Unlike many types of cancer where there are multiple causes, there is only one major cause of mesothelioma. Asbestos exposure is considered to be the predominant cause of this type of cancer that typically starts in the lungs and moves very rapidly and aggressively to other body organs. The mesothelial cells actually line the lungs and work to provide a barrier between the air and the body. When the asbestos shards, which are so small they get through the natural filters in the nose and airways, enter the lungs they stick into the mesothelial cells. This causes irritation and the build of scar tissue, eventually leading to the growth of irregular cancer cells. The shards also decrease normal cellular active and increase the production of free radicals, creating the ideal environment for malignant cancer cells to invade and take over. This process may take over 30 years to occur, but once it does it moves very rapidly through the body and there is no cure or treatment.