Etiology Of Carcinoma Of The Larynx

Our plain-English summary of Etiology Of Carcinoma Of The Larynx, by M.L. Newhouse, M.M. Gregory, H. Shannon (1980).

The study

• Authors: M.L. Newhouse, M.M. Gregory, H. Shannon
• Published: Biological Effects Of Mineral Fibres (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 30, Pp. 687-695 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 000846. The article is still under copyright, so we describe it here rather than post it.

In plain English

This study asked whether past asbestos exposure was linked to cancer and related changes of the larynx (voice box). A trained health visitor interviewed patients admitted for laryngeal examination, mostly at London's Royal National Throat Nose and Ear hospitals, before their diagnosis was known. The interviews covered jobs and dusty work, including asbestos. Biopsies were classified without knowledge of the patients' histories. The series had 305 men and 206 women. Women were not analysed further because only 15 had neoplastic changes and only two reported asbestos exposure. Among the men, 83 had neoplastic changes, including 59 squamous-cell carcinomas. This group was markedly older than the other groups and included significantly more cigarette smokers. Alcohol use did not differ significantly. Forty men recalled work exposure to asbestos. Of the 25 men first exposed more than 15 years before diagnosis, six (24.0%) had neoplastic disease, compared with 77 (29.1%) of unexposed men. This difference was not statistically significant. The authors concluded that past asbestos exposure was not found to be associated with neoplastic laryngeal conditions in these patients. They said the interaction of smoking, alcohol and asbestos should be explored further.

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 study of patients admitted for laryngeal endoscopy. Patients were interviewed before their diagnosis was known and then grouped by biopsy findings: neoplastic, cysts and polyps, inflammatory, or no disease. The authors chose this approach instead of a further mortality study.
• Who was studied: 305 men and 206 women admitted for endoscopy of the larynx, chiefly at the Royal National Throat Nose and Ear hospitals in London, with a few from the London Hospital, Mile End Hospital and Oldchurch Hospital, Romford. Only the men were analysed. Study dates are not given.
• Exposure: Self-reported occupational asbestos exposure, recorded at interview along with smoking and alcohol. Jobs included the building trade, electricians and carpenters, laggers and boilermakers, dockers, asbestos factory workers and fitters. No fiber type was specified. Exposure that began less than 15 years before diagnosis was treated as probably not relevant.
• Main results:
  • 83 men had neoplastic changes. Of these, 59 had squamous-cell carcinoma and the remaining 24 had carcinoma in situ or severe or moderate dysplasia.
  • Men with neoplastic changes were markedly older than the other groups (chi-square 42.9, P less than 0.001).
  • There was a significant excess of cigarette smokers in the neoplastic group (chi-square 7.87, P less than 0.01). Men with neoplastic changes made up 16 (16.3%) of non- and ex-smokers, 31 (30.7%) of those smoking 1 to 14 cigarettes a day, and 36 (34.0%) of those smoking 15 or more a day.
  • Among the men, the proportions of nondrinkers, medium and heavy drinkers did not differ significantly between the four groups. 12 men did not answer about alcohol.
  • Of 25 men first exposed to asbestos more than 15 years before diagnosis, 6 (24.0%) had neoplastic disease. Among men reporting no asbestos exposure, 77 (29.1%) had neoplastic disease. The chi-square for trend between these two groups was 0.28, which was not significant. None of the men first exposed less than 15 years before diagnosis had neoplastic changes.
  • Asbestos exposure was not more common in the neoplastic group than in the three other groups.
• The authors' conclusion: The authors concluded that cigarette smoking was a positive etiological factor. Alcohol considered independently of smoking did not appear related. Past asbestos exposure was not found to be associated with neoplastic conditions of the larynx in this group of patients. They said the interaction of smoking, alcohol and asbestos exposure should be explored further.
• Limitations the authors state:
  • The pathological assessment was limited to the biopsy material received, which might not always have represented the whole lesion.
  • Answers about alcohol were not insisted upon, and 12 men did not respond.
  • The authors noted that the London area has no preponderance of jobs with asbestos exposure.
  • The authors said it is difficult to explain why their findings differ from the earlier Liverpool and Canadian studies.

Topics

Medical terms in this study, explained in our Lexicon: Etiology, Carcinoma, Asbestos Exposure.

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