EFFECT OF BLACK TEA ON AZOXYMETHANE-INDUCED COLON-CANCER

Two sets of experiments on the role of tea in azoxymethane (AOM) induc ed colon cancer were performed, The first test involved male F344 rats given 1.25% solutions of black tea beginning at 5 weeks of age and en ding at 51 days of age, At 6 and 7 weeks of age, they received 15 mg/k g AOM and were held for 50 weeks, Another group received the AOM dosag e at 6 and 7 weeks and were placed on the tea solutions 2 days after t he last AOM dosage, at 51 days of age, and held for the 50-week period , The end point was the occurrence and multiplicity of colon cancer, c lassified as in situ, exophytic, invasive and Peyer's patch carcinomas , Tea failed to affect the incidence and multiplicity of colon cancers when given during or after the AOM administration, but tea after AOM increased the multiplicity of exophytic carcinomas, In a second series of tests, solutions of 0.6, 1.25, 1.75 or 2.5 % tea were given, begin ning 1 week prior to the two AOM doses and extending for 42 weeks, Als o, one group received 1.25% tea and 1.85% whole milk. The incidence of exophytic or invasive colon cancer and tumor multiplicity were simila r in all treatment groups, although the incidence of exophytic neoplas ms was higher with 2.5% tea, Thus, chronic administration failed to si gnificantly change the incidence and multiplicity of the AOM-induced c olon cancers, These findings are accounted for by the underlying mecha nism, namely the fact that tea solutions do not alter the amount of cy tochrome P-4502E1 required for the metabolic activation of AOM.