Cyproterone acetate in the treatment of metastatic cancer of the male breast.

Ten male patients with advanced cancer of the breast were treated with cyproterone acetate, an anti-androgenic compound with additional progestational properties. Seven patients achieved a response, for a median duration of 8 months. Plasma testosterone and estradiol levels fell significantly during therapy, but quantitatively this drop was not related to the therapeutic response. Cyproterone acetate is an effective and well-tolerated treatment for metastatic male breast cancer.