Occupational associations with lung cancer in two Ontario cities

Our plain-English summary of Occupational associations with lung cancer in two Ontario cities, by M.M. Finkelstein (American Journal of Industrial Medicine, 1995).

The study

• Author: M.M. Finkelstein
• Journal: American Journal of Industrial Medicine
• Published: 1995;27(1):127-36
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A death certificate based case-control study of lung cancer in two Ontario cities was performed to estimate the risk of lung cancer attributable to occupation in Ontario, and to estimate the proportion of occupational lung cancers receiving compensation from the Workers' Compensation Board. Occupation and industry were identified from the death certificate. A priori occupations for analysis were those whose members had received compensation for occupational cancer from the Ontario Workers' Compensation Board. Population attributable risks were computed using the relative risks observed in this study and employment data from the 1986 Census of Canada. Subjects were all men (N = 967) between the ages of 45 and 75 years resident in the cities of Hamilton and Sault Ste-Marie who died of lung cancer from 1979 to 1988. Controls (2,821) were matched on age, year of death, and city of residence. In agreement with other studies, an increased risk of lung cancer was observed for workers in the construction sector, for miners, and for truck drivers. It was estimated that only a small proportion of lung cancers attributable to occupation are compensated in Ontario. It is believed that many occupational cancers go uncompensated because of the failure to file claims, rather than because claims are rejected by Compensation Boards. Physicians are in a position to advise patients about the possibility of compensable disease and to act as advocates for them. By recognizing compensable illness, physicians have the opportunity to ease the financial burden of patients and their families. The challenge is a difficult one, but it is well worth pursuing.

In plain English

This death-certificate case-control study examined lung cancer and occupation in men aged 45 to 75 in Hamilton and Sault Ste-Marie, Ontario, who died from 1979 to 1988. It compared 967 men who died of lung cancer with 2,821 who died of other causes, matched on age, year of death and city. Jobs came from the certificates; smoking was not adjusted for. The analysis focused on occupations with workers' compensation awards for cancer. Risk was raised for most of these, but no single occupation's increase was statistically significant. Construction workers had significantly higher risk than industrial workers (relative risk 1.38, 95% confidence interval 1.06 to 1.79). Insulators had a relative risk of 3.84 (0.50 to 29.3), from 3 cases and 3 controls. Using 1986 census data, the author estimated that 327 of about 30,000 lung cancer deaths among Ontario men in the 1980s were attributable to carpentry work. In that period, 10 of 16 carpenters' cancer claims were accepted. The author concluded that about 10% compensation was a reasonable estimate for these occupations, and that the shortfall came from unfiled claims.

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: Death certificate based case-control study, with estimates of population attributable risk
• Who was studied: Men aged 45 to 75 resident in Hamilton and Sault Ste-Marie, Ontario, who died from 1979 to 1988: 967 lung cancer deaths (cases) and 2,821 controls who died of other causes, matched on age, year of death and city of residence
• Exposure: Occupation and industry as recorded on the death certificate. The study focused on occupations whose members had received workers' compensation for occupational cancer, including insulators, construction trades, miners, steelworkers and others. Specific exposures, such as asbestos, were not measured. Asbestos is mentioned only in the discussion as one possible explanation for the construction-sector risk.
• Main results:
  • For the occupations selected in advance, lung cancer risk was elevated for most, but no individual increase was statistically significant because each category had few subjects
  • Construction workers compared with industrial workers: relative risk 1.38 (95% confidence interval 1.06 to 1.79), based on 238 cases and 114 controls in construction
  • Industrial workers compared with all other occupations (excluding construction): relative risk 1.11 (95% confidence interval 0.95 to 1.30), which includes 1.0
  • Insulators: 3 cases and 3 controls, relative risk 3.84 (95% confidence interval 0.50 to 29.3), not statistically significant
  • Miners who had moved to the two cities: relative risk 1.46 (95% confidence interval 0.53 to 3.69) compared with other residents
  • Positive associations were reported for butchers, fire fighters, ironworkers, sheet metal workers and truck drivers. For truck drivers (41 cases, 97 controls) the relative risk was 1.24 (95% confidence interval 0.83 to 1.82).
  • Steelworkers: no increased risk in Sault Ste-Marie (relative risk 0.85). Relative risk was 1.10 in Hamilton, which the author attributed to previously identified high-risk areas.
  • Carpenters: an estimated 1.1% (327) of about 30,000 lung cancer deaths among Ontario men in 1980 to 1989 were attributed to the occupation. Over that period, 16 carpenters submitted cancer claims and 10 were accepted.
  • Estimated compensated lung cancers versus attributable lung cancers, 1980 to 1989: 10 of 93 among masons, 7 of over 300 among carpenters, and 10 of 250 among electricians
• The authors' conclusion: The author concluded that, for the specified occupations, an estimated compensation rate of about 10% is reasonable. The author also concluded that many occupational cancers go uncompensated because claims are not filed, rather than because claims are rejected.
• Limitations the authors state:
  • Splitting subjects among many occupations left too little statistical power for modest increases in risk to reach significance. The analysis was therefore restricted to occupations already suspected, and no new hypotheses are suggested.
  • There was no adjustment for differences in smoking between occupations
  • The comparison of industrial workers with other men is more likely to be confounded by smoking and socioeconomic differences, and may be biased upwards
  • Attributable-risk estimates are very sensitive to the relative risks, which had wide confidence intervals
  • For the attributable-risk calculations, the associations were assumed to be causal, and the two cities' risks were assumed to apply to the whole province
  • Usable occupational information was missing for 3% of subjects in Sault Ste-Marie and 17% in Hamilton, and these subjects were excluded
  • The occupation-specific results are not independent, because the same person can be a member of one occupation in one analysis and a comparison subject in another

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, Death Certificate, Case-Control Study, Population Attributable Fraction (PAF), Relative Risk.

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• Exploring the usefulness of occupational exposure registries for surveillance: the case of the Ontario Asbestos Workers Registry (1986-2012) — A.J. Koné Pefoyo, L. Genesove, et al. (2014)
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