Concomitant Versus Sequential Chemotherapy in the Treatment of Early-Stage and Metastatic Breast Cancer

Breast cancer is one of the most common malignancies in the Western world. Chemotherapy improves disease-free survival (DFS) and overall survival (OS) rates in women with early-stage breast cancer. Although anthracycline-and taxane-based regimens are considered most effective, the optimal way to administer them (sequentially vs. in combination) remains in question. In metastatic breast cancer, cytotoxic chemotherapy is the treatment of choice for patients with hormone receptor—negative tumors or rapidly progressive disease, regardless of hormone receptor status. The combination of chemotherapy and trastuzumab improves DFS and OS rates in patients with HER2-overexpressing metastatic breast cancer. In patients with HER2-negative tumors, the choice of single-agent sequential versus combination chemotherapy should be individualized. Sequential chemotherapy can produce OS rates similar to those of combination regimens and avoids the overlapping toxic effects of combination chemotherapy. However, response rates are generally higher and time to progression is longer with combination chemotherapy. At present, no predictive markers of response to chemotherapy are clinically useful in making treatment decisions for individual patients. Prospective studies are needed in order to validate the clinical utility of novel markers of response to specific chemotherapies and/or various schedules of administration.