Abstract
The objective of the study is to assess impact of systemic disease (SD) status on overall survival and brain metastasis (BM) control, adopting a novel landmark approach to categorize SD among breast cancer (BC) patients. This single institution retrospective study included BCBM patients who have received stereotactic radiosurgery (SRS) to brain. Separate endpoints [CNS failure-free survival (cFFS), overall survival (OS)] were analyzed from each Landmark (LM): LM1 (3-months), LM2 (6-months). Patients were categorized into early and non-early progression (EP, NEP) groups depending on SD status before LMs. Median survivals from LM were assessed with Kaplan Meier plots, compared with Log-Rank test. EP was associated with worse median cFFS and OS vs NEP in both LM analyses (cFFS- LM1: 3.6 vs. 9.7 months, p = 0.0016; LM2: 2.3 vs. 12.5 months, p < 0.0001; OS- LM1: 3.6 vs. 24.3 months, p < 0.0001; LM2: 5.3 vs. 30.2 months, p < 0.0001). In multivariate analyses, EP was associated with shorter cFFS [LM1: Hazard Ratio (HR) with 95% confidence interval (CI) 3.16, 1.46-6.83, p = 0.0034; LM2: 5.32, 2.33-12.15, p = <0.0001] and shorter OS (LM1: HR with 95% CI 4.28, 1.98-9.12, p = 0.0002; LM2: 7.40, 3.10-17.63, p = <0.0001) vs NEP. Early systemic disease progressions after 1st SRS to brain is associated with worse cFFS and OS in patients with BCBM.