Prognostic Analysis of Pathological Stage I Lung Adenocarcinoma Harboring Major EGFR Mutations

Background: While Epidermal growth factor receptor (EGFR) mutation-positive lung adenocarcinoma (LUAD) has favorable outcomes with targeted therapy, early-stage prognosis remains influenced by pathological factors and central nervous system (CNS) recurrence. The study aimed to clarify prognostic factors in pathological stage (pStage) I EGFR mutation-positive LUAD. Methods: Between 2015 and 2018, 2,191 pStage I LUAD cases with known EGFR status (excluding EGFR testing after recurrence) who received anatomical resection were included from multiple institutions in Japan. Univariate and multivariate analyses of disease-free survival (DFS) and overall survival (OS) were performed. Results: 1,073 (49.0%) cases harbored EGFR mutations, including 419 (19.1%) with 19del and 529 (24.1%) with L858R. In cases with major EGFR mutation (n = 948), multivariate analysis showed that the absence of noninvasive area (NIA) (hazard ratio [HR]: 1.778, 95% confidence interval [CI]: 1.174-2.692, P = .0065), pStage (IA2 vs. IA1, HR: 2.079, 95% CI: 1.129-3.827, P = .0345; IA3 vs. IA1, HR: 4.009, 95% CI: 2.088-7.696, P = .0001; IB vs. IA1, HR: 5.280, 95% CI: 2.871-9.709, P < .0001), and presence of lymphatic invasion (HR: 1.855, 95% CI: 1.103-3.119, P = .0197) were independent predictors of shorter DFS, and only advanced pStage was an independent predictor of CNS recurrence (relative risk for pStage IA3 or more: 9.729, P < .0001). Conclusion: In EGFR mutation-positive pStage I LUAD, those without NIA, with higher pStage and lymphatic invasion were independent predictive factors for DFS, and pStage ≥ IA3 was an independent predictor of CNS recurrence.