Staging is the medical term used to describe how far the cancer has spread through your body. Once you are diagnosed with mesothelioma, your doctor will probably order additional imaging tests to determine the stage (or extent) of your disease. The tests may include a chest x-ray, a CT scan, an MRI, or an endoscopic ultrasound (EUS).
The staging process is very important to help your doctor plan the appropriate course of treatment. Both your treatment options and overall prognosis will vary depending on what stage of mesothelioma you are in. Generally, the outlook is better if the cancer is diagnosed in the early stages. This is why it is very important to go for frequent medical checkups if you know that you have a history of asbestos exposure, particularly if you show any signs of asbestos disease such as asbestosis or pleural plaques.
Mesothelioma is considered to be localized if the cancer is found only on the pleura or peritoneum where it originated. Mesothelioma is considered to be advanced if it has spread beyond the original site to the lymph nodes, chest wall, lungs, or other internal organs.
Pleural mesothelioma is formally divided into four main stages. The other forms of mesothelioma have not been assigned formal stages.
- Stage I pleural mesothelioma is localized. This means that the cancer is limited to either the right or left pleura, and may also be found in the lining of the lung or the diaphragm on the same side.
- Stage II mesothelioma has spread beyond the lining of the chest to the lymph nodes, chest wall, esophagus, and/or lung on the same side.
- Stage III mesothelioma has penetrated the chest wall, heart, peritoneum, and/or other nearby organs. The cancer may have spread into lymph nodes on the other side of the chest or even outside the chest.
- Stage IV mesothelioma has spread, or metastasized, to distant organs. The cancer may have spread throughout the body via the bloodstream or lymph nodes.