Hormonal effects of different doses of estramustine phosphate (Estracyt) in patients with prostatic carcinoma

Ten patients with previously untreated prostatic carcinoma were studied to evaluate the hormonal effects of different doses of estramustine phosphate (Estracyt). The drug was given by mouth in increasing doses; during the first month 70 mg daily, during the second 140 mg, during the third 280 mg and during the fourth and following months 560 mg. The following hormonal parameters were studied before the treatment and then once weekly during a period of four months: testosterone, dihydrotestosterone, androstenedione, cortisol, FSH and LH. The levels of the steroids were also re-assessed one to two years later. The patients were also followed clinically at regular intervals. Initial testosterone levels of approximately 20 nmol/l plasma were reduced to approximately 0.6 nmol/l already by the lowest Estracyt dose of 70 mg/day. No further decrease was obtained by a stepwise increase of doses up to 560 mg/day. The plasma levels of dihydrotestosterone, androstenedione, FSH and LH were also reduced significantly following the administration of the lowest daily Estracyt dose and then remained at that low level. Cortisol levels increased steadily during the four months of the study. After longterm treatment the hormonal indices were by and large the same as during the last initial treatment period. Initially, the clinical effect of the treatment was excellent. In 4 patients, however, the therapy had to be discontinued after some time, because of complicating oedema (2 patients) or refractoriness to therapy (2 patients). Three years after initiating the therapy 6 patients still were on Estracyt treatment. All of them were doing well subjectively. In 5 patients the prostatic cancer was in remission or at least stable. In one patient, however, skeletal metastases were progressing. In conclusion, Estracyt was found to possess a maximal hormonal (oestrogenic) effect already in doses far below those usually recommended.