[Effects of sex hormones on carcinogenesis of the stomach].

Influences of sex-hormones on gastric cancer development induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats were studied. Well-differentiated adenocarcinoma developed in glandular stomach of 81% of male rats given 50 micrograms/ml of MNNG in drinking water for 4 months and sacrificed on the 12th month of the experiment. No gastric cancer was found in female rats given MNNG. In the additional estradiol-treated or castrated male rats, and the additional testosterone-treated or oophorectomized female rats, the incidence of carcinoma was 68% and 29%, and 33% and 5%, respectively. In the latter 3 groups, gastric erosion of the early stage was also low incidence. Histologically, poorly-differentiated adenocarcinoma was observed more frequently in these groups than in the alone MNNG-treated male group. These results have sagg-suggested that female-sex-hormone may inhibit and male-sex-hormone may accelerate the gastric carcinogenesis.