Validity of International Association for the Study of Lung Cancer Proposals for the Revision of N Descriptors in Lung Cancer

ObjectiveThis study was conducted to assess the validity of the pending suggestions for N descriptors by the International Association for the Study of Lung Cancer.MethodsMedical records from 1032 patients with non-small cell lung cancer who had pulmonary resection and proven stage I–III were retrospectively reviewed. Lymph node stations were grouped together into six “zones”: peripheral or hilar for N1 and upper or lower mediastinal, aortopulmonary, and subcarinal for N2. Survival was analyzed according to the proposed subdividing N descriptors: single-zone N1 (N1a), multizone N1 (N1b), single-zone N2 (N2a), and multizone N2 (N2b).ResultsThe 5-year survival rate was 63.8% for N0, 42.3% for N1a, 36.5% for N1b, 35.8% for N2a, and 17.4% for N2b. There were three distinct prognostic groups for N1 and N2 nodes: N1a, N1b or N2a, and N2b disease. In multivariate analysis, age, sex, type of surgery, T stage, and node status were independent prognostic factors. Hazard ratios versus N0 for N1a, N1b or N2b, N2b, and N3 were 1.577, 2.164, 3.291, and 5.897, respectively.ConclusionAmalgamating lymph node stations into zones and subdividing N descriptors described a significant stepwise deterioration of disease status. Although more studies are needed, the lymph node zone and subdivided N descriptors could be one of step for desirable approach of forthcoming tumor, node, metastasis classification in non-small cell lung cancer.