Optimizing the treatment of metastatic breast cancer.

There is currently no standard care for metastatic breast cancer; consequently, individual patient and tumor characteristics are among several factors considered in treatment decisions. Clinical studies continue to clarify the roles of endocrine therapy, chemotherapy, and biologic therapy, and results have been promising. For patients with hormone receptor-positive disease, several endocrine agents are currently available including selective estrogen receptor (ER) modulators (tamoxifen and toremifene), aromatase inhibitors (anastrozole, exemestane, and letrozole), as well as the selective ER down-regulator, fulvestrant. Effective first- and second-line, single-agent chemotherapeutic treatments include the taxanes, anthracyclines, vinorelbine, capecitabine, and gemcitabine. The benefits of sequential, single-agent versus combination chemotherapy are also being evaluated. Although combination chemotherapy generally results in a greater objective response, it is associated with similar survival and usually greater toxicity compared with sequential, single-agent chemotherapy. Research involving biologic therapy continues to provide encouraging results for patients with metastatic breast cancer. Chemotherapy plus trastuzumab has been shown to result in greater overall survival versus chemotherapy alone in human epidermal growth factor 2 (HER-2)-positive patients. Trastuzumab has been associated with cardiotoxicity when administered with conventional anthracyclines. Newer formulations of anthracyclines have been developed (e.g., liposomal anthracyclines) to decrease the incidence of cardiotoxicity, and these provide additional treatment options for patients with metastatic breast cancer. The potential effect of all of these endocrine, chemotherapeutic, and biologic treatments on quality of life is an important consideration. Additionally, integrating patient concerns into treatment decisions and collaborating with cross-disciplinary healthcare providers can help to manage the disease more effectively.