Medical Castration of Males with Megestrol Acetate and Small Doses of Diethylstilbestrol*

Abstract

An alternative program for medical castration for treatment of prostate cancer has been developed using a progestational antiandrogen, megestrol acetate (MA), in combination with small doses of diethylstilbestrol (DES; 0.1 mg/day). The administration of MA (40-80 mg/day) with 0.1 mg DES to nine patients resulted in castrate levels of plasma testosterone (less than 0.4 ng/ml) and significant suppression of both FSH and LH (P less than 0.05) for up to 12 months. Although large clinical trials must ultimately establish its safety, clinical side effects of this combined therapy to date have consisted of mild gynecomastia in two patients. The symptoms did not necessitate discontinuing the medications. It is concluded that the use of 0.1 mg DES with a minimum of 40 mg/day MA results in medical castration with sustained suppression of plasma testosterone. Because of the possible additional therapeutic advantage of blockade of intracellular androgen-mediated action by MA in androgen-dependent tumors, this combined therapy should be further explored as a possible initial treatment of choice for advanced prostate cancer.