Estimating the number of asbestos-related lung cancer deaths in Great Britain from 1980 to 2000

Our plain-English summary of Estimating the number of asbestos-related lung cancer deaths in Great Britain from 1980 to 2000, by A.J. Darnton, D.M. McElvenny, J.T. Hodgson (The Annals of Occupational Hygiene, 2006).

The study

• Authors: A.J. Darnton, D.M. McElvenny, J.T. Hodgson
• Journal: The Annals of Occupational Hygiene
• Published: 2006;50(1):29-38
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Inhalation of asbestos fibres is known to cause two main kinds of cancer-mesothelioma and lung cancer. While the vast majority of mesothelioma cases are generally accepted as being caused by asbestos, the proportion of asbestos-related lung cancers is less clear and cannot be determined directly because cases are not clinically distinguishable from those due to other causes. The aim of this study was to estimate the number of asbestos-related lung cancers among males by modelling their relative lung cancer mortality among occupations within Great Britain in terms of smoking habits, mesothelioma mortality (as an index of asbestos exposure) and occupation type (as a proxy for socio-economic factors).

Methods: Proportional mortality ratios for lung cancer and mesothelioma for the 20-year period from 1980 to 2000 (excluding 1981) were calculated for occupational groups. Smoking indicators were developed from three General Household Surveys carried out during the 1980s and 1990s. Poisson regression models were used to estimate the number of asbestos-related lung cancers by estimating the number of lung cancer deaths in each occupation assuming no asbestos exposure and subtracting this from the actual predicted number of lung cancer deaths.

Results: The effect of asbestos exposure in predicting lung cancer mortality was weak in comparison to smoking habits and occupation type. The proportion of current smokers in occupational groups and average age at which they started smoking were particularly important factors. Our estimate of the number of asbestos-related lung cancers was between two-thirds and one death for every mesothelioma death: equivalent to between 11 500 and 16 500 deaths during the time period studied.

Conclusions: Asbestos-related lung cancer is likely to have accounted for 2-3% of all lung cancer deaths among males in Great Britain over the last two decades of the 20th century. Asbestos-related lung cancers are likely to remain an important component of the total number of lung cancer deaths in the future as part of the legacy of past asbestos exposures in occupational settings.

In plain English

This study estimated how many lung cancer deaths among men in Great Britain from 1980 to 2000 (excluding 1981) were related to asbestos. Asbestos-related lung cancers cannot be told apart from other lung cancers, so the authors built a statistical model (Poisson regression) of male lung cancer deaths at ages 16 to 74 across 131 occupational groups. Each group's mesothelioma proportional mortality ratio (PMR) was used as an index of its relative asbestos exposure. Smoking habits came from the General Household Survey, and occupation type was also included. Smoking, especially the proportion of current smokers, had far more influence than asbestos. A group with very high asbestos exposure (mesothelioma PMR of 5) had a relative lung cancer risk of 1.12 compared with an unexposed group with the same smoking habits. The authors estimated between two-thirds and one asbestos-related lung cancer for every asbestos-related mesothelioma. That equals 11 500 to 16 500 male deaths, or 2 to 3% of male lung cancer deaths. They noted that the mesothelioma index mainly reflects amphibole exposure, that death certificates record only the last job, and that trends over time were not modelled.

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: Population-level statistical modelling study (Poisson regression) of male lung cancer deaths by occupational group, using proportional mortality ratios
• Who was studied: Men aged 16 to 74 who died in Great Britain from 1980 to 2000 (excluding 1981). There were 333 537 lung cancer deaths, of which 302 771 (91%) were in the 131 occupational groups (out of 211) included in the analysis.
• Exposure: Asbestos exposure was not measured directly. Each occupation's mesothelioma proportional mortality ratio (PMR), taken from the British mesothelioma register, was used as an index of relative asbestos exposure. Smoking measures came from the General Household Surveys of 1986, 1988 to 89 and 1990 to 91.
• Main results:
  • Asbestos (as measured by the mesothelioma PMR) had a much weaker influence on lung cancer than smoking. The relative lung cancer risk for a group with mesothelioma PMR of 5, compared with a group with no exposure and the same smoking habits, was 1.12.
  • Among the smoking measures, the proportion of current smokers in an occupational group typically had the largest influence on predicted lung cancer deaths.
  • The model predicted 6900 asbestos-related lung cancers among men aged 16 to 74 in the included occupations.
  • Rescaled to all ages and all occupations, this gave an estimated 11 500 asbestos-related lung cancer deaths among males during the period.
  • There were 17 491 male mesothelioma deaths (all occupations and ages), of which 16 500 were taken as likely due to asbestos. The resulting ratio of asbestos-related lung cancer deaths to mesothelioma deaths was 0.7 in the main model.
  • An alternative model without occupational order group fitted much worse (deviance 314.14 on 125 degrees of freedom) and suggested a ratio of 1. The authors took the ratio to lie between two-thirds and one.
• The authors' conclusion: The authors concluded that a substantial number of male lung cancer deaths in Great Britain in 1980 to 2000 (excluding 1981) were asbestos related. They estimated 11 500 to 16 500 deaths, or 2 to 3% of all male lung cancer deaths.
• Limitations the authors state:
  • The mesothelioma PMR is an indirect measure that is hard to relate to actual physical cumulative asbestos exposures.
  • Mesothelioma PMRs mainly reflect amphibole exposures. If chrysotile exposures were not positively correlated with these and chrysotile contributed substantially to lung cancer, the model would likely underestimate asbestos's contribution. The authors think the two exposures are likely positively correlated.
  • Death certificates record only the last occupation, so workers may have left the job where exposure occurred, which dilutes differences between occupations.
  • Trends over time in lung cancer mortality, smoking and asbestos exposure were not taken into account.
  • Smoking data were collected at the time of the surveys, possibly long after the asbestos exposures implied by the mesothelioma PMRs.
  • Including occupational order group may have removed some variation that properly belongs to asbestos exposure, so the main model may underestimate it.
  • Only smoking and asbestos were considered directly as lung cancer risk factors. Other risk factors were at most partly accounted for through occupation type.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma, Habit, Asbestos Exposure, Proportional mortality.

Related studies

• Estimating the number of asbestos-related cancer deaths in Great Britain — M. Greenberg (2006)
• Mesothelioma mortality in Great Britain from 1968 to 2001 — D.M. McElvenny, A.J. Darnton, et al. (2005)
• Monitor. Mesothelioma deaths in Great Britain — M. Kinoulty (2004)
• The expected burden of mesothelioma mortality in Great Britain from 2002 to 2050 — J.T. Hodgson, D.M. McElvenny, et al. (2005)
• Chest physician-reported, work-related, long-latency respiratory disease in Great Britain — M. Carder, A. Darnton, et al. (2017)
• Occupational cancer burden in Great Britain — L. Rushton, S.J. Hutchings, et al. (2012)

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