Gonadotropin releasing hormone (GnRH) analogs for the treatment of breast and prostatic carcinoma.

'Superagonist' analogs of GnRH produce a paradoxical inhibition of gonadotropin secretion when given on a long-term basis, and may well produce a more complete 'medical oophorectomy' than antiestrogens in premenopausal breast cancer patients. Here we review the background and pharmacology of these agents, together with the experience of their use with prostate cancer and early trials in breast cancer. Their effectiveness without significant toxicity, together with new biodegradable implants for their easily acceptable long-term administration, suggest that a highly selective medical means of fully inhibiting ovarian estrogen production is now available for more extensive trials in breast cancer patients.