Objective: This study was conducted to assess the validity of the pending suggestions for N descriptors by the International Association for the Study of Lung Cancer.
Methods: Medical 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).
Results: The 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.
Conclusion: Amalgamating 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.