Both Anti-HER2 Treatment and Chemotherapy After Whole-Brain Radiation Therapy Improve Survival in Patients With Brain Metastases From HER2-Positive Breast Cancer

Abstract

Whole brain radiation therapy (WBRT) remains the most widely used treatment for brain metastasis (BM) from breast cancer (BC), especially for pts with multiple intracranial lesions. Growing evidence has suggested that systemic treatment can improve survival in addition to WBRT. The purpose of this study is to evaluate the role of post-WBRT anti-HER2 and other systemic treatments on survival after BM from Her-2 positive BC. A total of 54 pts with BM from HER2-positive BC treated with WBRT in single institute between January 2006 and February 2012 was retrospectively analyzed, 42 pts (77.8%) had multiple lesions. The brain was the first metastatic site for 15 pts (27.8%). Post-WBRT anti-HER2 treatment was given in 21 pts (38.9%), 9 pts received trastuzumab, 9 pts received lapatinib and the other 3 received both trastuzumab and lapatinib. Post-WBRT chemotherapy was given in 39 pts, 19 in combination with anti-HER2 treatment. Prognostic analysis was performed including age at BM, KPS/RPA, ER/PR status, number of BM, interval between BC diagnosis and BM, presence of extracranial metastases, extracranial metastases control, chemotherapy after WBRT and anti-HER2 treatment after WBRT. Radiation dose of EQD2 ≤40 Gy (α/ß = 4.6 Gy) was given in 26 pts (74.3%). The median interval from diagnosis of BC to the identification of BM was 29 months (range, 2-136 months). In univariate analysis, age, KPS/RPA classes, number of BM, extracranial metastases control, chemotherapy after WBRT and anti-HER2 treatment after WBRT were significant prognostic factors for overall survival (OS) (p < 0.05). While in multivariate analysis, extracranial metastases control, chemotherapy after WBRT and anti-HER2 treatment after WBRT were significant prognostic factors for OS. No impact of radiation doses and ER/PR status on OS were found. The median survival for the whole group was 12 months, which was 21 and 9 months, respectively (p = 0.004) in pts with and without anti-HER2 treatment after WBRT, 16 and 6 months in pts with and without chemotherapy (p < 0.001). In our retrospective study, both anti-HER2 treatment and chemotherapy after WBRT were found to improve survival in pts with BM from HER2-positive BC.