History of mesothelioma The first studies on the association between asbestos and malignant mesothelioma appeared in the 1950s. Weiss’ case report of asbestosis and pleural malignancy and Van der Schoot’s paper describing three insulation workers with malignant disease were the first of many to be published (13, 14). Wagner confirmed the association between asbestos and malignant mesothelioma through his work in the 1950s in South Africa, a country that mined all three commercial types of asbestos (15).
Because most asbestos exposures occurred in the work environment, malignant mesothelioma has traditionally been considered an occupational disease. Paraoccupational malignant mesothelioma has been described in households of asbestos workers in which cohabitants had been exposed via contaminated clothes (16). The term ‘environmental malignant mesothelioma’ has been used to describe disease identified in people living close to asbestos mines or factories or when people have been exposed to asbestos or asbestos-like material present in the soil (17, 18).
Other factors have been recognised as potential causes of malignant mesothelioma. Radiotherapy to the chest has been reported but the number of patients with this association is limited (19). The role of SV40 (one of the simian viruses) viral infection as an important etiologic cofactor in malignant mesothelioma remains under discussion (20, 21).
Exposure to asbestos is more common in occupations with a predominantly male workforce, which explains why the current incidence of malignant mesothelioma is higher among men than women. Most mesothelioma patients have been primary asbestos workers or people who handled raw asbestos in the mining, milling, transportation, and manufacturing of the material. As this high-risk occupational exposure has been limited by the total ban on the use of asbestos products in Australia, the exposure-mix may change to include a greater proportion of people who have been exposed in non-occupational settings.
A dose-response relationship between cumulative asbestos exposure (increased levels or duration of exposure, or both) and malignant mesothelioma has been demonstrated (22). A ‘safe’ threshold of cumulative exposure, below which there is no increased risk, has not been defined (23).
The latency period, or the period between first exposure to asbestos and the diagnosis of mesothelioma, shows a wide range (20–60 years) and there are indications that the latency in Australia has increased in recent years (24). The median age at diagnosis of malignant mesothelioma in Australia is slightly above 70 years, with many patients presenting with comorbidities mesothelioma (4).