Endocrine Treatment of Metastatic Breast Cancer

Endocrine treatment represents the first choice in the treatment of endocrine-responsive non-life-threatening advanced breast cancer. Hormone receptor expression can be ascertained either on the metastasis (if biopsy can be taken easily) or on the primary tumor. The selection of endocrine therapy takes into account the menopausal status of the patient, the type of previous adjuvant endocrine treatment, the diseasefree interval and past medical history. In premenopausal patients, the combination of LHRH (luteinizing hormone-releasing hormone) agonists and a second endocrine treatment (tamoxifen, anastrozole, fulvestrant, progestagens) is more effective than the single agents. In postmenopausal patients with recurrent disease progressing after or during adjuvant tamoxifen, third-generation aromatase inhibitors (AIs) are the preferred first-line endocrine treatment. In second-line treatment, fulvestrant, a second AI or tamoxifen again are reasonable options. There is no cross-resistance between steroidal and non-steroidal anti-aromatase agents. Steroidal AIs (exemestane) have shown activity after failure of non-steroidal AIs (anastrozole, letrozole). Vice versa, patients receiving exemestane as first anti-aromatase agent may also benefit from letrozole or anastrozole after disease progression. Simultaneous endocrine and cytostatic therapy is not recommended because the combination induces increased toxicity and does not improve overall survival. Maintenance endocrine therapy following chemotherapy appears to improve relapse-free and overall survival.