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Introduction: The incidence of brain metastasis complicated with breast cancer (BCBM) is approximately 10-15%. Given that the survival status of the BC patients is not optimistic, the choice of clinical treatments should be based on individualized clinical characteristics of the BC patients. Thus understanding of the patient clinical characteristics is critical for patient management and forecasting the prognoses of the patients. Methods: The trial was designed as a real-world observational study. The BCBM patients who were enrolled in the clinics from 2012 to 2017 were recruited and the study data on the patient demographic, tumor biological characteristics, and clinical treatments were retrospectively collected for evaluating overall survival (OS), and the OS impact factors. The Kaplan-Meier and Log-rank tests were performed to assess patient survivals. The Cox regression analyses were applied to explore the OS impact factors. All the statistical significance was set as α=0.05 except as other specified. Results: A total of 117 female BCBM patients (mean age: 48.28±9.49 years) were enrolled in this study including 32 patients (27.4%) with extracranial metastases and 85 patients (72.6%) without extracranial metastases. Of all the subjects, by classification of the molecular types, 13.3% of the patients were diagnosed with luminal A tumor and 45.8% were observed with luminal B tumor. The patients with HER2 positive accounted for 19.3% of all the subjects and 21.7% of the subjects were triple-negative BC patients. In the clinical treatments, 65.8% of the patients were administered with chemotherapies, 14.5% with target therapies, and 11.1% with radiotherapies. The median of the OS duration was approximately 38.57 months. The OS rates were decreased along with the observation period: The 18-month OS rate was 73.6% (95% confidential interval, CI 0.558, 0.852) and the 48-month OS rate was 24.9% (95% CI 0.045, 0.537), respectively. In the patients with >3 metastatic brain tumors, the median of the OS duration was 20.27 months and the median of the OS duration was 38.57 months in the patients with ≤3 metastatic brain tumors. The OS durations in the patients with ≤3 metastatic brain tumors were longer than the durations in the patients with >3 metastatic brain tumors from 12 month- to 36 month- observation period. In the patients with Ki-67≤14%, the OS durations were longer than the durations of the patients with Ki-67>14%. In the 18 month-observation period, the OS duration was longer in the patients with HER2 positive as compared with that of the patients with HER2 negative. In the univariate and multivariate analyses, those patients with chemotherapies were significantly associated with longer OS durations (p<0.05). The multivariate analyses showed that the menopausal patients were related to shorter OS durations (p<0.05). Conclusions: The real-world study offered the clinical evidences on the clinical characteristics of the BCBM patients, patient management, and patient survivals. The patient survivals improved significantly after clinical treatments with BCBM. The tumor biological characteristics and chemotherapies were predictive for the status of patient survivals. Citation Format: Ouyang Q, Tang Y, Hu Z, Tian C, Xie N, Liu L, Xiao H, Li J, Wu H, Yang X, Yang C. A single-center real-world observational study to explore clinical treatments and prognoses of the Chinese patients with breast cancer complicated with brain metastases [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-65.