Laryngeal cancer: an explanation for the apparent occupational association

Our plain-English summary of Laryngeal cancer: an explanation for the apparent occupational association, by A. Chovil (Medical Hypotheses, 1981).

The study

• Author: A. Chovil
• Journal: Medical Hypotheses
• Published: 1981;7(7):951-6
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001990).

Abstract

The apparent association of laryngeal cancer with asbestos and possibly other occupational exposures can be accounted for by the hypothesis that chronic vocal abuse peculiar to certain working conditions will act as a promoting factor for active carcinogens found mainly in tobacco smoke.

In plain English

This article was a hypothesis paper and presented no new data. The author proposed that laryngeal cancer results mainly from fat-soluble cancer-causing agents in tobacco smoke penetrating the lining of the larynx. Alcohol and chronic vocal abuse (straining the voice) were suggested as possible promoters. The author argued that the apparent link between asbestos and laryngeal cancer arises because vocal abuse is more common in outdoor or noisy jobs, which the author suggested includes asbestos trades such as insulation on major construction projects and shipbuilding. Reviewing earlier reports, the author described the asbestos association as weak. According to the author, it diminished when smoking and drinking were controlled for and showed no suggestion of a dose response. Citing occupational death statistics for England and Wales, the author noted the highest laryngeal cancer rates among unskilled manual labourers. For the occupational groups these statistics listed with significantly increased laryngeal cancer mortality, the author judged asbestos exposure not particularly probable, except possibly engine room ratings. The author concluded the asbestos relationship fitted an indirect rather than causal link. No asbestos fiber types were named.

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: Hypothesis paper (opinion and discussion of earlier published evidence; no new data collected)
• Who was studied: No study population. The author drew on earlier published reports, including occupational mortality data from the Registrar General for England and Wales (1978 report).
• Exposure: Asbestos (no fiber type named), discussed alongside tobacco smoke, alcohol, chronic vocal abuse, nickel, mustard gas and isopropyl alcohol manufacture. The author linked asbestos trades such as insulation work on major construction projects and shipbuilding with outdoor or noisy working conditions.
• Main results:
  • The author described the asbestos and laryngeal cancer association in earlier literature as weak. It rested on one cohort study, two case-control studies and a letter to the Lancet.
  • According to the author, the asbestos relationship diminished when smoking and drinking were controlled for.
  • According to the author, the earlier asbestos studies gave no suggestion of a dose response.
  • In the Registrar General for England and Wales data, laryngeal cancer showed a strong socioeconomic relationship. The maximum incidence was in Class 5 (unskilled manual labour).
  • The Registrar General's report listed several occupational groups with significantly increased mortality ratios for laryngeal cancer. These were service, sport and recreation workers; stevedores and dock labourers; labourers not elsewhere classified; machine tool operators; deck and engine room ratings, barge and boatmen; and publicans and innkeepers. The author judged that asbestos exposure would not be anticipated as particularly probable for any of these groups, with the possible exception of engine room ratings. The author argued that vocal strain could be postulated for all of them.
• The authors' conclusion: The author concluded that the increased prevalence of vocal abuse in certain occupational situations produces an apparent association with agents such as asbestos and possibly nickel. In the author's view, the weak, inconstant relationship is more consistent with an indirect relationship than a causal one.

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, Occupational Exposure.

Related studies

• 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)
• Occupational risk factors for laryngeal carcinoma: Connecticut, 1975-1980 — R.T. Zagraniski, J.L. Kelsey, et al. (1986)
• A case-control study of occupational risk factors for laryngeal cancer — P. Wortley, T.L. Vaughan, et al. (1992)
• Diet and other risk factors for laryngeal cancer in Shanghai, China — W. Zheng, W.J. Blot, et al. (1992)
• The history, aetiology and epidemiology of laryngeal carcinoma — M.A. Rafferty, J.E. Fenton, et al. (2001)
• The epidemiology of laryngeal cancer in Brazil — V. Wünsch Filho (2004)

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