Highest Mediastinal Lymph Node Metastasis Was Not an Independent Prognostic Factor in Pathological Stage N2 Non-Small Cell Lung Cancer

This study aimed to investigate the impact of the highest mediastinal lymph node (HMLN) metastasis on overall survival (OS) and disease-free survival (DFS) in patients with pathological stage N2 (pN2) non-small cell lung cancer (NSCLC).

Methods Patients with pN2 NSCLC treated between 2001 and 2014 were retrospectively included, while those with R1/R2 resection or insufficient lymph node dissection were excluded. Patients were categorized into two groups: Patients with pN2 NSCLC treated between 2001 and 2014 were retrospectively included, while those with R1/R2 resection or insufficient lymph node dissection were excluded. Patients were categorized into two groups: those with HMLN metastasis (HMLN⁺ group) and those without (HMLN^- group). The Kaplan-Meier method and Cox proportional hazards models were used to assess prognostic factors for OS and DFS. Propensity score matching (PSM) was employed to minimize selection bias.

Results The study included 332 patients, of whom 142 (42.8%) had HMLN metastasis. After PSM, 90 matched pairs were generated. Patients in the HMLN+ group were more likely to have adenocarcinoma (P = 0.002) and have pN2b disease (P < 0.001). Initially, the HMLN- group demonstrated significantly better OS and DFS than the HMLN+ group (OS: The study included 332 patients, of whom 142 (42.8%) had HMLN metastasis. After PSM, 90 matched pairs were generated. Patients in the HMLN⁺ group were more likely to have adenocarcinoma (P = 0.002) and have pN2b disease (P < 0.001). Initially, the HMLN^- group demonstrated significantly better OS and DFS than the HMLN⁺ group (OS: P = 0.017; DFS: P = 0.005). However, after PSM, no significant difference was observed between the groups (OS: P = 0.49; DFS: P = 0.33). Multivariable analysis confirmed that HMLN metastasis was not an independent prognostic factor for OS (P = 0.138) or DFS (P = 0.078).

HMLN metastasis was not an independent prognostic factor for OS or DFS in patients with stage N2 NSCLC. Patients with HMLN metastasis were more likely to have pN2b disease, which may account for the poorer survival observed in this group.