The Stages of Mesothelioma
When a patient is diagnosed with mesothelioma, he or she will undergo several imaging studies, such as MRI, x-rays and CT scans, to determine how far the cancer has spread. This is an important determination because the patient’s treatment and prognosis is largely decided by the extent to which the cancer has spread.Often doctors will talk to patients about whether the cancer has metastasized. This term refers to the spread of cancer from the initially affected site to other body parts.
Doctors measure the extent of the spread of cancer in the body using a scale that divides the disease into stages. The stages of mesothelioma are often defined by two scales: the long-standing Butchart System and the more recently developed TNM system. Your doctor may use either of these scales when discussing your condition with you.
Within the Butchart System, there are four stages of mesothelioma. This system uses the extent of the primary tumor mass to measure the cancer.
- Stage I. In Stage I only one side of the pleura lining the chest is affected, and the cancer is not affecting the chest wall.
- Stage II. In Stage II the chest wall, esophagus, heart, or the pleura lining the other side of the chest are affected. The lymph nodes located in the chest may also be affected.
- Stage III. In Stage III the cancer has spread through the diaphragm to the lining of the abdominal cavity or is present in lymph nodes other than those in the chest.
- Stage IV. In Stage IV the cancer has entered the bloodstream and is affecting other organs besides the lungs.
A more recent scale is the TNM System developed by the International Mesothelioma Interest Group. The letters TNM stand for Tumor, lymph Node, and Metastasis. This system is more similar to the staging systems used for other cancers than the Butchart System because it combines information about the tumor, lymph nodes, and metastases to determine the cancer’s stage.
- Stage I. In Stage I one side of the pleura lining the chest is affected, and the cancer has spread to the outer lining of the lung in only a few spots. The lymph nodes are not affected.
- Stage II. In Stage II the disease is affecting one side of the pleura lining the chest, has spread to the outer lining of the lung, the diaphragm or into the lung itself.
- Stage III. In Stage III one side of the pleura lining the chest is affected and has either spread to the first layer of the chest wall, the fatty parts of the chest, a single spot in the chest wall, the outer layer of the heart, or lymph nodes anywhere on the same side of the chest.
- Stage IV. In Stage IV one side of the pleura lining the chest is affected, and the cancer has spread to either the chest wall, the diaphragm, the organs in the chest, the blood vessels, the spine, the pleura lining the other side of the chest, the nerves leading to the arm, the lymph nodes other than those on the first side of the chest, and other organs in the body via the bloodstream.
Since most of the medical studies that have been done are confined to the study of pleural mesothelioma, both of these systems only refer to that disease.