Oestrogen in the treatment of prostatic carcinoma. What is the safe and effective dose of ethinyloestradiol?

The treatment of prostatic carcinoma with diethylstilboestrol (DES) and ethinyloestradiol (Lynoral) has become less popular since the introduction of new forms of treatment such as antiandrogens, estramustine phosphate and LHRH analogues. One of the reasons for this decline in popularity is the risk of cardiovascular side effects during treatment with oestrogens. In the literature, different dosages of DES and ethinyloestradiol are recommended and different rates of cardiovascular side effects are reported. In a prospective study, 18 patients were treated with ethinyloestradiol 0.05 mg/day. In most cases this lowered the plasma testosterone permanently below castrate level during therapy. Also, because the acid phosphatase returned to normal in almost all patients, this treatment seemed adequate. In 4 patients the treatment was stopped because of side effects, in 3 of these because of cardiovascular complications. The cardiovascular side effect at this dose are considerable (29%) but comparable rates are reported in some studies following placebo treatment of patients with prostatic carcinoma.