Combination Therapies in Advanced, Hormone Receptor–Positive Breast Cancer

About 17% of women with breast cancer have locally advanced or metastatic disease at the time of diagnosis, and 30% to 40% of women diagnosed with early-stage disease will eventually have recurrence. The majority of breast cancers express estrogen or progesterone receptors, and hormonal therapies (HTs) remain the treatment of choice for these cancers after the resection of primary tumors. In addition to their effectiveness, HTs often have fewer severe side effects compared with chemotherapies. As breast cancer recurs or progresses, however, it becomes less responsive to successive HT, and the duration of response decreases. Recent advances have identified specific combinations of HTs that can extend the duration of response in appropriate patients with advanced breast cancer. Furthermore, research into signaling pathways has led to the availability of targeted agents that improve efficacy and duration of response when used in combination with specific HTs. Despite their effectiveness and advantages, these combination therapies increase the burden of side effects and the care required for proper management. In addition, practitioners must educate patients about the increasing complexity regarding treatment decisions, and provide care as part of a patient-centered team that optimizes both the medical outcomes and quality of life of patients with breast cancer.