Mesothelioma Treatment Overview

How malignant mesothelioma is treated

There are treatments for all patients with malignant mesothelioma. Three kinds of treatment are used:

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Surgery (taking out the cancer).
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Radiation therapy (using high-dose x-rays or other high-energy rays to kill cancer cells).
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Chemotherapy (using drugs to fight the cancer).

Surgery is a common treatment of malignant mesothelioma. The doctor may remove part of the lining of the chest or abdomen and some of the tissue around it. Depending on how far the cancer has spread, a lung also may be removed in an operation called a pneumonectomy. Sometimes part of the diaphragm, the muscle below the lungs that helps with breathing, is also removed.

Radiation therapy uses high-energy x-rays to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external radiation therapy) or from putting materials that produce radiation (radioisotopes) through thin plastic tubes in the area where the cancer cells are found (internal radiation therapy).

If fluid has collected in the chest or abdomen, the doctor may drain the fluid out of the body by putting a needle into the chest or abdomen and using gentle suction to remove the fluid. If fluid is removed from the chest, this is called thoracentesis. If fluid is removed from the abdomen, this is called paracentesis. The doctor may also put drugs through a tube into the chest to prevent more fluid from accumulating.

Chemotherapy uses drugs to kill cancer cells. Chemotherapy may be taken by pill, or it may be put into the body by a needle in the vein or muscle. Chemotherapy is called a systemic treatment because the drug enters the bloodstream, travels through the body, and can kill cancer cells throughout the body. In mesothelioma, chemotherapy may be put directly into the chest (intrapleural chemotherapy).

Intraoperative photodynamic therapy is a new type of treatment that uses special drugs and light to kill cancer cells during surgery. A drug that makes cancer cells more sensitive to light is injected into a vein several days before surgery. During surgery to remove as much of the cancer as possible, a special light is used to shine on the pleura. This treatment is being studied for early stages of mesothelioma in the chest.
Mesothelioma Treatment by stage

Treatment depends on where the cancer is, how far it has spread, and the patient's age and general health.

Standard treatment may be considered because of its effectiveness in patients in past studies, or participation in a clinical trial may be considered. Not all patients are cured with standard therapy and some standard treatments may have more side effects than are desired. For these reasons, clinical trials are designed to find better ways to treat cancer patients and are based on the most up-to-date information. Clinical trials are ongoing in many parts of the country for many patients with malignant mesothelioma.
Advanced Malignant Mesothelioma (Stages II, III, and IV)

Treatment may be one of the following:

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Draining of fluid in the chest or abdomen (thoracentesis or paracentesis) to reduce discomfort. Drugs also may be put into the chest or abdomen to prevent further collection of fluid.
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Surgery to relieve symptoms.
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Radiation therapy to relieve symptoms.
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Chemotherapy.
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A clinical trial of surgery, radiation therapy, and chemotherapy.
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Chemotherapy given in the chest or abdomen.

Localized Malignant Mesothelioma (Stage I)

The cancer is found in the lining of the chest cavity near the lung and heart or in the diaphragm or the lung. If the cancer is only in one place in the chest or abdomen, treatment will probably be surgery to remove part of the pleura and some of the tissue around it. If the cancer is found in a larger part of the pleura, treatment may be one of the following:

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Surgery to remove the pleura and the tissue near it to relieve symptoms, with or without radiation therapy after surgery.
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Surgery to remove sections of the pleura, the lung, part of the diaphragm, and part of the lining around the heart.
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External beam radiation therapy to relieve symptoms.
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A clinical trial of surgery followed by chemotherapy given inside the chest.
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A clinical trial of surgery, radiation therapy, and/or chemotherapy.

Pleural mesothelioma

Pleural mesothelioma is of two kinds: (1) diffuse and malignant (cancerous), and (2) localized and benign (non-cancerous.)

Benign mesothelioma can often be removed surgically, are generally not life-threatening, and are not usually related to asbestos exposure. Malignant mesothelioma, 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 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. KMESA 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.

The treatment options for people with mesothelioma have improved significantly, especially for those whose cancer is diagnosed early and treated vigorously. Many people are treated with a combination of therapies, sometimes known as multimodal therapy.

Specific types of treatment include:

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Chemotherapy and other drug-based therapies
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Radiation therapy
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Surgery and
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Intra-operative photodynamic therapy.

There are also experimental treatments like gene therapy and immunotherapy, angiogenesis inhibitors, and clinical trials for various new treatments and combinations of treatments.

Treatments that reduce pain and improve lung function, are becoming more successful (although they cannot cure mesothelioma.) Pain control medications have become easier to administer. Debulking is a surgical process of removing a substantial part of the tumor and reducing the pleural thickening; this can provide significant relief. X-ray therapy has also been successfully used to control the tumor and the pain associated with it for a while.
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.

Benign Mesothelioma:

A rare form of mesothelioma is the cycstic mesothelioma of the peritoneum. Its prognosis is benign. Its occurrence has been described primarily in young women. However the diagnosis presents difficulties, requiring extensive electron miscroscopy and immunohistochemical studies.

Rare Sites:

Mesothelioma of the pericardium, is a very seldom seen cardiac cancer. The mass is usually detected at a late stage by echocardiography, the prognosis is very poor , with or without therapy. Mesothelioma of the ovaries and the scrotum have also been reported in the literature. The management differs based on the stage of the disease, the prognosis is also very poor. The etiology of the few cases of mesothelioma described in children remains unclear and is not believed to be asbestos-related, the therapy and prognosis differ on an individual basis.