The impressive advances in breast cancer treatment observed in recent years also apply to the metastatic setting, where a subset of patients with favorable metastatic disease enjoy long-term survival with systemic therapy. In patients with distant disease, the primary tumor in the breast has not classically been though to merit specific locoregional therapy. However, about 6% of Stage IV patients in the USA and up to 20% in limited resource environments present with synchronous distant metastases at the time of initial diagnosis. For this group, who have an intact primary tumor, retrospective studies suggest that local therapy for the primary site may be beneficial. However, these retrospective analyses are biased in that women receiving local therapy to the primary site were younger and had biologically favorable tumors and lower volume metastatic disease. Two completed randomized clinical trials have shown conflicting results, and others are ongoing. In this chapter, we discuss the results of these studies through the present day and summarize their conclusions and their implications for clinical management.