Mesothelioma is a rare type of malignant cancer that is usually caused by exposure to asbestos. The cancer affects the mesothelium which is a protective membrane that covers most of the internal organs of the body. The mesothelium is known by different names depending on where it is found in the body. When it covers the lungs and chest cavity, it is known as the pleura; over the heart, it is called the pericardium; and in the abdominal cavity it is called the peritoneum. It is also found in other places such as the testes and uterus (womb). The mesothelium normally secretes a lubricating fluid that allows organs to move easily against nearby structures.

How Mesotheliomas Occur

Mesotheliomas usually begin in the lungs or abdomen before they spread to other parts of body (they usually do not spread to the brain, bone or adrenal glands). The mechanism by which mesotheliomas occur has not been properly elucidated. It is possible that deposition of asbestos fibers in the mesothelium causes diverse interactions with the mesothelial cells and induces reactions with the defensive mechanisms of the body. These cause the mesothelium to become abnormal and divide without control and order. It then metastasizes to other parts of the body.

Types of Mesothelioma

1.       Epithelioid mesothelioma: This is the most common type of mesothelioma and usually has a better outcome than other types.

2.       Mixed or Biphasic mesothelioma: This is the second most common type. It has features of epithelioid and sarcomatoid mesotheliomas.

3.       Sarcomatoid or Fibroid mesothelioma: This is the least common type.

Mesotheliomas are also named according to tissue from which they originate. When they originate in the pleura, they are called pleural mesotheliomas; when they occur in the pericardium, they are called pericardial mesotheliomas, and so on.

Risk Factors for Mesothelioma

Mesothelioma occurs in a person who has been exposed to asbestos such as from inhaling asbestos particles or from exposure to asbestos dust or fibers. It is occurs more commonly in people who work with asbestos but there are also other risk factors for mesothelioma.

1.       Exposure to asbestos such as in people who work with asbestos , people who live near naturally occurring asbestos, people living in buildings with roofing and floors containing asbestos, and persons living with asbestos workers

2.       Exposure to radiation such as thorium dioxide that was once used in x-rays.

3.       Infection with simian virus 40 (SV 40).

4.       Inhalation of other fibrous silicates such as erionite.

5.       Idiopathic: Sometimes the cause is unknown.

Signs and Symptoms of Mesothelioma

These signs and symptoms depend on where the cancer occurs. The following are the symptoms that occur in the most commonly affected organs.

Lungs:

1. Shortness of breath

2. Bloody cough (hemoptysis)

3. Chest pain

4. Fluid buildup around the lungs (pleural effusion)

5. Cough and wheezing

6. Difficulty swallowing

Abdomen:

1. Abdominal pain

2. Abdominal swelling

3. Nausea and vomiting

4. Fluid buildup in the abdominal cavity (ascites)

5. Tumors

6. Intestinal (bowel) obstruction

Other signs and symptoms include:

1. Pain in other parts of the body (when the cancer has spread)

2. Sweating

3. Fatigue

4. Anemia

5. Abnormal blood clotting

6. Fever

7. Weight loss

8. Swelling of the face and the arms

9. Yellowing of the eyes and skin (jaundice)

10. Tumors

Treatment of Mesothelioma

Surgery: This can be done to attempt a cure or to reduce the symptoms of the disease. It might be done to attempt a cure when the mesothelioma is diagnosed early and is still localized. In this procedure, the surgeon tries to remove the affected area of mesothelium. It is done to reduce symptoms in some situations such as where the cancer affects swallowing or breathing and this is the option when the mesothelioma has spread.

Chemotherapy: This involves the use of drugs. They are usually administered via injections intravenously (through veins) or intracavitary (directly into the cavity in which the mesothelioma occurs). Drugs are also used to prevent accumulation of fluid in the chest and abdomen.

Radiation therapy: This uses radiation to shrink the tumor. It is sometimes used as an adjunct to surgery to remove small tumors that could not be reached during surgery. It is preferred in people who are too ill to have surgery and also used to relieve symptoms.

Thoracocentesis and paracentesis: This is removal of fluid from the chest and abdomen respectively.