Value of a multinational approach in determining the causation of cancer

Our plain-English summary of Value of a multinational approach in determining the causation of cancer, by C.S. Muir (The Yale Journal of Biology and Medicine, 1986).

The study

• Author: C.S. Muir
• Journal: The Yale Journal of Biology and Medicine
• Published: 1986;59(5):485-96
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

MacMahon and Pugh define epidemiology as the use of knowledge on the frequency and distribution of disease to search for determinants. This paper demonstrates that a multinational approach in cancer epidemiology can be of great value in at least four circumstances: namely, the compilation and standardization of data, the assessment of risk, the pooling of study populations to obtain interpretable results, and the provision of resources for specific epidemiologic investigations. One or two examples are given for each category--the determination of international cancer incidence patterns, the evaluation of the risk posed by chemicals to man, assessment of the effects of low doses of ionizing radiation, determination of the long-term effects of exposure to asbestos substitutes, and studies on the influence of diet on esophageal cancer.

In plain English

This article was a review by the author, from the International Agency for Research on Cancer (IARC). It argued that multinational collaboration helps in finding the causes of cancer, and it did not report a new study. Instead it described earlier collaborative work, including a study of workers making asbestos substitutes (glass wool, continuous glass filament and rock wool). That study covered 13 plants in seven European countries chosen to have no significant asbestos exposure, with 24,609 workers. The article reported a twofold excess of lung cancer thirty or more years after first employment. When workers were compared with local rather than national death rates, the excess for glass wool and continuous filament was no longer significant, but the excess for rock wool was unchanged. The rock wool excess was mainly among workers who began 40 or more years earlier, before dust-suppressive agents were used. One mesothelioma occurred. Smoking habits were usually unknown, but the author gave reasons against smoking as the sole explanation. The author concluded that international collaboration is likely to be increasingly used against environmental cancer problems.

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/commentary describing examples of multinational cancer research, mostly coordinated by IARC; no new study is reported
• Who was studied: Main asbestos-related example: pooled cohorts of 24,609 workers in the man-made mineral fiber production industry at 13 plants in seven European countries (selected from 72 plants). Other examples covered women treated for cervical cancer in eight countries and villagers in a high-risk area for esophageal cancer in China.
• Exposure: Production of the asbestos substitutes glass wool, continuous glass filament and rock wool; plants were required to have no significant exposure to asbestos
• Main results:
  • In the European man-made mineral fiber cohort, the article reported a twofold excess of lung cancer for the period thirty years or more since first employment
  • In a further five-year follow-up of the cohort, there were 2,719 deaths against 2,459 expected (SMR 111, statistically significant), most of the excess due to violence (accidents). Excluding violence, the SMR fell to 102.
  • For lung cancer 30 or more years after first exposure, the SMR was 173 using national rates and 153 using local rates, both marked as significant at the 5 percent level
  • Using local rather than national rates, the lung cancer excess for glass wool and continuous filament production workers was no longer significant, while that for rock wool remained unchanged
  • Lung cancer mortality showed no pattern with duration of employment. The three- to fourfold excess was mainly among workers who started rock wool exposure some 40 or more years earlier, when dust-suppressive agents and resin binders were not used.
  • One case of mesothelioma occurred in a person who had been employed for less than one year and died 13 years later
  • In a separately described study (Boice et al.) of women treated for cervical cancer, 5,146 second cancers were observed against 4,736 expected
  • In a separately described randomized double-blind trial in China, retinol, riboflavin and zinc had no effect on esophagitis
• The authors' conclusion: The author concluded that many problems of environmental carcinogenesis can best be solved by international collaboration, and that such collaboration is likely to be increasingly used
• Limitations the authors state:
  • In the man-made mineral fiber cohort, an increase in lung cancer due to smoking was difficult to exclude because the smoking habits of cohort members were usually not known
  • The esophageal intervention cohort would need follow-up for many years, since no more than ten cases could be expected from 300 persons in ten years

Topics

Medical terms in this study, explained in our Lexicon: Causation, Epidemiology, Esophageal Cancer.

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