Stages of Mesothelioma
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.
Mesothelioma is a rare and aggressive form of cancer that primarily affects the mesothelium, a protective membrane that covers various internal organs, most commonly the lungs and chest cavity. There are different staging systems used to describe the extent of mesothelioma, with the Butchart staging system, Brigham staging system, and the TNM system being the most commonly employed. Here’s an overview of each:
- Butchart Staging System: The Butchart staging system is one of the earliest staging systems used for mesothelioma. It was primarily developed for pleural mesothelioma (mesothelioma affecting the lining of the lungs), and it categorizes the disease into four stages:
- Stage I: Mesothelioma is localized to the pleura (lining of the lungs).
- Stage II: Mesothelioma has invaded the chest wall or involves the diaphragm.
- Stage III: Mesothelioma extends into the peritoneum (abdominal lining), heart, or through the diaphragm.
- Stage IV: Mesothelioma has spread to distant organs or lymph nodes.
This system provides a basic overview of disease progression but lacks detailed information about the extent of tumor involvement and lymph node status.
- Brigham Staging System: The Brigham staging system, also known as the International Mesothelioma Interest Group (IMIG) staging system, is a more detailed and widely accepted staging system for pleural mesothelioma. It evaluates three key factors:
- Tumor (T) stage: This describes the extent of the primary tumor.
- Lymph node (N) stage: It assesses the involvement of lymph nodes.
- Metastasis (M) stage: This stage evaluates whether the cancer has spread to distant organs.
The combination of these factors results in a more precise and detailed staging system, such as stage T1N0M0 for early-stage disease and stage T4N3M1 for advanced disease.
- TNM Staging System: The TNM (Tumor, Node, Metastasis) staging system is used for various types of cancer, including mesothelioma. It provides a standardized way to describe the extent of the disease. In the TNM system for mesothelioma, each factor is assigned a stage, and these are combined to create an overall stage. The TNM stages typically range from stages 0 to IV, with IV indicating the most advanced disease.
For example, T1 N0 M0 indicates a small tumor with no lymph node involvement or distant metastasis, while T3 N2 M1 indicates a larger tumor with extensive lymph node involvement and distant metastasis.
It’s essential to consult with a medical professional to determine the specific stage of mesothelioma, as the choice of staging system and the interpretation of test results can vary among healthcare providers. Accurate staging is crucial for determining treatment options and predicting prognosis in mesothelioma cases.
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.
Butchart System – primary tumor mass extent
Stage I: Mesothelioma can be found in the left or right pleura. The diaphragm on the same side may also beinvolved.
Stage II: Mesothelioma is presented in the chest wall. It can also involve heart, pleura on both sides or the esophagus. 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.
During TNM (tumor, node, and metastasis) doctors look at these three factors to determine the cancer stage:
The size and the location of the primary tumor. (Tumor, T)
Are lymph nodes involved? (Node, N)
Are there metastasis in other organs? (Metastasis, M)
Tumor. 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 tumor stages are described:
TX: It is impossible to evaluate the primary tumor.
T0: There are no evidences of tumor.
T1: The tumor 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 tumor into the ipsilateral parietal pleura but visceral pleura is not involved.
T1b: The tumor can be found in the ipsilateral parietal pleura. Visceral pleura is 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 tumor.
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 contralateral pleura, pericardial effusion with positive cytology, invasion of the myocardium, and/or endothoracic 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), contralateral mediastinal, internal mammary and/or the ipsilateral or scalene lymph node(s) or contralateral 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 tumor 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 tumor 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 tumor 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 tumor invasion into any of the ipsilateral pleural surfaces and one of the following: visceral pleural tumor, 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, 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 endothoracic fascia (the membrane that surrounds the thorax), mediastinal fat with spread to the lymph nodes, but not to 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), the contralateral 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 tumor is of any size (T4, Any N, M0; any T, N3, M0; or any T, any N, M1).
Brigham System: (variables of nodal status and tumor resectability)
Stage I: Mesothelioma is resectable and there is no lymph node involvement;
Stage II: The lymph node are involved but mesothelioma is still respectable;
Stage III: There may be an extrathoracic lymph node involvement and the mesothelioma is unresectable and extended into chest wall, heart, or through diaphragm, peritoneum;
Stage IV: Distant metastatic disease