Hormone changes in patients with prostatic carcinoma during treatment with estramustine phosphate

Hormone analyses of plasma were done on 9 patients with prostatic carcinoma before, during and after treatment with estramustine phosphate. In previously untreated men estramustine phosphate suppressed the plasma testosterone levels. Furthermore, suppression of increased gonadotropins was obtained in irradiated or orchiectomized patients. These hormone changes were caused by high plasma levels of estradiol and/or total estrogens during treatment, with estramustine phosphate, which were still present 2 to 3 months after discontinuation of the drug. We conclude that estramustine phosphate acts, at least partially, as an estrogen and may cause estrogen-dependent side effects.