Assessment of tumor characteristics and factors affecting survival in patients with primary metastatic breast carcinoma: a Multicenter Study of the Anatolian Society of Medical Oncology.

Primary metastatic breast cancer (PMBC) comprises 3-10% of all BCs. PMBC is a heterogeneous disease. To date, little is known about the tumor characteristics, treatment results, and overall survival (OS) of patients with PMBC. Patients were considered to have PMBC if distant metastasis was evident within 3 months of the initial diagnosis of BC. Between September 2007 and April 2013, 466 PMBC patients were included in this study and analyzed retrospectively. The median age of the patients was 50 (18-90) years. Bone/soft tissue metastases were more frequent in the hormone receptor (HR)(+) human epidermal growth factor receptor (HER)2(-) group compared with the HR(-)HER2(-) and HR(-)HER2(+) groups (p < 0.001), whereas visceral organ metastasis was more frequent in the HR(-)HER2(-) and HR(-)HER2(+) groups (p < 0.001). The OS was affected by Eastern Cooperative Oncology Group performance status, tumor histology, receptor status, and the site of metastasis (p < 0.001, p < 0.001, p < 0.001, and p = 0.011, respectively). According to the first-line systemic treatment choices of the patients, the longest median OS was observed in the HR(+)HER2(+) group who received hormonotherapy combined with trastuzumab after chemotherapy (86 months, 95% CI 23.8-148.1) and the shortest median OS was observed in the HR(-)HER2(-) group who received chemotherapy only (24 months, 95% CI 17.9-30.0) (p < 0.001). Bisphosphonate therapy or radiotherapy had no significant effect on OS (p = 0.733, 0.603). In multivariate analysis, hormonotherapy, chemotherapy + trastuzumab, trastuzumab + hormonotherapy following chemotherapy, and surgery were the most important prognostic factors for OS, respectively (p < 0.001, p = 0.025, p = 0.027, p = 0.029). The general characteristics of the primary tumor are important for the prognosis and survival of patients with PMBC. Interestingly, patients who underwent primary breast tumor surgery, even those at the metastatic stage upon admission, had the longest survival.