Occupation and male lung cancer: a case-control study in northern Sweden

Our plain-English summary of Occupation and male lung cancer: a case-control study in northern Sweden, by L.A. Damber, L.G. Larsson (British Journal of Industrial Medicine, 1987).

The study

• Authors: L.A. Damber, L.G. Larsson
• Journal: British Journal of Industrial Medicine
• Published: 1987;44(7):446-53
• Cited by: 51 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Using a case-control study comprising about 600 men with lung cancer in northern Sweden the potential risk of different occupations and groups of occupations was studied. Longitudinal data concerning occupation, employment, and smoking habits were obtained by questionnaires. Some occupational groups (underground miners, copper smelter workers, electricians, and plumbers) exposed to previously known lung carcinogenic agents such as radon daughters, arsenic, and asbestos, had considerably increased odds ratios, which persisted after adjustment for smoking. A slightly raised odds ratio was observed in a group of blue collar workers potentially exposed to lung carcinogenic agents; this rise in the group as a whole mainly disappeared after adjustment for smoking. Farmers and foresters had strikingly low odds ratios, which could only partly be explained by their more moderate smoking habits. The population aetiological fraction attributable to occupation was estimated as 9%.

In plain English

This case-control study looked at which jobs were linked to lung cancer in men in the three northernmost counties of Sweden. Cases were men whose lung cancer was reported to the Swedish Cancer Registry in 1972-7 and who had died by May 1979. Each case was matched to a dead control. Living controls were also drawn, but only men aged 80 or under (467 in all). Postal questionnaires gave work and smoking histories. Relatives answered for cases and dead controls. One question asked about occupational asbestos exposure. Underground miners, copper smelter workers, and plumbers and electricians had raised odds ratios that persisted after smoking adjustment. The authors called asbestos a probable explanation for plumbers and electricians. Asbestos exposure reported in the questionnaires for 20 or more years gave a smoking-adjusted odds ratio of 3.6 (95% CI 1.9 to 7.2) against dead controls, but 1.1 (0.7 to 2.0) against living controls. The authors suggested that living controls reported asbestos exposure more adequately than relatives did. Farmers and foresters had low odds ratios. After smoking adjustment, the authors estimated that 9% of cases were attributable to occupation.

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: Case-control study, with two control groups (dead controls and living controls), using postal questionnaires
• Who was studied: 604 men with lung cancer reported to the Swedish Cancer Registry in 1972-7 who had died before May 1979, from the three northernmost counties of Sweden. Living controls were limited to men aged 80 or under (467 drawn). Questionnaire answers were obtained for 589 cases, 582 dead controls and 453 living controls.
• Exposure: Occupations held for at least one year, including plumbers and electricians (grouped because they are often exposed to asbestos), plus a separate questionnaire item on occupational asbestos exposure. Lifetime smoking was also recorded. No fiber types were specified.
• Main results:
  • Plumbers and electricians with 20 or more years in the job, compared with dead controls: 24 cases and 7 controls. Odds ratio 3.5 (95% CI 1.4 to 9.6) unadjusted, and 2.6 (1.0 to 7.8) after adjustment for smoking.
  • Plumbers and electricians with 20 or more years in the job, compared with living controls: 23 cases and 10 controls. Odds ratio 2.4 (1.1 to 5.6) unadjusted, and 1.8 (0.7 to 4.7) after adjustment for smoking.
  • Occupational asbestos exposure according to questionnaires, for 20 or more years, compared with dead controls: 64 cases and 22 controls. Odds ratio 3.2 (1.9 to 5.5) unadjusted, and 3.6 (1.9 to 7.2) adjusted for smoking. For 1 year or more: 99 cases and 45 controls, adjusted odds ratio 2.6 (1.6 to 4.3).
  • Occupational asbestos exposure according to questionnaires, for 20 or more years, compared with living controls: 46 cases and 40 controls. Odds ratio 1.2 (0.7 to 1.9) unadjusted, and 1.1 (0.7 to 2.0) adjusted for smoking.
  • The questionnaire-based asbestos exposure gave a high odds ratio against dead controls but not against living controls.
  • Farmers and foresters had significantly low odds ratios, even after adjustment for smoking.
  • With adjustment for smoking, the population aetiological fraction for risk occupations was 9%, whether dead or living controls were used. Without smoking adjustment, and counting both risk groups, it was 17% with dead controls and 18% with living controls.
• The authors' conclusion: The authors concluded that obvious excess lung cancer risks were found in occupations previously shown or highly suspected to carry such risks (underground miners, copper smelter workers, electricians and plumbers). They considered asbestos a probable explanation for the increase among electricians and plumbers.
• Limitations the authors state:
  • Relatives who answered for cases and dead controls may have reported asbestos exposure less adequately than living controls reporting for themselves.
  • Several occupations of interest, including insulators, were not analysed separately because the numbers were too small.
  • Even detailed adjustment for smoking may have been inadequate.
  • Findings from the age-stratified subgroups must be evaluated with great caution because of random errors and multiple comparisons.

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, Case-Control Study, Habit, Carcinogenic, Odds Ratio.

Related studies

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• Occupation and mesothelioma in Sweden: updated incidence in men and women in the 27 years after the asbestos ban — N. Plato, J.I. Martinsen, et al. (2016)
• Reducing the underreporting of lung cancer attributable to occupation: outcomes from a hospital-based systematic search in Northern Italy — S. Porru, A. Carta, et al. (2016)
• Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: a case-control study in Sweden — P. Gustavsson, R. Jakobsson, et al. (1998)
• Low-dose exposure to asbestos and lung cancer: dose-response relations and interaction with smoking in a population-based case-referent study in Stockholm, Sweden — P. Gustavsson, F. Nyberg, et al. (2002)
• Occupation and larynx and hypopharynx cancer: a job-exposure matrix approach in an international case-control study in France, Italy, Spain and Switzerland — F. Berrino, L. Richiardi, et al. (2003)

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