Nutritional factors in lung, colon, and prostate carcinogenesis in animal models.

Dietary factors are now considered to be among the most important environmental risk determinants for cancer. In addition to epidemiological studies, experimental animal studies are an important tool to investigate dietary modulation in carcinogenesis. Results of recent experimental studies on the effect of some nutrients indicate that vitamin A did show an inverse relation with the occurrence of preneoplastic respiratory lesions but not with respiratory tract tumors in benzo[a]pyrene-induced respiratory carcinogenesis. Dietary fat increases respiratory tract tumors and preneoplastic lesions. In colon carcinogenesis, a fat-fiber interrelation was noticed in 1,2-dimethyl-hydrazine- and N-methyl-N'-nitro-N-nitrosoguanidine-induced tumors. Preliminary results in prostate carcinogenesis indicate that dietary fat did not influence the incidence of prostate cancer in a recently developed rat model. Some possible mechanisms in colon and prostate carcinogenesis are discussed.