A Quest Into The Environmental Causes Of Cancer Of The Lung

Our plain-English summary of A Quest Into The Environmental Causes Of Cancer Of The Lung, by W.C. Hueper (1955).

The study

• Author: W.C. Hueper
• Published: Washington, Dc: Public Health Service, Monograph No. 36, Pp. 1-54 (1955)
• Type of article: Government report
• Our copy: from Johns-Manville's own medical library, J-M no. 001861.

In plain English

This 1955 U.S. Public Health Service monograph was a review, not a new study. The author surveyed published epidemiological, medical and animal evidence on environmental causes of lung cancer. The known or suspected causes covered were urban air pollution and workplace agents: nickel, chromium compounds, arsenic, iron, beryllium, coal tar, petroleum oils, asbestos, isopropyl oil, mustard gas and radioactive ores. In the asbestos section, the author counted 80 published cases of lung cancer occurring with asbestosis. Of the 52 cases with sex recorded, 37 were men and 15 were women, a ratio of 2.5 to 1. The author compared this with a usual ratio of 5:1 to 10:1 for lung cancer of unknown cause. The author cited other investigators' findings, such as Merewether's 31 lung cancers among 266 asbestosis cases (11.65 percent). The author described animal experiments with asbestos as equivocal and treated asbestosis as the prerequisite for the cancer. The author concluded that the evidence made it unlikely that cigarette smoking was a major factor in lung cancer, and pointed instead to occupational and industry-related causes.

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: Review (government monograph) of published epidemiological, medical and experimental evidence on environmental causes of lung and other respiratory cancers; no new data were collected
• Who was studied: Published reports on general populations and occupational groups in several countries, from 1879 to the early 1950s. For asbestos, the reports were 80 recorded cases of lung cancer with asbestosis from the United States, Canada, England and Germany.
• Exposure: Many inhaled agents, which the author presented as known or suspected respiratory carcinogens. The author left some of them undecided, notably iron dust. For asbestos, the agent was asbestos dust. The author distinguished Italian, South African and Australian asbestos ('amphibils') from Canadian, Russian, German and French asbestos (hydrated magnesium silicate) but named no specific fiber types. The author stated that some 35,000 U.S. workers were exposed to asbestos dust.
• Main results:
  • Among the asbestosis lung cancer cases with sex recorded, there were 37 males and 15 females (52 cases), a male to female ratio of 2.5 to 1. The author compared this with a usual 5:1 to 10:1 for lung cancers of unknown cause.
  • 26 percent of the asbestosis lung cancers appeared before age 44. The author interpreted this as a moderate shift toward younger ages.
  • The author cited Merewether's finding (another investigator's data, 1924 to 1946) of 31 cases of lung cancer among 266 cases of asbestosis (11.65 percent). In the same source, there were 91 lung cancers among 6,884 autopsied cases of silicosis (1.32 percent).
  • The histological types of the asbestosis-associated lung cancers were 22 squamous carcinomas, 7 oat cell carcinomas, 4 anaplastic carcinomas and 6 adenocarcinomas. The author said these did not deviate essentially from cancers of unknown cause.
  • The author regarded asbestosis as the prerequisite for the later lung cancer. On this basis, the author criticized studies counting lung cancer across whole asbestos-industry workforces as misleading.
  • The author described animal experiments with asbestos as equivocal: negative results in guinea pigs, and a claim of bronchogenic carcinoma in two mice that the author said needed confirmation.
  • For iron dust, the author judged the evidence uncertain and withheld a definite conclusion.
• The authors' conclusion: The author concluded that the available data made it unlikely that cigarette smoking was a major factor in lung cancer or its rise. In the author's view, the conclusive evidence on specific causes pointed to occupational or industry-related factors.
• Limitations the authors state:
  • The author stated that available information on occupational causes of lung cancer was very defective, because there had been no extensive and prolonged analyses of lung cancer deaths among industrial groups.
  • The author described the 'polymer cancer' concept, under which the author grouped asbestosis-associated cancers, as tentative and needing more evidence.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer.

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