What are the stages of mesothelioma?
Mesothelioma is an unusually aggressive cancer that is most often caused by asbestos exposure.
In its earliest stages, mesothelial cancer cells can form localized tumors in regions like the chest and abdomen. However, as this disease progresses, it can spread to nearby lymph nodes and metastasize to different and more distant parts of the body.
A Brief Overview of Mesothelioma
Mesothelioma is a rare cancer that can affect the lungs, heart, and abdomen.
Although mesothelioma forms in the mesothelium, a thin layer of cells that lines many of the body’s organs, it can quickly metastasize. Once it has metastasized, it can move with surprising speed, spreading so fast that conventional cancer treatments often prove ineffective. Survival rates are low, with most doctors prioritizing patients’ comfort over finding a cure.
Understanding the Causes of Mesothelioma
Mesothelioma takes its name from the “mesothelium.”
Your mesothelium is a thin layer of epithelial cells found throughout your body’s biggest cavities. These include, but are not limited to, the following:
The pleura of the lungs;
The peritoneum of the abdomen; and
The pericardium of the heart.
Together, these three interconnected systems constitute an integral part of the “serous membrane.” Your mesothelial cells serve as a sort of lubricant for different systems within the serous membrane, preventing tissue from sticking and helping fluid move between cavities.
How healthy cells become invaded by cancer cells
Under ordinary conditions, your mesothelial cells pose no threat to your health. In fact, their presence is essential to your well-being. However, like other cells in your body, mesothelial cells can mutate. Most mutations are harmless, but some trigger very rapid processes of replication. If and when mesothelial cells reproduce too fast, they can become cancerous and form tumors.
Some mutations occur naturally, but mesothelioma is closely associated with a discrete set of risk factors.
Mutation factors can include:
Inherited traits.
People who inherit mutated variants of the BAP1 gene may be more likely to develop mesothelioma as adults.
Erionite exposure.
Erionite is a zeolite mineral found in parts of the Western United States. It is used for gravel road surfacing, is classified as a carcinogen, and is believed to cause mesothelioma.
Irradiation.
Some scientists believe that irradiation of the chest or the abdomen can trigger the sorts of mutations that cause mesothelioma.
However, compared to inherited traits and erionite exposure, mesothelioma has a much more common cause: asbestos.
Asbestos Exposure: The Leading Cause of Malignant Mesothelioma
Asbestos is a type of naturally-occurring mineral that can be found in deposits throughout the United States and around the world. Exposure to asbestos, even in small quantities, is a leading risk factor for mesothelioma, asbestosis, and a range of other serious diseases.
People are typically exposed to asbestos through one or more of the following routes:
Primary asbestos exposure, sometimes termed “occupational asbestos exposure,” is asbestos exposure that happens in the workplace. Occupational asbestos exposure was very common between the 1940s and the early 1980s. People who worked in construction, manufacturing, and certain military occupational specialties are often at-risk for mesothelioma.
Secondary asbestos exposure, or “domestic asbestos exposure,” is asbestos exposure that is indirect. Most people with histories of secondary asbestos exposure lived with somebody who worked with or around asbestos.
Environmental asbestos exposure can be caused by naturally-occurring asbestos, or by companies that pollute the natural environment with asbestos-based waste.
Although asbestos today is regulated at the state and federal level, tens of millions of Americans were exposed to this mineral between the end of World War 2 and the early 1980s.
How Doctors Diagnose Mesothelioma and Other Asbestos-Related Illnesses
Unlike many other diseases, asbestos-related conditions—including mesothelioma—have very long latent periods. In other words, symptoms may not emerge for decades after an initial asbestos exposure. If and when symptoms do become apparent, they can seem deceptively mild and are often so vague that they are either ignored or attributed to another illness.
Early-stage mesothelioma symptoms could, for instance, include any of the following:
Chest pain
Painful coughing or wheezing
Shortness of breath
Lumps of tissue under the skin of the chest
Unexplained or unwanted weight loss
General feelings of nausea, malaise, or uneasiness
The issue of latency and asbestos-related cancers like mesothelioma
Since these symptoms are common to many other illnesses, most people don’t realize that they have mesothelioma until their symptoms have escalated to the point that they can no longer be ignored. Even then, most doctors have very little experience with mesothelioma. Before reaching a diagnosis, physicians will usually recommend:
Taking a medical imaging test, like an X-ray or a CT scan.
If a lump, mass, or suspected tumor is visible in the results of the imaging test, patients may be referred for a biopsy.
Biopsies are surgical procedures that remove a small section of a suspected tumor. The sample is sent to a laboratory, where it is analyzed for abnormalities.
Mesothelioma can only be definitively diagnosed after a biopsy.
The 4 Stages of Mesothelioma
The results of a biopsy can provide critical information about a mesothelioma diagnosis.
By analyzing samples of cancerous tissue, physicians and laboratory technicians can determine:
If a tumor is cancerous
How a tumor formed
The origin of cancerous cells
This information, along with the results of other tests, can be used to determine the disease’s current stage as well as its likely course. Staging, in particular, is critical in assessing a patient’s most probable prognosis, including their chances of long-term survival.
The TNM Staging System
Different organizations using different staging systems. In the United States, the most frequently-used staging system is the American Joint Committee on Cancer’s “TNM system.”
The TNM system uses three pieces of information to determine stage:
The extent and size of the main tumor.
Whether the tumor has spread to nearby lymph nodes.
Whether the tumor has metastasized, or spread to distant organs, tissue, and systems.
The Stages of Malignant Mesothelioma
The progress of mesothelioma, like many other types of cancer, is typically expressed as:
Stage I Mesothelioma
Stage I mesothelioma is the earliest stage at which cancer can be detected.
Different forms of mesothelioma are diagnosed in slightly different ways. In the case of malignant pleural mesothelioma, Stage I cancer is often categorized as either of the following:
Stage IA cancer, for mesothelioma isolated to the pleural lining of the chest wall. It may or may not affect adjoining systems, including tracts of the lung.
Stage IB cancer, for mesothelioma that has grown into nearby structures but is still small or isolated enough that it could be surgically removed.
Mesothelioma remains in Stage I so long as it does not spread to nearby lymph nodes or metastasize and spread to other parts of the body.
Stage II Mesothelioma
Mesothelioma that progresses to Stage II is present in the pleural lining of the affected organ, and it has spread to nearby lymph nodes.
Stage III Mesothelioma
Stage III mesothelioma is usually categorized as:
Stage IIIA mesothelioma, or mesothelioma that has grown into nearby lymph nodes and structures. For malignant pleural mesothelioma to be categorized as Stage IIIA mesothelioma, the cancer must have grown into the first layer of the chest wall, the fatty tissue between the lungs, or the pericardial covering of the heart.
Stage IIIB mesothelioma, or mesothelioma that has spread to nearby lymph nodes on either side of the body. It may still be removed by surgery, and has not yet metastasized.
Stage IV Mesothelioma
Mesothelioma in its final stage may or may not have grown into nearby structures or lymph nodes, but it has spread to distant systems. These systems could include:
Bones
Distant organs
The mesothelial lining of other cavities
Stage IV mesothelioma cannot usually be removed with surgery. Survival rates are very low, with most patients living between 4 and 16 months after their initial Stage IV diagnosis.