The IASLC Lung Cancer Staging Project: proposals for the revision of the N descriptors in the forthcoming seventh edition of the TNM classification for lung cancer

J Thorac Oncol. 2007 Jul;2(7):603-12. doi: 10.1097/JTO.0b013e31807ec803.


Introduction: Accurate staging of lymph node involvement is a critical aspect of the initial management of nonmetastatic non-small cell lung cancer (NSCLC). We sought to determine whether the current N descriptors should be maintained or revised for the next edition of the international lung cancer staging system.

Methods: A retrospective international lung cancer database was developed and analyzed. Anatomical location of lymph node involvement was defined by the Naruke (for Japanese data) and American Thoracic Society (for non-Japanese data) nodal maps. Survival was calculated by the Kaplan-Meier method, and prognostic groups were assessed by Cox regression analysis.

Results: Current N0 to N3 descriptors defined distinct prognostic groups for both clinical and pathologic staging. Exploratory analyses indicated that lymph node stations could be grouped together into six "zones": peripheral or hilar for N1, and upper or lower mediastinal, aortopulmonary, and subcarinal for N2 nodes. Among patients undergoing resection without induction therapy, there were three distinct prognostic groups: single-zone N1, multiple-zone N1 or single N2, and multiple-zone N2 disease. Nevertheless, there were insufficient data to determine whether the N descriptors should be subdivided (e.g., N1a, N1b, N2a, N2b).

Conclusions: Current N descriptors should be maintained in the NSCLC staging system. Prospective studies are needed to validate amalgamating lymph node stations into zones and subdividing N descriptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Non-Small-Cell Lung / classification*
  • Carcinoma, Non-Small-Cell Lung / mortality
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Global Health
  • Humans
  • International Cooperation*
  • Lung Neoplasms / classification*
  • Lung Neoplasms / mortality
  • Lung Neoplasms / pathology
  • Neoplasm Staging / methods*
  • Retrospective Studies
  • Severity of Illness Index
  • Societies, Medical*
  • Survival Rate / trends