Effect of epidermal growth factor receptor mutation on early-stage non-small cell lung cancer according to the 8th TNM classification

Objective This study evaluated the effect of EGFR mutation on early-stage non-small cell lung cancer (NSCLC) based on the 8th TNM classification. Materials and methods The study retrospectively examined 1231 patients who underwent curative resection for pathological stage 0–I (8th TNM classification) NSCLC and EGFR mutation analysis from January 2006 to December 2018 at Kanagawa Cancer Center. The disease-free survival (DFS), overall survival (OS) and disease-specific survival (DSS) of EGFR-mutant lung cancer (Mt) and EGFR wild-type lung cancer (Wt) patients at each stage were compared between two patient groups using the log-rank test. Cox regression analyses were performed to identify prognostic factors. Results The number of stage 0, IA1, IA2, IA3, and IB Mt/Wt patients was 79/92, 202/189, 145/144, 45/75, and 74/186, respectively. There was no statistically significant difference in DFS between Mt and Wt patients at any pathological stage. The 5-year OS of Mt/Wt patients was 96.9 %/98.5 % for stage 0 (p = 0.671), 92.2 %/92.2 % for stage IA1 (p = 0.997), 93.9 %/82.6 % for stage IA2 (p = 0.039), 87.3 %/91.4 % for stage IA3 (p = 0.768), and 85.3 %/69.3 % for stage IB (p = 0.017). The 5-year DSS of Mt/Wt patients was 95.7 %/95.4 % for stage IA2 (p = 0.684) and 93.2 %/77.5 % for stage IB (p = 0.016). In Cox regression analyses, Mt was not identified as a prognostic factor for OS among stage IA2 NSCLC patients (HR, 0.62; 95 % CI, 0.20–1.93; p = 0.413). However, Mt was a favorable prognostic factor for OS (HR, 0.44; 95 % CI, 0.19–1.00; p = 0.049) and DSS (HR, 0.38; 95 % CI, 0.17–0.87; p = 0.022) among stage IB NSCLC patients. Conclusion EGFR mutation had no effect on the prognosis of stage 0–IA NSCLC but significantly affected the OS and DSS of stage IB NSCLC. Effect of EGFR mutations on postoperative prognosis of patients with stage 0–I NSCLC differed with each stage.