To find out how far the cancer has spread process called staging is usually used. Staging of mesothelioma is based on MRI, x-rays, CT scans. The stage (extent of spread) of the cancer influences the choice of the treatment and outlook for patients with mesothelioma. A staging classification exists only for pleural mesothelioma because this disease occurs most frequently and has been studied the most.

There are three staging systems that are currently in use.

Butchart System is the most popular and the oldest staging system. It divides mesotheliomas into four stages. Main markers of this staging are mass and spread, lymph node involvement, and metastasis. The newest system called Brigham System stages mesothelioma according to lymph node involvement and the ability to surgically remove (respectability).

The less staging is the better prognosis has a patient.

1. Butchart System - primary tumour mass extent

Stage I: Mesothelioma can be found in the left or right pleura. The diaphragm on the same side may also be involved.

Stage II: Mesothelioma is presented in the chest wall. It can also involve heart, pleura on both sides and the oesophagus. The involvement of lymph nodes is also possible.

Stage III: Mesothelioma has succeeded in penetration into the lining of the peritoneum or abdominal cavity. The involvement of lymph nodes beyond those in the chest is also possible.

Stage IV: There is metastasis in other organs and spreading through the bloodstream.

2. TNM System is a more recent system used to stage mesothelioma by considering variables such as the tumor size and spread, lymph node involvement, and metastasis. In the TNM system, the disease is divided into four stages: During TNM (tumour, node, and metastasis) doctors look at these three factors to determine the cancer stage:

The size and the location of the primary tumour. (Tumour, T)
Are lymph nodes involved? (Node, N)
Are there metastases in other organs? (Metastasis, M)

Tumour. To describe the stage of mesothelioma TNM system uses the "T" plus a letter or number (0 to 4). Division into smaller groups of some stages is also possible. It helps to describe a patient's condition in more detail. This staging is used to develop the best treatment plan. Below are tumour stages are described:

TX: It is impossible to evaluate the primary tumour.

T0: There are no evidences of tumour.

T1: The tumour can be found in the thin membrane that lines the inner chest walls on the same side of the body (the ipsilateral parietal pleura). The visceral pleura can also be involved.

T1a: There is an involvement of tumour into the ipsilateral parietal pleura but visceral pleura are not involved.

T1b: The tumour can be found in the ipsilateral parietal pleura. Visceral pleura are also involved.

T2: There are evidences of involvement of the ipsilateral pleural surfaces. One of the following must also be involved: the diaphragmatic muscle, lung and visceral pleural tumour.

T3: There are evidences of involvement of the ipsilateral pleural surfaces. One of the following body parts must also be invaded: mediastinal fat and/orendothoracic fascia (the membrane that surrounds the thorax.

T4: There are evidences of involvement any of the ipsilateral pleural surfaces. One of the following signs can also be found: any involvement of rib, diffuse or multifocal invasion of soft tissues of the chest wall, invasion of any mediastinal organ(s), invasion through the diaphragm to the peritoneum, invasion into the spine, extension to the internal surface of the pericardium, direct extension to the contra lateral pleura, pericardial effusion with positive cytology, invasion of the myocardium, and/or end thoracic fascia and/or invasion of the brachial plexus.

Node. Lymph nodes that are situated not near the chest in other parts of the body are called distant lymph nodes and near the chest - regional lymph nodes.

NX: It is impossible to assess regional lymph nodes.

N0 (N plus zero): There are no evidences of regional lymph node metastasis.

N1: Metastasis can be found in the hilar lymph node(s) and/or ipsilateral bronchopulmonary.

N2: There is metastasis to the ipsilateral internal mammary or mediastinal lymph node(s) and/or subcarinal lymph node(s).

N3: Metastasis can be found in the hilar lymph node(s), contra lateral mediastinal, internal mammary and/or the ipsilateral or scalene lymph node(s) or contra lateral supraclavicular.

Distant metastasis.  Shows whether the cancer has spread to other organs.

MX: It is impossible to assess distant metastasis.

M0 (M plus zero): There are no evidences of distant metastasis.

M1: There is metastasis.

Cancer stage grouping

The stage of the cancer is determined by combining the T, N, and M classifications.

Stage I: The tumour has not spread to the lymph nodes or other parts of the body but has invaded the ipsilateral parietal pleura, with or without involvement of the visceral pleura. (T1, N0, M0).

Stage IA: The tumour has not spread to the lymph nodes or other parts of the body but has invaded the ipsilateral parietal pleura, without involvement of the visceral pleura. (T1a, N0, M0).

Stage IB: The tumour has not spread to the lymph nodes or other parts of the body but has invaded the ipsilateral parietal pleura, with involvement of the visceral pleura. (T2a, N0, M0).

Stage II: There evidences of tumour invasion into any of the ipsilateral pleural surfaces and one of the following: visceral pleural tumour, the lung invasion or the invasion of the diaphragmatic muscle.

There is no spreading of cancer throughout the body or in the lymph nodes (T2, N0, and M0). Stage III: There are evidences of cancer in any of the ipsilateral pleural surfaces. Also one of the following are involved: the lung or the diaphragmatic muscle.

There is also an involvement of the following: the end thoracic fascia (the membrane that surrounds the thorax), mediastinal fat with spread to the lymph nodes, but not too distant parts of the body. Lymph nodes are also invaded, but not throughout the body (T1 or T2, N1, M0; T1 or T2, N2, M0; T3, any N, M0).

Stage IV: There are evidences of cancer in any of the ipsilateral pleural surfaces. Also one of the following are involved: soft tissues of the chest wall, rib, the spine, the peritoneum through the diaphragm, mediastinal organ(s), and the contra lateral pleura.

There may be an invasion of the myocardium, and/or invasion of the brachial plexus, extension to the internal surface of the pericardium, pericardial effusion with positive cytology. It also means that the cancer has spread to distant lymph nodes, or the cancer has spread to other parts of the body and that the tumour is of any size (T4, Any N, M0; any T, N3, M0; or any T, any N, M1).

3. Brigham System is the latest mesothelioma cancer staging system and is based on tumor resectability (ability to surgically remove) and lymph node status. The Brigham system is divided into four stages:

Stage I: Mesothelioma is resectable and there is no lymph node involvement;

Stage II: The lymph node is involved but mesothelioma is still respectable;

Stage III: There may be an extra thoracic lymph node involvement and the mesothelioma is unresectable and extended into chest wall, heart, or through diaphragm, peritoneum;

Stage IV: Distant metastatic disease.