Lung cancer risk of workers in shoe manufacture and repair

Our plain-English summary of Lung cancer risk of workers in shoe manufacture and repair, by K.H. Jöckel, H. Pohlabeln, U. Bolm-Audorff, et al (American Journal of Industrial Medicine, 2000).

The study

• Authors: K.H. Jöckel, H. Pohlabeln, U. Bolm-Audorff, I. Brüske-Hohlfeld, H.E. Wichmann
• Journal: American Journal of Industrial Medicine
• Published: 2000;37(6):575-80
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The occupational lung cancer risk in manufacturing and repair of shoes was studied by pooling of two major case-control studies from Germany.

Methods: Some 4184 incident hospital-based cases of primary lung cancer and 4253 population controls, matched for sex, age, and region of residence were intensively interviewed with respect to their occupational and smoking history. Based on the occupational coding and a free text search, all individuals who had ever worked in shoe manufacturing or repair for at least half a year were identified. Shoemaker-years were calculated as the cumulated duration of working in shoe manufacturing or repair. Odds ratios (OR) and 95% confidence intervals (CI) were calculated via conditional logistic regression. Additional adjustment for smoking and occupational asbestos exposure was used.

Results: Seventy-six cases and 42 controls who had ever worked in shoe manufacture or repair (OR = 1.89, 95% CI: 1.29-2.78). After adjustment for smoking, this risk was lowered to 1.69 (95% CI: 1.09-2.62). Further adjustment for asbestos exposure only slightly changed the risk estimates upwards. The smoking adjusted OR in males was 1.50 (95% CI: 0.93-2.41) and 2.91 (95% CI: 0.90-9.44) in females. Logistic regression modeling showed a positive dose-effect relationship between duration of exposure in shoe manufacture and repair and lung cancer risk. The odds ratio for 30 years of exposure varied between 1.98 and 2.24 depending on the model specified.

Conclusions: The study demonstrates an increased lung cancer risk for shoemakers and workers in shoe manufacturing. The risk seems to double after being 30 years in these occupations.

Copyright 2000 Wiley-Liss, Inc.

In plain English

This study pooled two German lung cancer case-control studies and identified shoe manufacture and repair workers within them. These included 4184 hospital patients with primary lung cancer and 4253 population controls, interviewed about jobs and smoking. Seventy-six cases and 42 controls had done such work for at least six months. For both sexes, the odds ratio was 1.89 (95% CI 1.29 to 2.78) allowing only for age, region and sex, 1.69 (1.09 to 2.62) also adjusted for smoking, and 1.74 (1.12 to 2.69) adjusted for smoking and occupational asbestos. Smoking-adjusted, it was 1.50 (0.93 to 2.41) in men and 2.91 (0.90 to 9.44) in women, though only 13 female cases and 5 female controls were exposed. In men, risk rose with years worked. Adjusted for smoking and asbestos, men's odds ratio for 30 years of work was 2.16 (1.07 to 4.37) or 2.13 (1.01 to 4.47), depending on the model. The authors stated no relevant asbestos exposure is expected in this industry. They concluded this work may be associated with lung cancer risk, that over 30 years seems to double it, and that causes need research.

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: Pooled analysis of two German lung cancer case-control studies (the BIPS study and the GSF study), within which shoe workers were identified
• Who was studied: 4184 hospital-based patients with newly diagnosed primary lung cancer and 4253 population controls, matched for sex, age and region of residence, in parts of western and eastern Germany. The BIPS study ran from 1988 to 1993 in Bremen and Frankfurt. The GSF study ran from 1990 to 1996, with interviews up to the end of 1994 included.
• Exposure: Ever having worked in shoe manufacture or repair for at least half a year. Duration was measured as cumulative 'shoemaker-years'. Occupational asbestos exposure, assessed with 17 supplementary questionnaires, was treated as a confounder, not as the main exposure.
• Main results:
  • 76 cases and 42 controls (both sexes) had ever worked in shoe manufacture or repair. Their crude odds ratio for lung cancer was 1.89 (95% CI 1.29 to 2.78). This figure was stratified by age, region and sex, but not adjusted for smoking or asbestos.
  • After adjustment for smoking, the odds ratio for ever working in shoe manufacture or repair (both sexes) was 1.69 (95% CI 1.09 to 2.62).
  • After adjustment for both smoking and occupational asbestos exposure, the odds ratio (both sexes) was 1.74 (95% CI 1.12 to 2.69).
  • The smoking-adjusted odds ratio was 1.50 (95% CI 0.93 to 2.41) in men (63 exposed cases, 37 exposed controls) and 2.91 (95% CI 0.90 to 9.44) in women (13 exposed cases, 5 exposed controls). The authors noted the female sample was very small.
  • In men, the models estimated that the odds ratio doubled after about 21 years of exposure (logarithmic model) or 28 years (linear model).
  • In men, adjusted for smoking and asbestos exposure, the odds ratio for 30 years of exposure compared with no exposure was 2.16 (95% CI 1.07 to 4.37) in the logarithmic model and 2.13 (95% CI 1.01 to 4.47) in the linear model.
  • Adding occupational asbestos exposure to the model slightly increased the risk estimates, more so for longer duration of shoe work. The authors considered this plausible because no relevant asbestos exposure is expected in this industry.
• The authors' conclusion: The authors concluded that the study adds to existing evidence that working in shoe manufacture and repair may be associated with a risk of lung cancer, and that more than 30 years of such work seems to double the risk. They said the causative agents are still debated and need further research.
• Limitations the authors state:
  • The response rate among controls in the GSF study was relatively low (40%), a potential source of bias. The authors judged selection bias an unlikely explanation because the exposure rates among controls were similar in the two studies (1.0% and 0.8%).
  • The authors did not try to identify which substances cause the excess risk. Shoemakers are exposed to many potential carcinogens, and the numbers of exposed cases and controls were small.
  • Small numbers made it hard to analyse duration of work and time since first exposure together.

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, Odds Ratio, confidence interval, Asbestos Exposure.

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