A population-based case-control study was conducted to examine the effect of ingestion of vitamin C, carotenoids and retinol on risk of pharyngeal cancer. Data were available from 166 cases of pharyngeal cancer or their next-of-kin, and from 547 controls similar in age and sex to the cases. Odds ratios (ORs) relating consumption of vitamin C, carotenoids and retinol from foods and vitamins C and A from supplements to risk of pharyngeal cancer were calculated using multiple logistic regression analysis. After adjustment for smoking and alcohol consumption, a significant increase in risk associated with low intake of vitamin C from foods was observed. Compared to the highest quartile, the OR for the lowest quartile of intake was 2.5 (95% confidence interval, 1.5-4.2). No overall effect of dietary carotenoid or retinol consumption was noted after adjustment for smoking and alcohol. Decreasing use of either vitamin C or vitamin A supplements was associated with increasing cancer risk among the case group as a whole. However, the effect of vitamin C supplement use was substantially lower when next-of-kin respondents were excluded from analysis. Also, the O R for use of vitamin A supplements is based on a very small number of cases reporting use, and must be viewed with caution. The results of our study suggest that intake of vitamin C may be protective against pharyngeal cancer, and are consistent with the results of previous studies which reported a decreased risk of pharyngeal cancer associated with intake of fruits and vegetables.
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