What is Mesothelioma?
Mesothelioma is a type of cancer which generally affects the lining of the lungs (pleural mesothelioma). It is also found layers of tissue in the abdominal area (peritoneal mesothelioma), and very rarely, in the heart or the testicles.
The main cause of this type of cancer is exposure to asbestos. It mostly occurs in adults between 50 and 70 years old and is more prevalent in men than women. About 70 to 80 percent of cases are found in men. (1)
While the use of asbestos was prohibited in the western world in the 1980s, this condition can take between 15 and 60 years to manifest. (2)
Asbestos is a naturally occurring mineral, composed of many tiny fibers. Found in rocks and soil in many parts of the world, there are two main types of fiber: serpentine and amphibole.
Serpentine fibers are curly and long, while amphibole are straight and look like a rod. Both fibers can be airborne and inhaled into the lungs.
Serpentine fibers are easier to clear from the respiratory tract. The amphibole fibers are from a type of asbestos called crocidolite (blue asbestos). Exposure to these has a high risk of contracting mesothelioma.
The fibers, once inhaled, work their way into the lining of the lungs (pleura). They then cause irritation and changes in the genes, which lead to cancerous growths.
Some of the inhaled fibers might be coughed up and then swallowed. This could be the cause of mesothelioma in the abdomen.
Used extensively between the 1930s and 1980s in many industrial and environmental settings, many people were exposed to these fibers. Asbestos is both fire and heat resistant.
People at risk in the workplace include miners, insulation installers and manufacturers, shipbuilders, factory workers, plumbers and construction workers.
Family members of people who have worked with asbestos are also at risk, as the fibers are often carried on clothing.
Asbestos was previously used as an insulating material in many homes, schools, public and commercial buildings. As the fibers are in the building materials, exposure levels are likely to be low. However, they can become airborne during removal or remodeling, or through natural degeneration and decomposition.
The amount and length of exposure can influence how likely someone is to develop mesothelioma. Other factors, like genes, affect the likelihood of developing this condition after exposure to asbestos.
Other causes of mesothelioma include exposure to radiation, exposure to a mineral fiber called zeolite, or infection with the SV40 virus.
Some polio vaccines administered by injection between 1955 and 1963 contained SV40 contamination. Up to 30 million US citizens might have been at risk of exposure in this way.
Laboratory studies on animals have shown a link between this virus and risk of mesothelioma. However, there has not yet been a proven definitive link between SV40 and the risk it poses in humans. (3, 4)
The symptoms of this condition manifest either in the lungs or abdomen. They can be similar to those linked with other conditions. But if you have been in contact with asbestos, and the symptoms persist, you should see a doctor.
Pleural Mesothelioma (Lungs)
Pain might appear in the lower back or side of the chest. A shortness of breath and a persistent cough are further symptoms.
A person could have an elevated temperature (fever) and experience excessive sweating.
Extreme tiredness and lethargy (fatigue) or an unexplained weight loss are further signs for concern. The arms and face might start swelling.
A feeling of food being stuck in the throat and difficulty swallowing (dysphagia), or hoarseness in the voice might also be noticed.
Peritoneal Mesothelioma (Abdomen)
Pain and swelling in the area of the abdomen, or fluid in the abdomen, are symptoms of this type of mesothelioma.
An unexplained weight loss, nausea, vomiting and constipation or diarrhea are further symptoms. (5)
The most often used staging system in respect of pleural mesothelioma is the International Mesothelioma Interest Group (IMIG) system. There are no stages at present for abdominal mesothelioma; the above stages are sometimes used for both types of cancer.
It is founded on the system used for different types of cancer called the TNM (tumor, node, metastasis) system.
It describes the position and size of the initial tumor (T). It also looks at whether the cells of mesothelioma have travelled to lymph nodes nearby (N). Finally, it examines whether the mesothelioma cells might have metastasized or travelled to other body parts (M).
Following diagnosis, these factors are identified and used to stage the mesothelioma.
At this first stage, the mesothelioma cells are located in the lining around the lung (pleura) on one side of the chest.
The mesothelioma can be located in the outer layer of the lining, outside the lungs (parietal pleura), only affecting one side.
The mesothelioma cells are found in the inside layer of the linings outside the lungs (visceral pleura), again on one side of the chest only. They will not have spread to the diaphragm or lung tissue.
