TNM System

The TNM System is a more modern staging system for malignant mesothelioma. The TNM System is based on the extent of the tumor, metastasis, and lymph node involvement. Again, the TNM System divides malignant mesothelioma into four stages:

* Stage 1 - Malignant mesothelioma is present in the left or right chest cavity (pleura) and may have metastasized to the lung, the sac around the heart (pericardium) or the diaphragm on the same side. Lymph nodes at stage 1 are not involved.
* Stage 2 - Malignant mesothelioma has reached from one side of the chest cavity to a lymph node near the lung area on the same side as the cancer. The cancer has metastasized to the diaphragm, pericardium (sac around the heart), or the lung on the same side as the primary tumor.
* Stage 3 - Malignant mesothelioma has penetrated the chest lining, heart, esophagus, muscle, ribs and vital organs within the chest cavity on the same side as the cancer. Lymph nodes may or may not be involved during this stage.
* Stage 4 - Malignant mesothelioma has metastasized to the pleural area and the lymph nodes on the opposite side of where the cancerous tumor is located. It may also have reached the chest cavities or lungs on both sides, or may have spread to the abdomen.