The treatment and outlook for those stricken with mesothelioma largely depends on the stage of their cancer. Therefore, it is important to understand the three staging systems used for pleural mesothelioma. Since mesothelioma of the pleura occurs most frequently and has been the most studied, it is the only type of mesothelioma for which a staging classification exists. All three of the staging systems divide mesothelioma into four stages depending mainy on the primary tumor mass and the extent to which the disease has spread. The higher the stage number, the more advanced the mesothelioma; patients in Stage 1 of the disease have a signigicantly better prognosis than those with a more advanced stage.
The Butchart staging system is the oldest of the three and was designed specifically for mesothelioma. It is based on the size and spread of the primary pleural cancer. In Stage I, mesothelioma is in the pleura on the right or left side only and it may have grown into the covering of the hearth (pericardium) and the diaphragm. In Stage II, mesothelioma has grown into the chest wall and it may be in the pleura on both sides. Additionally, it may also have grown into the esophagus, heart and/or lymph nodes in the chest. If mesothelioma has penetrated the abdominal cavity, then it has progressed to Stage III. Mesothlioma may also be found in lymph nodes beyond the chest in Stage 3. In Stage IV, mesothelioma has spread through the bloodstream to other organs.
The TNM staging system focuses on (T) tumor, (N) lymph nodes and (M) metastasis and applies to other types of cancer. Stage I of the TNM system is identical to Stage 1 of the Butchart staging system (mesothelioma affects right or left pleura and may have grown into the covering of the hearth and the diaphragm). In Stage II of the TNM system, mesothelioma has spread to both layers of the pleura on the same side of the body. In Stage III, mesothelioma has spread to the chest wall, esophagus or lymph nodes on the same side of the chest. Like the Butchart system, in Stage IV of the TNM system, mesothelioma has spread through the bloodstream to other organs in the body such as the liver, brain or bone or to lymph nodes on the other side of the chest.
The Brigham staging system is based on whether the mesothelioma can be removed by surgery and whether the lymph nodes are involved or not. In Stage I, mesothelioma can be removed with surgery and there are no lymph nodes containing cancer cells. In Stage II, mesothelioma can be removed with surgery but lymph nodes containing cancer cells are present. In Stage III, mesothelioma cannot be removed with surgery because it has spread into the chest wall, heart, or through the diaphragm into the peritoneum. There may or may not be lymph nodes containing cancer cells in Stage III. Similar to the Butchart and TNM staging systems, Stage IV of the Brigham system indicates the mesothelioma has spread through the bloodstream to other organs in the body such as the liver, brain or bone.
Stages of Mesothelioma