A study of the histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom

Our plain-English summary of A study of the histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom, by F Whitwell, Muriel L Newhouse, Diane R Bennett (1974).

The study

• Authors: F Whitwell, Muriel L Newhouse, Diane R Bennett
• Published: British Journal of Industrial Medicine, 31, 298-303 (1974)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This study examined the microscopic cell types of lung cancer in United Kingdom asbestos workers who died of lung cancer, most of them officially certified as having asbestosis. The authors gathered clinical notes, necropsy reports and slides from pneumoconiosis panels for deaths from 1962 to 1970. They added further Scottish cases to the end of 1972 and patients from a London East End asbestos factory, all but three of whom had certified asbestosis. Of 197 listed patients, 88 men and nine women had adequate postmortem tumour tissue. The women were too few to analyse as a separate group. Among the men, adenocarcinoma was the commonest type. Its share was higher with moderate or severe asbestosis than with normal or mild lung findings, but the difference was not statistically significant. All 69 men whose smoking habits were recorded had smoked cigarettes at some time. Smoking habits did not differ significantly by cancer type. The authors concluded that asbestos may act together with cigarette smoke, probably multiplicatively, to produce adenocarcinoma in the distal airways. They noted that cancers in mild asbestosis may be under-represented and that a comparable non-asbestos series was hard to find.

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: Retrospective case series: review of clinical records, necropsy reports and histological slides of lung cancer deaths among workers with certified asbestosis, plus additional asbestos factory patients
• Who was studied: United Kingdom workers who died of lung cancer. Most had been certified by pneumoconiosis medical panels as having asbestosis, with deaths from 1962 to 1970, plus additional Scottish cases from 1970 to the end of 1972. Patients from a London East End asbestos factory were also added, all but three of whom had certified asbestosis. Of 197 patients listed, 88 men and nine women with adequate postmortem tumour tissue were typed. The analysis concerns the 88 men.
• Exposure: Occupational asbestos exposure, in nearly all cases severe enough for certified asbestosis; three of the London East End factory patients did not have certified asbestosis. Fibre types are not stated. Cigarette smoking was also recorded.
• Main results:
  • Among the 88 men, adenocarcinoma was the commonest type of lung cancer. The percentage printed is unreadable in the scanned text.
  • The share of adenocarcinoma was higher in men with moderate or severe asbestosis than in men with normal or mild lung findings. This difference was not statistically significant.
  • Smoking habits were recorded for 69 of the 88 men. All had smoked cigarettes; three had given up more than 20 years before death and eight others more recently.
  • Sixty-seven per cent of the men with squamous and oat-cell carcinomas were moderate or heavy smokers. The figures for the other groups are damaged in the text. There was no significant difference in smoking habits between cell types.
  • Mean duration of exposure was 17.8 years for men with squamous-cell carcinoma and 21.9 years for men with adenocarcinoma. The difference was not statistically significant.
  • The mean latent period (years from first exposure to death) ranged from 27.3 to 33.2 years across the cell-type groups.
  • A quarter of the men had started work with asbestos by age 18, and nearly one-fifth were not exposed until after age 40.
  • Mean age at death by cell type was very similar to that found in non-asbestos lung cancer cases.
  • The authors estimated that adenocarcinoma frequency in an unselected population probably lies between 15 and 20 (unit damaged in the text). They described this as about half the frequency they found in more severe asbestosis.
• The authors' conclusion: The authors concluded that when asbestos dust, which reaches the distal parts of the bronchial tree, acts as a co-carcinogen with cigarette smoke, the maximum carcinogenic effect, probably multiplicative, produces adenocarcinoma in the distal respiratory tract.
• Limitations the authors state:
  • Lung cancers in early and slight asbestosis may not be adequately represented, so any cell-type relationship with asbestosis is likely to be exaggerated in this series.
  • Finding a comparable series of non-asbestos, presumably cigarette-induced, lung cancers for comparison was very difficult; the authors called it insuperable.
  • The series did not contain all people with certified asbestosis and lung cancer who died in the United Kingdom in the period. The authors attributed this to administrative errors, missing necropsies, lost records or inadequate sections.
  • Smoking information came from routine clinical notes, which can be misleading and usually underestimate smoking.
  • Earlier Liverpool cases used for comparison came from an area where asbestos exposure was common, so they may underestimate differences between asbestos-exposed and non-exposed populations.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Autopsy, Pneumoconiosis, Adenocarcinoma, Habit.

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