title: Carcinogenesis in rat esophagus by intraperitoneal injection of different doses of methyl-n-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 either 12.5 or 25 mg/kg, the incidence of esophageal squamous cell papillomas was 85 to 100% and that of esophageal squamous cell carcinomas was 40 to 65%. With 12 injections, the mean survival time was 25 to 31 weeks. Treatment with 1 or 2 doses of 50 mg/kg produced a lesser incidence (less than 20%) of esophageal tumors, with a longer survival time of 67 to 77 weeks. 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). Hence, a 6- or 12-week treatment schedule was adequate for inducing esophageal tumors and could be used for studies on agents modifying esophageal tumor induction by methyl-n-amylnitrosamine.
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004938:Esophageal Neoplasms / Q000139:chemically induced*; D005260:Female; D008297:Male; D009374:Neoplasms, Experimental / Q000139:chemically induced; D009602:Nitrosamines / Q000633:toxicity*; D009669:Nose Neoplasms / Q000139:chemically induced; D010212:Papilloma / Q000139:chemically induced*; D051381:Rats; D014134:Tracheal Neoplasms / Q000139:chemically induced
chemical_list: D009602:Nitrosamines; C025033:N-amyl-N-methylnitrosamine