Enhancing effect of ethanol or sake on methylazoxymethanol acetate‐initiated large bowel carcinogenesis in ACI/N rats

Abstract

Effects of ethanol or saké on intestinal carcinogenesis by methylazoxymethanol (MAM) acetate were examined in two experiments. In the first experiment, 39 male ACI/N rats were given two weekly intraperitoneal injections of MAM acetate (25 mg/kg body wt) and divided into two groups, with Group 1 being given 10% ethanol and Group 2 being given distilled water. The incidence of colonic cancer in Group 1 (15/17, 88%) was higher than in Group 2 (9/16, 56%, p = 0.040). Differences in the incidences of rectosigmoidal colonic neoplasms were even more marked (59% vs. 19%, p = 0.019) and their proportion of the total number of large intestinal neoplasms was greater in Group 1 (36%) than in Group 2 (15%, p = 0.046). In the second experiment, 97 female ACI/N rats were divided into 6 groups, with the animals of Groups 1-5 being given MAM acetate (2 times, 25 mg/kg body wt). Rats in Group 6 received saline. The rats received isocaloric drinks: Group 1, saké; Group 2, 50% saké; Groups 3 and 6, 15% ethanol; Group 4, 7.5% ethanol; and Group 5, nonalcoholic water. Incidences of rectosigmoidal colonic neoplasms in Groups 1, 2, and 3 (53%, 46%, and 50%) tended to be higher than in Group 5 (38%). Their proportions of the total number of large intestinal neoplasms in Groups 1 (68%) and 2 (67%) were slightly greater than in Group 5 (45%). The results suggest an enhancing effect of ethanol or saké on rectosigmoidal colonic carcinogenesis.