Single dose carcinogenicity of procarbazine in rats.

Rats carrying a 2-day-old subcutaneous air pouch were treated with single doses of procarbazine. Local fibrosarcomas developed in the pouch after oral, intraperitoneal and local administration of 300 mg/kg, but no tumours were induced if the drug was injected into unstimulated subcutaneous tissue. Tumours only appeared in those animals in which growth of the granuloma tissue was stimulated with a dose of croton oil. The high dose of procarbazine (300 mg/kg) also induced an increase in total tumour incidence at other sites.