New endocrine approaches in the treatment of breast cancer

As a result of tamoxifen becoming the first endocrine compound with proven activity in breast cancer, a. broad spectrum of new substances have been tested and several are now available for clinical use. New pure antiestrogens show no estrogenic activity as a result of different receptor binding, and some other derivatives of tamoxifen demonstrate varied toxicity profiles. The second and third generation of aromatase inhibitors can selectively inhibit the aromatase enzyme in the peripheral tissue and perhaps even in tumor cells. Gonadotrophin-releasing hormone (GnRH)-analogues can suppress ovarian function in premenopausal patients and thus prevent surgical ovarectomy. The value of a new group of anti-progestional substances has not yet been clarified. In this overview the most important compounds are reviewed for efficacy and toxicity in breast cancer patients.