Staging allows the patient and doctor to determine treatment options. Staging is divided into 3 areas, designated by the capital letters TNM:
• T refers to whether the original tumor has exceeded its margins.
• N stands for lymph nodes that are affected.
• M refers to metastasis to other areas of the body.
Pleural mesothelioma is further divided into overall stages:
Stage I -The cancer is present only on the pleura of the chest wall and the outer lining of the lungs.
Stage II-The cancer has spread into the lining of the lung, the internal lung tissues, or the diaphragm.
Stage III-The cancer has invaded chest lymph nodes, or has not yet invaded lymph nodes but has spread to the mediastinum or the outer layer of the heart.
Stage IV-The cancer is present in adjacent structures, with or without spread to remote areas of the body.
Stage I mesothelioma is used to describe disease progression characterized by the presence of mesothelioma within the right or left pleura, which is the membrane that covers the lungs. The cancer may also be present, on the same side only, in the lung, pericardium, or diaphragm.
Stage 2 mesothelioma describes the state in which the cancer spreads to the extent of invading one or more additional areas, including the pleura on both sides, the chest wall, esophagus, heart, and/or lymph nodes in the chest.
Stage 3 mesothelioma indicates further spread of the cancer, involving penetration through the diagram into the peritoneum, which is the lining of the abdomen. This state my also involve additional lymph nodes beyond the chest area.
Stage 4 mesothelioma is the final state of mesothelioma, in which the cancer cells have gained entry to the bloodstream, enabling the disease to spread to other organs throughout the body. The process of spreading via the bloodstream is referred to as distant metastes.
The stage of mesothelioma determines a patient’s treatment options. The most common type of staging system is the TNM system. The TNM staging system is based on three variables: the size and location of the tumor, the involvement of the lymph nodes, and metastasis. The TNM system is made up of four stages. In Stage I the lymph nodes are not involved and mesothelioma involves either the right or left pleura. In Stage II the lymph nodes are affected on the same side as the mesothelioma on the pleura and/or lung. In Stage III the lymph nodes may or may not be affected but the chest wall, heart, and other organs in the chest are affected by mesothelioma. And in the final stage, Stage IV, mesothelioma has spread throughout the chest and into most of the chest lymph nodes. Distant metastases are also included in this stage.
Stage One
The tumor is confined within the capsule of the pleura.
Stage Two
The tumor is confined within the capsule of the pleura and there are positive intrathoracic lymph nodes
Stage Three
There is local extension of the disease into the chest wall, heart, and peritoneum with or without extrathoracic lymph node involvement
Stage Four
Distant metastatic disease
Mesothelioma is staged using the TNM classification system for classifying malignant tumors.
- The T refers to the size and local spread of the primary tumor
- Size of the tumor can be designated by the number 1-4
- The N describes spreading of the tumor into lymph nodes
- Spread of the tumor to lymph nodes can be designated by the numbers 0-3
- N0- there is no spread to lymphatic nodes
- N1-there is spread of the tumor to nearest lymph nodes
- N3- there is spread of the tumor cells to distant lymph nodes
- The M describes distance metastasis
- Metastasis is designated by the numbers 0-1
- M0- no metastasis
- M1-metastasis to distant tissues
The T stage of malignant mesothelioma is categorized as follows:
T1: Mesothelioma involving either side of pleura lining of the thorax. The mesothelioma is confined to the pleura lining of the lung, and possibly a few additional spots.
T2: Mesothelioma involving either side of pleura lining of the thorax which has also spread from the pleura into the diaphragm, the outer lining of the lung, or the lung itself.
T3: Mesothelioma involving either side of pleura lining of the thorax which has also spread into the first layer of the thorax, the adipose layer of the mediastinum, any single location in the thoracic cavity, or the pericardium.
