Malignant mesothelioma is a rare, aggressive cancer caused by inhalation of asbestos fibers.
An estimated 3,000 people are diagnosed with the disease each year in the United States, according to the American Cancer Society.
Malignant mesothelioma is found in the mesothelium, a layer of cells that line the inside of most internal organs.
The type of malignant mesothelioma depends on the part of the mesothelium affected.
The most common type — pleural mesothelioma — affects the tissue surrounding the lungs. Other types include peritoneal mesothelioma, which affects the tissue in the abdomen; pericardial mesothelioma, which affects the lining of the heart; and mesotheliomas of the tunica vaginalis, which initiate in the lining of the testicles.
Malignant mesotheliomas may be further classified into three main categories.
Epithelioid mesothelioma — the most common subtype, accounting for more than half of cases — is associated with a better prognosis than other types.
Sarcomatoid or fibrous malignant mesothelioma accounts for about 10% of cases.
Mixed or biphasic mesotheliomas — which account for 30% to 40% of cases — has both epithelioid and sarcomatoid cells.
Individuals who have been exposed to asbestos in factories, foundries, shipyards and aboard U.S. Navy ships are at increased risk for malignant mesothelioma.
Professions associated with higher risk for the disease include plumbers, roofers, electricians, mechanics, custodians and janitors.
People who have been heavily exposed to asbestos do not always develop malignant mesothelioma. Conversely, prolonged exposure to asbestos is not needed for malignant mesothelioma to occur. Some people are affected from exposure of asbestos when a family member tracks microscopic asbestos fibers into the home. Family history of mesothelioma also increases a person’s risk.
ymptoms and diagnosis
General symptoms of malignant mesothelioma may not appear until several decades after asbestos exposure.
Symptoms of pleural mesothelioma may include chest pain, pleural effusion, shortness of breath, persistent cough, fever or weight loss.
Symptoms of peritoneal mesothelioma may include swelling or pain in the abdomen, peritoneal effusion, weight loss, anemia, fever and bowel obstruction.
Malignant mesothelioma may be diagnosed after a physical exam, X-ray, CT scan and biopsy.
Treatment of malignant mesothelioma is based primarily upon the type, stage and location of disease.
When diagnosed at an early stage, surgery may cure malignant mesothelioma. In cases when it is not possible to remove all of the cancer, surgery may be performed to reduce painful symptoms and to stop malignant mesothelioma from spreading.
Chemotherapy may be used prior to surgery, and both chemotherapy and radiation may be used after surgery to reduce risk for recurrence.
In most cases, however, malignant mesothelioma is an aggressive cancer that is diagnosed at a late stage, and the cure rate is low.
Clinical trials are currently assessing the use of targeted, biological and gene therapies as new approaches to treating malignant mesothelioma.
Researchers are testing the use of immunotherapy or biological response modifier therapy to restore the body’s immune system so it can attack the cancer cells. In addition, researchers are assessing the use of vaccine therapy to alert the immune system to better recognize and fight malignant mesothelioma cells. – by Jennifer Southall
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