STUDIES ON THE ESOPHAGUS .3. CARCINOGENESIS IN RAT ESOPHAGUS BY INTRA-PERITONEAL INJECTION OF DIFFERENT DOSES OF METHYL-NORMAL-AMYLNITROSAMINE

Abstract

The carcinogenicity of methyl-n-amylnitrosamine in MRC-Wistar rats was determined after i.p. injection at a variety of dose schedules. After 6 weekly methyl-n-amylnitrosamine injections of 25 mg/kg or 12 weekly injections of 12.5 or 25 mg/kg, the incidence of esophageal squamous cell carcinomas was 40-65%. With 12 injections, the mean survival time was 25 to 31 wk. Treatment with 1 or 2 doses of 50 mg/kg produced a lesser incidence (< 20%) of esophageal tumors, with a longer survival time of 67 to 77 wk. One 85-mg/kg injection caused esophageal carcinomas in 5 of 7 rats. The treated groups also had squamous cell papillomas and carcinomas in the nasal cavity (up to 50% incidence) and trachea (up to 30% incidence). A 6 or 12 wk treatment schedule was adequate for inducing esophageal tumors and could be used for studies on agents modifying esophageal tumor induction by methyl-n-amylnitrosamine.