Influence of age and sex on carcinoma and cirrhosis of the liver in AXC strain rats ingesting 0.025% N-2-fluorenyldiacetamide.

Inbred A X C male and female rats, 4, 12, 24, and 52 weeks of age, ingested 0.025% N-2-fluorenyldiacetamide in a semisynthetic diet. Both age and sex were important in the development of hepatic lesions. The 4- and 12-week-old males developed a higher incidence of carcinomas and cirrhosis of the liver than did the females of the same ages or the males and females 24 and 52 weeks of age. Four-week-old male rats had more carcinomas per liver, larger carcinomas, more poorly differentiated (as compared with well differentiated), and some carcinomas were cholangiocellular as well as hepatocellular. There were a few hepatic lesions in the younger female rats; however, female rats of all ages were relatively resistant to hepatic carcinogenesis.