Modulation of pancreatic carcinogenesis by antioxidants

Previously performed short-term (4-month) studies demonstrated that vitamin s C and E, beta-carotene and selenium modulate growth of early putative pre neoplastic acinar lesions induced in rat pancreas by azaserine. The present paper summarizes the results of long-term studies performed with azaserine -treated rats maintained on diets high in either beta-carotene, Vitamins C and E or selenium. It appeared that rats given a diet high in beta-carotene , vitamin C or selenium. but not Vitamin E, developed Fewer pancreatic tumo urs than controls. The chemopreventive effects of these micronutrients were . most pronounced when beta-carotene and/or selenium were given during the promotion phase of the carcinogenic process. Surprisingly, cell proliferati on in azaserine-induced preneoplastic acinar lesions was higher in rats giv en beta-carotene and/or selenium via the diet in comparison to controls. It is considered unlikely that any antioxidant alone can be associated with p rotection against cancer. It is concluded that dietary supplementation of c ombinations of antioxidants may have practical application in chemopreventi on of cancer. (C) 1999 Elsevier Science Lid. All rights reserved.