Carcinogenic Effects of Diethylnitrosamine in RF Mice

Summary

Noninbred 10-week-old male mice of the RF/Un strain were given 4 mg of diethylnitrosamine (DEN)/100 ml drinking water daily for 22 weeks. Tumors were first observed in high incidences after 22 weeks of treatment (mice 32 weeks old) and consisted of pulmonary adenomas, liver hepatomas, and squamous cell carcinomas of the stomach. In histologically examined animals, the incidences were 74% for lung tumors, 90% for liver fumors, and 100% for stomach tumors in animals that survived the 22-week treatment period. In addition, 4 mice (18%) had esophageal tumors (squamous cell carcinomas). In contrast to previous reports on mice in which the principal tumors were hemangioendotheliomas and adenomas of the liver, hepatomas were the principal liver tumors produced. This fact and the observation of a high incidence of squamous cell carcinomas of the forestomach point to the influence of drug metabolism, excretion, and perhaps certain other physiologic factors on the site of tumor production by DEN. No significant effect of DEN on leukemia incidence was observed.