Mesothelioma is a relatively rare form of cancer, entirely preventable because it is primarily caused by exposure to asbestos. It is an aggressive cancer, but mesothelioma symptoms can go unnoticed for an extended period of time. As a consequence, it has often spread considerably by the time it is diagnosed, and life expectancy following diagnosis is typically less than two years.

The organs of the body are surrounded and protected by a thin membrane called the mesothelium. Mesothelioma is when the cells of the mesothelium become cancerous, multiplying without order, damaging tissue and internal organs, and spreading to other parts of the body. Mesothelioma can be benign (non-cancerous) or malignant (cancerous); however, because cases are rarely benign, malignant mesothelioma is usually simply referred to as mesothelioma.

There are three common types of mesothelioma, which play an important role in determining treatment:

• Peritoneal mesothelioma (attacking the lining of the stomach)
• Pleural mesothelioma (the most common form, attacking the lining of the lungs)
• Pericardial mesothelioma (attacking the lining of the heart)

The number of mesothelioma cases has been on the rise, still, there are only about 2,000 new diagnoses per year.