Which is the better prognostic factor for resected non-small cell lung cancer: the number of metastatic lymph nodes or the currently used nodal stage classification?

This retrospective study was conducted to evaluate the prognostic significance of the number of metastatic lymph nodes (nN) in resected non-small cell lung cancer (NSCLC) in comparison with the currently used pathologic nodal (pN) category in the staging system.A total of 1659 patients who underwent potentially curative resection for NSCLC from 2000 to 2006 were included in this study. The association between the nN and survival was explored, and the results were compared with those using the location-based pN stage classification.The patients were divided into four categories according to the number of metastatic nodes: nN0, absence of metastatic nodes; nN1, metastasis in one to two nodes; nN2, metastasis in three to six nodes; and nN3, metastasis in seven or more nodes. The 5-year overall survival for nN0, nN1, nN2, and nN3 was 89.2%, 65.1%, 42.1%, and 22.4%, respectively (p < 0.001). The nN category could be used to subdivide pN1 and pN2 patients into two (nN1 and nN2) and three (nN1, nN2, and nN3) prognostically distinct subgroups, respectively. Multivariate analysis showed the nN category was an independent prognostic factor for resected NSCLC. The difference in overall survival between pN1 and pN2 was not significant (55.4% versus 47.8%, p = 0.245). Patients in each nN category could not be subdivided into different prognostic subgroups according to the pN classification.The nN category in this study was shown to be a better prognostic determinant than the location-based pN stage classification.