Mediastinal lymph-nodes metastasis beyond the lobe-specific: an independent risk factor toward worse prognoses.

PURPOSE Five-year survival rates were widely dispersed in pN2 non-small cell lung cancer (NSCLC). The present study aims to investigate the prognosis of patients with lymph node metastasis beyond lobe-specific mediastinal regions. METHODS A total of 654 pathologically proved N2-NSCLC patients were enrolled. All patients underwent a major pulmonary resection and radical mediastinal lymphadenectomy. Two separate groups were assigned according to the definition of lobe-specific nodal metastasis: Group LS (lobe-specific) and Group NLS (non-lobe-specific). Survival rates were calculated using Kaplan-Meier and Cox regression models. RESULTS There were 376 cases in Group LS and 278 cases in Group NLS. Univariate analyses showed that the risk factors of 5-year survival were operation type, MLN positivity ratio, nodal station, nodal zone, and LS/NLS metastasis. The 5-year survival among those in Group LS was significantly better than that of Group NLS (27.5% vs. 11.7%, p <0.0001). Multivariate analysis confirmed that the grouping method of LS/NLS and number of involved nodal zones were the most prominent risk factors for 5-year survival. CONCLUSION Lymph node metastasis beyond lobe-specific lymph nodes is an independent risk factor of 5-year survival and is associated with worse prognoses for N2 NSCLC patients.