Endocrine Therapy for Breast Cancer

Abstract

Endocrine therapy can result in palliation of disease in 50% to 60% of patients with hormone receptor—positive breast cancer. The choice of agents for endocrine therapy depends on the menopausal status of the patient. In premenopausal women, luteinizing hormone-releasing hormone agonists or tamoxifen can be used as initial therapy. In postmenopausal women, aromatase inhibitors or tamoxifen can be used as initial therapy. The use of anastrozole, an aromatase inhibitor, as initial therapy in postmenopausal women with estrogen receptor—positive tumors results in increased response rates, longer control of disease, and fewer side effects. Patients who respond to initial therapy have a higher probability of response to secondary and tertiary endocrine therapies. There is a partial lack of cross-resistance between steroidal and nonsteroidal aromatase inhibitors; thus, these agents may provide palliation of disease if used sequentially in patients with hormone receptor—positive tumors. Endocrine therapy alone or with chemotherapy can significantly reduce the risk of recurrence and has a favorable impact on survival. A number of new endocrine agents are in clinical development, and preliminary data from these studies are encouraging. The role of these agents in the treatment of breast cancer will be evaluated in ongoing trials.