Abstract
The carcinogenicity of 5-fluorouracil (5-FU), an antineoplastic drug, was examined in (C57BL/6×C3H)F1 mice. Groups of 51 or 52 mice of each sex were given 5-FU orally in their drinking water at doses of 60 or 30 ppm for 82 weeks and were then observed for 4 weeks. Control mice were given tap water for 86 weeks. Mean total intakes of 5-FU per mouse were 196 and 98mg in males, and 136 and 67 mg in females, respectively. The survival rates of each group at week 86 were more than 80% in both sexes. There were no significant differences between body weights of mice given 5-FU and those of controls in both sexes. Harderian gland adenomas, alveolar adenomas of the lung, lymphoma/leukemias and intestinal tumors in both sexes, liver cell tumors in males, and a few tumors in other organs of both sexes were found. Eight (15%) of 52 male mice treated with the high dose of 5-FU developed Harderian gland adenomas and the incidence was higher than that of controls, but the difference was marginal and no dose-response was found. In other organs, no significant increase of any particular tumor type was observed in the treated groups of both sexes.
