Gastric tumor induction by 1,2-dimethylhydrazine in Wistar rats with intestinal metaplasia caused by X-irradiation

Five-week-old male Wistar rats were S-irradiated with a total of 20 Gy in 2 equal fractions at a 3-day interval, 1,2-Dimethylhydrazine (DMH) solution was injected i.m. into the bark musculature at a dose of 20 mg/kg body weig ht weekly for 10 weeks, beginning 20 weeks after the final irradiation. Twe lve months after the initial carcinogen treatment, tumors in the fundus of the glandular stomach were observed in 5 of 23 animals receiving both X-irr adiation and DMH treatment. No tumors of the glandular stomach were observe d in the DMH and X-ray alone or nontreatment groups. It is concluded that t he presence of intestinal metaplasia may increase sensitivity to the induct ion of gastric tumors by carcinogens like DMH.