Mesothelioma Mesothelial Cells Stages

Like other cancers, stages of mesothelioma are assigned according to the cancer’s severity and the extent of its progression. With mesothelioma, life expectancy will vary depending on each of the stages of mesothelioma. This stage will affect your prognosis, and to what extent your cancer treatment is likely to be effective. A staging system has been developed only for pleural mesothelioma, as it is the most common type of mesothelioma.

Mesothelioma and the TNM Staging System

Cancers are most often staged according to the TNM classification system. The TNM staging system was developed by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (IUAC). TNM classification is divided into three components:

  • “T” refers to the primary tumor site (in pleural mesothelioma, the lungs).
  • “N” refers to spread to the surrounding lymph nodes. Lymph nodes are part of the immune system which aid in fighting infection, and are often the first place a cancer will spread.
  • “M” refers to distant metastasis, or spread of the cancer beyond surrounding lymph nodes to other parts or systems of the body.

Staging Pleural Mesothelioma - The TNM System

Numbers are added to these letters to further specify the extent of the cancer. The primary tumor can be classified into “T-groups,” from T1 to T4, indicating how far the primary tumor has spread. In the case of pleural malignant mesothelioma, the tumor may begin in the chest wall on one side (T1), and can spread to include such areas as:

  • Deeper tissue layers
  • Lung
  • Muscle
  • Pericardium (tissue surrounding the heart)
  • Ribs
  • Space between the lungs
  • Trachea.

Spread of the cancer to lymph nodes and other areas can also be further detailed. For example, N0 means no spread to lymph nodes, whereas N followed by a number (N1-N3) indicates lymph node involvement of increasing distance or severity. Distant metastasis is noted as either present or absent (M1 or M0).

The primary tumor site, lymph node involvement and distant metastasis are taken together to establish a stage from I (least severe) to IV (most severe):

  • Stage I: Mesothelioma is present in the mesothelium in the lungs.
  • Stage II: Mesothelioma has spread from the lining of the lungs to the actual lungs themselves, the diaphragm or the lungs’ outer lining.
  • Stage III: Mesothelioma has spread to the chest wall.
  • Stage IV: Mesothelioma has spread to other organs or lymph nodes.

Mesothelioma Prognosis

Prognosis is the term used to describe the projected outcome for an individual with a disease. Mesothelioma’s prognosis is determined in part by the stage of the cancer. The stage is determined through the collective results of a multitude of tests, including:

  • Biopsy (testing small tissue samples)
  • Imaging, such as MRI or CT scans
  • Physical exam and report of symptoms of mesothelioma.

Life expectancy varies from case to case, depending on the stage of the cancer, and how well it might respond to treatment. Early detection is important, as earlier cancer stages are less severe and generally more responsive to treatment.


American Cancer Society Staff. (n.d.). How is malignant mesothelioma staged? Retrieved December 29, 2009, from the American Cancer Society Web site:

American Joint Committee on Cancer Staff. (n.d.). What is cancer staging? Retrieved December 29, 2009, from the American Joint Committee on Cancer Web site: Staff. (n.d.). Mesothelioma staging. Retrieved December 29, 2009, from the Web site:

Mesothelioma Site Staff. (n.d.). Mesothelioma staging: Has the cancer spread? Retrieved December 30, 2009, from the Mesothelioma Site Web site: