Two independent lines of chemically-induced colonic carcinoma, serially graftable in syngeneic rats, have been used to investigate the effects of immunoprophylaxis and immunotherapy. Rats were immunised by various procedures, including BCG, irradiated tumour grafts, and cancer cells treated by mitomycin and neuraminidase. A partial inhibition of tumour growth was observed in one of the four protocols. On the other hand, a significant enhancement of tumour growth was obtained in two other experiments.

1,2-Dimethylhydrazine(DMH) was administered s.c. to a group of 20 inbred BD-IX rats at the dose of 15 mg/kg body weight, weekly for 7 months. Intestinal adenocarcinoma have been found in all of the treated animals, often associated with hyperplastic or dysplastic lesions. The intestinal cancers gave metastases in 14 animals. The low incidence of extra-intestinal malignancies, the relatively short induction time, the similarity to human colorectal adenocarcinoma, make the DMH-induced intestinal cancer a highly effective experimental model.