Occupational asbestos exposure is associated with pharyngeal squamous cell carcinoma in men from the greater Boston area

Our plain-English summary of Occupational asbestos exposure is associated with pharyngeal squamous cell carcinoma in men from the greater Boston area, by S.M. Langevin, M.H. O'Sullivan, J.L. Valerio, et al (Occupational and Environmental Medicine, 2013).

The study

• Authors: S.M. Langevin, M.H. O'Sullivan, J.L. Valerio, M. Pawlita, K.M. Applebaum, M. Eliot, M.D. McClean, K.T. Kelsey
• Journal: Occupational and Environmental Medicine
• Published: 2013;70(12):858-63
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Asbestos is the name given to a group of naturally occurring silicate mineral fibres that were widely used in industry during the 20th century due to their desirable physical properties. Although use in the USA has fallen over the last three decades, significant exposure in the developing world continues and the burden of disease is considerable. Asbestos is a known risk factor for several malignant diseases, including lung cancer and mesothelioma, and has more recently been implicated in pharyngeal and laryngeal cancer. However, studies of asbestos and cancers of the larynx or pharynx with adequate sample size that control for major head and neck squamous cell carcinoma (HNSCC) risk factors remain relatively sparse.

Methods: We report findings from a case-control study of 674 incident male HNSCC cases from the greater Boston region and 857 population-based male controls, matched on age (±3 years), sex, and town or neighbourhood of residence. Multivariable logistic regression was used to assess the association between occupational asbestos exposure and HNSCC by primary tumour site.

Results: 190 cases (28.2%) and 203 controls (23.7%) reported occupational exposure to asbestos. Occupational asbestos exposure was associated with elevated risk of pharyngeal carcinoma in men (OR 1.41, 95% CI 1.01 to 1.97), adjusted for age, race, smoking, alcohol consumption, education, income and HPV16 serology, with borderline increasing risk for each decade in the exposed occupation (OR 1.10, 95% CI 0.99 to 1.23).

Conclusions: These observations are consistent with mounting evidence that asbestos is a risk factor for pharyngeal cancer.

In plain English

This was a population-based case-control study of men in the greater Boston area. It compared 674 men newly diagnosed with head and neck squamous cell carcinoma, recruited in 1999 to 2003 and 2006 to 2011, with 857 men without the disease matched on age and town or neighbourhood. Work exposure to asbestos was self-reported on a questionnaire. The type and dose of asbestos were not known. In all, 190 cases (28.2%) and 203 controls (23.7%) reported occupational asbestos exposure. After adjusting for age, race, smoking, alcohol, education, income and HPV16 antibody status, reported exposure was associated with higher odds of pharyngeal cancer (odds ratio 1.41, 95% CI 1.01 to 1.97). Each decade in an asbestos-exposed job gave a borderline odds ratio of 1.10 (95% CI 0.99 to 1.23). No significant associations were seen for oral cavity or laryngeal cancer. The authors noted limited numbers, especially for larynx. The authors concluded that their findings are consistent with mounting evidence that asbestos is a risk factor for pharyngeal cancer.

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: Population-based case-control study analysed with multivariable logistic regression
• Who was studied: 674 men with incident head and neck squamous cell carcinoma (223 oral cavity, 333 pharynx, 118 larynx) and 857 population-based male controls from Boston and surrounding towns, recruited December 1999 to December 2003 and October 2006 to June 2011. Women were excluded because they had minimal occupational asbestos exposure.
• Exposure: Self-reported occupational asbestos exposure, analysed as ever versus never exposed and as total years worked in asbestos-exposed jobs. Fiber type and dose were not determined.
• Main results:
  • 190 cases (28.2%) and 203 controls (23.7%) reported occupational asbestos exposure
  • For pharyngeal squamous cell carcinoma, ever occupational asbestos exposure had an adjusted OR of 1.41 (95% CI 1.01 to 1.97), based on 100 exposed cases and 203 exposed controls
  • For pharyngeal carcinoma, each decade worked in an asbestos-exposed occupation had an OR of 1.10 (95% CI 0.99 to 1.23), which the authors described as a borderline dose-response relationship
  • No significant associations were found for oral cavity cancer (OR 0.86, 95% CI 0.59 to 1.24) or laryngeal cancer (OR 1.04, 95% CI 0.64 to 1.67)
  • A sensitivity analysis using conditional logistic regression gave nearly identical point estimates
  • Models of asbestos combined with heavy smoking and/or drinking showed no interaction for any tumour site, on either the additive or the multiplicative scale
• The authors' conclusion: The authors concluded that their observations are consistent with mounting evidence that asbestos is a risk factor for pharyngeal cancer.
• Limitations the authors state:
  • Exposure was self-reported. Differential misclassification or recall bias cannot be ruled out.
  • The study could not obtain direct information on dose or type of asbestos and could not distinguish forms of asbestos. Duration of work was used as an indirect measure of dose.
  • Statistical power for laryngeal cancer was limited: 118 cases, of whom 35 reported asbestos exposure.

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: Asbestos Exposure, Squamous Cell Carcinoma, Silicate, Lung Cancer, Mesothelioma, Laryngeal Cancer, Case-Control Study, Occupational Exposure.

Related studies

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