Staging and Other Prognostic Factors
After a diagnosis of mesothelioma is confirmed, the patient’s doctor may order additional tests to determine the extent, or “stage” of the cancer. Staging of mesothelioma is based in part on imaging studies such as chest x-rays, CT scans and MRI scans. Mesothelioma is described as localized if the cancer cells are located only on the membrane surface where the cancer originated. It is classified as advanced if the cancer has spread beyond its original site to other parts of the body, commonly the lymph nodes, chest wall, lung tissue or abdominal organs.
The treatment and outlook for patients with mesothelioma depends largely on the stage of their cancer. Unfortunately, mesothelioma often is not diagnosed until the cancer is in the late stages of development. As a result, the prognosis for the majority of patients with mesothelioma is poor. After the disease has progressed to Stage III or IV, treatment options are more limited and less effective.
Pleural mesothelioma is the only form of the disease to which a stage is assigned. Formal stages aren’t used for other types of mesothelioma because these types are rare and are not as well studied. There are four main TNM stages of pleural mesothelioma: Stage I pleural mesothelioma is localized, meaning it is limited to one portion of the lining of the chest. Stage II mesothelioma may have spread beyond the lining of the chest to the diaphragm or to a lung. Stage III mesothelioma may have spread to other structures within the chest and may involve nearby lymph nodes. Stage IV mesothelioma is an advanced cancer that has spread, or metastasized, to distant areas. Mesothelioma most commonly metastasizes to the brain, lymph nodes in the chest and areas of the lung that are away from the tumor.
Along with the TNM stage of the patient’s mesothelioma, there are additional prognostic factors that determine the mesothelioma survival rate.