EGFR mutation status on brain metastases from non-small cell lung cancer

Abstract

Objectives: The purpose of this study was to examine the impact of EGFR mutations on the incidence of brain metastases in patients with advanced non-small cell lung cancer (NSCLC).

Materials and methods: A retrospective, population-based study was conducted using a provincial cancer registry to identify patients with metastatic NSCLC. Patients with diagnostic EGFR mutation testing were divided into EGFR mutation positive (EGFR+) and EGFR wild type (WT) cohorts. The primary endpoint was the incidence of brain metastases. Cumulative incidence curves were estimated using the competing risk method. The secondary endpoint was overall survival.

Results: For 543 patients there were 121 EGFR+ and 422 EGFR WT. The cumulative incidence of brain metastases was 39.2% for EGFR+ patients compared to 28.2% for EGFR WT (p=0.038; HR 1.4). In multivariate analysis, younger age and EGFR+ status were significant factors for developing brain metastases. The median survival for the EGFR+ and EGFR WT cohorts were 22.4 and 7.9 months (p<0.001), respectively. In multivariate analysis, poor performance status and brain metastases were factors significant for worse survival.

Conclusions: There is a higher incidence of brain metastases for patients with EGFR+ metastatic NSCLC, even when adjusted for differences in survival, compared to EGFR WT. For patients with and without brain metastases, survival prognosis with stage IV NSCLC is much longer with EGFR+ disease.

Keywords: Brain metastases; Chemotherapy; EGFR; Lung cancer; TKI.