The investigation of brain tumor occurrence in other occupational groups: introduction

Our plain-English summary of The investigation of brain tumor occurrence in other occupational groups: introduction, by I.J. Selikoff (Annals of the New York Academy of Sciences, 1982).

The study

• Author: I.J. Selikoff
• Journal: Annals of the New York Academy of Sciences
• Published: 1982;381:116-8
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This short introduction to a conference session on brain tumors in occupational groups addressed why earlier presentations had reached conflicting conclusions, with methodological problems suggested as a possible explanation. To illustrate these difficulties, the author presented mortality data from an earlier study of 17,800 asbestos insulation workers in the United States and Canada, all identified on January 1, 1967, and followed to December 31, 1976 (166,853 man-years of observation). Causes of death were classified both by best available evidence (autopsy, surgical, clinical) and by death certificate alone. Expected deaths were based on U.S. white male rates. About 3,000 men were more than 30 years from onset of exposure. Increased asbestos-associated cancers were readily identified for common sites. However, almost nothing was seen earlier than 20 years from onset: there were 325 deaths before 20 years, compared with 1,946 at 20 or more years. Only 83 of 995 cancers, and 5 of 175 mesotheliomas, occurred before 20 years. For less common cancers, including brain (14 observed by best evidence and 17 by death certificate, against 10.4 expected), the data were not sufficient for confidence. The author concluded that small numbers and inadequate latency make cancer hard to detect, even for a well-defined carcinogen, so continued debate about brain tumors was to be expected.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This short piece was the author's introduction to a conference session on brain tumors in occupational groups. It was not a new study. To show how hard cancer risks can be to detect, the author presented tables from an earlier study (Selikoff, Hammond and Seidman, 1979). That study followed 17,800 asbestos insulation workers in the United States and Canada, identified on January 1, 1967, through December 31, 1976 (166,853 man-years). The article does not name fiber types. Only 325 deaths occurred before 20 years from onset of employment. Before that point, only 83 of 995 cancers and 5 of 175 mesotheliomas were seen. For brain cancer, 10.4 deaths were expected, against 14 by best evidence (ratio 1.35) and 17 by death certificate (ratio 1.63). No significance tests were reported. The author said that even this large cohort did not give enough data to be absolutely confident about less common cancers. With small numbers and too little time since exposure, the author said, cancer would be hard to find even in a well-identified cohort exposed to a well-defined carcinogen.

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: Introductory remarks to a conference session (not original research), illustrated with tables reprinted from the author's earlier published cohort study of insulation workers (Selikoff, Hammond and Seidman, 1979)
• Who was studied: 17,800 men who were members of the asbestos insulation workers' union in the United States and Canada on January 1, 1967, followed through December 31, 1976, for 166,853 man-years of observation
• Exposure: Occupational asbestos exposure as insulation workers. The fiber type is not specified. Results were analysed by years since onset of exposure or employment.
• Main results:
  • Only 325 deaths occurred among the men less than 20 years from onset of employment
  • Before 20 years from onset, only 83 of the 995 cancers were seen
  • Only 5 of 175 mesotheliomas were seen before 20 years from onset, and even these were almost 20 years from onset
  • Brain cancer deaths in the whole cohort: 10.4 expected; 14 observed by best evidence (ratio 1.35) and 17 by death certificate (ratio 1.63). No statistical tests were reported.
  • Cancer of all sites in the whole cohort: 319.7 expected; 995 observed by best evidence (ratio 3.11) and 922 by death certificate (ratio 2.88)
• The authors' conclusion: The author concluded that with small numbers and inadequate time since exposure, cancer would be hard to detect even in a well-identified cohort exposed to a well-defined carcinogen. The author said this made the debates over brain tumor studies understandable and expected them to continue.
• Limitations the authors state:
  • The author stated that even with this large cohort and 166,000 person-years, there was not enough data to be absolutely confident about less common cancers such as bladder, testis, skin, lymphoma, leukemia and pancreas

Topics

Medical terms in this study, explained in our Lexicon: Insulator, Autopsy, Death Certificate, Mesothelioma, Latency.

Related studies

• Mortality of brain tumors among asbestos insulation workers in the United States and Canada — H. Seidman, I.J. Selikoff, et al. (1982)
• Assessing Tumor-Infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method from the International Immuno-Oncology Biomarkers Working Group: Part 2: TILs in Melanoma, Gastrointestinal Tract Carcinomas, Non-Small Cell Lung Carcinoma and Mesothelioma, Endometrial and Ovarian Carcinomas, Squamous Cell Carcinoma of the Head and Neck, Genitourinary Carcinomas, and Primary Brain Tumors — S. Hendry, R. Salgado, et al. (2017)
• Occupational risk factors for brain cancer in Canada — S.Y. Pan, A.M. Ugnat, et al. (2005)
• INTEROCC case-control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents — A. Lacourt, E. Cardis, et al. (2013)
• Simian virus 40 transformation, malignant mesothelioma and brain tumors — F. Qi, M. Carbone, et al. (2011)
• The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents — D.M. McElvenny, M. van Tongeren, et al. (2018)

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