Estramustine Phosphate Sodium

Abstract

Estramustine phosphate is approved by the Food and Drug Administration for oral use in the palliative treatment of patients with metastatic and/or progressive carcinoma of the prostate. Estramustine is a conjugate of 17β-estradiol and the carbamate of nitrogen mustard. Although its therapeutic efficacy has been demonstrated, it is not clear to what extent each constituent contributes to estramustine's effectiveness. Estramustine phosphate therapy achieves objective response rates of 60–90 percent in advanced stage D prostatic cancer patients with no prior hormonal therapy. These results are consistent with those obtained with conventional hormonal therapy in similar patient populations. Therapeutic efficacy does not appear to increase when estramustine is used concurrently with other cytotoxic chemotherapeutic agents. An objective response rate of 20–30 percent can be anticipated in patients refractory to conventional hormonal therapy. It is in this group, the estrogen-resistant patients, that estramustine shows the most promise. Adverse effects of estramustine are similar to those of diethylstilbestrol. Gastrointestinal and cardiovascular side effects appear to be the most important and may be severe enough to require discontinuation of therapy.