Propensity-Matched Analysis of Clinical Relevance of the Highest Mediastinal Lymph Node Metastasis

The clinical relevance of the highest mediastinal lymph node (HMLL) metastasis in patients with pathological N2 non-small cell lung cancer (NSCLC) is still controversial. Our study aimed to reassess the effect of HMLL metastasis on survival.

Patients with stage pT1-4N2M0 NSCLC who underwent major lung resection and systemic lymphadenectomy at Peking University People's Hospital from 2004 to 2015 were identified. Patients in the HMLL-positive group were matched to patients in the HMLL-negative group using 1:1 propensity score matching analysis. Overall survival was estimated by Kaplan-Meier method and compared using log-rank test, and multivariable Cox proportional hazard regression was constructed to identify risk factors associated with overall survival. The cumulative incidence of cancer specific mortality was evaluated through a competing risk analysis.

A total of 266 NSCLC patients with stage pT1-4N2M0 NSCLC were enrolled. Of those, 128 cases were HMLL positive and 138 cases were HMLL negative. A higher proportion of patients in the HMLL-positive group were female (P = .034) and had a higher rate of adenocarcinoma (P = .003). Compared with the HMLL-negative, the HMLL-positive group was not associated with worse survival in unmatched cohorts (adjusted hazard ratio = 1.21; 95% confidence interval, 0.87-1.68). After propensity score matching, 109 pairs were selected. No survival difference remained in matched cohorts (adjusted hazard ratio = 1.00; 95% confidence interval, 0.70-1.42).

Highest mediastinal lymph node metastasis does not exhibit worse survival in patients with stage pT1-4N2M0 NSCLC. The clinical relevance of HMLL metastasis needs further examination.