Women who present with new breast cancer and synchronous metastases have traditionally been treated with systemic agents, with no specific therapy for the primary tumor unless local symptoms require palliation. However, a number of retrospective analyses of survival outcomes in these patients show that surgery for the primary tumor is associated with prolongation of survival. These studies suggest the possibility that local therapy for the primary tumor provides value beyond palliation of symptoms and points to the need for prospective data to guide treatment plans for women with de novo metastatic breast cancer. The coherence of the available data is improved by the findings that surgical resection of the primary tumor is of value only when free surgical resection margins are achieved, and that maintenance of local control at the primary site is associated with a survival advantage. Nevertheless, many questions remain, including the optimal timing of surgery for the primary tumor, whether the potential benefit applies only to women with favorable metastatic sites (e.g. bone-only metastases), and whether local radiotherapy should follow surgical treatment of the primary tumor if this is elected. There is also a lack of data addressing the value of axillary surgery in the metastatic setting. These substantial knowledge gaps limit our ability to deploy optimal use of therapeutic modalities for a patient population that reaches large numbers world-wide, and among whom survival duration is increasing due to more effective systemic therapy.
