set to 1 SD of the distribution of controls. ORs for the continuous analysis were 0.95 for retinol, 0.61 for carotene, 0.91 for lycopene, 0.83 for vitamin D , 0.74 for vitamin E, 0.63 for vitamin C, 0.82 for thiamine, 0.87 for ribof lavin, 0.59 for vitamin B-6, 0.61 for folic acid, 0.62 for niacin, 0.91 for calcium, 0.88 for phosphorus, 0.65 for potassium, 0.82 for iron, 0.67 for non-alcohol iron and 0.89 for zinc; the 95% confidence interval excluded on e for carotene, vitamin C and E, thiamine, vitamin B-6, folic acid, niacin, potassium and iron. ORs were similar for the 2 sexes and in strata of age. When the combined intake of vitamins C and E and carotene was considered, the protective effect of each nutrient was more marked or restricted to sub jects with low intake of the other 2. The association with vitamin C and ca rotene was independent of smoking and drinking habits, while that with vita min E was less evident in those heavily exposed to alcohol or tobacco. In g eneral, the more a micronutrient was correlated to total vegetable and frui t intake, the stronger was its protective effect against oral cancer. int. J. Cancer 86:122-127, 2000. (C) 2000 Wiley-Liss, Inc.