Malignant mesothelioma is a cancer that develops in the mesothelium, a layer of epithelial cells that surrounds the heart, lungs, and stomach and intestines. Malignant mesothelioma is associated overwhelmingly with exposure to asbestos, a mineral used in a variety of industrial and commercial applications. The use of asbestos is now banned in much of the world and exposure to asbestos is no longer the commonplace of industrial life that it used to be, but mesothelioma has a very long latency period in many cases, and new cases are likely to continue developing into the indefinite future.

Malignant mesothelioma is an especially deadly form of cancer. A diagnosis of malignant mesothelioma is, for most patients, tantamount to a death sentence, with the typical prognosis being six to twelve months of life. There are no effective treatments for malignant mesothelioma; medical science focuses on palliative care to deal with the symptoms of the disease, not on attempting to cure it. Unlike some cancers (including the rare benign form of mesothelioma), surgery is ineffective for mesothelioma because the tumors are too large and too widespread in the body. Doses of chemotherapy or radiation which would be sufficient to eliminate or even check the cancer are so large that they would kill the patient even more quickly than the mesothelioma would.

Like all cancers, mesothelioma begins with a cell that loses its ability to respond to the signals the body sends to stop reproducing. Most human cells constantly reproduce themselves to replace cells lost due to trauma, stress, old age, and so on. In order to prevent this cell replication from getting out of control, the body sends out chemical signals to tell cells “that’s enough – stop dividing”. Cancers begin when a cell mutates, no longer “listening” to the body’s signal to stop trying to stay alive. When the damaged cell divides, it passes its mutations on to its progeny – more cancer cells. Eventually the rogue cells form a tumor or mass. Malignant mesothelioma cells form new tumors and new mass quickly and aggressively.

One of the reasons that malignant mesothelioma develops so aggressively is that the asbestos fibers which trigger the initial damage also cripple the body’s ability to fight back. When foreign bodies such as asbestos fibers lodge in the body’s tissues, the body generates macrophages, warrior cells that seek out and destroy the alien material. Asbestos, however, causes the mesothelial tissues to generate chemical substances that are toxic to the macrophages, greatly hindering their ability to clean out the damaged areas. In addition, asbestos fibers cause those macrophages which do manage to encapsulate asbestos fibers to produce hydroxyl radicals, which are themselves carcinogenic. Asbestos thus creates the cancer in the first place, encourages the development of new cancer, and shuts down the body’s ability to fight cancer, all at the same time. It is no wonder that malignant mesothelioma is such a deadly disease.

Although all forms of mesothelioma, including Pleural mesothelioma, Peritoneal mesothelioma, and Pericardial mesothelioma, are deadly, a particular mesothelioma may have one of three types of cells, which vary in their effects and the prognosis for the patient. The most common cells are epithelioid, seen in 50 to 70% of patients. Life expectancy for those whose mesothelioma forms epithelioid cells is just over eight months. Sarcomatoid cells are the least common type; the life expectancy for this form of the disease is seven months. Biphasic mesothelioma involves production of both kinds of cells and is the most deadly form of the disease; the life expectancy for biphasic patients is less than six months after diagnosis.