Mesothelioma trends in the ACT and comparisons with the rest of Australia.

OBJECTIVES Inhalation of asbestos fibres is the predominant cause of malignant mesothelioma. Domestic exposure to asbestos is a major community concern in the Australian Capital Territory (ACT) because of loose-fill asbestos home insulation. Little is known about how trends in mesothelioma rates in the ACT compare with those elsewhere. The objective of this study was to describe trends in mesothelioma rates in the ACT and compare them with those for the rest of Australia. METHODS We used de-identified data from the ACT Cancer Registry (1982- 2014), and the Western Australia (WA) Cancer Registry and the Australian Cancer Database (1982-2011). We calculated crude mesothelioma rates, by 3-year periods, for the ACT and for the rest of Australia (excluding WA). We used Poisson regression to analyse mesothelioma trends from 1994 to 2011 (complete reporting period) using an indirect standardisation approach to adjust for age and sex. RESULTS There were 140 mesothelioma cases reported to the ACT Cancer Registry between 1982 and 2014 - 81% male and 19% female. Between 1994 and 2011, age- and sex-adjusted mesothelioma rates in the ACT increased over time, on average by 12% per 3-year period (relative risk [RR] 1.12; 95% confidence interval [CI] 0.99, 1.26). Compared with the rest of Australia (excluding WA), ACT rates were, on average, lower (RR 0.84; 95% CI 0.69, 1.02), but they increased at a higher rate (RR 1.12 per 3-year period; 95% CI 0.99, 1.27). These results are strongly influenced by the higher rate of mesothelioma observed in the ACT in 2009-2011, when ACT rates became similar to those for the rest of Australia (excluding WA). CONCLUSIONS Although mesothelioma rates may have increased more in the ACT than the rest of Australia (excluding WA) during the past two decades, there is considerable uncertainty in the trends. More information is needed regarding the health risks associated with living in a house with loose-fill asbestos insulation. This is the subject of further studies within the ACT Asbestos Health Study.