The mesothelioma has now spread to both layers lining the outside of the lungs (pleura), but on a single side of the body. It will also have grown to create a tumor mass in the tissue surrounding the lungs (pleural tissue). It might have travelled into the muscle of the diaphragm or the tissue of the lungs.
The mesothelioma has traveled to the wall of the chest or the lining around the heart, called the pericardium. It is, however, still able to be removed by surgery. Alternately, it might have traveled to the lymph nodes on the area of the chest where the primary tumor is located.
The mesothelioma has traveled to other parts of the wall lining the chest and now cannot be removed by surgery. It might have grown through the muscle of the diaphragm, entering the lining of the abdominal cavity, called the peritoneum.
It may also have spread to the lining outside the lungs (pleura) in the opposite side from the original tumor. Additionally, it could be found in the organs in the chest or the inner lining of the of the heart (pericardium).
It might have metastasized to lymph nodes, located on the opposite part of the chest from the original tumor. It might also be located in the area at the top of the collarbone. It could have spread elsewhere in the body. (6, 7)
There are four types of standard treatment for mesothelioma. They include surgery, radiation therapy, chemotherapy and targeted therapy.
Surgery used for this type of cancer includes: removing the cancer and part of the healthy tissue surrounding it (wide local excision). Some of the covering of the lungs, the chest lining, and outer surface of the lungs (pleurectomy and decortication) may also be removed.
An extrapleural pneumonectomy removes a whole lung and some of the chest lining, as well as the diaphragm and the lining around the heart.
Pleurodesis involves a surgical procedure which uses drugs or chemicals. They are placed into the space between the two layers of tissues around the lung (pleural cavity) to form a scar. Any fluid will be drained first, the resulting scarring can prevent it building up again.
Radiation therapy or chemotherapy might be administered following surgery.
This type of therapy can be administered in two ways.
Externally, a machine like an x-ray delivers radiation to kill cancer cells. Internally, radioactive substances are administered, via a needle or catheter, directly to the location of the cancer.
This therapy uses drugs to prevent the growth of further cancer cells by killing them, or preventing them dividing and spreading.
The drugs can be taken orally or injected into a muscle or vein. When they enter the bloodstream, they fight cancer cells throughout the body (systemic chemotherapy).
The drugs can also be administered in a more localized way, to stop the growth of cancer only in that area (regional chemotherapy)
Another type of chemotherapy used for this cancer is hyperthermic intraperitoneal chemotherapy. Used to treat abdominal mesothelioma, following surgery, anticancer drugs are heated in fluid which is pumped through the abdomen. This kills remaining cancer cells.
This therapy uses drugs or antibodies to try and eliminate, and prevent the growth and spread, of specific cancer cells.(8)
What is mesothelioma? Mesothelioma is a type of cancer which generally affects the lining of the lungs or abdomen.
What are the signs of mesothelioma? Signs of this condition include: pain in the chest or abdomen, shortness of breath and a persistent cough. Swelling might appear in the abdomen, the sufferer may have unexplained weight loss and be very tired.
How do you develop mesothelioma? The main cause of mesothelioma is inhalation of asbestos fibers.
How are you diagnosed for mesothelioma? Following a physical examination and checking medical history, imaging tests or tissue samples might be required.
What is the best treatment for mesothelioma? Treatment for this condition includes surgery, radiation therapy, chemotherapy or targeted therapy. A doctor will decide the best course of treatment, depending on the type and severity of mesothelioma.
What are the long term complications of mesothelioma? Mesothelioma is an aggressive form of cancer, often not detected until the later stages. Recurrence is also possible following treatment. (9)
Is mesothelioma considered a disability? Disability benefits might apply in some cases for this condition, dependent on medical records. (10)
Is there a cure for mesothelioma? Treatment of this condition, when diagnosed in its early stages, might result in a cure. However, many cases are not detected until a person is too ill, or the cancer is too advanced for curative treatment. (11)
Is mesothelioma life threatening? This condition is potentially life threatening. (12)
Mesothelioma is an aggressive form of cancer, usually developed following exposure to asbestos fibers. It can take many years to manifest, and is often not detected until it has reached a late stage.
If the disease is detected at an early stage, treatment is available which might be curative.