Alcohol, smoking, and occupational factors in cancer of the larynx: a case-control study

Our plain-English summary of Alcohol, smoking, and occupational factors in cancer of the larynx: a case-control study, by W. Ahrens, K.H. Jöckel, W. Patzak, et al (American Journal of Industrial Medicine, 1991).

The study

• Authors: W. Ahrens, K.H. Jöckel, W. Patzak, G. Elsner
• Journal: American Journal of Industrial Medicine
• Published: 1991;20(4):477-93
• Cited by: 75 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A hospital-based case-control study of laryngeal cancer was conducted in Bremen in 1986 and 1987 with 100 prevalent male laryngeal cancer patients and 100 male hospital controls with diseases not considered to be related to smoking, alcohol, or occupational exposures, who were frequency matched by age. The odds ratio for heavy smoking (more than 30 pack-years) reached a value of 3.5 (95% confidence limits (CL) 1.1, 7.9). Ex-smokers showed a significant decrease in risk; this reached the level of those who had never smoked about 15 years after smoking cessation. For daily consumers of alcohol an odds ratio of 3.2 (95% CL 1.4, 7.5) was observed. Among the 17 occupations in which at least ten subjects had worked, excess risks were observed for stock keeping and transportation workers, and for leather and textile workers. The odds ratio was significantly increased for the latter (p less than 0.05). Among all those persons ever employed in a priori defined-risk occupations, an odds ratio of 2.74 (95% CL 1.23, 6.06) was observed. Considering responses to an exposure check-list, no increased risks could be shown for exposure to asbestos, coal tar, or welding fumes. On the other hand, excess risks were observed for exposures to diesel oil, gasoline, and mineral oil, controlling for smoking and alcohol. The findings in occupational and exposure subgroups were based on small numbers of cases and controls and, consequently, were subject to large sampling errors. Many of the results are consistent, however, with occupational risk factors reported from other studies.

In plain English

This hospital-based case-control study in Bremen, Germany, compared men with cancer of the larynx (voice box) with male hospital controls. Of 100 cases recruited, 15 diagnosed long before were excluded, leaving 85 cases and 100 controls. Compared with the lowest smoking and drinking categories, smoking 30 or more pack-years had an odds ratio of 3.0 (95% confidence limits 1.11 to 7.85), and daily drinking had an odds ratio of 3.2 (1.36 to 7.50). Textile and leather workers had an adjusted odds ratio of 8.19, with a very wide confidence interval. Men ever employed in occupations previously suspected of raising this cancer's risk had an odds ratio of 2.74 (1.23 to 6.09). Self-reported asbestos exposure was not associated with increased risk (adjusted odds ratio 1.1, 0.5 to 2.4). However, employment in the 8 German occupations with the highest rates of compensated asbestos-related disease (9 cases, 2 controls) had an adjusted odds ratio of 5.7 (1.12 to 28.67). Estimates were higher for self-reported gasoline (borderline significant), mineral oil and diesel oil (intervals including 1). The authors concluded their asbestos data were not conclusive, noting small numbers, many comparisons and self-reported exposure.

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
• Who was studied: Men with histologically confirmed primary cancer of the larynx from the Ear, Nose and Throat Clinic of the Central Hospital St. Jürgen, Bremen, Germany, and male hospital controls from the same hospital. Patients were interviewed between July 1986 and January 1987. Of 100 cases recruited, 15 diagnosed as long ago as 1976 were excluded, leaving 85 cases and 100 controls in the analysis.
• Exposure: Smoking (pack-years), frequency of alcohol drinking, lifetime occupations and industries, and a checklist of 19 self-reported occupational exposures. The checklist included asbestos, coal tar or bitumen, welding, diesel oil, mineral oil and gasoline. No asbestos fiber type is specified.
• Main results:
  • Compared with the lowest smoking category, the odds ratio adjusted for age and alcohol was 2.6 (95% CL 1.02, 6.59) for smokers of 6-29 pack-years. It was 3.0 (95% CL 1.11, 7.85) for smokers of 30 or more pack-years.
  • Risk decreased with time since quitting smoking. Men who had quit 16 or more years earlier had an odds ratio of 0.9 (95% CL 0.17, 4.25) compared with men who had never smoked.
  • Daily drinkers of alcohol had an adjusted odds ratio of 3.2 (95% CL 1.36, 7.50), compared with men drinking less than once a week.
  • Heavy smokers (30 or more pack-years) who drank daily had an odds ratio of 7.7 (95% CL 1.8, 32.5), compared with light smokers who drank less than once a week.
  • Textile and leather workers (8 cases, 2 controls) had an adjusted odds ratio of 8.19 (95% CL 1.49, 45.03). This was the only occupational group whose lower confidence limit was above 1.
  • 28% of cases and 10% of controls had ever worked in occupations defined in advance as suspected laryngeal cancer risks. The adjusted odds ratio for this group was 2.74 (95% CL 1.23, 6.09), compared with men never employed in those occupations. Within this group, 6 cases and 1 control had been asbestos workers.
  • Self-reported asbestos exposure on the checklist was not associated with increased risk. Its odds ratio adjusted for age, smoking and alcohol was 1.1 (95% CL 0.5, 2.4).
  • Cases were found more often than controls in the 8 German occupations with the highest rates of compensated asbestos-related disease. The adjusted odds ratio for employment in these occupations was 5.7 (95% CL 1.12, 28.67). Four of 9 cases had worked in a local asbestos-cement factory, compared with none of the 2 controls.
  • The highest risk estimates were for self-reported exposure to gasoline (adjusted odds ratio 2.8, 95% CL 1.0, 7.7), mineral oil (2.2, 95% CL 0.9, 5.3) and diesel oil (1.7, 95% CL 0.8, 3.5). The gasoline result reached only borderline significance.
• The authors' conclusion: The authors concluded that their data did not settle whether asbestos exposure causes cancer of the larynx.
• Limitations the authors state:
  • The study included only a small number of people.
  • Because many odds ratios were calculated, some significant results may be due to chance.
  • Prevalent cases (people already diagnosed earlier) had to be included.
  • The interviewer knew whether each person was a case or a control, so interviewer bias cannot be excluded.
  • Exposure was self-reported, with no information on the form of the exposure (solid matter, aerosols, dusts or fumes).

Topics

The National Library of Medicine indexes this study under subjects our site covers: Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: Laryngeal Cancer, Case-Control Study, Occupational Exposure, Odds Ratio.

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• Exposure to cement dust, related occupational groups and laryngeal cancer risk: results of a population based case-control study — A. Dietz, H. Ramroth, et al. (2004)
• A case-control study of occupational risk factors for laryngeal cancer — P. Wortley, T.L. Vaughan, et al. (1992)
• 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)
• Occupational risk factors for lung cancer in women: results of a case-control study in Germany — I. Jahn, W. Ahrens, et al. (1999)

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