The agonist analogues of gonadotropin-releasing hormone provide an alternate medical therapy for prostatic cancer. Current methods of administration of these analogues by daily injection or nasal spray is sub-optimal in an elderly population. We have performed a pharmacological and endocrine evaluation of a new depot preparation of one such analogue, buserelin, active for 2 months. Thirty patients with advanced symptomatic prostatic cancer were treated. Serum testosterone was suppressed for the duration of treatment which ranged up to 14 months. The release characteristics of the depot were consistent and showed minimal variation between patients. This 2-month preparation of buserelin offers and advantage to the patient with prostatic cancer, over current treatment regimens.

Tumor flare is reported in up to 40% of patients treated with gonadotrophin-releasing hormone analogues for prostate cancer. In order to investigate the optimal way to eliminate tumor flare, we have treated patients with one of three different antiandrogen regimens used in combination with gonadotrophin-releasing hormone (GnRH) agonist. The early results of this study are presented here. Thirty patients with advanced symptomatic disease were randomized to receive either cyproterone acetate 50 or 100 mg three times daily or flutamide 250 mg three times daily given for 1 week before and during the first month of GnRH agonist treatment. The endocrine profiles of these patients were compared with those of historic controls treated with depot agonist alone. Three patients treated with low-dose cyproterone acetate and one with flutamide developed a transient exacerbation of their disease. No patients treated with the higher-dose cyproterone acetate regimen developed tumor flare. No patients treated with cyproterone acetate had an increase in serum testosterone above baseline following depot GnRH agonist implantation. All patients treated with flutamide had increases in serum testosterone, but this did not significantly increase further with implantation. This study suggests that all patients receiving GnRH agonist treatment should be pretreated with cyproterone acetate 100 mg three times daily for 1 week before implantation and for the first treatment month.