Occupational exposures, environmental tobacco smoke, and lung cancer

Our plain-English summary of Occupational exposures, environmental tobacco smoke, and lung cancer, by F. Veglia, P. Vineis, K. Overvad, et al (Epidemiology, 2007).

The study

• Authors: F. Veglia, P. Vineis, K. Overvad, H. Boeing, M. Bergmann, A. Trichopoulou, D. Trichopoulos, D. Palli, V. Krogh, R. Tumino, J. Linseisen, K. Steindorf, O. Raaschou-Nielsen, A. Tjonneland, C.A. Gonzalez, C. Martinez, M. Dorronsoro, A. Barricarte, L. Cirera, J.R. Quiros, N.E. Day, R. Saracci, E. Riboli
• Journal: Epidemiology
• Published: 2007;18(6):769-75
• Cited by: 49 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: There is uncertainty regarding the association of occupational exposures with lung cancer. We have studied the association between 52 high-risk job titles and lung cancer incidence in a large prospective study, with more than 200,000 participants followed for more than 6 years and 809 incident cases of lung cancer.

Methods: Hazard ratios and 95% confidence intervals were computed by the Cox proportional-hazard regression model, adjusting for country, age, sex, social class, diet, physical activity, and smoking habits. We used a CAREX-based job-exposure matrix to infer exposure to lung carcinogens. False-positive report probability was calculated as a measure of potentially false-positive results.

Results: Eighteen occupations, mainly related with agriculture, constructions, and metal processing, were associated with increased risk. In addition, incidence tended to increase with the number of hazardous jobs reported. When the occupations were classified according to the presumed exposure to specific carcinogenic agents, the hazard ratios were 1.5 (95% confidence interval = 1.2-1.9) for asbestos, 1.4 (1.1-1.8) for heavy metals, 1.4 (1.1-1.8) for polycyclic aromatic hydrocarbons, and 1.6 (1.2-2.1) for work-related environmental tobacco smoke. The estimated population attributable risk for employment in at least 1 at-risk job was 16% in men and 12% in women.

Conclusions: This large prospective study suggests that exposure to occupational lung carcinogens is still a problem, with such exposures producing moderate to large increases in risk.

In plain English

This prospective study used the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Participants in six countries reported whether they had ever worked in 52 selected jobs linked to cancer. Of 217,055 people followed for a median 6.1 years, 809 developed lung cancer. The authors grouped jobs by presumed exposure; the asbestos group included asbestos production, construction, demolition, shipyards, insulation production and car repair. Results were adjusted for smoking and other factors. Eighteen individual occupations were associated with a statistically significant increase in risk. Ever working in an asbestos-related job gave a hazard ratio of 1.53 (95% CI 1.2 to 1.9) overall and 1.52 (1.2 to 2.0) in men. In women it was 1.51 (0.8 to 3.0), a range that included no increase. Risk rose with more asbestos-related jobs. The authors estimated that asbestos-related jobs accounted for 7.8% (95% CI 3.2 to 14) of lung cancers in men and 0.8% (0 to 3.2) in women. Exposure was inferred from reported jobs, without job duration. The authors concluded that occupational lung carcinogens remain associated with moderate to large risk increases.

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: Prospective cohort study (analysis of the EPIC cohort), using Cox regression and a consensus job-exposure classification based on the Italian CAREX job-exposure matrix
• Who was studied: 217,055 EPIC participants aged 35 to 74 at recruitment (1992 to 1998), from centers in Spain, Greece, Denmark, Germany, four Italian centers and one UK center (Cambridge) whose questionnaires asked about occupational history. They were followed for a median of 6.1 years, and 809 developed lung cancer.
• Exposure: Self-reported past employment in 52 selected at-risk jobs, grouped by presumed exposure to asbestos, heavy metals, polycyclic aromatic hydrocarbons (PAHs), environmental tobacco smoke (ETS) and silica. Asbestos exposure was inferred for asbestos production, construction and demolition, shipyards, insulation production and car repair stations. Fiber types were not specified, and there was no information on how long each job was held.
• Main results:
  • Eighteen individual occupations were associated with a statistically significant increase in lung cancer risk when men and women were analyzed together.
  • Asbestos-related jobs (yes vs. no), all participants: hazard ratio 1.53 (95% CI 1.2 to 1.9)
  • Asbestos-related jobs, men: hazard ratio 1.52 (95% CI 1.2 to 2.0)
  • Asbestos-related jobs, women: hazard ratio 1.51 (95% CI 0.8 to 3.0)
  • Asbestos score, linear trend with the number of asbestos-related jobs: hazard ratio 1.20 (95% CI 1.1 to 1.3)
  • Single jobs, men and women combined, adjusted hazard ratios: shipyards 1.74 (95% CI 1.2 to 2.6); construction industry 1.65 (1.2 to 2.2); demolition worker 1.79 (1.1 to 2.8)
  • At least one of the 52 at-risk occupations, all participants: hazard ratio 1.42 (95% CI 1.2 to 1.7)
  • Estimated population attributable risk for asbestos-related jobs: 7.8% (95% CI 3.2 to 14) in men and 0.8% (0 to 3.2) in women
  • Estimated population attributable risk for at least one at-risk occupation: 16% in men and 12% in women
  • When current and former smokers were stratified by smoking intensity and duration, the hazard ratios were reasonably stable, which the authors took to suggest limited confounding by smoking
• The authors' conclusion: The authors concluded that past exposure to occupational lung carcinogens, including passive smoking, is still associated with moderate to large increases in risk, and that a significant proportion of incident lung cancer cases is still attributable to occupational exposures.
• Limitations the authors state:
  • Occupational history came from simple questions about a list of jobs already considered hazardous, so new occupational risk factors could not be found.
  • Exposure misclassification from limited information is expected to push the hazard ratios toward no effect, so the authors consider their conclusions likely conservative.
  • Time spent in each job, age at employment and time since leaving the job were not investigated.
  • There were too few cases among nonsmokers to analyze that group separately.
  • The grouping of jobs by common exposures may be inaccurate.
  • The population attributable risk figures should be treated with caution because the cohort may not represent the general population in how common the exposures are.

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: Occupational Exposure, Lung Cancer, Hazard Ratio, confidence interval, Habit, Carcinogenic, Population Attributable Fraction (PAF).

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