mesothelioma etiology
While an association of malignant mesothelioma with radiation or exposure of zeolite, the disease serious pulmonary recurrent diverticulosis, and even a case of lipoid aspiration pneumonia have been reported, asbestos continues to be the most frequent etiology contact documented in nearly half of all patients with primary malignant pleural and peritoneal. While only one of the first 13 cases of testicular malignant mesothelioma in the literature involved an asbestos-exposed individual, 3 of the 4 cases described have been exposed recently. To date, asbestos does not appear to be implicated in the etiology of mesothelioma anywhere benign or primary malignant pericardial effusion.
The association with asbestos and excess risk of bronchogenic cancer had established in 1955 by Doll, although case reports first appeared in 1935.
The role of asbestos in the etiology of mesothelioma was documented in a convincing manner by Wagner et al. in 1960. It was noted that 45 of 47 patients with this rare cancer in South Africa previously had a history of contact with asbestos. Of particular importance was that most patients were not miners of asbestos, but had lived and worked in the vicinity where asbestos was used.
The percentage of patients mesothelioma with a history of contact with asbestos can be brought has ranged from zero to almost 80-90% in the number of coastal areas with maritime transport industries in the United States States and England, and South Africa and the mining areas of Canada. A proportion of patients with no history of exposure to asbestos can have been forgotten or cryptic exposure. Asbestos bodies are frequently found at autopsy of individuals in the general population. However, the lack of asbestos bodies in the careful examination of lung tissue taken at autopsy from patients with mesothelioma no known contact with asbestos supports the lack of exposure significant asbestos. Asbestos bodies, also called ferruginous bodies, consisting of hemosiderin and glycoprotein-coated fiber core. While other fibers organic and inorganic can produce ferruginous bodies, which are found in the lungs of most humans have cores of asbestos. Uncoated fibers in the lung are much more numerous ferruginous bodies visible.
Since 1960, a number of prominent epidemiologists have been quantified, primarily through of carefully designed case-control studies, cancer risks associated with asbestos. The lifetime risk of mesothelioma heavily exposed individuals is estimated as high as 7-10'r in several studies.
While the proportion of cases of pleural mesothelioma, peritoneal in some cohorts of workers heavily exposed to asbestos approximately 3:2, an overall ratio of 2:5 is observed in most series, probably due to the much larger number of people exposed transiently.
Striking is the long latency period for developing mesothelioma. Although some cases have been reported 20 years or so after the first exposure, peak incidence occurs after 35-45 years.
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Article Source: ArticlesBase.com – Mesothelioma Epidemiology
