5-Azacytidine carcinogenesis in BALB/c mice.

5-Azacytidine, a drug used in the treatment of acute leukaemias and beta-thalassemia, was administered i.p. to BALB/c mice at a dose of 2.0 mg/kg body wt. once a week for 50 weeks to test its carcinogenicity. The treatment induced a significant increase in lung tumours (males P less than 0.001, females P less than 0.05), lymphomas (males P less than 0.01, females P less than 0.01), skin tumours (males P less than 0.05, females P less than 0.01) in both sexes and mammary carcinomas (P less than 0.01) and a variety of other tumours in female mice. These results, with other investigations reported in literature, suggest that 5-azacytidine is carcinogenic in mice.