Leptomeningeal failure in patients with breast cancer receiving stereotactic radiosurgery for brain metastases

Purpose: Prior studies suggest a high incidence of leptomeningeal failure (LMF) in breast cancer metastatic to brain. This study examines breast cancer-specific variables affecting development of LMF and survival after Gamma-Knife Radiosurgery (GKS). Methods: Between 2000-2010, 149 (breast) and 658 other-histology patients were treated with GKS. Hormone/HER2, age, local/distant brain failure, prior craniotomy, and prior whole-brain radiotherapy (WBRT) were assessed. Median follow-up was 54 months (range, 0-106). Serial MRI determined local and distant-brain failure and LMF. Statistical analysis with categorical/continuous data comparisons were done with Fisher's-exact, Wilcoxon rank-sum, log-rank tests, and Cox-Proportional Hazard models. Results: Of 149 patients, 21 (14%) developed LMF (median time of 11.9 months). None of the following predicted for LMF: Her2-status (HR = 0.49, p = 0.16), hormone-receptor status (HR = 1.15, p = 0.79), prior craniotomy (HR = 1.58, p = 0.42), prior WBRT (HR = 1.36, p = 0.55). Non-significant factors between patients that did (n = 21) and did not (n = 106) develop LMF included neurologic death (p = 0.34) and median survival (8.6 vs 14.2 months, respectively). Breast patients who had distant-failure after GKS (65/149; 43.6%) were more likely to later develop LMF (HR 4.2, p = 0.005); including 15/65 (23%) patients who had distant-failure and developed LMF. Median time-to-death for patients experiencing LMF was 6.1 months (IQR 3.4-7.8) from onset of LMF. Median survival from LMF to death was much longer in breast (6.1 months) than in other (1.7 months) histologies Conclusion: Breast cancer patients had a longer survival after diagnosis of LMF versus other histologies. Neither ER/PR/HER2 status, nor prior surgery or prior WBRT predicted for development of LMF in breast patients. (C) 2017 Elsevier Ltd. All rights reserved.