The effect of previous endocrine therapy on responses to a single dose of an LHRH analogue.

Serum concentrations of gonadotropins, testosterone and dehydrotestosterone were determined in patients receiving conventional endocrine therapy for advanced metastatic adenocarcinoma of prostate. The effect over 4 h of a single dose of a long acting analogue of LHRH was determined in these patients and compared to the response in patients receiving the analogues as first choice of treatment. Oestrogen therapy was found to suppress basal and stimulated gonadotropins and testicular androgens. Cyproterone therapy only partially reduced basal hormone concentrations and the response to the LHRH analogue was delayed. Orchidectomy resulted in elevated gonadotropins and an exaggerated response to the analogue. As patients who relapse while failing conventional therapy, may subsequently be treated by further endocrine manipulation, precise determination of their endocrine status should predict any expected benefit. Patients previously treated with stilboestrol are unlikely to respond to orchidectomy or LHRH analogue.