Use of luteinising hormone-releasing hormone agonist (leuprorelin) in advanced post-menopausal breast cancer: clinical and endocrine effects

Fifteen post-menopausal patients with advanced breast cancer were treated with the LH-RH agonist leuprorelin (D-leu6-des-gly10-Gn-RH-ethylamide) given in a dosage of 7.5 mg as a monthly subcutaneous depot injection, to assess the clinical activity and endocrine response to treatment. None of the 15 patients showed an objective response to treatment, although four patients had stable disease for at least 6 months. No toxicity was demonstrated. Endocrine effects after 4 weeks' treatment were as follows: mean levels of serum gonadotrophins fell to 10% of their pretreatment values; there were no significant changes in the levels of prolactin on treatment; there was a significant decrease in the levels of serum testosterone in 12 out of 14 patients; there were no significant changes in the levels of oestradiol, androstenedione and oestrone. The lowering of serum testosterone suggests that androgens in post-menopausal women may be partly produced by the ovaries, stimulated by LH and FSH. This fall in testosterone may explain why some post-menopausal breast cancer patients in other studies have been reported to respond to treatment with LH-RH agonists, as it would decrease the substrate for the peripheral synthesis of oestrogens.