Occupation and larynx and hypopharynx cancer: a job-exposure matrix approach in an international case-control study in France, Italy, Spain and Switzerland

Our plain-English summary of Occupation and larynx and hypopharynx cancer: a job-exposure matrix approach in an international case-control study in France, Italy, Spain and Switzerland, by F. Berrino, L. Richiardi, P. Boffetta, et al (Cancer Causes & Control, 2003).

The study

• Authors: F. Berrino, L. Richiardi, P. Boffetta, J. Estève, I. Belletti, L. Raymond, L. Troschel, P. Pisani, L. Zubiri, N. Ascunce, E. Gubéran, A. Tuyns, B. Terracini, F. Merletti, Milan JEM Working Group
• Journal: Cancer Causes & Control
• Published: 2003;14(3):213-23
• Cited by: 53 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To investigate the effect of exposure to occupational agents on the risk of hypopharyngeal/laryngeal cancer.

Methods: Case-control study conducted during 1979-1982 in six centres in South Europe. An occupational history and information on exposure to non-occupational factors were collected for 1010 male cases of hypopharyngeal/ laryngeal cancer as well as for 2176 population controls. The exposure to 10 occupational agents was assessed through a job-exposure matrix. As occupational histories had been collected since 1945 major analyses were restricted to subjects aged less than 55 years (315 cases and 819 controls).

Results: Significant elevated risks adjusted for non-occupational variables (smoking, alcohol consumption and diet) and other occupational exposures were consistently found for organic solvents (odds ratio (OR) for ever-exposure: 1.7, 95% confidence interval: 1.1-2.5) and asbestos (OR: 1.6, 1.0-2.5). A significant positive trend for both probability of exposure and duration was found for exposure to solvents. A positive association between exposure to formaldehyde and laryngeal cancer was also suggested. No association was found for exposure to arsenic and compounds, chromium and compounds, and polycyclic aromatic hydrocarbons. Analyses restricted to subjects aged 55 or more did not show elevated risks, with the exception of wood dust (OR: 1.8, 1.3-2.7).

Conclusions: In our study occupational exposure to solvents was associated with an increased risk of hypopharyngeal/laryngeal cancer. Results also provide additional evidence of an excess of risk for exposure to asbestos.

In plain English

This population-based case-control study, run in 1979–1982 in six centres in France, Italy, Spain and Switzerland, studied men with laryngeal or hypopharyngeal cancer (1010 cases, 2176 controls). Workplace exposures were estimated with a job-exposure matrix; asbestos types were not distinguished. Because job histories began in 1945 (except in Varese, where they were lifelong), the main analyses used men under 55 (315 cases, 819 controls). In that group, after adjustment for smoking, alcohol, diet, socio-economic status and other workplace agents, ever exposure to asbestos had an odds ratio of 1.6 (95% CI 1.0–2.5); for organic solvents it was 1.7 (1.1–2.5). For asbestos, the trend with duration of exposure had a p of 0.06. For men exposed at least 10 years beginning at least 20 years earlier, the asbestos odds ratio fell to 1.4 (0.8–2.4). Men aged 55 or more showed no statistically significant associations except with wood dust. The authors concluded that solvents had a possible causal role and that the results added evidence for an asbestos association. They noted that misclassification by the matrix could be expected to underestimate risks.

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: Multicentre population-based case-control study, with occupational exposure assessed through a job-exposure matrix
• Who was studied: 1010 male cases of laryngeal or hypopharyngeal cancer and 2176 male population controls with occupational data, from six centres: Calvados (France), Turin and Varese (Italy), Pamplona and Zaragoza (Spain), and Geneva (Switzerland), late 1970s to early 1980s. Main analyses were restricted to men under 55 (315 cases, 819 controls), because occupational histories started in 1945 except in Varese, where lifelong histories were collected. Men aged 55 or more (695 cases, 1357 controls) were analysed separately.
• Exposure: Probability and intensity of exposure to 16 agents, among them asbestos, man-made mineral fibres, solvents, PAH, formaldehyde and wood dust. These were assigned to each job held after 1944 by an expert-built job-exposure matrix. Asbestos types were not distinguished.
• Main results:
  • Men under 55: ever exposure to asbestos had an odds ratio of 1.6 (95% CI 1.0–2.5) after adjustment for non-occupational factors and other occupational exposures.
  • Men under 55: ever exposure to organic solvents had an odds ratio of 1.7 (95% CI 1.1–2.5). Solvents showed a positive trend with duration of exposure (p 0.003).
  • Men under 55: for asbestos, odds ratios for possible and probable exposure were almost identical. The odds ratio decreased (1.4, 95% CI 0.8–2.4) when restricted to men exposed for 10 or more years with 20 or more years since first exposure.
  • Men under 55: the positive trend with duration of asbestos exposure had p 0.06. By tertiles of weighted exposure, the asbestos odds ratios were 1.4 (0.8–2.3), 1.9 (1.2–3.2) and 1.6 (0.96–2.6), with p for trend 0.037, which the authors described as positive but not monotonic.
  • Men under 55: when exposure to asbestos or man-made mineral fibres was combined, the odds ratio was 1.7 (95% CI 1.0–2.8; 151 exposed cases) for possible exposure and 2.7 (95% CI 1.4–5.2; 67 exposed cases) for probable exposure.
  • Men under 55: asbestos odds ratios were similar for endolarynx cancer (possible 1.7, 0.98–3.0; probable 1.8, 0.8–4.0) and hypopharynx cancer (possible 1.8, 0.9–3.9; probable 1.8, 0.6–5.0).
  • Men aged 55 or more: none of the most frequent agents, including asbestos, was associated with cancer risk at a statistically significant level. The exception was wood dust (odds ratio 1.8, 95% CI 1.3–2.7, 87 exposed cases).
• The authors' conclusion: The authors concluded that solvents had a possible causal role in cancer of the larynx and hypopharynx. They also concluded that the results provided additional evidence in favour of a positive association between occupational asbestos exposure and laryngeal/hypopharyngeal cancer.
• Limitations the authors state:
  • Exposure misclassification by the job-exposure matrix was likely non-differential, so an underestimate of risk could be expected. Positive residual confounding may also remain.
  • In validation studies, over one-third of jobs the matrix classified as probably exposed were judged not exposed by experts.
  • Occupational histories covered only work from 1945 onward (except in Varese), so histories were incomplete for older men.
  • Low and selective response among controls may have led to overestimation of risks for agents assigned by the matrix.
  • The study could not distinguish between types of asbestos.

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: Case-Control Study, Laryngeal Cancer, Occupational History, Occupational Exposure, Odds Ratio, confidence interval.

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• Laryngeal and hypopharyngeal cancer and occupational exposure to asbestos and man-made vitreous fibers: results of a case-control study — J.L. Marchand, D. Luce, et al. (2000)
• Occupational exposure to chlorinated solvents and risk of head and neck cancer in men: a population-based case-control study in France — C. Barul, A. Fayossé, et al. (2017)
• Occupational exposure and laryngeal and hypopharyngeal cancer risk in central and eastern Europe — O. Shangina, P. Brennan, et al. (2006)
• A case-control study of occupational risk factors for laryngeal cancer — P. Wortley, T.L. Vaughan, et al. (1992)
• International renal-cell cancer study. IV. Occupation — J.S. Mandel, J.K. McLaughlin, et al. (1995)

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