The effect of tumor subtype on survival and the graded prognostic assessment (GPA) for patients with breast cancer and brain metastases.

Abstract

238 Background: The Diagnosis-Specific Graded Prognostic Assessment (DS-GPA) was published to clarify prognosis for patients with brain metastases. This study refines the existing Breast GPA by analyzing a larger cohort and tumor subtype. Methods: A multi-institutional retrospective database of 400 breast cancer patients treated for newly-diagnosed brain metastases was generated. Prognostic factors significant for survival were analyzed by multivariate Cox regression (MCR) and recursive partitioning analysis (RPA). Factors were weighted by magnitude of their regression coefficients to define the GPA index. A GPA score of 4.0 represents the best prognosis, 0.0, the worst. Results: Significant prognostic factors by MCR and RPA were Karnofsky Performance Status (KPS), HER2, ER/PR status, and the interaction between ER/PR and HER2. RPA showed age was significant for patients with KPS 60-80. The median survival time (MST) overall was 13.8 months, and for GPA scores of 0-1.0, 1.5-2.0, 2.5-3.0 and 3.5-4.0 was 3.4 (n=23), 7.7 (n=104), 15.1 (n=140) and 25.3 (n=133) months, respectively (p < 0.0001). See table. Among HER2-negative patients, being ER/PR-positive improved MST from 6.4 to 9.7 months whereas in HER2-positive patients, being ER/PR-positive improved MST from 17.9 to 20.7 months. The log-rank statistic (predictive power) was 110 for the Breast-GPA versus 55 for tumor subtype. Conclusions: The Breast-GPA documents wide variation in prognosis and shows clear separation between subgroups of patients with breast cancer and brain metastases. This tool will aid clinical decision-making and stratification of clinical trials. These data confirm the effect of tumor subtype on survival and show the Breast-GPA offers significantly more predictive power than the tumor subtype alone. [Table: see text]