Did You Know?
In the United States, 2,000-3,000 patients are diagnosed with malignant pleural mesothelioma each year.
Pleural mesothelioma is a malignant mesothelioma that spreads within the chest cavity and sometimes involves the lung.
Asbestos exposure is the most common risk factor associated with mesothelioma. Asbestos refers to a family of magnesium-silicate mineral fibers that have been commonly used for insulation and in the shipbuilding and construction industries. A history of asbestos exposure is found in 80 percent of patients who present with mesothelioma. Other factors, which may promote mesothelioma, include: chronic lung infections, tuberculous pleuritis, radiation (Thorotrast) and exposure to the simian virus 40 (SV40) or mineral fibers (Zeolite). Although tobacco smoking has not been associated with the development of mesotheliomas, the combination of smoking and asbestos exposure greatly increases the risk of lung cancer.
- In the United States, 2,000-3,000 patients are diagnosed with malignant pleural mesothelioma each year.
- Mesothelioma affects men more frequently than women and is more common in white Americans.
- The median age of onset of symptoms is 70.
- Seven percent of workers exposed to asbestos become affected.
- The latent period between exposure to asbestos and the onset of symptoms can be 20-40 years.
- The median survival time is between 4-12 months, depending on the stage of presentation. The three-year survival is 10 percent and the overall five-year survival is approximately 5 percent.
The severity of the condition varies from person to person, but in most cases the onset of Pleural Mesothelioma is usually very slow with the most common presenting symptom being persistent pain localized in the chest. Sometimes the pain is accompanied by severe difficulty in breathing or shortness of breath. Cough, weight loss, fever and night sweats are less common.
(1) diffuse and malignant (cancerous).
(2) localized and benign (non-cancerous.)
Benign mesotheliomas can often be removed surgically, are generally not life-threatening, and are not usually related to asbestos exposure. Malignant mesotheliomas, however, are very serious. Fortunately, they are rare - about two thousand people are diagnosed with mesothelioma in the U.S. each year.
Pleural mesothelioma signs and symptoms may include:
- Shortness of breath
- Painful breathing
- Chest pain under the rib cage
- Unusual lumps of tissue under the skin on your chest
- Unexplained weight loss
- Dry (nonproductive) cough
The remainder of this section is about diffuse malignant pleural mesothelioma.
Pleural mesothelioma is a cancer of the cells that make up the pleura or lining around the outside of the lungs and inside of the ribs. Its only known cause in the U.S. is previous exposure to asbestos fibers, including chrysotile, amosite or crocidolite. Exposure to these fibers within ten years of a diagnosis of this type of cancer can be considered as a likely contributing factor in the disease process. It is the most common type of mesothelioma, accounting for about 75% of all cases.
Mesothelioma is sometimes diagnosed by coincidence, before there are any symptoms. For instance, tumors have been discovered through routine chest x-rays. However, when symptoms occur, they may include shortness of breath, weakness, weight loss, loss of appetite, chest pains, lower back pains, persistent coughing, difficulty in swallowing, alone or in combination. An initial medical examination often shows a pleural effusion, which means an accumulation of fluid in the pleural space - the area between the lungs and the chest wall.
The first step in detecting pleural mesothelioma is, typically, a chest x-ray or CT scan. This is often followed by a bronchoscopy, using a viewing scope to look inside the lungs.
The actual diagnosis usually requires obtaining a piece of tissue through a biopsy. This could be a needle biopsy, an open biopsy, or through a tube with a camera (thoracoscopy or chest scope.) If an abnormality is seen through the camera then a tissue sample can be taken at the same time, using the same tube. This is a hospital procedure that requires anesthesia, but is not usually painful. The tissue sample is tested by a pathologist.
Fluid build-up from the pleural effusion can generally be seen on a chest x-ray and heard during a physical examination, but a firm diagnosis of mesothelioma can only be made through a biopsy and pathological testing. This is important because there are also benign pleural effusions and other tumors that have a similar appearance to mesothelioma. Diagnosing mesothelioma can be quite difficult; it requires special lab stains, and much experience in understanding them.
The spread of the tumor over the pleura causes pleural thickening. This can reduce the flexibility of the pleura and encase the lungs in an increasingly restrictive girdle. With the lungs restricted, they get smaller and less functional, and breathing becomes more difficult. At first a person with mesothelioma may be breathless only when he or she exercises, but as lung function drops, he or she can become short of breath even while resting.
The tumor spreads by direct invasion of surrounding tissue. As it spreads inward it can compress the lungs. As the tumor spreads outward it can invade the chest wall and ribs, and this can be extremely painful.
Current medical science does not know exactly how and why, at a cellular level, asbestos fibers cause mesothelial cells to become abnormal (malignant or cancerous.) Thus it is not known whether only one fiber causes the tumor or whether it takes many fibers. It seems that asbestos fibers in the pleura can start a tumor as well as promote its growth; the tumor does not depend on any other processes for its development.
There is as yet no known cure for
malignant mesothelioma. The prognosis depends on various factors, including the size and stage of the tumor, the extent of the tumor, the cell type, and whether or not the tumor responds to treatment. The Firm has represented many clients who lived for five to ten years after diagnosis, most of them in good health for a majority of those years. Some mesothelioma victims succumb within a few months; the average survival time is about a year.
