Effect of medroxyprogesterone acetate on DMBA-induced rat mammary carcinoma and on immunological reactivity

The antineoplastic activity of medroxyprogesterone acetate (MPA) was investigated in rats bearing DMBA-induced mammary carcinomas, a classical model of hormone-dependent tumor. Using a repeated injection schedule of relatively short duration, MPA was markedly effective (80% CR + PR) not only on relatively small (1-1.5 cm) tumors but also on advanced (4.5-5.5 cm) neoplasms. MPA effectiveness was comparable to that of a frankly toxic adriamycin regimen. In antitumorally effective schedules MPA was incapable of significantly affecting in either direction cellular and humoral immunological reactivities in rodents.