Primary systemic therapy in breast cancer: past lessons and new approaches

Primary systemic therapy (PST) is a common treatment strategy used to optimize surgical outcomes for women with locally advanced breast cancer. Several cooperative group trials have shown equivalent survival outcomes between neoadjuvant and adjuvant chemotherapy and have identified pathologic complete response (pCR) as a biologic marker for survival. Research efforts to optimize PST include the development of strategies to predict individual response and to guide the choice of chemotherapy. These emerging approaches are informed by our knowledge of subtypes of breast cancer, as well as genomic technologies, such as chemosensitivity signatures. Following definitive surgery, the management of residual disease is controversial.