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Evidence of associations between single nutrients and head and neck cancer (HNC) is still more limited and less consistent than that for fruit and vegetables. However, clarification of the protective mechanisms of fruit and vegetables is important to our understanding of HNC etiology. We investigated the association between vitamin C intake from natural sources and cancer of the oral cavity/pharynx and larynx using individual-level pooled data from ten case-control studies (5,959 cases and 12,248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium. After harmonization of study-specific exposure information via the residual method, adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using unconditional multiple logistic regression models on quintile categories of 'non-alcohol energy-adjusted' vitamin C intake. In the presence of heterogeneity of the estimated ORs among studies, we derived those estimates from generalized linear mixed models. Higher intakes of vitamin C were inversely related to oral and pharyngeal (OR = 0.54, 95% CI: 0.45-0.65, for the fifth quintile category versus the first one, p for trend<0.001) and laryngeal cancers (OR = 0.52, 95% CI: 0.40-0.68, p for trend = 0.006), although in the presence of heterogeneity among studies for both sites. Inverse associations were consistently observed for the anatomical subsites of oral and pharyngeal cancer, and across strata of age, sex, education, body mass index, tobacco, and alcohol, for both cancer sites. The inverse association of vitamin C intake from foods with HNC may reflect a protective effect on these cancers; however, we cannot rule out other explanations., (© 2014 UICC.)

Data from a series of case-control studies, conducted in Italy and Switzerland between 1991 and 2001, have been analyzed to evaluate the role of n-3 polyunsaturated fatty acid (PUFA) intake in the etiology of cancer of oral cavity and pharynx (736 cases, 1772 controls), esophagus (395 cases, 1066 controls), large bowel (1394 colon, 886 rectum, 4765 controls), breast (2900 cases, 3122 controls) and ovary (1031 cases, 2411 controls). Controls were patients admitted to hospital for acute, non-neoplastic conditions, unrelated to modifications in diet. The multivariate odds ratios (OR) for the highest quintile of n-3 PUFAs compared to the lowest one were 0.5 for oral and pharyngeal cancer, 0.5 for oesophageal cancer, 0.7 for colon cancer, 0.8 for rectal and breast cancer and 0.6 for ovarian cancer; the estimates and the trends in risk were significant for all cancer sites, excluding rectal and breast cancer. The estimates for an increase in n-3 PUFAs of 1 g/week were 0.70 for oral and pharyngeal cancer, 0.71 for oesophageal, 0.88 for colon, 0.91 for rectal, 0.90 for breast and 0.85 for ovarian cancer. All the estimates were statistically significant, excluding that for rectal cancer, and consistent across strata of age and gender. These results suggest that n-3 PUFAs decrease the risk of several cancers., (Copyright 2003 Wiley-Liss, Inc.)

The relation between selected micronutrients and oral and pharyngeal cancer risk was investigated using data from a case-control study conducted between 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 in the study areas. Controls were 1,775 subjects with no history of cancer admitted 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, sex, center, education, occupation, body mass index, smoking and drinking habits and non-alcohol energy intake. Micronutrients were analyzed both as continuous 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 riboflavin, 0.59 for vitamin B6, 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 one for carotene, vitamin C and E, thiamine, vitamin B6, 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 subjects with low intake of the other 2. The association with vitamin C and carotene was independent of smoking and drinking habits, while that with vitamin E was less evident in those heavily exposed to alcohol or tobacco. In general, the more a micronutrient was correlated to total vegetable and fruit intake, the stronger was its protective effect against oral cancer.