Mesothelioma (definition of)

Mesothelioma is cancer of the visceral lining, known as the mesothelium. This is a lubricative later between the inner wall of the chest and abdomen and the internal organs which secretes a fluid that keeps these surfaces slick and able to move without chafing.

A known cause of mesothelioma is exposure to amphibole asbestos. This is different from the more common chrysotile variety that causes asbestosis. Unlike the latter, which is relatively soft, amphibole asbestos ("blue" crocidolite, "brown" amosite and tremolite) has a hard, crystalline structure that resembles microscopic needles. When these are inhaled or ingested, they bore through organ tissue over time from the inside out; elements of the body's own immune system, known as macrophages, also attack these fibers as if they were an organic pathogen and wind up ripping themselves to shreds, resulting in the spillage of acidic proteins that scar the internal surfaces of these organs and causing chronic inflammation.

Scientists are not certain how these asbestos fibers interact with cellular DNA that causes them to mutate, but evidence suggests that the chronic inflammation may be a factor.

Mesothelioma is unlike most forms of cancer in that it spreads in a sheetlike manner rather than forming lumps. The disease also has a lengthy latency period; symptoms may not be apparent until years or even decades after the asbestos exposure took place. The symptoms are similar to those of many other respiratory diseases.

All of this means that mesothelioma is very difficult for doctors to diagnose. While stage 1 or stage 2 mesothelioma is often potentially curable, in most cases the disease is diagnosed in an advanced stage for which there is often no cure. Typically, patients have less than a year after a diagnosis is confirmed.

Although mesothelioma of the respiratory system, or the pleural variety is the most common, the disease can also attack the mesothelial lining of the abdomen or the heart, in which case it is described as peritoneal or pericardial respectively.

Mesothelioma was first described in the early 1700s, but was not recognized as a separate form of cancer separate from the lungs until about 1960, when it was noted among South African asbestos miners. View more mesothelioma information.