Definition of Mesothelioma
Mesothelioma: A malignant tumor of the mesothelium. The
mesothelium is the thin lining on the surface of the body cavities
and the organs that are contained within them. Most mesotheliomas
begin as one or more nodules that progressively grow to form a solid
coating of tumor surrounding the lung, abdominal organs, or heart.
Mesothelioma most commonly occurs in the chest cavity and is
associated with exposure to asbestos in up to 90% of cases. It has
been shown that some asbestos fibers that are inhaled quickly work
their way through the lung tissue and into the chest (pleural)
cavity. Asbestos fibers that are swallowed have been shown to
penetrate the wall of the intestine and appear in the abdominal
(peritoneal) cavity.
The risk of mesothelioma increases with the intensity and duration
of exposure to asbestos. It is debatable whether or not there is any
safe exposure level. Mesothelioma typically does not occur for 20 to
50 years following exposure to asbestos. Some forms of asbestos,
particularly crocidolite fibers, are more likely to cause
mesotheliomas. There is also evidence that mesotheliomas may be
caused by other agents including radiation, viruses, and man-made
mineral fibers. There is no relationship to smoking.
Mesothelioma is currently difficult to treat in most cases and
survival beyond two years is unusual.
Last Editorial Review: 12/23/1999 8:55:00 AM
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