What is Mesothelioma

Mesothelioma is a serious and rare form of lung cancer.  It is most frequently seen in men between the ages of 50 to 70. Women are affected far less frequently. In the US, between 2000 and 3000 cases are diagnosed each year.  Estimates suggest that the incidence of mesothelioma for every 100,000 in the US is about 1.8 and 0.9 internationally.  This form of cancer affects people of every race equally. The number of people who have been diagnosed with mesothelioma has increased significantly in the past 30 years.  Although many advances in treatment have been made, there is no cure for this type of cancer. 

In mesothelioma, the cells of the mesothelium become cancerous and grow out of control. The mesothelium is a protective, two-layered membrane that covers the internal organs of the body including the lungs, heart and abdominal organs. Between these layers, the cells produce fluid, which allows easy movement of the heart and lungs within the chest cavity.  The layer that covers the lungs is called the pleura, and the layer that covers the heart is called the pericardium. The peritoneum lines the abdominal cavity.  Mesothelium also lines the male and female reproductive organs.   Mesothelioma can affect any of these cells, but is usually seen in the pleural or peritoneal mesothelium. The most common form of mesothelioma is pleural.

The primary risk factor for developing mesothelioma is exposure to asbestos. Between 70-80% of people diagnosed with mesothelioma have been exposed to asbestos, usually in the workplace.  Although it is possible to develop mesothelioma without any exposure to asbestos, it is very rare. While one person for every million people in the US will be diagnosed with mesothelioma, about 7-13 men who have been exposed to asbestos will be diagnosed with the disease. Symptoms frequently take 20 years to develop, but can take as long as 50 years to occur. 

When cancerous cells invade the mesothelium, it becomes increasingly difficult to breathe.   In the pleural form of mesothelioma, tumors growing in the mesothelium cause pleural effusions, which prevent the smooth movement of the lungs and other organs in the chest.  Peritoneal mesothelioma invades the abdominal cavity and can cause loss of appetite weight loss, nausea and vomiting.  Most patients seek medical care after having symptoms only 4-6 months.

Mesothelioma is a very aggressive form of cancer.  Because it takes so long for symptoms to appear it can spread to the other organs in the chest, the chest wall and into the lymph nodes. The cancerous cells spread, or metastasize from the mesothelium into other parts of the body and damage internal tissues and organs.  Treatment is more effective when the disease is detected early.

Treatment is aimed at reducing the size of tumors, and relieving symptoms.  Chemotherapy, radiation treatment and surgery are some of the traditional treatment strategies used to help patients live longer, with fewer symptoms.  New advances in photodynamic therapy and immunotherapy give hope for prolonging the lives of patients with mesothelioma.  On average, however, the life expectancy after being diagnosed with mesothelioma is less than one year.