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In the present issue of the Canadian Respiratory Journal, there is a paper that unsettled me. Payne and Pichora (1) (pages 148–152) examined compensation claims for mesothelioma in Ontario from 1980 through 2002, and compared these filings with mesothelioma cases as diagnosed in the Ontario Cancer Registry (OCR). This was a fairly straightforward design involving the comparison of two robust databases. By way of checking agreement, all claims for occupational cancer were compared with OCR data and the match rate was 86%, and 93% of the compensated mesothelioma claims were represented in the OCR. Of the individuals with compensated mesothelioma claims, approximately 85% had appropriate OCR diagnoses.
On average, approximately 35% of patients with mesothelioma filed for compensation during the 22 years that the study examined. Filing rates increased gradually from 20% to 30%, to 43% over the 22-year period. Claims were more common for men, peaking at 57% of mesothelioma cases, and were higher in people 50 to 59 years of age than in older age groups, although most of the OCR mesothelioma cases were in individuals older than 60 years of age.
I was unpleasantly surprised by these results. Mesothelioma is a distinctive disease and is attributable to asbestos in the great majority of cases (2). One could argue that in men, mesothelioma is almost by definition a marker for asbestos exposure, usually of a nontrivial nature and most often related to the workplace. Although it can occur without occupational exposure, mesothelioma has been documented to occur in people exposed to asbestos by living in the neighborhood of operations or industries that use it, or in people (often women) exposed to the clothing of asbestos workers (2). Of all occupational lung diseases, mesothelioma is the one most clearly related to a specific agent and not to other lifestyle issues. This has been widely known since the 1960s. Indeed, it was essentially this rationale that prompted Payne and Pichora (1) to investigate mesothelioma – they were concerned by data indicating that compensation claims for occupational diseases were generally low and believed that because of its unique causation, mesothelioma represented an excellent test case.
Why the low level of compensation claims? It is not credible to argue that the majority of mesothelioma patients did not have asbestos exposure and that the workplace is the primary area for such exposure. Many patients who did not submit claims must have had asbestos exposure. Another possible reason for the lack of claims is that individuals with mesothelioma have a very short life expectancy, so one could argue that there is often very little to compensate. However, this really is not true because compensation can be granted to survivors, and I suspect that few mesothelioma patients leave large estates. This survival bias may account for the finding that claims are higher before retirement than after, although the 20- to 40-year window between exposure and the development of mesothelioma all but guarantees that the disease will frequently occur after retirement.
I believe, as do the authors, that the answer lies in results from Lambton County, Ontario. I do not know where Lambton County is, but I suspect that it had shipyards or other asbestos-related industries at one time. In any event, the incidence of mesothelioma in Lambton County is approximately four times the provincial average and 77% of its mesothelioma patients applied for workers’ compensation. Obviously, asbestos awareness is much higher in Lambton County than elsewhere and I would argue that this awareness must reside – to a large extent – in the medical community. The doctors in Lambton County have got the message regarding mesothelioma and other physicians need to do so. It is encouraging to read that several provinces have made or are making mesothelioma a reportable disease, with automatic notification to physicians that their patients have a disease that is very likely subject to workers’ compensation (1).