[Malignant degeneration of experimental ulcerative colitis of the rat following s.c. injection of 1,2-dimethylhydrazine (author's transl)].

Animal experiments were performed to answer the question whether ulcerative colitis is predisposed to malignant degeneration. Male Wistar rats were given aqueous solutions of degraded Carrageenan (4%; w/v). After induction of ulcerative colitis, 1,2-Dimethylhydrazine (DMH; 132 mg/kg body weight) was applicated during a period of 7 weeks. 17 of 18 rats developed multiple adenocarcinomas in the distal colon 15 weeks after the last injection of DMH. The Carrageenan induced colitis was localized predominantly in the distal part of the large bowel. Only 3 rats of a control group of 18 animals exposed to DMH only showed carcinomas of the colon. The difference is proven significant (P less than 0.01). Carrageenan for itself caused no malignancy. The results of the experiments demonstrate that, during ulcerative colitis, the colon of the rat is more susceptible to induction of cancer than the intact one.