Treatment of rat prostatic adenocarcinoma with medroxyprogesterone acetate (MPA): effects on growth and morphology.

Abstract

Rats bearing the Dunning R3327H prostatic carcinoma were castrated and supplemented with testosterone propionate. These rats were then treated with estradiol benzoate or medroxyprogesterone acetate alone or in combination with estradiol. During the treatment period of six weeks, the growth rate of the prostatic tumors was measured. At the end of the treatment period the morphology of the tumors was also studied. It was found that medroxyprogesterone acetate is as effective as estradiol in inhibiting the growth of the Dunning prostatic carcinoma and that the combination of medroxyprogesterone acetate and estradiol was more efficient in that respect than estradiol alone. Morphometric evaluation of the tumor epithelium and stroma showed a decrement of epithelial growth in all treatment groups, while the groups treated with medroxyprogesterone acetate, both alone or in combination with estradiol, also showed an inhibited growth of the tumor stroma. It was concluded that medroxyprogesterone acetate probably has direct inhibitory effects on prostatic tumor cells in the Dunning model and that medroxyprogesterone acetate may act in an additive manner with estradiol.