[Effect of medroxyprogesterone acetate on antitumor efficacies and side effect of 5-fluorouracil]

Effect of medroxyprogesterone acetate (MPA) on the lethal toxicity, bone marrow toxicity and antitumor efficacies of 5-fluorouracil (5-FU) was examined. The following results were obtained. In aged female ddY mice, the lethal toxicity and body weight loss caused by 5-FU were reduced by MPA. MPA also reduced the bone marrow toxicity of 5-FU in aged female ddY mice. These effects of MPA were not observed in young male ddY mice. Moreover, MPA did not affect the antitumor activity of 5-FU against MPA-insensitive mouse breast carcinoma FM3A, or rather augmented its antitumor activity against MPA-sensitive human breast carcinoma MCF-7. These results indicate that MPA reduces the side effects of 5-FU and augments the antitumor activity of 5-FU in female mice.