Four Stages of Mesothelioma

Once doctors have diagnosed a patient with the malignant cancer mesothelioma, they perform a battery of tests known as mesothelioma staging. A staging system allows the physician to pinpoint the extent of the cancer in the patient, as well as create the best treatment plan for the specific level of development. 

Mesothelioma staging is based on imaging studies such as x-rays, Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI) scans.  In the four stage system, mesothelioma is given a Roman numerical value based on the extent of the cancer’s spread, with Stage I having the least amount of cancerous development, and Stage IV having the most.

Currently, physicians employ one of two staging systems to diagnose and treat mesothelioma. The most recently developed system is called the TNM Staging System.  In this system, information about the amount of cancerous cells in tumors, lymph nodes and metastasis (the spread of cancerous cells to distant organs) is combined in a process called stage grouping.  More specifically, the T stands for tumor, its size as well as how it has spread to nearby organs, the N stands for the spread of the cancer to the lymph nodes, and the M is for metastasis.  These stages are then categorized by Roman numerals from I to IV:

• Stage I: Mesothelioma involves the right or left pleura. It may also have spread into the lung, pericardium, or diaphragm on the same side. It has not yet spread to the lymph nodes.
• Stage II: Mesothelioma has spread from the pleura on one side to the nearby lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium, or diaphragm on the same side.
• Stage III: Mesothelioma has spread into the chest wall muscle, ribs, heart, esophagus, or other organs in the chest on the same side as the primary tumor, with or without spread to lymph nodes on the same side as the main tumor.
• Stage IV: Mesothelioma has spread into the lymph nodes in the chest on the side opposite that of the primary tumor, or directly extends to the pleura or lung on the opposite side, the peritoneum, or into organs in the abdominal cavity or neck. Any mesothelioma with evidence of distant metastasis (spreading to other organs via the bloodstream) or spread to organs beyond the chest or abdomen is included in this stage.

The second primary system used to identify mesothelioma is known as the Butchart system.  This system is based primarily on the size of the cancerous tumor, but, like the TNM system, it bases its severity on a Roman numerical system from I to IV:

• Stage I: Mesothelioma is present within the right or left pleura, and may also involve the lung, pericardium, or diaphragm on the same side.
• Stage II: Mesothelioma invades the chest wall or involves the esophagus, heart, or pleura on both sides. The lymph nodes in the chest may also be involved. .
• Stage III: Mesothelioma has penetrated through the diaphragm into the peritoneum. Lymph nodes beyond those in the chest may also be involved.
• Stage IV: Mesothelioma has penetrated through the diaphragm into the peritoneum. Lymph nodes beyond those in the chest may also be involved.