Mesothelioma is a rare type of cancer that begins in the lining of the chest, lungs, or abdominal cavities. According to the American Cancer Society, the leading cause of mesothelioma is asbestos exposure. Asbestos is a highly toxic and naturally occurring mineral that was widely used in construction and other industries until the late 1990s. After a mesothelioma diagnosis, an individual may feel devastated and overwhelmed. Usually, after a mesothelioma diagnosis, people do not know what to do.