The utility of the new category by number of stations for lymph nodal involvement in non-small cell lung cancer

Abstract Purpose In the nineth edition of the TNM staging system, the new nodal involvement (N) subcategories to N2 for single-station involvement (N2a) and multiple-station involvement (N2b) has been adopted Although there are significant differences in survival rates for each group of pN categories in the nineth 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 1000 NSCLC patients treated by pulmonary resection. Result Survival rates were significantly different in 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 < .01, None vs Multiple station; P < .01, Single station vs Multiple station; P < .01). There were significant differences among each group categorized by number of pN station in multivariate analysis for OS (None vs Single station; P = .04, None vs Multiple station; P < .01, Single station vs Multiple station; P < .01). Conclusion There were significant differences among None, Single station, and Multiple station in each survival curves, 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. Trial registration The Institutional Review Board of Kanazawa Medical University approved the protocol of this retrospective study (approval number: I392), and written informed consent was obtained from all patients