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 OR 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.