Brain Metastases From Breast Carcinoma: Validation of the Radiation Therapy Oncology Group Recursive Partitioning Analysis Classification and Proposition of a New Prognostic Score

Purpose: To validate the Radiation Therapy Oncology Group Recursive Partitioning Analysis (RTOG RPA) classification and determine independent prognostic factors, to create a simple and specific prognostic score for patients with brain metastases (BM) from breast carcinoma treated with whole-brain radiotherapy (WBRT). Methods and Materials: From January 1998 through December 2003, 132 patients with BM from breast carcinoma were treated with WBRT. We analyzed several potential predictors of survival after WBRT: age, Karnofsky performance status, RTOG-RPA class, number of BM, presence and site of other systemic metastases, interval between primary tumor and BM, tumor hormone receptor (HR) status, lymphocyte count, and HER-2 overexpression. Results: A total of 117 patients received exclusive WBRT and were analyzed. Median survival with BM was 5 months. One-year and 2-year survival rates were 27.6% (95% confidence interval [CI] 19.9-36.8%) and 12% (95% CI 6.5-21.2%), respectively. In multivariate analysis, RTOG RPA Class III, lymphopenia (≤0.7 × 10⁹/L) and HR negative status were independent prognostic factors for poor survival. We constructed a three-factor prognostic scoring system that predicts 6-month and 1-year rates of overall survival in the range of 76.1-29.5% (p = 0.00033) and 60.9-15.9% (p = 0.0011), respectively, with median survival of 15 months, 5 months, or 3 months for patients with none, one, or more than one adverse prognostic factor(s), respectively. Conclusions: This study confirms the prognostic value of the RTOG RPA classification, lymphopenia, and tumor HR status, which can be used to form a prognostic score for patients with BM from breast carcinoma.