The analyses of the retrospective database of the International Association for the Study of Lung Cancer (IASLC), consisting of more than 81,000 evaluable patients diagnosed with lung cancer between 1990 and 2000, formed the basis of recommendations to the Union for International Cancer Control and the American Joint Committee on Cancer for the revision of the sixth edition of the tumor, node, and metastasis (TNM) classification of lung cancer. However, despite the large number of patients, not all descriptors could be validated.
