Enhanced Survival with Lymphadenectomy in Early-Stage Metachronous Second Primary Lung Cancer: A Retrospective Analysis

Introduction: Lymphadenectomy is a cornerstone in the surgical management of resectable primary lung cancer. However, its prognostic significance in early-stage metachronous second primary lung cancer (MSPLC) remains poorly understood. This retrospective study aimed to evaluate the prognostic impact of lymphadenectomy in these patients using data from the Surveillance, Epidemiology, and End Results (SEER) Database. Methods: A retrospective cohort study was conducted using data from the SEER Database for patients surgically treated for stage I MSPLC between 2004 and 2015. Propensity score-matching was employed to create comparable cohorts, and the Cox proportional hazards model was utilized to estimate the hazard ratio (HR) for overall survival after lymphadenectomy compared to non-lymphadenectomy. Survival analysis was performed using Kaplan-Meier curves and the log-rank test. Results: Among 920 identified patients with MSPLC, 574 (62.4%) underwent lymphadenectomy. Propensity score-matching yielded 255 patients in both the lymphadenectomy and non-lymphadenectomy groups. Over a median follow-up of 38 months, the 5-year overall survival probability after a diagnosis of MSPLC was 58.7% in the lymphadenectomy group and 43.9% in the non-lymphadenectomy group (HR: 0.76; 95% confidence interval 0.64-0.90; p = 0.002). Conclusion: In this population-based study, lymphadenectomy is associated with prolonged overall survival in patients with stage I MSPLC. These findings suggest the potential benefit of incorporating lymphadenectomy into the surgical management of MSPLC, providing valuable guidance for thoracic surgeons in clinical decision-making.