Malignant mesothelioma (MM) is a very aggressive
tumor that is caused by environmental,
biologic, and genetic factors. Among these factors,
asbestos plays a major role. The link between
asbestos and MM has been firmly established through numerous epidemiologic studies conducted during the past 40 years. However, the causal role of
chrysotile asbestos compared with
crocidolite asbestos in MM, the method of correctly establishing
asbestos exposure, the amount of
asbestos necessary to cause MM, and the mechanisms of
asbestos tumorigenicity are still being debated. Along with
asbestos, Simian virus 40 (SV40),
a DNA monkey virus, has recently been implicated in the etiology of MM. Simian virus 40
large T antigen (Tag) and
small t antigen (tag) are largely responsible for the carcinogenicity of the virus, and it is possible that SV40 and
asbestos are cocarcinogens. Finally, a genetic factor identified in 3 villages in Cappadocia, Turkey, where 50% of individuals die of MM, appears to be the cause of a high incidence of the disease. In these villages,
genetic predisposition for MM works together with
erionite, a nonasbestos fiber found in the stones used in construction of houses. The diagnosis of MM is made histologically and confirmed through electron microscopy and immunohistochemistry. Currently available
therapies for MM prolong survival by a few months at most. An SV40
vaccine is being developed for human use and it is hoped that it may reduce the incidence of MM in
asbestos workers.