Endocrine agents in the treatment of advanced breast cancer [Endokrine ansatze in der therapie des metastasierten mammakarzinoms]

There are plenty of endocrine agents available for patients with advanced breast cancer. They have good therapeutic evidence and show fewer side effects in women with hormone-receptor-positive tumors, as well as in a smaller percentage of patients with receptor negative tumors. Application of endocrine agents follows defined indications. They are given sequentially with the least toxic therapy given first. The suppression of estrogen synthesis with GnRH analogues is the first step of treatment for premenopausal patients. If the tumor progresses, the sequential application for premenopausal patients is the same as for postmenopausal women with continuous application of GnRH analogues. Antiestrogen tamoxifen is considered the first-line endocrine therapy for postmenopausal advanced breast cancer. Alternatively, Toremifen shows the same effectiveness and side effects as tamoxifen. Although it is postulated that is less carcinogenic, this must be demonstrated conclusively in long-term follow-up. The aromatase inhibitors are defined as second-line endocrine therapy. Newer selective aromatase inhibitors such as formestane, letrozole and anastrozole are p.o. active and have substituted classical aminoglutethimide. There are numerous new aromatase inhibitors that will be investigated in clinical trials of advanced and primary breast cancer. Progestins are given as third-line endocrine therapy. They have a high risk of thromboembolic complications, but good palliative and supportive effect. Antiprogestins, androgens and antiandrogens are still under investigation and have so far shown only limited success in clinical trials.