Promotion of liver cancer development by brief exposure to dietary 2-acetylaminofluorene plus partial hepatectomy or carbon tetrachloride

Adult male Fischer rats were exposed to a necrogenic dose (200 mg/kg) of diethylnitrosamine or to nonnecrogenic doses of N-methyl-N-nitrosourea 1,2-dimethylhydrazine, or benzo-(a)pyrene following partial hepatectomy or sham hepatectomy. This treatment by itself led to no hepatocellular carcinomas by 8 to 18 months, except in animals given N-methyl-N-nitrosourea, which showed a 30% incidence by 12 months. With each treatment regimen, exposure to dietary 2-acetylaminofluorene for 2 weeks coupled with partial hepatectomy or the administration of a necrogenic dose of CCI₄, was associated with an incidence of 68 to 94% of cancer at 8, 12, or 18 months, depending upon the initiating carcinogen used. Appropriate controls showed either no hepatocellular carcinoma or a much lower incidence. It is concluded that the 2-week exposure to dietary 2-acetylaminofluorene plus partial hepatectomy or the administration of CCI₄ has a strong promoting effect on liver carcinogenesis with four different chemical carcinogens.