Occupational risk factors for lung cancer: a case-control study in West Germany

Our plain-English summary of Occupational risk factors for lung cancer: a case-control study in West Germany, by K.H. Jöckel, W. Ahrens, I. Jahn, et al (International Journal of Epidemiology, 1998).

The study

• Authors: K.H. Jöckel, W. Ahrens, I. Jahn, H. Pohlabeln, U. Bolm-Audorff
• Journal: International Journal of Epidemiology
• Published: 1998;27(4):549-60
• Cited by: 89 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The aim of this study is to evaluate carcinogens and occupations suspected to cause lung cancer and to generate new hypotheses about occupational risks.

Methods: In a hospital-based study 1004 incident lung cancer cases and the same number of population controls matched for region, sex and age were interviewed between 1988 and 1993 for their smoking and occupational history. Exposure assessment was based on 33 job-specific supplementary questionnaires. Conditional logistic regression was used to calculate odds ratios (OR) and to control for smoking and occupational asbestos exposure.

Results: Lifelong prevalence of exposure to asbestos was 20.5% for exposure of more than 940 lifetime working hours among controls, corresponding to an OR of 1.62 (95% confidence interval [CI] : 1.28-2.05) that was reduced to 1.45 after adjustment for smoking (P < 5%). Statistically elevated risks after adjustment for smoking and asbestos were seen in metal production and processing workers, transportation workers and freight handlers, in the rubber and plastics industry, in metal production, in engine and vehicle building, and installation. Significantly increased OR after adjustment for smoking and asbestos that deserve further attention were seen in plastics processing workers (OR = 3.49), and sheet and structural metal workers (OR = 2.01 and 2.37, respectively).

Conclusions: The results of the study confirm previously described occupational risks. Because of the possibility of controlling for occupational asbestos exposure, the study gives clear indications for prevention and further research.

In plain English

This West German case-control study interviewed 1004 newly diagnosed lung cancer patients (839 men, 165 women) from Bremen and Frankfurt hospitals in 1988-1993, and 1004 population controls matched for region, sex and age, about smoking and jobs. Asbestos exposure was estimated in lifetime working hours, not distinguishing amphibole from chrysotile. Among men, more than 940 lifetime hours of asbestos exposure was linked to lung cancer (odds ratio 1.62, 95% CI 1.28-2.05), falling to 1.45 after smoking adjustment. An excess asbestos risk appeared in every smoking category. Men in the insulating trade (heat and freezing) had a smoking-adjusted odds ratio of 6.71 (95% CI 1.57-28.77). After adjustment for smoking and asbestos, plastics processing workers had an odds ratio of 3.49 (95% CI 1.07-11.37), and men with at least 10,000 hours of diesel fume exposure had 1.51. Few women were asbestos-exposed, and numbers were too small for conclusions about individual occupations. The authors concluded asbestos has to be regarded as one of the major occupational causes of lung cancer in the region, with a strong indication that other occupational carcinogens play a central role.

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: Hospital-based case-control study with individually matched population controls, analysed with conditional logistic regression
• Who was studied: 1004 incident lung cancer cases (839 males, 165 females) from hospitals in Bremen (1988 to 1993) and Frankfurt/Main (February 1989 to March 1990), and 1004 population controls matched for region, sex and age (within 5 years), from Bremen, Frankfurt and surrounding areas
• Exposure: Occupational asbestos exposure, measured as cumulative lifetime working hours from job-specific supplementary questionnaires. Exposed individuals were grouped in tertiles: under 940 hours, 940 to 5280 hours, and over 5280 hours. Amphibole and chrysotile asbestos were not distinguished. The study also looked at occupations, industries, welding, metal cutting and diesel fumes.
• Main results:
  • In men, more than 940 lifetime working hours of asbestos exposure applied to 21% of controls and 29% of cases. This level of exposure was associated with significantly elevated odds ratios, which were slightly reduced after adjustment for smoking.
  • For asbestos exposure above 940 lifetime working hours (20.5% of controls), the odds ratio for lung cancer was 1.62 (95% CI 1.28-2.05). It fell to 1.45 after adjustment for smoking.
  • In men with more than 5280 lifetime hours of asbestos exposure, the smoking-adjusted odds ratio was 1.47 (95% CI 1.04-2.07)
  • A consistent excess risk for asbestos was seen in each smoking category. A formal test found no indication of departure from a multiplicative joint effect of smoking and asbestos (P-value for interaction 0.73).
  • The authors calculated a population attributable risk for asbestos of 8%
  • Among known risk occupations, after adjustment for smoking, the authors reported significantly elevated odds ratios for the insulating trade (heat and freezing), OR 6.71 (95% CI 1.57-28.77), and for shipbuilding, OR 1.55 (95% CI 1.03-2.34)
  • After adjustment for smoking and asbestos, odds ratios were significantly increased in plastics processing workers (OR 3.49, 95% CI 1.07-11.37) and in sheet and structural metal workers (OR 2.01 and 2.37, respectively)
  • Among men, 73 controls and 111 cases reported at least 10,000 hours of diesel fume exposure. This gave an OR of 1.54 (95% CI 1.13-2.10), which was 1.51 and still significant after adjustment for smoking and asbestos.
  • Grouping all known and suspected risk occupations gave smoking-adjusted odds ratios of 1.67 in males (95% CI 1.34-2.09) and 2.17 in females (95% CI 1.14-4.11)
  • For men who did welding, the OR of 1.35 was reduced to 1.25 (95% CI 0.94-1.65) after adjustment for smoking and asbestos exposure. The authors wrote that asbestos heat protection plays an important role in welding-associated lung cancer risk.
• The authors' conclusion: The authors concluded that their study confirmed the well-known association between occupational asbestos exposure and lung cancer. They wrote that asbestos has to be regarded as one of the major occupational causes of lung cancer in the study region, and that there is also a strong indication that other occupational carcinogens play a central role.
• Limitations the authors state:
  • The analysis could not distinguish between amphibole and chrysotile asbestos
  • In-depth analysis of the joint effect of smoking and asbestos was hampered by small numbers, since only 4 non-smoking cases were not exposed to asbestos
  • Only three female cases and one female control had been exposed to asbestos, so the results for women were not adjusted for asbestos
  • Sample sizes within the categories of known risk occupations were too small for definite conclusions for females. For suspected risk occupations, numbers of women were too small for inferences about individual occupations.

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, Occupational History, Odds Ratio, Asbestos Exposure, confidence interval.

Related studies

• Occupational risk factors for lung cancer in women: results of a case-control study in Germany — I. Jahn, W. Ahrens, et al. (1999)
• Occupational lung cancer risk for men in Germany: results from a pooled case-control study — I. Brüske-Hohlfeld, M. Möhner, et al. (2000)
• Occupational asbestos exposure as a risk factor for laryngeal carcinoma in a population-based case-control study from Germany — H. Ramroth, W. Ahrens, et al. (2011)
• Occupational risk factors for renal cell carcinoma: agent-specific results from a case-control study in Germany. MURC Study Group. Multicenter urothelial and renal cancer study — B. Pesch, J. Haerting, et al. (2000)
• Lung cancer risk and welding: results from a case-control study in Germany — K.H. Jöckel, W. Ahrens, et al. (1998)
• Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany — H. Pohlabeln, K.H. Jöckel, et al. (2000)

Browse more research in International Journal of Epidemiology, or return to medical research.