From the Royal Brompton Hospital, Imperial College, London,; the Princess Margaret Hospital, Toronto, Ontario, Canada; and the Division of Thoracic Surgery, Department of Cardiothoracic Surgery, New York University School of Medicine, New York, NY
Authors’ disclosures of potential conflicts of interest are found at the end of this article.
Supported by a grant from the American Joint Committee for Cancer Staging and End Results Reporting.
Address reprint requests to Harvey I. Pass, MD, Division of Thoracic Surgery, Department of Cardiothoracic Surgery, New York University School of Medicine, 530 First Avenue, Suite 9V, New York, NY 10016; e-mail: harvey.pass{at}med.nyu.edu
Overview: Prior to the 1997 publication of a new international staging system for lung cancer, there were four editions of the tumor-node-metastasis classification system. The 1997 publication was founded on a database of 5,253 patients with non-small cell lung cancer (NSCLC), of which 4,351 were treated at the M.D. Anderson Cancer Center between 1975 and 1988. This system has been criticized because of the small size of the sample on which it is based, the inability to modify descriptors at a pace with advancing technology, the restricted geographic and institutional heterogeneity, the dominance of patients who were treated surgically, and the lack of validation. To address these shortcomings, the International Association for the Study of Lung Cancer (IASLC) established its Lung Cancer Staging Project in 1998. A total of 67,725 patients with NSCLC who were treated by all modalities of care between 1990 and 2000 from 46 sources in more than 19 countries were included. Recommendations for changes to the tumor, node, and metastasis descriptors led to the development of candidate stage groupings as a training subset, which were then tested in a validation subset. The suggestions for change included additional cutoffs for tumor sizes at 2, 5, and 7 cm, with tumors greater than 7 cm moving from T2 to T3; reassigning the category given to additional pulmonary nodules in some locations; and reclassifying pleural effusion as a metastasis descriptor. In addition, it was suggested that T2b N0 M0 cases be moved from stage IB to stage IIA, T2a N1 M0 cases from stage IIB to stage IIA, and T4 N0-1 M0 cases from stage IIIB to stage IIIA. Moreover, the proposals made by the IASLC for the forthcoming seventh edition of the tumor-node-metastasis system staging system confirmed the relevance of the tumor-node-metastasis system classification to small cell lung cancer (SCLC). The SCLC subcommittee of the IASLC Lung Cancer Staging Committee recommended that tumor-node-metastasis system staging be applied in SCLC and that stratification by tumor-node-metastasis system stage be incorporated into clinical trials in stages I to III of SCLC. The seventh edition of the tumor-node-metastasis system, Classification of Malignant Tumors, will incorporate these changes in 2009.
