In lung cancer, the stage of the disease at the time of diagnosis is a major factor in determining how to treat the cancer, and how long the patient can expect to live. In general, survival is longest for patients with very early-stage disease and shortest for patients with very advanced disease that has spread to several areas of the body. However, some groupings with very different clinical features can have similar prognosis. Staging is based on the results of physical and surgical examinations, and laboratory and imaging tests, including biopsies.
To determine the stage, medical professionals first categorize each tumor by size and by how far it has extended. This identification method is called the TNM system.
The TNM categories then determine the stage (numbered 0 to IV) of the cancer.
The International Association for the Study of Lung Cancer recently revised the non-small cell lung cancer staging system in 2009. Extensive analysis was performed on an international database. The major staging categories remain the same, while additonal subgroupings within the T, N, and M descriptors were added.
The TNM System
TNM stands for Tumor, regional lymph Nodes, and Metastasis (cancer spread beyond the original tumor).
T refers to the size and spread of the tumor. In TX and T0, the tumor is either unable to be assessed or indicated by cancer cells in sputum or lung samples but it cannot be seen.
Tis: Carcinoma in situ. The cells are cancerous, but the tumor does not show evidence of spreading.
In T1, the tumor is 3 cm or less in size, is still contained in the lung or the membrane covering the lung, and has not reached the main airway. In T1a, the tumor is less than or equal to 2 cm and in T1b, the tumor is greater than 2 cm but less than or equal to 3 cm in diameter.
Review Date: 07/01/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.