Mesothelioma is a type of cancer that occurs in the thin layers of tissue that surround different organs in the body. These layers are known as the mesothelium. The most common type of mesothelioma is of the lungs and chest cavity, but it can also occur in other parts of the mesothelium like around the abdomen, or in the sac that surrounds the heart (the pericardium).
Mesothelioma does not occur as frequently as other types of lung cancer like adenocarcinoma. In the United States, the American Cancer Society predicts about 228,820 cases of lung cancer in the year 2020. In contrast, there are about 3,000 cases of mesothelioma each year in the United States across all types.