August 27, 2009 - The just-released 7th edition of the TNM (tumor, node, metastases) staging system for lung cancer will profoundly impact treatment decisions and patients' eligibility for clinical trials.
One in six lung cancer patients will receive a different staging category based on the 7th edition of the TNM staging system, reported Dr. Peter Goldstraw, chair of the staging project of the International Association for the Study of Lung Cancer (IASLC), at the association's World Conference on Lung Cancer.
Highlights of the new staging system for non-small cell lung cancer (NSCLC) include the following:
- New subcategories of stage T1 (early-stage) disease are based on size: Tumors measuring 2 cm or smaller will now be classified as T1a, whereas tumors larger than 2 cm and up to 3 cm will be classified as T1b. T2 disease will also be subdivided into T2a (tumors larger than 3 cm and up to 5 cm) and T2b (tumors larger than 5 cm and up to 7 cm).
- A new category (T3) will be used to describe tumors larger than 7 cm.
- Patients previously considered T4 because of additional tumor nodules in the same lung as the primary tumor will now be classified as T3. If these patients are node negative, they will be considered to have stage IIB disease.
- Patients with additional tumor nodules in the bilateral lung (previously M1) will now receive a designation of T4, and they will be down-staged from stage IV to stage IIIA.
- The presence of malignant pleural effusions, long referred to by oncologists as "wet IIIBs" and treated as if the patient had disseminated disease, will now be officially staged that way, as stage IV disease.
- Specifically, pleural dissemination will no longer be classified T4, but will now fall into a new category (M1a), the same designation given when additional nodules are found in the contralateral lung.
- Distant metastases will be subclassified within M1 as M1b disease.
- Staging changes will include the reclassification of patients with T2b tumors (5-7 cm) who have node-negative disease to stage IIA.
- Patients with T3 tumors (larger than 7 cm) will be considered to have stage IIB disease if they are node negative, but stage IIIA if they have associated features of M1, listed above.
The "N" classification within TNM that describes the number of involved lymph nodes will remain unchanged in the 7th edition.
The revisions to the TNM system are based on multidisciplinary contributions from the world lung cancer community, drawing on data compiled from more than 100,000 lung cancer cases from 46 centers in 19 countries. The IASLC led the revision effort, but both the International Union Against Cancer (UICC) and the American Joint Committee on Cancer (AJCC) have accepted the recommendations.
For more information: www.iaslc.org
April 17, 2024 
