Brain metastases (BM) are a significant cause of morbidity and mortality. Advancement of systemic therapies for patients with BC has improved control of extra-cranial metastases and survival. Intracranial control however continues to be challenging. SRT has been shown to provide excellent local control (LC) with minimal toxicity, although breast specific data is comparatively lacking.
This study aims to describe outcomes of first SRT including LC, distant brain control (DC), time to intracranial progression (TTP) and overall survival (OS) in a cohort of patients with BC who received SRT from 2001 to 2016 at the Royal Marsden Hospital. Kaplan Meier and log-rank methods were used for statistical analysis.
64 patients underwent SRT for 129 BM. Median age was 52.4 years. 58 (91%) were ECOG 0/1. 18 (28%) were hormone receptor positive (HR+)/HER-2 negative, 38 (59%) were HER-2 enriched (HER-2+), and 8 (13%) were triple negative (TN). The median number of BM treated with SRT was 1 (range 1 - 12). Median dose and range was 20 Gy (12 – 35 Gy) in 1 fraction (1 – 10). 29 (45%) were treated using a linear accelerator, 34 (53%) with CyberKnife and 1 with GammaKnife. 27 (42%) had prior whole or partial brain radiotherapy (WBRT). 21 (33%) had prior surgery. 30 (49%) had concurrent endocrine therapy, 25 (40%) had targeted therapy and 8 (13%) had chemotherapy. Follow-up imaging was available for 57 patients. Median follow up was 15 months. 1 year LC was 54% and DC was 56%. Median TTP was 7.1 months (95%CI: 6.1 – 10.8) and was significantly worse for TN compared to HER-2+ patients (5.3 vs 9.9 months, p = 0.046). Salvage radiotherapy or surgery was performed after SRT in 13 (23%) patients for local failure, and 20 (35%) for distant failure. 7 (12%) patients had radionecrosis following SRT. OS from SRT was 19.6 months (95%CI: 14.9 – 23.1), and was significantly worse for TN patients (13.6 vs 22.1 months, p = 0.003), age ≥ 60 years (14.9 vs 19.8 months, p = 0.028) and multiple brain metastases (14.0 vs 22.6 months, p = 0.010).
Outcomes in patients with BC and BM treated with SRT are excellent overall. Outcomes are worse in TN disease, older patients and patients with multiple BM, and should be considered in SRT decision making.
Clinical trial identification
Legal entity responsible for the study
The Royal Marsden NHS Foundation Trust
The Royal Marsden NHS Foundation Trust/Ross Smith Cridlan Trust
All authors have declared no conflicts of interest.