Comparison of initial and sequential salvage brain-directed treatment in patients with 1–4 vs. 5–10 brain metastases from breast cancer (KROG 16–12)

Purpose: We aimed to compare the initial and salvage brain-directed treatment and overall survival (OS) between patients with 1–4 brain metastases (BMs) and those with 5–10 from breast cancer (BC). We also organized a decision tree to select the initial whole-brain radiotherapy (WBRT) for these patients. Methods: Between 2008 and 2014, 471 patients were diagnosed with 1–10 BMs. They were divided into two groups based on the number of BM: 1–4 BMs (n = 337) and 5–10 BMs (n = 134). Median follow-up duration was 14.0 months. Results: Stereotactic radiosurgery (SRS)/fractionated stereotactic radiotherapy (FSRT) was the most common treatment modality (n = 120, 36%) in the 1–4 BMs group. In contrast, 80% (n = 107) of patients with 5–10 BMs were treated with WBRT. The median OS of the entire cohort, 1–4 BMs, and 5–10 BMs was 18.0, 20.9, and 13.9 months, respectively. In the multivariate analysis, the number of BM and WBRT were not associated with OS, whereas triple-negative BC and extracranial metastasis decreased OS. Physicians determined the initial WBRT based on four variables in the following order: number and location of BM, primary tumor control, and performance status. Salvage brain-directed treatment (n = 184), mainly SRS/FSRT (n = 109, 59%), prolonged OS by a median of 14.3 months. Conclusion: The initial brain-directed treatment differed notably according to the number of BM, which was chosen based on four clinical factors. In patients with ≤ 10 BMs, the number of BM and WBRT did not affect OS. The major salvage brain-directed treatment modality was SRS/FSRT and increased OS.