Carcinogenic effects of niridazole on rodents infected with Schistosoma mansoni.

The carcinogenicity of 1-(5-nitro-2-thiazolyl)-2-imidazolidinone (niridazole), a widely used schistosomicide, was examined in Swiss mice and Syrian golden hamsters. Schistosoma mansoni infection was evaluated as a cofactor. High incidences of drug-related neoplasms of the forestomach, lungs, mammary glands, urinary tract, and ovaries were found in mice, and tumors of the forestomach and urinary tract were found in hamsters. Infection with schistosomes had no apparent influence on tumor incidence. The results indicated a need for reevaluation of the possible carcinogenicity of this drug in man and suggested that care should be taken during its clinical use.