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Mesothelioma Staging

Specific staging systems have been designed to measure the progression of various forms of cancer. These systems enable doctors to describe a patient’s condition in a uniform and more accurate manner so that treatment can be tailored for each individual’s needs. Several staging systems have been designed for pleural mesothelioma, including the TNM System, the Butchart System and the Brigham System.

TNM Staging System

The International Mesothelioma Interest Group has developed the TNM System. It has been adopted by the American Joint Committee on Cancer (AJCC) and it is similar to the staging systems of other forms of cancer.

Pleural mesothelioma is staged by careful examination of imaging studies. TNM stands for the three determining classification stages in the system. ‘T’ designates tumor, ‘N’ denotes the lymph nodes, and ‘M’ represents metastasis (the spread of the cancer to other organs). There are four stages of mesothelioma and each stage is designated by a Roman numeral (I-IV).

The information from the T, M and N categories combine to determine how far the cancer has advanced. Stage I is the earliest stage of mesothelioma, meaning the cancer is localized and has not advanced from its original outbreak site. Stage IV is the end stage of pleural mesothelioma, representing when the cancer has advanced and spread to other organs in the body.
Within in the TNM system there are four tumor stages (T stages):

T1: Either the right or the left pleura lining (chest lining) is affected by the cancer. The cancer has spread to the lining covering the lung and possibly to a few other minute spots.
T2: At this stage the mesothelioma tumor is affecting one side of the chest, but it has also spread into the lung’s outer lining, the diaphragm, or the lung’s interior.
T3: By this stage the cancer is affecting one side of the chest, but it has also grown into a single place in the chest wall, the chest wall’s first layer, the heart’s outer covering layer, or the mediastinum’s fatty part (the mediastinum is the area containing the esophagus, trachea and thymus).
T4: T4 is the most advanced tumor stage. In this stage, the mesothelioma has spread from either the right or left pleura lining into the chest wall, muscle, ribs, esophagus, trachea, blood vessels or thymus. It may metastasize to the spine as well and affect the opposite side of the chest. The heart lining could be affected at this stage and the tumor may have spread to the brachial plexus, which are the nerves that control the arm.

There are also four lymph node stages:
Lymph nodes are clusters of special immune system cells located under the arms and elsewhere in the body. There are four N stages in the TNM System to determine how far the mesothelioma has spread to the lymph nodes.

N0: This stage signifies the cancer has not spread to the lymph nodes.
N1: This stage means the cancer cells have spread to lymph nodes on the same side of the chest where mesothelioma has developed.
N2: At this stage, the cancer has spread into the lymph nodes in front of the heart (the space called the mediastinum) or into the lymph nodes near the left or right bronchi. The cancer-affected lymph nodes are located on the side of the mesothelioma’s origin.
N3: In this stage, the cancer has spread to lymph nodes near the collarbone and/or to lymph nodes on the opposite of the mesothelioma-affected lung.

Metastasis stages include:

M0: The tumor has not metastasized to distant regions of the body.
M1: The tumor has metastasized to distant areas of the body.

To determine the stage of mesothelioma, the tumor, lymph node, and metastasis stages are combined (stage grouping).

Stage I (T1, N0, M0): At this stage, mesothelioma has not spread to the lymph nodes or to distant organs. It is localized on one side of the pleural lining and has possibly spread to a few spots in the lung’s outer lining.
Stage II (T2, N0, M0): At this stage, mesothelioma has either spread into the lung’s outer lining, into the diaphragm, or inside the lung. There is still no lymph node involvement and the cancer has not spread to distant organs.
Stage III (T 1 or T2, N1 or N2, M0; or T3, N0 or N1 or N2, M0): At this stage the mesothelioma has not metastasized to distant organs, but it has spread considerably in the chest area. It may involve the lung’s interior, the heart’s outer lining, and/or the diaphragm. It may or may not involve the lymph nodes.
Stage IV (T 4, any N, M; or any T, N3, MO; or any T, any N, M 1): In this stage the tumor may be quite advanced and have spread to the opposite side of the chest. The cancer may be inside the lungs, heart, and/or in the mediastinum. It may have spread to the spine and/or the brachial plexus. Once pleural mesothelioma is this advanced, it is defined as stage IV, even if there is no lymph node involvement and the cancer has not spread to distant organs.

Pleural mesothelioma may also be designated as stage IV if there is extensive lymph node involvement (N3) at any T stage, even though the cancer has not metastasized to distant organs. If pleural mesothelioma has metastasized to distant organs it is also considered stage IV, even if the tumor is localized and there is no lymph node involvement.

The Butchart System

The oldest and most common staging system for pleural mesothelioma is the Butchart System. This system is based on the size of the tumor and divides pleural mesothelioma into four separate stages:

Stage 1 – The cancer has affected either the right or left side of the chest cavity (pleura) and may be seen in the diaphragm.
Stage 2 – In this stage, both the left and right sides of the pleura have been affected. The cancer may have metastasized to the heart, stomach or esophagus and lymph nodes may be affected.
Stage 3 – This stage signifies the cancer has reached the abdominal cavity and lymph nodes passed the chest may be affected.
Stage 4 – At this stage, the mesothelioma has affected other organs in the body and has entered the blood stream.

The Brigham System

The Brigham System evaluates several variables in the staging process, including the involvement of lymph nodes and the surgical ability to remove the mesothelioma tumor. Because surgical removal of mesothelioma is usually not an option, this system is not typically used. The Brigham System separates pleural mesothelioma into four stages:

Stage 1 – The mesothelioma tumor can be surgically removed and the lymph nodes are not affected.
Stage 2 – The mesothelioma tumor can be surgically removed, but the lymph nodes are affected.
Stage 3 – The mesothelioma tumor cannot be surgically removed and the cancer has move into the chest wall, heart, abdominal cavity or diaphragm. The lymph nodes may be affected.
Stage 4 – The mesothelioma tumor cannot be surgically removed and the cancer has metastasized (spread) to other areas of the body.

Usefulness of Staging

Staging helps doctors decide which treatment option will work best for the patient. In addition, a cancer care team will also take into consideration the general health and age of a patient. The types of cells making up the mesothelioma tumor may play a factor in deciding treatment as well.

Epithelioid cells respond best to treatment and according to the American Cancer Society, 50 to 70 percent of mesotheliomas are epithelioid. Up to 20 percent of mesotheliomas are composed entirely of sarcomatoid cells, which are aggressive, difficult cancers to treat. The remainder of mesotheliomas are biphasic, containing a mixture of both epithelioid and sarcomatoid cells. The more aggressive the cancer cell type, the more aggressive treatment may be if diagnosed early enough.

If you would like to understand more about staging mesothelioma, please fill out the request form on this page to receive a complimentary informational packet in the mail. You can also call 1-800-ASBESTOS if you would prefer to speak with a Patient Advocate who can explain the staging system and potential treatment options.

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