Toronto • May 28-29, 2010 • Student Day and Workshops: May 27
Paper: Mesothelioma surveillance: Validation of diagnoses from a tumour registry
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Session : symposium. Symposium: Asbestos
Day/Time: Saturday at 14:00
Room: Armoury Suite, 2nd Floor
Objectives:
Mesothelioma is a rare cancer associated with occupational exposure to asbestos fibres in 70 to 90% of cases. A recent study reported that 22% of mesothelioma cases from the Quebec Tumour Registry (QTR) were found in the provincial workers' compensation board files between 1983 and 1997. This medical chart review study was set up to assess whether “false positive” mesotheliomas in the QTR could explain some of the discrepancy between the two data sources.
Methods:
Clinical information was extracted from medical charts of incident mesothelioma cases identified through the QTR in 2001 and 2002, and was combined with photocopies of medical imaging and pathology reports to constitute chart summaries. Consent was obtained from families to have access to biopsy material and medical imaging media. A panel of 3 specialists reviewed the available information and material. The pathologist gave an independent revised diagnosis using only the available pathological material and additional immunohistochemistry (IHC) staining if necessary and possible. The chest physician and the radiologist gave a common revised diagnosis after reviewing the chart summary and available medical imaging. A final consensus “revised diagnosis” was then attributed to each case from the panel of 3 specialists according to 5 categories: certain/probable, possible, unlikely, not a mesothelioma, impossible to classify.
Results:
The QTR reported 190 incident cases of mesothelioma (81% males) for the period. The mean age (±SD) at diagnosis was 68 years (± 10) for males, and 63 (± 13) for females. The specialists classified 62% of the charts as “certain/probable” mesotheliomas, 19% rated “possible”, 11% “not a mesothelioma”, and 8% “unlikely to be a mesothelioma”. When only satisfactory chart summaries were considered (i.e. with missing reports), 73-77% of the charts were rated as “certain/probable” mesotheliomas, and about 10% were still considered “not a mesothelioma”.
Conclusions:
Following a screening test paradigm, the positive predictive value of the QTR data was estimated to be around 75%, which implies that about 25% of QTR cases could be false positives. This explains part of the discrepancy between tumour registry and compensation data, but could not assess the underestimation in the QTR, as mesothelioma can be confused with other diagnoses. Tumour registry data appears to be a valuable source of information for the surveillance of mesothelioma but is not sufficient to get a complete estimate of mesothelioma burden.
