Effects of Whole-brain Radiotherapy Combined with Targeted Therapy on Improving Survival of HER2-positive Breast Cancer Patients with Brain Metastases

Objective To investigate if the whole-brain radiation therapy (WBRT) and targeted therapy (TTx) have the enhanced effect on improving overall survival (OS) and intracranial tumor control measured indirectly by progression-free survival (PFS) in HER2-positive breast cancer brain metastases (BCBM) patients.

Methods We conducted a retrospective analysis of 39 female HER2-positive BCBM patients admitted in 2013-2015 and followed up till December 1st, 2016.WBRT was defined as ≥20 Gy and all TTx were initiated before WBRT.Kaplan-Meier curves and multivariate Cox regression models were used for analyzing OS and PFS.

Results Average age was 52 years old; 46% patients were with ≥4 BM lesions, 64% with ER/PR+, 74% with high Ki-67 expression(≥14%); 18(46%) patients received WBRT and 15(38%) received TTx.One-year mortality was 47% and treatment failure (death or new/relapsed BM) rate was 58%.Median survival time (MST) of OS and PFS were 13.3 and 10.1 months, respectively.Multivariate adjusted HR (P) of WBRT were 0.170 (0.002) for OS and 0.107 for PFS(P < 0.001).The number (median OS) of patients who received WBRT & TTx, TTx alone, WBRT alone and neither were 8(15.1), 7(14.7), 10(17.6) and 14(4.3), respectively.Their multivariate adjusted HR(P) for OS were 0.049(P < 0.001), 0.243(0.077), 0.154 (0.007) and 1.000 (ref.), respectively.The analysis on PFS had similar results.

Conclusion WBRT and targeted therapy have the enhanced effect on improving OS and PFS of HER2-positive BCBM patients.