Endocrinological and clinical aspects of LHRH action (ICI 118630) in hormone dependent breast cancer.

The effect of an LHRH agonist, D-Ser (But)6Azgly10-LHRH (Zoladex, ICI 118630) on pituitary gland and ovarian function has been investigated in patients with advanced breast cancer. In both pre and postmenopausal women ICI 118630 produced a substantial rise in circulating concentrations of gonadotrophins within 2 h of the first injection. However, on continued exposure to the drug plasma LH and FSH levels decreased to below pre-treatment values (14-21 days). This was especially evident in postmenopausal women. In premenopausal patients plasma progesterone and estradiol levels were significantly reduced after 2 and 4-6 weeks of therapy respectively, reaching values observed in oophorectomized or postmenopausal patients. No substantial acute or long-term influence of the drug on these hormones was seen in postmenopausal women. Breast tumor remissions were recorded primarily in premenopausal patients with estrogen receptor positive tumors. No responses were seen in patients with estrogen receptor negative disease. Minimal side effects were recorded.