e11526 Background: Stage IV breast cancer is an incurable disease. Systemic therapy is usually the main treatment for these patients. Locoregional therapy, such as surgery or radiotherapy, is controversial. Recent studies suggested locoregional treatments of the primary breast cancer can provide some benefit for these patients. Methods: We conducted a chart review of de novo stage IV breast cancer patients at a cancer center hospital in TAIWAN from 1990 to 2008. A total of 276 patients were reviewed and 268 patients met the inclusion criteria. Tumor characteristics, anti-tumor treatments and survival were analyzed. Results: The median survival of 268 patients was 21.5 months. We divided these patients into two groups. There were 140 patients with less than 21.5 months of survival and 128 patients with more than 21.5 months of survival. In univariate analysis, infiltrating ductal carcinoma (p=0.002), ER-positive (p<0.0001), PR-positive (p<0.0001), and no overexpression of HER2 (p=0.0125) were associated with longer survival. The clinical primary tumor size (p=0.11) and positive axillary lymph node involvement (p=0.61) were not different significantly between two groups. About metastatic site, patients with liver mets (p<0.0001) and lung mets (p=0.025) were associated with shorter survival. Bone mets (p=0.63) was not associated with survival. Patients receiving local treatment of primary tumor, including surgery (p<0.0001) or locoregional radiation (p=0.0034), had longer survival. In multivariate analysis, patients who received surgery of primary breast cancer (HR=0.52, p=0.0006) or received systemic chemotherapy (HR=0.47, p=0.002) had better survival. In subgroup analysis, patients without liver metastasis who received surgery of primary breast cancer had longer overall survival significantly (p<0.0001). In contrast, surgery to the primary breast cancer had no benefit in survival (p=0.91) in patients with liver metastasis. Conclusions: Our institutional experience suggests locoregional treatment for primary breast cancer appear to be beneficial for de novo breast cancer patients, especially those without liver mets.