Sublobar resection is more beneficial than lobar resection in elderly patients with contralateral metachronous second primary lung cancer: an analysis based on the SEER database.

Background: The optimal surgical approach for treating stage I second primary lung cancer (SPLC) in elderly patients with a history of lobar resection remains uncertain. To address this knowledge gap, we conducted a comparative analysis of lobar resection versus sublobar resection outcomes in elderly patients diagnosed with contralateral stage I SPLC, utilizing population-based databases. Methods: We identified elderly patients diagnosed with T1-2N0M0 SPLC from the Surveillance, Epidemiology, and End Results (SEER) database (2008-2015) who had undergone prior lobar resection for their first primary lung cancer. To ensure accurate classification of SPLC, we applied the Martini and Melamed criteria, which distinguish multiple primary lung cancers based on histologic and anatomic features. Survival outcomes were compared using Kaplan-Meier analysis and multivariable Cox proportional hazards regression. To mitigate potential confounding factors, we constructed a matched cohort through propensity score matching (PSM), balancing baseline characteristics between the lobar and sublobar resection groups. Results: A total of 373 patients met the inclusion criteria, comprising 253 in the sublobar resection group and 120 in the lobar resection group. Following PSM, 297 patients were retained for analysis. The analysis revealed that sublobar resection was associated with significantly improved overall survival (OS) compared to lobar resection in elderly patients with contralateral SPLC, with 5-year OS rates of 43.4% versus 34.3% (P=0.03). Conclusions: For elderly patients with contralateral SPLC, sublobar resection is better than lobar resection.