The aetiology of mesothelioma: are risk factors other than asbestos exposure important?

Mesothelioma is an important cause of mortality in Eng-pleural scars following empyema or therapeutic pneumo-thorax. 14 land and Wales, accounting for over 1000 deaths each year. 1 The incidence of mesothelioma is rising and, if the For mesothelioma associated with asbestos exposure it is possible that other factors may act synergistically with predictions of Peto et al are correct, then by the year 2020 there will be approximately 3000 deaths a year from asbestos in causing disease. A familial cluster of five cases of mesothelioma has been reported which suggests a role mesothelioma, with 1% of men currently aged 49–54 years dying from this disease. 1 There is a wealth of epi-for genetic susceptibility. 15 However, in this family four of the cases worked in the building trade and therefore demiological and experimental evidence supporting a strong association between asbestos exposure and meso-unrecognised asbestos exposure cannot be excluded. A high prevalence of smoking amongst patients with mesothelioma thelioma. 2 Do we need to look any further for other causes of this disease? has been noted before 16 but, in a controlled study, no significant association was found. 17 An interesting new In this issue of Thorax Yates et al report the clinical and pathological characteristics of all patients with meso-development is the possible role of Simian virus 40 (SV40) as a risk factor for mesothelioma. This virus contaminated thelioma diagnosed within the south east of England in 1987 3 and, of the 272 cases reviewed, 30 (11%) had no the polio vaccine in the late 1950s and early 1960s and was accidentally inoculated into millions of people in Eur-evidence of exposure to asbestos. Others have reported similar rates of asbestos exposure amongst patients with ope and the USA. 18 Experimentally, SV40 has been shown to induce pericardial and pleural mesothelioma in ham-mesothelioma. 4–6 It seems likely, therefore, that a few sters 19 and the presence of SV40 DNA has recently been patients develop disease without exposure to asbestos, identified in a number of pathological specimens of although under-reporting of exposure and over-diagnosis mesothelioma. 20 21 may explain some of these cases. The problem of un-In summary, most cases of mesothelioma may be ex-recognised asbestos exposure is a particularly important plained by exposure to asbestos but spontaneous disease public health issue for, in spite of the fact that the risk of does occur and other mineral and organic fibres may be …