450PD Leptomeningeal metastases in non-small cell lung cancer patients with EGFR mutations

Abstract

INTRODUCTION Leptomeningeal metastases (LM) have increased in patients with non-small cell lung cancer (NSCLC), and prognostic factors and outcomes for LM with epidermal growth factor receptor (EGFR) mutations have not been well studied. METHODS We retrospectively analyzed lung cancer patients from January 2011 to June 2015 at our institute. Treatments and clinical outcomes of LM were reviewed. RESULTS Of 5,387 lung cancer patients, 184 (3.4%) were diagnosed with LM. Patients with LM harboring EGFR mutations (9.4%) were significantly more common than those with wild-type EGFR (1.7%; p < 0.001). The median overall survival (OS) after LM was 8.7 months (95% confidence interval [CI] = 7.3-10.1). Among 109 patients with common EGFR mutations, the 88 patients who received tyrosine kinase inhibitor (TKI) therapy demonstrated longer OS than those who did not (10.0 months vs. 3.3 months; p < 0.001), but 42 patients who underwent whole brain radiotherapy (WBRT) did not show longer OS than those without WBRT, and a combination of WBRT and TKIs did not add any survival benefit beyond those only receiving TKIs. A multivariate analysis indicated that TKI therapy (p < 0.001, hazard ratio [HR] = 0.218) was an independent predictor of favorable survival, while poor Eastern Cooperative Oncology Group performance status (p < 0.001, HR = 3.657) was a predictor of poor survival. CONCLUSIONS LM were much more frequent in NSCLC patients harboring EGFR mutations. EGFR-TKIs were the optimal treatment for LM, but active treatment with WBRT did not prolong OS for EGFR-mutated patients.