Recently, I attended a unique event made possible by the International Association for the Study of Lung Cancer that I was excited to participate in.
It was a review of the TNM (Tumor, Node, and Metastases) staging system for lung cancer with its relevance to clinical situations. There was a small group of oncology professionals present, which was nice because it allowed us to ask questions, and the speaker had enough time to address them all.
As you know, in oncology, staging is important to determine the location and extent of disease. Often, staging is a part of the overall cancer diagnosis and a very important part, too, because it often determines treatment course and prognostic value.
The TNM staging system is used for most solid cancer and was designed in order to provide a common and consistent language as well as a defined process for all clinicians to use in the identification, care, and treatment of cancer.
This system has been used since the 1970s, and is currently maintained and updated by the American Joint Committee of Cancer (AJCC) and the International Union Against Cancer.
Many more updates are planned as we learn more about the molecular markers in cancer and the identification of new markers. There is also discussion about incorporating all aspects that encompass a cancer diagnosis into the TNM staging system, including clinical, radiologic, pathologic, biologic, and molecular features to further provide a truly all-encompassing and comprehensive staging system. I often wonder if one day we will also include gender, race, and other genetic components.
Overall, the tumor (T) size is where many changes occurred, causing staging to either be staged “down” or “up.” For example, T1 was subdivided into T1a and T1b. T2 was subdivided into T2a and T2b. The description to T3 was modified to include a tumor of >7cm or phrenic nerve, or parietal pericardium invasion or diaphragmatic invasion. No node (N) changes were made with this seventh edition. And the M1 category was subdivided into M1a and M1b.
Some of the advantages of TNM-7 and its clinical implications were interesting:
- It more accurately reflects the survival and prognosis of patients with varying types of NSCLC.
- It reinforces tumor size is crucial to prognosis with better-defined size points.
- Differentiates more clearly between early stages of lung cancer.
- Validates past recommendations.
Of course, limitations were also disclosed:
- The analysis was completed in a retrospective manner.
- There were no changes in nodal staging.
- Migration of some of the new stage groups may now blur previous established guidelines for patient management and treatment.
- PET scans are not part of the staging system yet.
The next edition, the eighth edition, will be based on prospective data and is expected to be released in 2016. Some of the information that may be examined or included in this next update:
- More direction on nodal location, number, and size.
- Genetics may start to be incorporated.
- New imaging techniques (i.e. PET scan versus CT scan alone) may be included.
- Prognostic impact for the histologic type and grade.
- Additional information on the impact of the pleural invasion on T (tumor) stages.
Posters are available for a quick reference, along with an app for your smartphone or tablet, which may help to build your knowledge and also help you to keep up with the changes in the area of lung cancer.
How often to you refer to the AJCC Cancer Staging Handbook? Do you find the resources and the updates helpful?
- A Review of the TNM Staging System Seventh Edition for Lung Cancer and Its Clinical Relevance presentation. Presented on September 11, 2013. Information provided by the International Association for the Study of Lung Cancer.
- Gobel, B.H., Triest-Robertson, S. and Vogel, W.H. (2009). Advanced Oncology Nursing Certification Review and Resource Manual. Pages 653-654. Oncology Publishing Division of the Oncology Nursing Society, Pittsburgh, PA.