Survival but not brain metastasis response relates to lung cancer mutation status after radiosurgery

Samuel M. Shin, Benjamin T. Cooper, Abraham Chachoua, James Butler, Bernadine Donahue, Joshua S. Silverman, Douglas Kondziolka

We prospectively addressed whether EGFR and KRAS mutations, EML4-ALK, ROS1 and RET rearrangements, or wild-type (WT), affects radiosurgery outcomes and overall survival (OS) in non-small cell lung cancer (NSCLC) patients with brain metastases (BM). Of 326 patients with BM treated in 2012-2014 with Gamma Knife radiosurgery (GKRS), 112 NSCLC patients received GKRS as their initial intracranial treatment. OS, intracranial progression-free survival, and time to intracranial failure were determined. Univariate and multivariate analysis were performed to determine factors affecting OS. Toxicity of treatment was evaluated. Median follow-up was 9 months. Patients with EGFR mutant BM had improved survival compared to WT. Median time to development of BM was higher in EGFR mutant patients, but this difference was not significant (2.2 vs 0.9 months; p = 0.2). Median time to distant brain failure was independent of EGFR mutation status. Karnofsky performance status (KPS), non-squamous histopathology, targeted therapy, systemic disease control, EGFR mutation, and low tumor volume were predictive of increased OS on univariate analysis. KPS (p = 0.001) and non-squamous histopathology (p = 0.03) continued to be significant on multivariate analysis. Patients with EGFR mutant BM underwent salvage treatment more often than those without (p = 0.04). Treatment-related toxicity was no different in patients treated with GKRS combined with targeted therapies versus GKRS alone (5 vs 7 %, p = 0.7). Patients with EGFR mutant BM had improved survival compared to a WT cohort. Intracranial disease control following radiosurgery was similar for all tumor subtypes. Radiosurgery is effective for BM and concurrent treatment with targeted therapy appears to be safe.