Re: Meta-analysis of asbestos and gastrointestinal cancer

Our plain-English summary of Re: Meta-analysis of asbestos and gastrointestinal cancer, by R.W. Morgan (American Journal of Industrial Medicine, 1991).

The study

• Author: R.W. Morgan
• Journal: American Journal of Industrial Medicine
• Published: 1991;19(3):407-11
• Type of article: Comment, Letter, Meta-analysis
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004114).

In plain English

This was a letter to the editor. In it, the author criticized a 1988 review and meta-analysis by Frumkin and Berlin on asbestos and gastrointestinal cancer. That review had used each cohort's lung cancer standardized mortality ratio (SMR) as a stand-in for asbestos dose, splitting cohorts at an SMR of 200. The author argued this was unwise because of confounders such as smoking. The author also argued that it labeled some cohorts with many mesotheliomas 'low exposure', and that misdiagnosed mesotheliomas could create a false link between lung and digestive cancer. The author pooled the 35 of those 44 cohorts or subcohorts that reported any mesothelioma, covering some 140,000 workers and 502 mesotheliomas. The pooled SMRs were 121 (89-160) for esophagus, 97 (82-113) for stomach, 94 (83-107) for colorectal, and 103 (97-110) for all gastrointestinal cancer. The author noted that published digestive cancer SMRs were higher in cohorts with lung cancer SMRs over 200. However, the author concluded that the totality of the evidence suggests no increased digestive tract cancer risk for people exposed to enough asbestos to cause mesotheliomas.

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: Letter to the editor critiquing a published meta-analysis, with a brief pooled reanalysis (meta-analysis) of cohorts that reported mesotheliomas
• Who was studied: 35 of the 44 asbestos-exposed cohorts or subcohorts used by Frumkin and Berlin (1988), namely those reporting any mesothelioma. The table lists about 140,000 workers studied and 502 mesotheliomas reported. No locations or dates are given.
• Exposure: Asbestos exposure in general (no fiber types named). Cohorts were selected by reporting any mesothelioma, which the author treated as a sign of dose-related exposure.
• Main results:
  • Across the 35 cohorts reporting mesotheliomas, the pooled analysis indicated no increase in digestive cancer risk.
  • Esophageal cancer SMR in the pooled cohorts: 121 (95% confidence limits 89-160)
  • Stomach cancer SMR in the pooled cohorts: 97 (95% confidence limits 82-113)
  • Colorectal cancer SMR in the pooled cohorts: 94 (95% confidence limits 83-107)
  • All gastrointestinal cancer SMR in the pooled cohorts: 103 (95% confidence limits 97-110)
  • The author acknowledged that published SMRs for digestive cancer are higher in cohorts with lung cancer SMRs over 200.
  • The author argued that the criticized analysis, which split cohorts around a lung cancer SMR of 200 and used it as a surrogate for dose, was unwise because of strong confounders such as smoking.
• The authors' conclusion: The author concluded that the totality of the evidence suggests that, for persons exposed to enough asbestos to cause mesotheliomas, there is no increase in risk of cancer of the digestive tract.

Topics

Medical terms in this study, explained in our Lexicon: Meta-Analysis.

Related studies

• Asbestos exposure and gastrointestinal malignancy review and meta-analysis — H. Frumkin, J. Berlin (1988)
• Aerodigestive and gastrointestinal tract cancers and exposure to crocidolite (blue asbestos): incidence and mortality among former crocidolite workers — A. Reid, G. Ambrosini, et al. (2004)
• Insulin-like growth factor II messenger RNA-binding protein 3 expression in gastrointestinal mesenchymal tumors — H. Yamamoto, K. Arakaki, et al. (2014)
• Asbestos and gastrointestinal cancer. A review of the literature — R.W. Morgan, D.E. Foliart, et al. (1985)
• 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)
• Simple nutritional intervention in patients with advanced cancers of the gastrointestinal tract, non-small cell lung cancers or mesothelioma and weight loss receiving chemotherapy: a randomised controlled trial — C. Baldwin, A. Spiro, et al. (2011)

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