Expanding multiple features of extracranial metastasis to predict survival for patients with breast cancer brain metastasis: A population-based retrospective analysis.

e13038 Background: Breast cancer brain metastasis (BCBM) is associated with poor survival outcomes and reduced quality of life. The Graded Prognostic Assessment (GPA) score model serves as a well-established tool for predicting the prognosis of BCBM. Notably, the presence of extracranial metastasis (ECM) is considered as a significant prognostic factor in the breast GPA. This study aims to further refine this factor to enhance the prognostic prediction for BCBM. Methods: This study included all inpatients diagnosed with BCBM at the Cancer Hospital, Chinese Academy of Medical Sciences (CHCAMS), from January 2010 to July 2021. The subsets were categorized by the presence, number, location, and control status of ECM. Baseline clinicopathological characteristics were documented and compared among subgroups. The primary endpoint was overall survival (OS) after the diagnosis of BCBM. We used the Kaplan–Meier method with log-rank test to compare the survival outcomes. Cox regression analyses were conducted to identify significant prognostic factors, which were then incorporated into a new Breast-GPA model. Results: A total of 286 patients with BCBM were included in the study. Kaplan–Meier survival curves suggested that patients without ECM when diagnosed with BCBM showed better survival (p=0.0068). In the subgroups with ECM, more than 3 organs involved, both bone and visceral metastasis and progressive ECM portended dismal OS (p=0.0032, 0.0014 and 0.00054). Multivariate analysis (MVA) demonstrated that the presence, number, and control status of ECM significantly influenced OS after BCBM (p=0.01, 0.03, and 0.048, respectively). The specific location of ECM also had a significant impact on the long-term survival (p=0.0014). By modifying the current GPA model to include categories for '3 or fewer controlled ECM', the predictive accuracy of the newly established GPA model was further enhanced. Conclusions: More extracranial sites, both bone and visceral invasion and uncontrolled ECM were independent prognostic factors for dismal survival outcomes of BCBM patients.