Mesothelioma

Mesothelioma is a form of cancer that is almost always caused by previous exposure to asbestos.[1] In this disease, malignant cells develop in the mesothelium, a protective lining that covers most of the body's internal organs. Its most common site is the pleura (outer lining of the lungs and chest cavity), but it may also occur in the peritoneum (the lining of the abdominal cavity) or the pericardium (a sac that surrounds the heart).

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. Unlike lung cancer, there is no association between mesothelioma and smoking

Signs and symptoms

Symptoms of mesothelioma may not appear until 20 to 50 years after exposure to asbestos. Shortness of breath, cough, and pain in the chest due to an accumulation of fluid in the pleural space are often symptoms of 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.

Mesothelioma that affects the pleura can cause these signs and symptoms:

Chest wall pain pleural effusion, or fluid surrounding the lung shortness of breath fatigue or anemia wheezing, hoarseness, or cough blood in the sputum (fluid) coughed up In severe cases, the person may have many tumor masses. The individual may develop a pneumothorax, or collapse of the lung. The disease may metastasize, or spread, to other parts of the body.

Treatment

Treatment of MM using conventional therapies has not proved successful and patients have a median survival time of 6 - 12 months after presentation. The clinical behaviour of the malignancy is affected by several factors including the continuous mesothelial surface of the pleural cavity which favours local metastasis via exfoliated cells, invasion to underlying tissue and other organs within the pleural cavity, and the extremely long latency period between asbestos exposure and development of the disease.

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.

Radiation

Chemotherapy

Immunotherapy

Heated Intraoperative Intraperitoneal Chemotherapy


Prevention & Expectations

What can be done to prevent the disease? 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.

What are the long-term effects of the disease? A mesothelioma is a highly aggressive tumor that is generally deadly. Current treatment of malignant mesothelioma is designed to make the person with cancer comfortable. Although long-term survival cannot usually be expected, the case of famed paleontologist Stephen Jay Gould is a noted example.

What are the risks to others? 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.