The future excess fraction of occupational cancer among those exposed to carcinogens at work in Australia in 2012

Our plain-English summary of The future excess fraction of occupational cancer among those exposed to carcinogens at work in Australia in 2012, by R.N. Carey, S.J. Hutchings, L. Rushton, et al (Cancer Epidemiology, 2017).

The study

• Authors: R.N. Carey, S.J. Hutchings, L. Rushton, T.R. Driscoll, A. Reid, D.C. Glass, E. Darcey, S. Si, S. Peters, G. Benke, L. Fritschi
• Journal: Cancer Epidemiology
• Published: 2017;47:1-6
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Studies in other countries have generally found approximately 4% of current cancers to be attributable to past occupational exposures. This study aimed to estimate the future burden of cancer resulting from current occupational exposures in Australia.

Methods: The future excess fraction method was used to estimate the future burden of occupational cancer (2012-2094) among the proportion of the Australian working population who were exposed to occupational carcinogens in 2012. Calculations were conducted for 19 cancer types and 53 cancer-exposure pairings, assuming historical trends and current patterns continued to 2094.

Results: The cohort of 14.6 million Australians of working age in 2012 will develop an estimated 4.8 million cancers during their lifetime, of which 68,500 (1.4%) are attributable to occupational exposure in those exposed in 2012. The majority of these will be lung cancers (n=26,000), leukaemias (n=8000), and malignant mesotheliomas (n=7500).

Conclusions: A significant proportion of future cancers will result from occupational exposures. This estimate is lower than previous estimates in the literature; however, our estimate is not directly comparable to past estimates of the occupational cancer burden because they describe different quantities - future cancers in currently exposed versus current cancers due to past exposures. The results of this study allow us to determine which current occupational exposures are most important, and where to target exposure prevention.

Copyright © 2016 Elsevier Ltd. All rights reserved.

In plain English

This was a modelling study that estimated how many future cancers would arise among Australians exposed to cancer-causing agents at work in 2012. The authors combined a national telephone survey of workplace exposures with published risk estimates and projected cancer rates to 2094. They covered 38 carcinogens, 19 cancer types and 53 cancer-carcinogen pairings. For the 14,594,000 Australians of working age (18 to 65) in 2012, they estimated 4,831,500 cancers over their lifetime. Of these, 1.4% (68,500) were attributed to occupational exposure in the people who were exposed at work in 2012: 2.5% (58,500) in males and 0.4% (10,000) in females. Asbestos was estimated to contribute more cancers than any other agent, 13,500 in total, including 7,500 mesotheliomas and 3,500 lung cancers. In males, 31.7% of future mesotheliomas were attributed to work exposure, compared with 0.2% in females. The authors noted that their estimate likely undercounts the total burden because it leaves out cancers in people not exposed at work in 2012 who had been exposed before or would be exposed later. They also said the long projections carry uncertainty of unknown size.

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: Modelling (burden of disease) study using the future excess fraction method to estimate future cancers among people exposed to carcinogens at work in 2012
• Who was studied: Australian residents aged 18 to 65 in 2012, estimated at 14,594,000 people (7,299,000 males and 7,295,000 females), followed in the model to 2094. Exposure prevalence came from the Australian Work Exposures Study, a telephone survey of 4993 Australian workers plus 505 workers from Western Australia.
• Exposure: 38 carcinogens classed by IARC as Group 1 or 2A and used in Australian workplaces, including asbestos (fiber type not specified). Exposure was grouped as 'low' (low or medium) or 'high'.
• Main results:
  • Across the whole 2012 working-age cohort, 1.4% (68,500) of future cancer registrations were estimated to occur in people exposed to occupational carcinogens in 2012, as a result of their exposure. The cohort total was an estimated 4,831,500 lifetime cancers.
  • By sex: 2.5% (58,500) of future cancers in males and 0.4% (10,000) in females were attributed to occupational exposures.
  • Asbestos was estimated to contribute the largest number of cancer registrations of any exposure, followed by solar ultraviolet radiation and benzene. Table 2 gives 13,500 asbestos-attributable cancers, including 7,500 mesotheliomas and 3,500 lung cancers.
  • Mesothelioma, for which asbestos was the only exposure considered, had the highest future excess fraction in males: 31.7% (7,500 cases). In females it was 0.2% (fewer than 100 cases), and 21.9% overall. The authors said this was likely because few females are occupationally exposed to asbestos.
  • Lung cancer was the largest single contributor (26,000 cases). In males, the largest contributors to lung cancer were silica, then diesel engine exhaust, then asbestos.
  • When restricted to cancer-carcinogen combinations with sufficient evidence only, 1.0% (50,000) of future cancers overall were attributed to occupational exposures. When restricted to Group 1 carcinogens, the figure was 1.3% (63,000).
• The authors' conclusion: The authors concluded that a significant proportion of future cancers will result from occupational exposures. They said their estimate is lower than previous estimates but not directly comparable, because it counts future cancers in currently exposed people rather than current cancers from past exposures. They said the results show which exposures to target for prevention.
• Limitations the authors state:
  • The estimate excludes cancers in people in the cohort who were not exposed in 2012 but had been exposed in the past or would be exposed in the future, so it is likely an underestimate of the total burden.
  • The exposure survey had a relatively low response fraction (53%), with an unknown effect on the results.
  • The relative risks used came from studies of past exposures and may not fully apply to currently exposed workers.
  • The long projections to 2094 introduce uncertainty of unknown size.
  • No latency period was explicitly included in the estimates. The authors assumed some people exposed in 2012 had also been exposed in the past.
  • A small overestimation is likely because the incidence rates used covered all registrations, not just first cancers. Leukaemias may be overestimated because subtypes were not considered.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Lung Cancer, Mesothelioma.

Related studies

• The future excess fraction model for calculating burden of disease — L. Fritschi, J. Chan, et al. (2016)
• Occupational exposure to carcinogens in Australian road transport workers — S. Si, R. Carey, et al. (2016)
• Estimates of work-related cancers in workers exposed to carcinogens — F. Deschamps, M. Barouh, et al. (2006)
• Cancer survival and prevalence in Australia: period estimates from 1982 to 2010 — Australian Institute of Health and Welfare (2013)
• The current burden of cancer attributable to occupational exposures in Canada — F. Labrèche, J. Kim, et al. (2019)
• Investigating cancer risks related to asbestos and other occupational carcinogens — J. Siemiatycki (2007)

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