Strain comparison of systemic N-nitrosohexamethyleneimine carcinogenesis in BALB/c, SENCAR and CD-1 mice.

SENCAR mice have been selectively bred for hypersusceptibility to 2-stage chemical skin carcinogenesis. In this study the relative susceptibilities of SENCAR, BALB/c and CD-1 mice to systemic carcinogenesis by N-nitrosohexamethyleneimine (NHEX) were examined. NHEX was administered twice weekly (1 mg/mouse) in corn oil by gavage for 30 weeks. NHEX caused primarily liver and lung tumors in all 3 strains of mice. Hemangiosarcomas (but not other liver tumors) were more common in CD-1 mice than BALB/c or SENCAR mice. Lung tumors (adenomas and adenocarcinomas) and forestomach tumors (squamous carcinomas) were more common in SENCAR mice than BALB/c or CD-1 mice. Survival was better in SENCAR mice dosed with NHEX than in the other 2 strains. These results indicate that SENCAR mice are not unusually sensitive to liver carcinogenesis by NHEX, but are relatively sensitive to tumorigenesis in 2 epithelial tissues, lung and forestomach.