Projected mesothelioma incidence in men in New South Wales

Our plain-English summary of Projected mesothelioma incidence in men in New South Wales, by M. Clements, G. Berry, J. Shi, et al (Occupational and Environmental Medicine, 2007).

The study

• Authors: M. Clements, G. Berry, J. Shi, S. Ware, D. Yates, A. Johnson
• Journal: Occupational and Environmental Medicine
• Published: 2007;64(11):747-52
• Cited by: 44 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Based on observed numbers of incident mesotheliomas since 1972, to predict future numbers in men in New South Wales.

Methods: The incidence of mesothelioma was modelled in two ways. First by using an age/birth cohort model, and second by using a model based on potential exposure to asbestos in terms of age and calendar year. The latter model included a term for clearance of asbestos fibres from the lungs, and a term for diagnostic fraction. The age and calendar year model was based on the model introduced by Hodgson and colleagues but replaced piecewise effects by smooth functions represented by cubic splines.

Results: The number of mesotheliomas between 2004 and 2060 was predicted as 6690 with the age-cohort model and as 6779 by the age and calendar year model, with peak annual numbers of 187 in the year 2021 and 196 in the year 2014 with the two models respectively.

Conclusions: The pattern of parameter estimates in the two models was in accord with the known use of amphibole asbestos in Australia. The predicted peak year of 2014-21 is 30-35 years after the phasing out of amphibole use, and this period is in accord with predictions for the UK and the US; in the latter country the peak was 10-15 years earlier corresponding to a marked decline of amphibole use in and following the 1960s.

In plain English

This study used cancer registry records to project future new mesothelioma cases in men in New South Wales, Australia. The authors fitted two statistical models to cases recorded by the New South Wales Central Cancer Registry. An age and birth cohort model used 2141 cases diagnosed in 1982–2002. An age and calendar year model, estimating potential asbestos exposure and allowing for fibre clearance from the lungs, used 2639 cases in men aged 20 and over in 1972–2003. For 2004–2060, the first model predicted 6690 cases, peaking at 187 in 2021. The second predicted 6779 cases (95% confidence interval 5243 to 9431), peaking at 196 in 2014; the 95% confidence interval for the peak ran from 172 cases in 2011 to 240 in 2020. That model's estimated exposure rose through the 1940s and 1950s, peaked in the early 1960s, then declined in the late 1970s and 1980s. The authors concluded that both models' estimates were in accord with known amphibole asbestos use in Australia. They assumed men born from 1970 had negligible risk, so future numbers may be marginally higher than predicted.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Statistical modelling and projection study of population cancer registry data, using an age/birth cohort model and an age/calendar year model (an extension of the Hodgson model)
• Who was studied: Men in New South Wales, Australia, with mesothelioma recorded by the New South Wales Central Cancer Registry: 2461 cases in 1972–2002 (ages 22–97). The age/cohort model was fitted to the 2141 cases diagnosed in 1982–2002. The age/year model used 2639 cases among males aged 20 and over in 1972–2003. Projections ran to 2060 using population projections from the Australian Bureau of Statistics.
• Exposure: Asbestos exposure was not measured directly. It was represented through birth cohort, or as potential exposure estimated by age and calendar year, with a term for clearance of fibres from the lungs. The estimates were compared with figures on amphibole (crocidolite and amosite) asbestos consumption in Australia.
• Main results:
  • Age/calendar year model: fitted to 2639 incident cases among males aged 20 years and over in 1972–2003
  • Age/birth cohort model: 6690 cases predicted for men in 2004–60, with a peak of 187 cases in 2021
  • Age/calendar year model: 6779 cases predicted for 2004–60, with a peak of 196 cases in 2014
  • Age/calendar year model: the 95% confidence interval for total cases in 2004–60 was 5243 to 9431
  • Age/calendar year model: the peak number of annual cases had a 95% confidence interval from 172 cases in 2011 to 240 cases in 2020
  • Age/birth cohort model sensitivity analysis: using population projections based on current mortality rates gave 5641 cases for 2004–60, a 16% decrease
  • Age/calendar year model: estimated exposure (dose potential) by calendar period rose rapidly through the 1940s and 1950s, peaked in the early 1960s, and declined rapidly in the late 1970s and 1980s
• The authors' conclusion: The authors concluded that the pattern of estimates in both models was in accord with the known use of amphibole asbestos in Australia. They also concluded that the predicted peak (2014–21), 30–35 years after amphibole use was phased out, is in line with predictions for the UK and US.
• Limitations the authors state:
  • The authors assumed that men born from 1970 are at negligible risk of mesothelioma
  • Because of that assumption, the predictions may be biased low
  • The age/birth cohort model assumes that age and birth cohort effects are independent
  • The relation between incidence and time since exposure after long periods since exposure stopped is not well determined, which adds uncertainty
  • A possible diagnostic trend, with fewer cases diagnosed in early years, made fitting the age/cohort model to all the data unsatisfactory. To avoid it, that model was restricted to the 2141 cases diagnosed in 1982–2002.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Amphibole Asbestos, Amphibole Group.

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