Mesothelioma Facts & FAQs
What is mesothelioma?
Mesothelioma is a cancer of the cells that make up the lining around the outside of the lungs and inside of the ribs (pleura), or around the abdominal organs (peritoneum).
What does asbestos have to do with mesothelioma?
The only known cause of mesothelioma in the U.S. is previous exposure to asbestos fibers. Asbestos manufacturers knew about the hazards of asbestos seventy years ago - but they kept this knowledge to themselves. The first warnings to workers exposed to asbestos were given in the mid-1960s, and they were terribly inadequate. Even today, workers are not always told they are working around asbestos and are at risk for asbestos disease.
What can someone with mesothelioma do?
- Seek out the best and most up-to-date information.
- Seek out the best medical care.
- Early screening for mesothelioma diagnosis.
- Stay in close contact with your doctor.
- Consider whether or not you want to bring a lawsuit because of this asbestos-related injury.
- Remember that resources are available to you through community and medical support groups, asbestos victims’ organizations, your place of worship, as well as your family and friends.
Pleural Mesothelioma
Pleural mesothelioma is of two kinds: (1) diffuse and malignant (cancerous), and (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.
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. This exposure is likely to have happened twenty or more years before the disease becomes evident, since it takes many years for the disease to "incubate." 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
Peritoneal Mesothelioma
Many of the organs in the abdomen are enveloped by a thin membrane of mesothelial cells, known as the peritoneum.
Peritoneal mesothelioma is a tumor of this membrane. Its only known cause in the U.S. is previous exposure to asbestos, but it can be many years after exposure before the disease appears. Peritoneal mesotheliomas account for about one-fifth of all mesotheliomas.
Like pleural mesothelioma, peritoneal mesothelioma can be either benign or malignant. This discussion is only about malignant peritoneal mesothelioma.
Mesothelioma is sometimes diagnosed by coincidence, before any symptoms have appeared. For example, the tumor is sometimes seen on a routine abdominal x-ray for a check-up or before surgery.
When the symptoms of peritoneal mesothelioma appear, they typically include abdominal pains, weakness, weight loss, loss of appetite, nausea, and abdominal swelling. Fluid often accumulates in the peritoneal space, a condition known as ascites. Over time the wasting symptoms can become more and more severe.
The growing tumor can exert increasing pressure on the organs in the abdomen, leading to bowel obstruction and distention. If the tumor presses upward, it can impair breathing capacity. If the tumor pushes against areas with many nerve fibers, and the bowel distends, the amount of pain can increase.
X-rays and CT scans are, typically, the first step towards detecting peritoneal mesothelioma. The actual diagnosis is typically achieved by obtaining a piece of tissue. The medical procedure of looking at the peritoneum is known as a peritoneoscopy. It is a hospital procedure and requires anesthesia. If an abnormality is seen, the doctor will attempt to obtain a tissue sample - this is known as a biopsy. The tissue sample will be examined by a pathologist who makes a diagnosis using microscopic analysis of specialized stains.
There are at least two explanations for how asbestos fibers can get into the peritoneum. The first is that fibers caught by the mucus of the trachea and bronchi end up being swallowed. Some of them lodge in the intestinal tract and from there they can move through the intestinal wall into the peritoneum. The second explanation is that fibers that lodge in the lungs can move into the lymphatic system and be transported to the peritoneum.
Medical science does not know exactly how or why, at a cellular level, a carcinogen like asbestos causes a cell to become malignant (cancerous.) Thus it is not known whether only one fiber can cause a tumor to develop or whether it takes many fibers, or what the exact conditions and predispositions are for this change to happen.
At this time there are treatments, but no known cure, for peritoneal mesothelioma. The prognosis depends on various factors, including the size and stage of the tumor, its extent, the cell type, and whether or not the tumor responds to treatment.
However, the options for relief and treatment of people with peritoneal mesothelioma have improved, especially for those whose cancer is diagnosed early and treated vigorously. Many people receive a combination of therapies, sometimes known as multimodal therapy.
Specific types of treatment include:
There are also clinical trials and various experimental treatments like gene therapy and immunotherapy, and antiangiogenesis drugs.
Further Resources
For more information about peritoneal mesothelioma and treatments, please explore this web site or visit:
Other Mesotheliomas
While the great majority of mesotheliomas are in either the pleura or the peritoneum, malignant mesotheliomas sometimes occur in other parts of the body, including the testicles (a variety of peritoneal mesothelioma) and the heart (a variety of pleural mesothelioma.) These are also caused by exposure to asbestos fibers. Benign mesotheliomas occur less frequently than malignant mesotheliomas. They are generally thought to be unrelated to asbestos exposure. Two thirds of benign mesotheliomas occur in females. (Kittle: Mesothelioma Diagnosis and Management, Year Book Medical Publishers, 1987).
