Three different staging systems have been created to stage mesothelioma. These systems are similar in the way they define the four stages of mesothelioma. Only one of these staging systems — the TNM system — is widely used.
There are three different staging systems for mesothelioma: TNM, Brigham and Butchart.
TNM is the most used system. It goes into greater detail than the other systems.
Butchart is the oldest system and has generally fallen out of use. The Brigham system was created to determine the likely success of surgery at each stage.
All of these systems were developed to stage pleural mesothelioma.
In 2011, researchers began adapting the TNM system to stage peritoneal mesothelioma.
No formal systems have been created to stage pericardial mesothelioma or testicular mesothelioma. These cancers are so rare that not enough data is available to create a staging system for them.
Staging helps patients understand how far their cancer has progressed. It has a big impact on prognosis and the treatments doctors recommend.
This is the most widely used system for pleural mesothelioma. It is also called the iMiG Staging System after the International Mesothelioma Interest Group, which is the organization that developed it.
Researchers are trying to adapt it for peritoneal mesothelioma, but more data is necessary and it will take time to develop.
For now, three peritoneal mesothelioma stages have been defined. A fourth stage should be defined in the near future.
The abbreviation TNM signifies three different parts of a diagnosis. Doctors add a number after each letter to describe how far the cancer has advanced.
As tumor size increases and the cancer spreads to other places, the number increases.
Doctors use the TNM framework to stage many different types of cancer. In 1995, the International Mesothelioma Interest Group modified this system for pleural mesothelioma.
After evaluating a case, doctors assign a value to each part of the TNM system. Next, they use this information to give the cancer a stage. For example, TNM staging guidelines say a T3N1M0 mesothelioma is a stage 3A cancer.
To create the TNM system, data was gathered on pleural patients from across the world. The goal was to create an improved staging system.
This system was updated in January 2018 to include subcategories such as stage 1A and stage 1B.
T1 N0 M0: In this earliest stage of mesothelioma, cancer has grown in the pleural lining on one side of the chest wall and may affect the lining near the breathing muscle (diaphragm), the area between the lungs (mediastinum) or the pleura covering the lung.
T2 N0 M0: Mesothelioma is growing in both layers of the pleura and has grown into the breathing muscle or lung tissue.
T3 N0 M0: Mesothelioma is within both layers of the pleura and has spread into at least one of the following:
T1-T2 N1 M0: At stage 2, mesothelioma has grown in the pleura lining one side of the chest wall (T1) and may have grown into the breathing muscle or the lung itself (T2). It has also spread to lymph nodes on the same side of the chest as the primary tumor (N1).
T3 N1 M0: In this subcategory of stage 3 mesothelioma, the cancer has spread from the pleura into a layer of the chest wall, the outer layer of the heart lining or the fatty tissue between the lungs. The cancer has also spread to lymph nodes on the same side of the chest as the primary tumor (N1). Surgery is still an option at this stage and earlier stages.
T1–T3 N2 M0: The primary tumor mass may or may not have spread beyond the pleura (T1-T3), but mesothelioma cells have spread to lymph nodes on the other side of the chest or above the collarbone (N2). Surgery is no longer an option at this stage or further stages.
T4, Any N, M0: Mesothelioma has grown in both layers of the pleura and may or may not have spread into lymph nodes. It has also spread into at least one of the following:
Any T, Any N, M1: By stage 4, mesothelioma may or may not have grown into places near the primary tumor (any T). It may or may not have spread to lymph nodes (any N). It has spread to distant places such as the bones, liver, abdominal lining or the lung or lung lining on the other side of the chest (M1).
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In 2011, the Peritoneal Surface Oncology Group International proposed a staging system for peritoneal mesothelioma. The group gathered data on peritoneal patients who had surgery with heated chemotherapy to create the staging system.
This system has not been formally adopted, but many doctors use it to stage peritoneal mesothelioma.
The system has three stages. A fourth stage has not been created yet because this system is based on patients who qualified for surgery. Researchers did not have enough data to define a fourth stage because only early-stage patients qualify for surgery.
In the future, a fourth stage will likely be defined. Until then, doctors generally define the fourth stage as when the cancer spreads to distant parts of the body.
T1 N0 M0: Presence of tumors is minimal and contained within the abdominal lining (peritoneum).
T2-T3 N0 M0: Tumors are moderate and contained in the abdominal lining.
T4 N0-N1 M0-M1: Presence of tumors is extensive (T4) and may or may not have spread to lymph nodes (N0-N1) or beyond the abdominal lining (M0-M1).
T1-T4 N1 M0-M1: Tumors may range from minimal to extensive (T1-T4). The cancer has spread to lymph nodes (N1) and may or may not have spread outside the abdominal lining (M0-M1).
T1-T4 N0-N1 M1: Presence of tumors may range from minimal to extensive (T1-T4). The cancer may or may not have spread to lymph nodes (N0-N1), but has spread outside the abdominal lining (M1).
The Brigham staging system was created by Dr. David Sugarbaker at the Brigham and Women’s Hospital in Boston. With this system, doctors look at organs, tissues and other parts of the body to learn how far pleural mesothelioma has spread.
This system is primarily designed to determine whether a patient qualifies for surgery. In the first two stages, tumors are small and easier to remove. In stage 3 and stage 4, the cancer has grown and spread and is not easy to operate.
Tumors are only in the lining of the lungs and cancer has not spread to the lymph nodes. Surgery is an option.
Tumors are within the lining of the lungs. Lymph nodes near the tumors are cancerous. Surgery is an option.
Inoperable tumors are in the lining of the lungs and have spread into one or more of the following:
Cancer has spread to distant parts of the body. Surgery is not an option.
Dr. Eric Butchart created this system in 1976 to make sure patients got the right treatment.
Now retired, Butchart was a cardiothoracic surgeon at the University Hospital of Wales in the United Kingdom when he developed this staging system.
Butchart realized aggressive treatment worked better for patients with small tumors that had not spread far. He based his staging system on this fact, which helped doctors decide what treatments would work best for each patient.
This system is outdated and no longer used, but it helped other doctors develop the staging systems we use today.
The cancer affects the pleura on only one side of the chest and may have spread to the heart lining and diaphragm.
Cancer has spread to the chest wall and may affect both sides of the pleura. It may have spread to the esophagus, heart or lymph nodes of the chest.
Cancer has spread to the breathing muscle or abdominal lining (peritoneum). Mesothelioma cells have also traveled through the lymphatic system to lymph nodes outside the chest.
The cancer has spread through the bloodstream to distant parts of the body. Tumors may now be present in the bones, liver, brain or other organs.
Karen Selby joined Asbestos.com in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators.