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Understanding Your Stage of Malignant Mesothelioma

Before deciding on treatment options, your doctor will need to know the extent of the malignant mesothelioma. This is called the stage. Your doctor will look at the results of the tests you had in order to determine the stage of the cancer.

The stage of cancer tells how much and how far the cancer has spread. At this time, mesothelioma around the lung (called pleural mesothelioma) is the only type that has a formal staging system. This is because it is the most common form of mesothelioma.

The AJCC (American Joint Committee on Cancer) staging system uses Roman numerals from I to IV (1 to 4) for the different stages. Stage I (the earliest stage) means you have the smallest amount of cancer. Stage IV (the most advanced stage) means you have the largest amount:

  • Stage I. The cancer is on 1 side of the body in the lining of the chest cavity near the lung and may also include the lining of the lung, mediastinum (area between the lungs), or diaphragm (breathing muscle). It has not spread to the lymph nodes or to distant parts of the body.

  • Stage II. The cancer involves the lining of the chest wall on 1 side of the chest, and the lining of the lung, diaphragm, and the mediastinum. The cancer may have grown into the diaphragm or lung as well. It has still not spread to lymph nodes or distant sites. 

  • Stage III. The cancer has spread into the lymph nodes that drain the chest and the lung on the same side of the body. Or it has moved into the heart sac or the space between the lungs. Or it has moved into the chest wall in 1 spot.

  • Stage IV. The cancer has spread through the breathing muscle (diaphragm) into the belly, to deep layers of the chest wall, to organs between the lungs (including the heart), to the other side of the chest or other lung, to lymph nodes near the collarbone, or to distant organs or tissues.

  • Recurrent. Recurrent cancer means that the cancer has come back after it has been treated.

Stage I and II usually have smaller tumors than stages III and IV. The size and stage of the tumor can influence the recommendations for treatment.