WHAT IS MESOTHELIOMA?

2007-05-09T00:11:00.000-07:00

Mesothelioma - is an uncommon form of cancer or a rare form of lung cancer, which affects the pleura, a sac which surrounds the lungs, the peritoneum, the lining of the abdominal cavity, or the pericardium, a sac that surrounds the heart.

Or it is also define as a benign (noncancerous) or malignant (cancerous) tumor affecting the lining of the chest or abdomen, caused by exposure/ingestion to asbestos fibers/particles. Mesothelioma affects the pleura of the lungs, often over a period of many years.

Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles, or have been exposed to asbestos dust and fibre in other ways, such as by washing the clothes of a family member who worked with asbestos, or by home renovation using asbestos cement products.

SIGNS AND SYMPTOMS:

Symptoms of mesothelioma may not appear until 20 to 50 years after exposure to asbestos The symptoms are abdomen pain, fatigue, weight loss, shortness of breath, persistent coughing or coughing blood, pain in the chest due to an accumulation of fluid in the pleural space (the later often for pleural mesothelioma).

Symptoms of peritoneal mesothelioma include weight loss and cachexia , abdominal swelling and pain due to ascites (a buildup of fluid in the abdominal cavity). Other symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia, and fever. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.

DIAGNOSIS:

Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history. A history of exposure to asbestos may increase clinical suspicion for mesothelioma. A physical examination is performed, followed by chest X-ray and often lung function tests. The X-ray may reveal pleural thickening commonly seen after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT) scan or an MRI is usually performed. If a large amount of fluid is present, abnormal cells may be detected by cytology if this fluid is aspirated with a syringe. For pleural fluid this is done by a pleural tap or chest drain, in ascites with an paracentesis or ascitic drain and in a pericardial effusion with pericardiocentesis.

If cytology is positive or a plaque is regarded as suspicious, a biopsy is needed to confirm a diagnosis of mesothelioma. A doctor removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside the chest and obtain tissue samples.

If the cancer is in the abdomen, the doctor may perform a laparoscopy. To obtain tissue for examination, the doctor makes a small opening in the abdomen and inserts a special instrument into the abdominal cavity. If these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.

SCREENING AND STAGING:

There is no universally agreed protocol for screening people who have been exposed to asbestos. However some research indicates that the serum osteopontin level might be useful in screening asbestos-exposed people for mesothelioma. The level of soluble mesothelin-related protein is elevated in the serum of about 75% of patients at diagnosis and it has been suggested that it may be useful for screening.

Mesothelioma is described as localized if the cancer is found only on the membrane surface where it originated. It is classified as advanced if it has spread beyond the original membrane surface to other parts of the body, such as the lymph nodes, lungs, chest wall, or abdominal organs.

TREATMENT:

The treatment program for mesothelioma depends on many factors, including: the stage of the cancer, where the cancer is, how far the cancer has spread, how the cancer cells look under the microscope and the patient’s age and desires.

Treatment of MM using conventional therapies has not proved successful and patients have a median survival time of 6 - 12 months after presentation.

There are three traditional kinds of treatment for patients with malignant mesothelioma:

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

Often two or more of these are combined in the course of treatment.

1. Surgery

Surgery, either by itself or used in combination with pre- and post-operative adjuvant therapies has proved disappointing with a 5 year survival rate of less than 10%. A pleurectomy/decortication is the most common surgery, in which the lining of the chest is removed. Less common is an extrapleural pneumonectomy (EPP), in which the lung, lining of the inside of the chest, the hemi-diaphragm and the pericardium are removed. It is not possible to remove the entire mesothelium without killing the patient.

2. Radiation

For patients with localized disease, and who can tolerate a radical surgery, radiation is often given post-operatively as a consolidative treatment. The entire hemi-thorax is treated with radiation therapy with radiation often times being given simultaneously with chemotherapy.

Delivering radiation and chemotherapy after a radical surgery has led to extended life expectancy in selected patient populations with some patients surviving more than 5 years. As part of a curative approach to mesothelioma, radiotherapy is also commonly applied to the sites of chest drain insertion, in order to prevent growth of the tumor along the track in the chest wall.

Although mesothelioma is generally resistant to curative treatment with radiotherapy alone, palliative treatment regimens are sometimes used to relieve symptoms arising from tumor growth, such as obstruction of a major blood vessel. Radiation therapy when given alone with curative intent has never been shown to improve survival from mesothelioma. The necessary radiation dose to treat mesothelioma that has not been surgically removed would be very toxic.

3. Chemotherapy

Chemotherapy is defined as the treatment of cancer using chemical substances. When cancer occurs, abnormal cells continue to divide uncontrolled. Anticancer, or chemotherapy drugs, work to destroy cancer cells by preventing them from multiplying. Pemetrexed is given in combination with cisplatin. Folic acid is also used to reduce the side-effects of pemetrexed.

Chemotherapy may be used to achieve different goals, depending on the stage of the cancer at the time of diagnosis and the age and health of the patient. Since chemotherapy for mesothelioma is not considered "curative", the goal is:

To control the cancer by stopping its spread or slowing its growth.
To shrink tumors prior to other treatments, such as surgery. This is called neoadjuvant chemotherapy.
To destroy microscopic disease which may remain after surgery. This is called adjuvant chemotherapy.
To relieve symptoms, such as pain. This is called palliative chemotherapy, and is given in cases when a drastic reduction in the tumor is not expected.

The most common way to administer chemotherapy is intravenously, or through a vein. A thin needle is inserted into a vein in the hand or in the lower arm. Intravenous administration of drugs allows for rapid entry into the blood stream. Drugs may also be delivered via catheters and/or ports.

Catheters are soft, thin, flexible tubes placed into a large vein in the body. They remain in place for as long as they are needed.
The catheter may sometimes be attached to a port, a small round plastic or metal disc placed under the skin on the chest. Ports also remain in place for as long as necessary.

4. Heated Intraoperative Intraperitoneal Chemotherapy (other type of treatment)

A procedure known as heated intraoperative intraperitoneal chemotherapy was developed by Paul Sugarbaker at the Washington Cancer Institute. The surgeon removes as much of the tumor as possible followed by the direct administration of a chemotherapy agent, heated to between 40 and 48°C, in the abdomen. The fluid is perfused for 60 to 120 minutes and then drained.

This technique permits the administration of high concentrations of selected drugs into the abdominal and pelvic surfaces. Heating the chemotherapy treatment increases the penetration of the drugs into tissues. Also, heating itself damages the malignant cells more than the normal cells.

PREVENTION:

Mesothelioma is not contagious and cannot be passed from one person to another. The exposure to the asbestos that caused the cancer occurred many years to several decades before the disease appeared. People who live with asbestos workers have a higher risk of getting this cancer.

Since the 1970s, the Environmental Protection Agency and the Occupational Safety and Health Administration have regulated the asbestos industry in the U.S. In the past, asbestos was used as a fire retardant and an insulator. Other products are now used in its place. The controversy involving exposure to different forms of asbestos continues.

There are two major types of asbestos: chrysotile and amphibole. It is thought that exposure to the amphibole form is more likely to cause mesothelioma. However, chrysotile has been used more frequently, hence many mesotheliomas are caused by chrysotile.

Removal is taking place in schools and other public buildings throughout the U.S. The hope is that these measures will greatly reduce the occurrence of this cancer.