Exposure to asbestos and the risk of gastrointestinal cancer: a reassessment

Our plain-English summary of Exposure to asbestos and the risk of gastrointestinal cancer: a reassessment, by D.A. Edelman (British Journal of Industrial Medicine, 1988).

The study

• Author: D.A. Edelman
• Journal: British Journal of Industrial Medicine
• Published: 1988;45(2):75-82
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000211).

Abstract

In 1964 it was first reported that asbestos workers had a higher risk of gastrointestinal cancer. This notion has persisted despite several studies that have found no increased risk. The risks of gastrointestinal cancer to workers exposed to asbestos were reassessed, based on the results of published studies on 32 independent cohorts of asbestos workers. Not all studies provided risk estimates (SMRs) for all gastrointestinal sites (ICD codes 150-159). No consistent evidence was found to indicate that exposure to asbestos increases the risk of gastrointestinal cancer. Generally, the higher SMRs came from studies conducted in the United States or Canada and might reflect factors not related to exposure to asbestos. In studies in which asbestos exposed and non-asbestos exposed workers were evaluated the SMRs were not consistently higher for the group exposed to asbestos. There was no apparent dose response relation between accumulated asbestos dose and the risk of gastrointestinal cancer. It is concluded that there is no dose response relation between exposure to asbestos and risk of gastrointestinal cancer, and asbestos workers are not at an increased risk of gastrointestinal cancer.

In plain English

This article was a review that reassessed whether asbestos workers have a higher risk of cancer of the digestive tract (gastrointestinal cancer, ICD codes 150 to 159). The author reviewed published results from 32 cohorts of asbestos-exposed workers. These included asbestos cement, manufacturing, mining and milling, and shipyard workers. The measure used was the standardised mortality ratio (SMR), which compares observed deaths with expected deaths. Studies of 'bystander' or drinking-water exposure were excluded. Of the SMRs summarised, ten were significantly greater than 1 and nine were significantly less than 1. Except for one study, the significantly raised SMRs came from United States or Canadian studies. Six studies also reported a comparison group not exposed to asbestos. In those, 6 of 12 SMRs were lower for the asbestos-exposed workers. Nine studies gave dose-response data, and the author found no consistent dose-response relation for gastrointestinal cancers. The author noted limitations. The studies did not account for known risk factors and combined cancer sites differently. Some may have counted mesotheliomas as gastrointestinal cancers. The author concluded there was no evidence supporting a cause-and-effect relation between asbestos exposure and cancer of any gastrointestinal site.

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 reassessment of published cohort studies (standardised mortality ratios), with discussion of published animal ingestion studies
• Who was studied: 32 cohorts of asbestos-exposed workers from published studies, grouped into United States/Canadian, United Kingdom, and other-country studies; studies of bystander and drinking-water exposure, and studies giving only proportional mortality ratios or odds ratios, were excluded
• Exposure: Occupational asbestos exposure in asbestos cement, insulation work, manufacturing (gas masks; paper, millboard, friction products; textiles), mining and milling, a nitric acid production plant, railroad, and shipyard/dockyard work, plus workers reported to registries, pneumoconiosis panels or applying for compensation; accumulated dose was not converted to common units
• Main results:
  • Except for one study, SMRs significantly greater than 1 (p less than 0.05) occurred only in the United States/Canadian studies
  • Among the summarised SMRs for gastrointestinal sites, ten were significantly greater than 1 and nine were significantly less than 1
  • Six studies included a comparison group not exposed to asbestos. In one of these, the comparison group was subjects selected from an agricultural area. There was no consistent pattern, and 6 of the 12 SMRs were lower for the asbestos-exposed workers
  • Nine studies gave dose-response data, and no consistent dose-response relation for gastrointestinal cancers was seen. The author attributed apparent relations in some studies to the way accumulated dose was measured. In one miners and millers study, the same pattern appeared for respiratory tuberculosis and cerebrovascular disease
• The authors' conclusion: The author concluded that, based on the epidemiological, clinical, and experimental studies evaluated, there is no evidence to support a cause-and-effect relation between asbestos exposure and cancer of any gastrointestinal site
• Limitations the authors state:
  • The reviewed studies did not evaluate gastrointestinal cancer death rates in terms of known risk factors
  • Different combinations of ICD codes prevented comparison of cancer risks among the 32 cohorts
  • Some studies may have included misdiagnosed mesotheliomas among gastrointestinal cancers, so reported SMRs may be overestimates
  • Accumulated dose, calculated as average exposure times duration, does not distinguish high short exposures from low long exposures
  • Accumulated asbestos doses were not converted to common units across studies

Related studies

• Exposure to asbestos and the risk of gastrointestinal cancer — (1988)
• Risk of gastrointestinal cancers from inhalation and ingestion of asbestos — J. Gamble (2008)
• Gastrointestinal cancer mortality of workers in occupations with high asbestos exposures — S.K. Kang, C.A. Burnett, et al. (1997)
• Asbestos ingestion and gastrointestinal cancer: a possible underestimated hazard — A. Di Ciaula (2017)
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