[Carcinogenesis induced by the neonatal administration of 5-bromo-2'-deoxyuridine (BUDR) and subsequent exposure to urethane in BALB/c mice].

Male and female BALB/c mice were subcutaneously injected with 1 mg 5-bromo-2'-deoxyuridine (BDU) on days 1, 3 and 7 after birth and/or given 0.1 ml 5% urethane solution 5 times every 3 days starting at the age of 3 months. Treatment with BDU alone was followed by retardation of growth, loss of body weight and liver mass but had no significant impact on tumor occurrence. Combined application of BDU and urethane was found to potentiate the effect of the latter agent resulting in an increase in the occurrence and multiplicity of lung adenoma. Male mice treated with the above combination showed a significantly higher occurrence of lung adenocarcinoma and hemoblastoses as compared to the other animal groups. It is suggested that genome instability caused by neonatal BDU treatment potentiates the carcinogenic effect of urethane.