Staging systems of lung cancer.

The staging of lung cancer involves assessment of the anatomic extent of disease based on the best available data. Such a definition of neoplastic burden facilitates the systematic analysis and meaningful communication of diagnostic, therapeutic, and prognostic information. Clinical staging involves the best estimate of extent of disease before performance of surgical resection or biopsy procedures (or both). Surgical-pathologic staging is based on the histopathologic analysis of resected specimens, including determining the extent of local and regional disease. During the past 50 years, two major classification schemes for staging of lung cancer have evolved--one for non-small-cell lung cancers (the TNM system, indicating the status of primary tumor [T], regional lymph node [N], and metastatic [M] involvement) and the other for small-cell carcinoma of the lung (based on limited versus extensive disease). In this report, we review the evolution of the current staging systems used for primary lung cancer and their prognostic implications.