T4: Mesothelioma involving either side of pleura lining of the thorax which has also spread into the thoracic wall, any organ located within the mediastinum, the spine, through the diaphragm, crossed the pleura through to the other side of the thorax, through the pericardium, the heart, or the brachial plexus.
The Butchart system stages the mesothelioma based on the bulk of the primary tumor. Stage one involves either the right or left pleura and may also involve the diaphragm on the same side. Stage two involves the pleura on both sides, the heart, esophagus or chest wall. Thoracic nodes may be involved. If nodes other than those in the thorax are involved or if the tumor has gone into the peritoneal cavity, then it is considered stage three. Any involvement of other organs or evidence of metastasis is stage four. The Brigham system shows node involvement and resectability. Stage one tumors are resectable and there is no node involvement. Stage two tumors are still resectable but there are nodes involved. Stage three is unresectable and extends into the chest wall, heart, diaphragm or peritoneal cavity. There may be involvement of nodes outside of the thorax. Stage four involves any distant metastasis.
The Butchart System is used most often and is based on the extent of the primary tumor mass. The stages are as follows:
• Stage I: Tumor is limited to the right or left pleura; it may also involve the ipsilateral diaphragm.
• Stage II: Tumor involves the chest wall, esophagus, heart, or pleural surfaces bilaterally; adenopathy in the chest is present.
• Stage III: Tumor has penetrated through the diaphragm to the abdomen; there is adenopathy beyond the chest.
• Stage IV: Metastatic disease is present in other organs throughout the body.
The TNM System (Stage I – V) is based on T (tumor), N (nodes) and M (metastases). The stages quantify levels of tumor involvement, presence of lymph nodes and presence of metastases.
The Brigham System (Stage I – IV) stages mesotheliomas based on the resectability of the tumor and status of lymph node involvement.
The Butchart System is the oldest staging system, the more recent is the TNM system, and the latest system used is the Brigham System. The Butchart System describes Stage 1 as involving the lining of one lung and the diaphragm on the same side, Stage 2 involves invasion into the chest wall, esophagus, heart, or involving both lungs, with possibily lymph nodes in chest being involved. Stage 3 involves the diaphragm extending into the lining of the abdominal cavity or peritoneum, and may effect lymph nodes beyond those in the chest. Stage 4 is the final stages and involves mets or spread of cancer to other organs. The TMN System Stage 1 involves the lining of one lung, the pericardium or diaphragm on the same side with no lymph node involvement. State 2 shows involvement of lymph nodes to the lung effected on the same side. Stage 3 involves chest wall muscle, ribs, heart, esophagus or other organs of the chest on the same side of the primary tumor. Stage 4 involves spread of disease to lymph nodes in the chest on the opposite side of the primary tumor, extends into the lung opposite the primary tumor, or extends directly into the organs of the abdominal cavity or neck. Mets are included in this stage. The Brigham system focuses on the resectability of the mass surgically. Stage 1 is that the tumor is resectable and lymph nodes are not involved. Stage 2 is mass is resectable but lymph nodes are involved. Stage 3 is mass is unresectable and extends into the chest wall, heart, or through the diaphragm, peritoneum, with or without lymph node involvement. Stage 4 occurs when doctors discover mets of distant organs.
Most recently the TNM staging system has been used to stage mesothelioma. However, historically, the Butchart system was used and now there is also a new staging system which may be increasingly implemented, the Brigham system. The Butchart system describes how extensive the primary tumor is, whereas the TNM system defines cancers by tumor extension, lymph node involvement, and whether there are metastases. The Brigham staging identifies how resectable a lesion may be.
Each system has four stages. Generally the first stage is localized disease which is easily resectable and involves no lymph nodes. In stage two, the cancer has spread and may affect lymph nodes, but is often treatable with surgical excision and adjunctive therapies. Stage three is extensive disease, often crossing internal boundaries such as the diaphragm but may still respond to debulking surgery and chemotherapy or radiation.. The fourth stage in all of the systems is defined by metastatic lesions.