Unfortunately, cystic benign mesotheliomas have a high incidence of local recurrence. (Katsube: Cystic Mesothelioma of the Peritoneum; Cancer 1982, 50:1615; Moore: Benign Cystic Mesothelioma; Cancer 1980, 45:2395) A July 1998 article by G.S. Letterie in the journal "Gynecology and Obstetrics" describes therapy with anti-estrogen tamoxifen as a non-surgical option for cases of symptomatic recurrent cystic mesotheliomas.
Diagnosis for Malignant Mesothelioma Cancer: Screening
The National Cancer Institute’s definition of screening for cancer is the examination or testing of people for early signs of certain type of cancer even though they have no symptons - this is the best way to achieve a diagnosis as early as possible. Early detection and diagnosis is particularly important for people with historical exposure to asbestos due to the latency period (up to 30 years) before which symptoms of malignant mesothelioma cancer may become apparent.
Early Signs of Mesothelioma Aid Diagnosis:
Recognizing early symptoms of malignant mesothelioma may aid in diagnosis. Symptoms include difficulty in breathing (dyspnea) and/or chest pains, fever, nausea or anemia; other signals are hoarseness, difficulty swallowing (dysphagia), or coughing up blood (hemoptysis). For many suffering from pleural mesothelioma, there may be pain in the chest or lower back. Those people with peritoneal mesothelioma may experience an expanding waist size or abdominal pain resulting from the growth of cancer cells in the abdomen.
Since many of these symptoms are also caused by less serious illnesses, it can be difficult to recognize asbestos-related diseases in the early stages. Due to this difficulty of early diagnosis of asbestos cancer and mesothelioma, the best way to determine your health risk is to consult a doctor for an initial examination, which may include a pulmonary function test (PFT) and x-rays.
Screening Methods to Identify Asbestos-Related Disease:
After a preliminary physical examination, the doctor may need to look inside your chest cavity with a thorascope for accurate diagnosis. During this thoracoscopy procedure, a cut will be made in your chest and a small piece of tissue (biopsy) may removed for examination. While you may feel some pressure, there is usually no pain.
Another special tool that may be used is the peritoneoscope, which allows for examination inside your abdomen. This instrument is inserted into an opening made in the abdomen, and a biopsy specimen may also be taken.
If the presence of fluid is indicated by either of these procedures, the doctor may drain it by inserting a needle into the affected area. Removal of chest fluid is called thoracentesis; removal of abdominal fluid is call paracentesis.
Other screening methods for diagnosis of asbestos-related disease include various imaging tests. In addition to X-rays, methods include magnetic resonance imaging (MRI) or positron emission tomography (PET). A more recent and promising screening method is the computed tomography (CT) scan.
Computed Tomagraphy / CT Scan:
Computed tomagraphy, or spiral CT scan, is a special radiographic technique that produces a clear cross-sectional image that allows a radiologist to see distinct aspects of the lung or pleura that are not readily apparent from the standard X-ray image. Recent studies (CHEST 2002;122:15-20 and MAYO CLIN PROC 2002;77:329-333) support the use of annual chest computed tomography (CT scans) exams as a valuable screening tool for people with a high risk of developing lung cancer, including mesothelioma cancer. There does appear to be conflicting assessment as to the cost-effectiveness of CT screening. A2003 study by Johns Hopkins raises this concern about the cost-effectiveness of CT scans and states, "There is a downside to this, including high costs and possible harm to individuals who may unnecessarily get invasive procedures if the scan detects a benign lung nodule." A more recent study in Chest, 2003:124:614-621 comes to a different conclusion: "A baseline low-dose CT scan for lung cancer screening is potentially highly cost-effective and compares favorably to the cost-effectiveness ratios of other screening programs."
Further Resources
- "A Systematic Review and Lessons Learned From Early Lung Cancer Detection Trials Using Low-Dose Computed Tomography of the Chest, " by Gerold Bepler, MD, PhD, et al; Cancer Control 10(4):306-314, 2003
- National Cancer Institute Cancer: Screening for Lung Cancer
- "There’s no such thing as a free asbestos screening," Worksafe! Newsletter (October 1998, p.6)
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