Proportion of Cancers Due to Occupation

Our plain-English summary of Proportion of Cancers Due to Occupation, by J. Higginson (1980).

The study

• Author: J. Higginson
• Published: Preventive Medicine 9:180-188 (1980)
• 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 conference paper by the author, from the International Agency for Research on Cancer, together with a review committee, reviewed how hard it is to assign cancers to occupation and estimated upper limits for the share of cancers due to workplace 'point-source' exposures. It went through cancer sites one by one. It reported no new study data. The paper named asbestos exposure as the predominant factor for mesothelioma. It cited an estimate by Elmes that about 600 of 30,000 lung and pleural cancers each year in the United Kingdom could be attributed to asbestos. It cited a SEER report of 1000 mesotheliomas a year in the United States. Using a ratio from a mortality survey of heavily exposed shipyard asbestos workers, it estimated that at most 1500 excess bronchogenic carcinomas a year out of about 70,000 might be linked to heavy asbestos exposure. The authors concluded that cancers due to occupation cannot be estimated precisely, and that their figures represent probable upper limits. They noted that the number of mesotheliomas was still rising.

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 and conference report giving estimates of the proportion of cancers due to occupation, site by site; no new study data
• Who was studied: No study population of its own. The paper draws on published and unpublished estimates, mainly for the United Kingdom and the United States. Its figures show cancer deaths by presumed cause in Birmingham (UK), Bombay, and a black population in Bulawayo
• Exposure: Occupational point-source exposures in general. Asbestos is discussed as the predominant factor for mesothelioma and as a cause of some lung cancers.
• Main results:
  • The paper cited an estimate by Elmes (personal communication) that, of 30,000 lung and pleural cancers each year in the United Kingdom, about 600 could be attributed to asbestos. This count includes asbestos workers who smoke, and mesothelioma.
  • The paper cited a SEER report giving an annual total incidence of 1000 mesotheliomas in the United States.
  • The paper cited a long-term mortality survey of heavily exposed asbestos workers in shipyards. For every one mesothelioma that developed after 20 or more years of heavy exposure, about three additional cancers appeared in excess, including about 1.5 excess bronchogenic cancers.
  • Applying the shipyard ratio to the 1000 annual US mesotheliomas, the author estimated that at most 1500 bronchogenic carcinomas a year may be in excess, out of about 70,000 such carcinomas each year.
  • The paper accepted estimates that cigarette smoking is responsible for about 85% of lung cancers. It judged that occupational sources probably cause not more than 10% of lung cancers in males, and noted that smoking may potentiate occupational hazards, notably asbestos.
  • The paper stated that a very small proportion of stomach cancers have been described as due to asbestos exposure. It said cancers of the large intestine are believed to be due largely to cultural or dietary factors rather than to exposures such as asbestos.
  • The review group cited reports from the United Kingdom that not more than 6% of cancers in males originate in the workplace.
• The authors' conclusion: The authors concluded that the number of cancers due to occupation cannot be estimated precisely. In their opinion, their estimates represent the probable upper limits of the contribution of point-source occupational exposures to cancer.
• Limitations the authors state:
  • The authors stated that most relative risk studies are based on small selected populations. They said the data needed are not available for any current national population of workers.
  • The group concluded that no national-level data permit adequate calculation of the numbers of exposed persons and their exposure levels.
  • The author stated that long-term trends cannot be forecast for lack of data, and that the number of mesotheliomas was still rising.
  • The group noted that all estimates had a degree of imprecision.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Mesothelioma, SEER, Bronchogenic Carcinoma.

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