Prognostic index for patients with brain metastases from breast cancer: A validation and refinement of the breast-specific graded prognostic assessment (GPA) index.

1097 Background: Breast cancer (BC) is the second most common cause of brain metastases (BM). Various prognostic indexes such as RPA to predict survival in BM patients have been developed in patients enrolled in RTOG trials. However, they did not predict BC specific-survival with BM accurately because they had mostly included lung cancer patients. BC specific graded prognostic assessment (GPA) has been developed (Sperduto et al., IJROBP. 2010) and modified (ASCO 2010 abst. #1028) to reflect unique biologic feature of BC. The purpose of this study is to appraise and refine the Sperduto’s BC-specific GPA index (S’ GPA). Methods: We retrospectively investigated 272 patients with BM from BC between 1995 and 2009 at Samsung Medical Center. 173 of 272 patients who had available clinical data with ER, PR, and HER2 status were included. We appraised the S’ GPA index in our cohort. Since treatment with trastuzumab significantly enhanced survival of HER2 overexpressing BC patients with BM, we refined the S’ GPA ind...