Abstract
Introduction: In the ninth edition of the TNM staging system, the new nodal involvement (N) subcategories to N2 for single-station involvement (N2a) and multiple-station involvement (N2b) have been adopted. Although there are significant differences in survival rates for each group of pN categories in the ninth edition, it can be assumed that survival rates in pN1 and pN2a are relatively similar. Methods: We retrospectively evaluated the utility of the new category by number of stations such as none, single station, and multiple station for pN in 1,000 NSCLC patients treated by pulmonary resection. Result: Survival rates were significantly different among none, single station, and multiple station (5-year RFS: none: 79.6%, single station: 47.3%, multiple station: 24.2%, all groups, p < 0.01; 8-year OS: none: 78.7%, single station: 65.2%, multiple station: 33.6%, all groups, p < 0.01). There were significant differences among each group categorized by number of pN station in multivariate analysis for RFS (none vs. single station: p < 0.01, none vs. multiple station: p < 0.01, single station vs. multiple station: p < 0.01). There were significant differences among each group categorized by number of pN station in multivariate analysis for OS (none vs. single station: p = 0.04, none vs. multiple station: p < 0.01, single station vs. multiple station: p < 0.01). Conclusion: There were significant differences among none, single station, and multiple station in each survival curve and in multivariate analysis for both RFS and OS. This category by number of pN station without dependence of location for lymph nodal involvement might be the new classification of lymph node involvement.
