Article by Miranda Sudo
What and How of Staging
Once a patient is diagnosed with malignant mesothelioma, doctors use staging to describe how much cancer is in the body and if it has spread. Although every patient is unique, the different stages are a good indicator of outlook and treatment options. There are 4 stages of mesothelioma, with the lower numbers meaning less spread.
Malignant Pleural Mesothelioma is the most common type of mesothelioma and the only type with a formal staging system. The TNM system is the most common way of staging and has 3 components:
- Tumor (T) – How large is the main tumor? How far has cancer spread in the pleura? Has it spread into other nearby pleura or structures?
- Nodes (N) – Has cancer spread to the lymph nodes?
- Metastasis (M) – Has cancer spread to distant organs, the lungs or pleura (lining of the lung) on the other side of the body, or the peritoneum (the lining of the abdomen)?
Numbers are then included after the T, N, and M to indicate how advanced each component is with higher numbers meaning more advanced (“Malignant mesothelioma stages”).
Stages of Mesothelioma
Stage IA
T1 – N0 – M0
In this stage, the mesothelioma is in the pleura lining the chest wall on one side of the chest. It may or may not affect the pleura lining the diaphragm (the thin breathing muscle below the lungs), the mediastinum (the space between the lungs), or the pleura covering the lung. It has not spread to the lymph nodes or distant parts of the body.
Stage IB
T2 or T3 – N0 – M0
The mesothelioma has now grown to the pleura coating the diaphragm, the mediastinum, and the lung on one side of the chest. With T2, it has also grown into either the lung or diaphragm. With T3, it has also grown into either the first layer of the chest wall; the fatty tissue in the mediastinum; a single place in the deeper layers of the chest wall; or the surface of the pericardium (outer covering layer of the heart).
Stage II
T1 or T2 – N1 – M0
The mesothelioma is in the pleura lining the chest wall on one side of the chest and may have grown into the diaphragm or the lung. It has now spread to nearby lymph nodes on the same side of the body as the primary tumor but not to distant parts of the body.
Stage IIIA
T3 – N1 – M0
The mesothelioma has grown to the pleura coating the diaphragm, the mediastinum, and the lung on one side of the chest. It has also grown into either the first layer of the chest wall; the fatty tissue in the mediastinum; a single place in the deeper layers of the chest wall; or the surface of the pericardium (outer covering layer of the heart). It has now spread to nearby lymph nodes on the same side of the body as the primary tumor but not to distant parts of the body.
Stage IIIB
T1-3, N2, M0
T4, Any N, M0
If the mesothelioma is T1-3, then in order for it to be considered stage III, the tumor must have also spread to nearby lymph nodes on the other side of the body, or lymph nodes above the collarbone (supraclavicular lymph nodes).
If the mesothelioma is T4 it is now in the pleura lining the chest wall, as well as the pleura coating the lung, diaphragm, and mediastinum on one side of the chest. The cancer may or may not have spread to the lymph nodes and hasn’t spread to distant parts of the body. It has also grown into at least 1 of the following:
- More than 1 place in the deeper layers of the chest wall, including the muscle or ribs
- Through the diaphragm and into the peritoneum (the lining around the abdomen)
- Any organ in the mediastinum (esophagus, trachea, thymus, or blood vessels)
- The spine
- Across to the pleura on the other side of the chest
- Through the heart lining (pericardium) or into the heart itself
Stage IV
Any T – Any N – M1
In this final stage, the mesothelioma may or may not have grown into nearby structures or spread to nearby lymph nodes. It has spread to distant organs, like the bones, the liver, the lung or pleura on the other side of the body, or the peritoneum (the lining of the abdomen) (“Malignant mesothelioma stages”).
Treatment Options
In stage I, if the mesothelioma is located in one part of the chest lining or in the peritoneal (abdomen) lining, surgery can be done to remove the part of the lining with cancer and the tissue around it. If possible, radiation therapy or chemotherapy should also be done to remove any cancer cells left behind after surgery. If the mesothelioma is located in more than one place in the chest, the following are the available treatment options:
- Pleurectomy Decortication – surgery to remove part of the pleura (a thin layer of tissue that covers the interior wall of the chest cavity), with or without radiation therapy, to relieve symptoms and improve quality of life.
- Extrapleural pneumonectomy – surgery to remove a diseased lung, part of the pericardium (membrane covering the heart), part of the diaphragm (muscle between the lungs and the abdomen), and part of the parietal pleura (membrane lining the chest).
- Clinical trials for anticancer drugs, surgery, radiation therapy, chemotherapy, or a new treatment.
- Radiation therapy as palliative therapy to relieve symptoms and improve quality of life
In stages II and IIIA, it can often be treated with surgery to remove the tumor and chemotherapy. If the mesothelioma is found in the chest, the following are the available treatment options:
- Pleurectomy and decortication, to relieve symptoms and improve quality of life.
- Immunotherapy with an immune checkpoint inhibitor.
- Combination chemotherapy and targeted therapy with or without a monoclonal antibody.
- Chemotherapy placed directly into the chest cavity to shrink the tumors and keep fluid from building up.
- Surgery to drain fluid that has collected in the chest, to relieve chest discomfort and improve quality of life. Pleurodesis may be done to stop more fluid from collecting in the chest.
- Radiation therapy as palliative therapy to relieve pain.
- Clinical trials for combinations of surgery, radiation therapy, and chemotherapy (“Malignant mesothelioma treatment”).
In stages IIIB and IV, when mesothelioma is also found in the peritoneum, the following are the available treatment options:
- Immunotherapy with an immune checkpoint inhibitor.
- Combination chemoimmunotherapy with or without a monoclonal antibody.
- Chemotherapy placed directly into the chest cavity to shrink the tumors and keep fluid from building up.
- Surgery to drain fluid that has collected in the chest, to relieve chest discomfort and improve quality of life. Pleurodesis may be done to stop more fluid from collecting in the chest.
- Radiation therapy as palliative therapy to relieve pain.
- Clinical trials for combinations of surgery, radiation therapy, and chemotherapy (“Malignant mesothelioma treatment”)
As shown above, there are more available and effective treatment options for the earlier stages of mesothelioma. Unfortunately, the majority of patients are not diagnosed until their cancer has reached the later stages. Recently, a new study was published examining a potential new blood test that would allow doctors to detect mesothelioma in the earlier stages. If approved, this test would also allow doctors to better distinguish mesothelioma from other lung diseases with similar symptoms (Dilek Yonar). If patients can get an accurate diagnosis earlier they will have access to more effective treatment options and a potentially higher survival rate.
Resources
Dilek Yonar, Mete Severcan, Rafig Gurbanov, Abdulsamet Sandal, Ulku Yilmaz, Salih Emri, Feride Severcan. “Rapid diagnosis of malignant pleural mesothelioma and its discrimination from lung cancer and benign exudative effusions using blood serum”. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease. Volume 1868, Issue 10 (2022): 166473. https://doi.org/10.1016/j.bbadis.2022.166473
Malignant mesothelioma stages. American Cancer Society. Retrieved August 30, 2022, from https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/staging.html
Malignant mesothelioma treatment. National Cancer Institute. Retrieved August 30, 2022, from https://www.cancer.gov/types/mesothelioma/patient/mesothelioma-treatment-pdq
