Levamisole and hamster pouch carcinogenesis.

Seventy-five male and female Syrian hamsters (Cricetus auratus), 10 months of age, were studied for the effects of systemically administered levamisole upon the process of chemical carcinogenesis of buccal pouch mucosa. In twenty-five animals (Group II) the left buccal pouch was painted three times weekly with a 0.5 per cent solution of 9,10-dimethyl-1,2-benzanthracene (DMBA) in heavy mineral oil. After each topical application of carcinogen to the buccal pouch, animals in Group II received approximately 0.7 mg. of levamisole hydrochloride orally by means of a pipette. In another twenty-five animals (Group I) the left buccal pouch was painted three times weekly with DMBA, but they were not given levamisole. The twenty-five animals in Group III served as untreated controls. In those animals which received levamisole chemical carcinogenesis of the buccal pouch was retarded. Fewer tumors developed, and they were of smaller size.