Key Points

• The common patterns of lymphatic drainage and metastasis must be recognized so that the principles of surgical staging can be applied properly.
• Familiarity with the various revisions of the staging system is necessary to correctly report new data and interpret published results.
• Complete mediastinal lymph node dissection or systematic sampling should be performed in all patients undergoing curative surgery. Either procedure can be performed easily with no increase in operative morbidity.

Intraoperative mediastinal and hilar lymph nodal staging is an essential component of the surgical treatment of lung cancer. Although the “T” category of the primary tumor is readily apparent to both surgeon and pathologist, the presence or absence of tumor within the intrathoracic lymph nodes is frequently not obvious. Indeed, the lymph nodes themselves may not be apparent and must be diligently sought. Microscopic assessment is required to determine accurately the “N” status. Furthermore, because histologic staging is completely dependent on the material submitted during the operative procedure, the surgeon must accurately identify and properly label the requisite specimens.

Knowledge of lung cancer metastatic patterns provides the rationale for lymph node dissection. Lymph node level definitions and lymph node dissection techniques are best appreciated in their anatomic and historical perspectives. Finally, the utility of mediastinal lymph node dissection can be fully comprehended only through review of the accompanying risks and benefits.