Malignant (cancerous) mesothelioma is the most serious type of the various diseases caused by asbestos.  There are up to three thousand new cases of malignant mesothelioma diagnosed each year in the United States alone (where asbestos has been regulated since 1970) and the disease is believed to be responsible for more than 200,000 deaths worldwide.  Mesothelioman is caused by exposure to asbestos fibers.

Mesothelioma is a somewhat rare type of cancer that has been linked exclusively with asbestos exposure.  With most cancers doctors can only talk about an increase in risk called a risk factor but there is no causal link.  With mesothelioma the link is so strong that the medical literature states that asbestos causes mesothelioma, rather than just saying it is a risk factor.

There are three types of mesothelioma, each affecting a different section of mesothelial tissue:

• Pleural mesothelioma is the most common type of malignant mesothelioma (accounting for an approximately 70 to 80% of all documented cases), affecting the mesothelial tissue lining the lung cavity (pleura).
  
• Peritoneal mesothelioma is the second most common type of malignant mesothelioma (roughly 10% to 20% of all documented cases) affecting the mesothelial tissue lining the abdominal cavity (peritoneum).
  
• Pericardial mesothelioma is a less common type of malignant mesothelioma (accounting for less than 10% of all documented cases), affecting the mesothelial tissue lining the heart sac (pericardium).
• Tunica vaginalis testi mesothelioma is a very rare form of malignant mesothelioma affecting the mesothelial tissue lining the testicles.  It is sometimes refered to as gonadal mesothelioma.