EGFR Mutation–Positive Unresectable Stage III Non-Squamous Lung Cancer Is Associated with a High Incidence of Brain Metastasis

Abstract

Purpose The impact of epidermal growth factor receptor (<i>EGFR</i>) mutation in locally advanced non–small cell lung cancer (NSCLC) remains controversial. This study was conducted to investigate the clinical outcomes and recurrence patterns after definitive chemoradiotherapy (CRT) in patients with unresectable stage III non-squamous-cell lung cancer according to <i>EGFR</i> mutation status.Materials and Methods We retrospectively reviewed 604 patients with pathologically confirmed stage III NSCLC who were treated with definitive CRT and were examined for <i>EGFR</i> mutation at Samsung Medical Center, Korea, from January 2013 to December 2018. Among them, we identified 236 patients with stage III non-squamous-cell lung cancer who were treated with definitive CRT and were examined for <i>EGFR</i> mutation status. We analyzed the frequency of <i>EGFR</i> mutation, progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and recurrence pattern.Results Among 236 patients, <i>EGFR</i> mutation was detected in 71 patients (30.1%) and the median follow-up duration was 41.7 months. There were no significant differences in PFS (9.9 vs. 10.9 months, p=0.236), and ORR to CRT (93.0% vs. 90.3%, p=0.623) according to <i>EGFR</i> mutation status. However, the <i>EGFR</i> mutant group showed significantly higher recurrence (88.7% vs. 75.2%, p=0.022), distant metastasis (76.1% vs. 61.2%, p=0.036) rates, especially brain (38.0% vs. 12.7%, p < 0.001), and better median OS (59.2 vs. 41.3 months, p=0.037) compared with patients without <i>EGFR</i> mutation.Conclusion Patients with <i>EGFR</i> mutation–positive unresectable stage III non-squamous lung cancer exhibited higher recurrence and distant metastasis rates, especially brain metastasis.