Relationship of dietary vitamin A and ascorbic acid intake to the risk for cancers of the lung, bladder, and prostate in Hawaii.

This report presents preliminary findings from 3 case-control studies in Hawaii in which we are examining the relationship of dietary vitamin A and ascorbic acid intake to the risk for cancers of the lung, bladder, and prostate. All 3 studies involved home interviews of cancer patients and neighborhood controls and use of quantitative dietary history method. In the lung cancer study, we found an inverse dose-response effect for total vitamin A intake in males only, with an odds ratio of 1.8 (P less than .05) for the lowest intake quartile relative to the highest; we found no association for ascorbic acid. In the bladder cancer study, we found lower (but not statistically significant) mean intakes of both vitamins in patients compared with controls, with the effect stronger for ascorbic acid. In the prostate cancer study, no effect was detected for total vitamin A or ascorbic acid in men less than 70 years old, but a direct association of vitamin A only with a dose-response gradient was found for men 70 years or older (odds ratio = 1.87; P less than .05, for the highest relative to the lowest intake quartile). Our findings at present indicate that vitamin A has a protective effect against lung and bladder cancers but not against prostate cancer and that ascorbic acid has a protective effect against bladder cancer as well. In our later analyses, we will examine the possibility that the effects of vitamin A vary with histologic type and that this may account for the lack of an association with lung cancer in women.