RADI-17. Outcomes for patients with triple negative breast cancer treated with upfront stereotactic radiosurgery for brain metastases

Abstract

Abstract Background Triple-negative breast cancer (TNBC) is an aggressive subtype with high propensity of developing brain metastases (BM). Clinical outcomes and prognostic factors after stereotactic radiosurgery (SRS) for BM were not well defined. Methods We identified 57 consecutive TNBC patients (pts) treated with single fraction SRS for BM during 05/2008–04/2018. Overall survival (OS) from BM diagnosis and freedom from BM progression (FFBMP) after initial SRS were evaluated. BM progression was defined as local and/or distant brain failure (LBF, DBF) after SRS. Kaplan-Meier analyses and Cox proportional hazard regression were used to estimate survival outcomes and identify prognostic factors. Results The median time to BM development from TNBC diagnosis was 23.7 months (mo) (range 0.7‒271.1). Median OS was 13.1 mo (95%CI 8.0‒19.5). On univariate analysis, Karnofsky performance score (KPS) >70 (p=0.03), number of BMs <3 (p=0.016), and BM among the first metastatic sites (p=0.04) were associated with longer OS. On multivariate analysis, KPS ≤70 was associated with higher risk of death (HR 3.0, p=0.03). Of 46 pts with adequate imaging follow-up, 29 (63%) had intracranial progression with a median FFBMP of 7.4 mo (95% CI 5.7–12.7). At 12 mo the estimated cumulative DBF rate was 61.1% (95%CI 40.8%–74.4%) and LBF rate was 17.8% (95%CI 2%–31.1%). Number of BMs (≥3 vs <3) was not associated with FFBMP (p=0.7). Of the 29 pts with BM progression, additional radiation therapy (RT) (vs. no RT) was associated with improved survival (21.7 vs. 7.0 mo, p<0.0001). Conclusions TNBC pts with BM treated with SRS had an OS of 13.1 mo and FFBMP of 7.4 mo. Good KPS was an independent prognostic factor for OS. Further studies with more pts or conducted prospectively are needed to better understand and to improve treatment outcomes in this pt population.