Mesothelioma

Mesothelioma - also known as 'diffuse' or 'malignant' mesothelioma - is a relatively rare form of cancer which affects the membranous lining of the chest (the pleura) and less commonly, the lining of the abdomen (the peritoneum) and of the heart (the pericardium). Mesotheliomas, which originate in the serosal lining of the pleural cavity, account for less than 10% of all cancer-related deaths. Incidence is high, however, in asbestos workers and their immediate families and among people who live along major routes used for transporting large quantities of asbestos.

Mesotheliomas have a latency period ranging from 20 to 45 years from exposure to tumor discovery, usually occur in people over age 50, and are invariably fatal. Typically, less than 2 years pass between the onset of symptoms and death.

Causes

The link between this tumor and asbestos exposure is well-established. Predisposition, chronic inflammation, radiation, recurrent lung infection seldom account for a mesothelioma. Smoking alone doesn't increase the risk for developing a mesothelioma; coupled with asbestos exposure, it increases the risk by about 50%.

It's unknown whether a mesothelioma begins in the visceral or parietal pleura; in animals, tumor­causing asbestos fibers migrate to mesothelial cells, penetrating the pleura. From there, the pleural lymphatics carry them to the pleural surface. Signs and symptoms result from pleural effusion, restricted lung function, tumor mass, infection, and advanced disease.

Signs and Symptoms

There are no immediate mesothelioma symptoms. The symptoms of mesothelioma may appear in 30 - 50 years after exposure to asbestos. A person with pleural mesothelioma has symptoms of shortness of breath and pain in the chest due to an accumulation of fluid in the pleur.

A person with peritoneal mesothelioma has symptoms of abdominal pain and weight loss, blood clotting abnormalities, anemia and fever.

Please note that these symptoms may be due to other reasons.

Diagnostic tests 

Early diagnosis is difficult and, in most cases, the first obvious sign of something being wrong is when an 'effusion' occurs.  This is an accumulation of fluid which gathers in the pleural space around the lung (or peritoneal space in the abdomen).  This often causes breathlessness and the doctor can draw or drain the fluid off to relieve this symptom.

On chest x-rays the signs are often not very definite and may possibly only show a slight thickening of the pleura.  It may be necessary for several tests and biopsies to confirm the diagnosis - and this may take a few weeks.

Treatment

No standard treatment exists for a mesothelioma. Surgery, radiation therapy, chemotherapy, and a combination of treatments are usually tried, but they seldom control the disease in most patients.

If surgery is performed, a pleuropneumonectomy is the usual procedure. Cisplatin and mitomycin are the most successful chemotherapy drug combinations. Doxorubicin and methotrexate achieve less successful results.

Prevention

Avoid exposure to asbestos.

Learn more about this disease with in a Mesothelioma Network.