OBJECTIVES Our study aimed to determine the predictive and prognostic values of the serum neuron-specific enolase (NSE) level in patients who had non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and who had been treated with EGFR-tyrosine kinase inhibitors (TKIs).

MATERIALS AND METHODS We retrospectively analyzed 151 patients who had NSCLC harboring EGFR mutations and had received either gefitinib or erlotinib as first-line treatment between 2005 and 2014. The serum NSE level was measured before initiation of EGFR-TKI treatment.

RESULTS Of the 151 patients, 92 (60.9%) had elevated NSE levels (> 16.3 ng/mL). Patients with elevated NSE levels showed significantly shorter progression-free survival (PFS) after EGFR-TKI treatment than those with normal NSE levels (median PFS, 10.5 months vs. 15.4 months; P = .034). Multivariate analysis demonstrated that elevated NSE levels (hazard ratio [HR], 1.656; P = .017), CNS metastasis at diagnosis (HR, 1.567; P = .037), and male gender (HR, 1.840; P = .005) were independent predictive factors for short PFS. A significant difference in overall survival (OS) was observed between patient groups with elevated and normal NSE levels (median OS, 17.0 months vs. 29.1 months; P < .001), and serum NSE level remained an independent prognostic factor for OS in multivariate analysis (HR, 2.671; P < .001).

CONCLUSION Patients with elevated serum NSE levels have significantly shorter PFS and OS. The NSE level is both a predictive marker of EGFR-TKI treatment and a prognostic marker in EGFR-mutant NSCLC patients.