Mesothelioma is a cancer doctors continue to research to get a better understanding of its cause and its cure. Current research and patient clinical trials have increased the prognosis of those diagnosed with this disease.
When cells begin to grow out of control, in almost any part of the body, they can become cancer. So what is mesothelioma and how does it begin?
Mesothelioma is an aggressive type of rare cancer that develops in cells that begin to grow out of control in the mesothelioma, which is the lining that surrounds many of the body’s internal organs. Approximately 3,000 cases are diagnosed each year in the U.S. Mesothelioma is more common in older adults than young people. The approximate age when the person is diagnosed for pleural mesothelioma is 69.
About 75% of mesothelioma cases begin in cells that line the sacs of the chest, the pleura, which is the outer lining of the internal chest wall and lungs. It is called pleural mesothelioma. Because the tissue which covers the heart (pericardium) is close to the pleura, mesothelioma sometimes spreads to the lining of the heart.
Pleural mesothelioma is often difficult to detect and currently, a CT scan of the chest is the best test for assessing how far the disease has progressed. Many cancers are diagnosed by serum markers; however, mesothelioma cannot be diagnosed this way as currently, no serum markers exist.
The lining of the abdominal cavity is called the peritoneum. It contains fluid which aids in keeping the contents of abdomen safe and accounts for approximately 25% of mesothelioma cases. Peritoneal mesothelioma usually does not spread to other parts of the body.
The least common type of mesothelioma is pericardial mesothelioma which involves the heart. The cancer invades the sac which surrounds the heart (pericardium). As it progresses, the heart is unable to efficiently get oxygen to the body. This causes a rapid decline in health.
Rarely mesothelioma will arise in the lining that surrounds the testis. This is called tunica vaginalis.
Cell Types of Mesothelioma
There are 3 types of cells that are grouped based on what they look like under a microscope.
• Epithelioid – The most common with a better prognosis than the other two types.
• Sarcomatoid or fibrous account for about 10% of mesotheliomas.
• Mixed type (biphasic type) the mesotheliomas have epithelioid and sacromatoid areas. This type accounts for the other 30%-40%.
Who is at Risk for Malignant Mesothelioma?
Anything that could affect the chance of you getting a disease is called a risk factor. Some factors can be changed, such as smoking, other factors such as family history or age cannot. Research has shown that there are some factors that will increase a person’s risk of this cancer such as exposure to the following:
• Asbestos – Asbestos is natural fibers found in rock and soil. When the fibers are inhaled they can get
down into the lungs and travel down the airways to enter the pleural lining of the lungs and chest. Exposure to asbestos is the number one risk factor for mesothelioma. People who have been exposed for a long period of time at an early age are more likely to develop mesothelioma which can take between 20 and 50 years to develop.
• Zeolites – Zeolites are related chemically to asbestos. One example of a zeolite is erionite. This mineral is common in both soil and rocks in parts of Turkey.
• Radiation – Mesothelioma from radiation is rare, however, there is a higher risk in patients that have had radiation treatments.
• SV40 virus – Vaccines given for polio between 1955 and 1963 were contaminated with SV40 which some studies, performed on lab animals, have indicated may increase the risk of developing mesothelioma. However, the largest studies on the issue in humans has not found an increased risk of mesothelioma. The conclusion is that the experts, at this time, don’t know if there is a correlation.
Age and Gender
It is possible for mesothelioma to occur in young people and children, however, it is rare in people under 45. Your risk of mesothelioma increases with age.
It is more common in men than women, likely because men’s jobs have exposed them to much more asbestos.
What are the Causes of Mesothelioma?
Mesothelioma cancer occurs in the thin membrane that surrounds the body’s internal organs. Cancer forms when the DNA in the cells of the body are damaged. DNA is the chemical in body cells that make up our genes, and changes in the genes might cause cells to grow out of control which then leads to cancer.
The main cause of mesothelioma is asbestos. When the tiny asbestos fibers are inhaled, they travel to the pleura through small air passages. Once there they cause inflammation and scaring which damage the cells’ DNA and those changes result in uncontrolled cell growth. If the fibers are swallowed they may reach the abdominal lining which causes peritoneal mesothelioma.
The link between asbestos and lung disease has been known since the 1800’s, however the link to mesothelioma has only been known since the 1960’s. Asbestos was heavily used in construction just after world war ll until the mid-1970’s, and thus the cases of mesothelioma are expected to rise sharply as those who worked in the industry get older.
Asbestos is a material heavily used in construction as insulation. It is heat and fire resistant. It was used widely in the following industries;
o Building industry
o Ship building industry
o Manufacture household appliances
o Motor industry
o Power stations
o Telephone exchanges
Asbestos comes in three main types, white, blue, brown. Brown and blue asbestos have been linked strongly to mesothelioma. The use
of all asbestos was banned in the late 1990’s.
Mesothelioma that has been caused by exposure to asbestos occurs environmentally, occupationally or by second-hand exposure. Families of workers were also at risk as workers came home with asbestos fibers on their work clothes, hair, and tools which exposed them to asbestos as well.
People living in areas near large deposits of asbestos, which is a naturally occurring mineral in the environment, have also been shown to have an increased risk of mesothelioma. The exposure is the most dangerous close to asbestos mines such as those found in California and Montana.
The risk of asbestos related illness is higher for people that worked directly with asbestos raw minerals or products that contained asbestos daily. The occupations in which mesothelioma is most prevalent include;
• Industrial workers
• Shipyard workers
• Boiler workers
• Construction workers
• Chemical plant workers
• Auto mechanics
The highest incidents of mesothelioma appear to be asbestos insulation workers. Approximately six percent of asbestos workers experience some type of respiratory illness or fall victim to mesothelioma. Asbestos workers are 300 times more likely than non-workers to be diagnosed with mesothelioma.
Asbestos removal is highly regulated and people or business that do not follow the regulations are heavily fined. The use of asbestos was restricted in 1970’s but workplace exposure still occurs.
The Symptoms of Mesothelioma
Mesothelioma is difficult to diagnoses. Neither pleura nor peritoneum mesothelioma have symptoms in the early stages. Once symptoms do develop they are often mistaken for common illnesses or everyday aches and pains. Early symptoms include a cough, muscle weakness, night sweats, fever, and fatigue. Unfortunately, early symptoms go undiagnosed or misdiagnosed until further warning signs become apparent from more serious symptoms. It is important to see your doctor if you have or develop any of these symptoms if you have also been exposed to asbestos.
Symptoms of pleural mesothelioma
• Shortness of breath
• Chest pain
• Unexplained weight loss
• Persistent cough
• Hoarse voice
• Difficulty swallowing
• Changes in shape of fingers/nails
Pleural mesothelioma is the only type of this cancer that is classified into stages.
Symptoms of peritoneal mesothelioma
• Localized abdominal pain
• Abdominal swelling
• Unexplained weight loss
• Diarrhea or constipation
• Fluid build-up in the abdomen
Pericardial mesothelioma symptoms
• Chest pain
• Paradoxical pulse
• Night sweats
• Weight loss
• Fatigue and weakness
Testicular mesothelioma symptoms
• Symptoms are nonspecific
• Mass or tumor located in the testes usually discovered during a surgical procedure.
Advanced stage mesothelioma symptoms
• Nerve problems
• Bone pain
• Horner’s syndrome
• Nerve problems in the arm
Mesothelioma symptoms often don’t emerge until about 20 to 50 years after initial exposure, and the symptoms do not appear until the disease has progressed into advanced stages.