Endocrine therapy for advanced breast cancer.
The demonstrated efficacy of pharmacologic antiestrogen therapy in treating hormone receptor-positive breast cancer has changed the landscape of treatment for the majority of women with metastatic disease, providing them with a well-tolerated therapeutic alternative to surgical oophorectomy and chemotherapy. A multitude of clinical trials have evaluated the various endocrine agents alone or in combination. Studies have established ovarian suppression as key for the management of premenopausal metastatic breast cancer patients, and aromatase inhibitor therapy as first-line treatment for their postmenopausal counterparts. Fulvestrant (Faslodex, AstraZeneca) has also been found to be efficacious and has been studied in the first-line and second-line settings. De novo and acquired endocrine therapy resistance represent a major challenge to the ongoing treatment of patients with hormone receptor-positive disease; strategies to circumvent or delay resistance, including the use of combination endocrine therapy and endocrine therapy with agents targeting various growth-factor signaling pathways, represent an active area of investigation. This review provides a summary of the various landmark trials that have established our current standards of practice in the management of patients with hormone receptor-positive metastatic breast cancer. A discussion of future directions and ongoing studies is also provided.