Pathology of tumors developed in guinea pigs given intraperitoneal injections of N methyl N nitrosourea

The carcinogenic effects of N methyl N nitrosourea after repeated intraperitoneal administration in inbred strain NIH 13 guinea pigs were studied; 50% of the animals that survived beyond 22 wk, after i.p. injection of MNU at a dose of 10 mg/kg body weight/wk for 18 wk, developed a broad spectrum of tumors: these included adenocarcinoma of pancreas in 2 animals, fibrosarcoma and hemangiosarcoma of the mesentery in 2 animals each, mesothelioma of the peritoneum in 1 animal and tumors of small intestine in 3 animals. These studies indicate the susceptibility of different types of tissue to the local effects of MNU after intraperitoneal administration.