In vivo, in vitro, prospective, and retrospective epidemiologic inquiries have suggested that retinoids inhibit cancer, and fats have been hypothesized to enhance and ascorbic acid to reduce cancer risk. Comparison of 260 patients from Buffalo with cancer of the prostate gland was made with two different control series of similar size and age distribution. Regardless of the control group, risk of prostate cancer gained with increases in ingestion of retinoids, animal fats, and vitamin C. These anomalous findings may be due to peculiarities in methodology. From the possible specificity of effect of the nutrients studied, as shown in experimental animals and in vitro, a hypothesis could be made that a substance like vitamin A or C, which may inhibit certain cancers, also may enhance risk of other cancer types or have neither effect.