To compare to the effect of early systemic disease progression (EP) vs. non-early progression (NEP) on central nervous system (CNS) failure-free survival (cFFS) and overall survival (OS) after stereotactic radiosurgery (SRS) among breast cancer patients with brain metastasis.

Breast cancer brain metastases are not uncommon and are associated with poor prognosis. Previous work has investigated the factors associated with the failure of CNS disease control after SRS to brain metastases, but have been limited by inclusion of various tumor types. Moreover, previous work has assessed the systemic disease status at the time of SRS. As the CNS failure events occur after SRS in these studies, it is essential to have a more dynamic assessment of systemic disease status after and not at the time of the SRS administration.

This single institution retrospective study included 104 breast cancer brain metastasis patients who received brain SRS. cFFS and OS were analyzed from two predefined Landmarks (LM): LM1 (3-months), LM2 (6-months). Patients were categorized into early and non-early progression (EP, NEP) groups depending on systemic disease status before LMs.

Early progression (EP) was associated with worse median cFFS and OS vs non-early progression (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 progression after SRS is associated with worse cFFS and OS in patients with brain metastasis from breast cancer.