Asbestos, Pleural Plaques, and Lung Cancer: Untangling the Relationships

Our plain-English summary of Asbestos, Pleural Plaques, and Lung Cancer: Untangling the Relationships, by P. Harber (American Journal of Respiratory and Critical Care Medicine, 2020).

The study

• Author: P. Harber
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 2020;201(1):4-6
• Type of article: Editorial, Comment
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

In plain English

This is an editorial, not an original study. The author commented on a study by Brims and colleagues in the same journal issue. That study asked whether people with known moderate-heavy asbestos exposure who had pleural plaques had a higher lung cancer risk than similarly exposed people without plaques. As the editorial describes it, the study used two Australian cohorts. One was Western Australian crocidolite miners and residents. The other was a nationwide group of workers exposed to mixed fiber types, including amphiboles and chrysotile. Brims and colleagues concluded that, after adjusting for asbestos exposure, sex, smoking and asbestosis, plaques themselves did not increase lung cancer risk. The author contrasted this with an earlier French study by Pairon and colleagues of 5,400 workers, which found an elevated hazard ratio of 2.41 (95% confidence interval 1.21 to 4.85) for plaques and lung cancer. The author noted that the Brims finding depends on precise exposure estimates. The author concluded that people with known moderate to heavy exposure should not be denied CT screening because they lack plaques. In general populations, the author wrote, bilateral plaques should prompt a detailed exposure history.

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: Editorial commentary on another study (Brims and colleagues) published in the same journal issue; it reports no original data of its own
• Who was studied: No population of its own. The editorial discusses the Brims study's two Australian cohorts: Western Australian crocidolite miners and community members with residential exposure, and a nationwide group of workers in occupations with extensive exposure. All participants were known to have significant asbestos exposure.
• Exposure: In the Brims study as described: mainly crocidolite in the Western Australian cohort, and mixed fiber types including multiple amphiboles and chrysotile in the national worker group
• Main results:
  • Brims and colleagues (not this editorial) concluded that pleural plaques, when adjusted for extent of asbestos exposure and other risk factors, did not increase lung cancer risk
  • In the Brims study's national worker group, the association of cumulative exposure with lung cancer risk was not statistically significant: HR 1.81, 95% confidence interval 0.94 to 3.50
  • The editorial cites an earlier French study (Pairon and colleagues: 5,400 asbestos-exposed workers in a CT screening program, 6-year follow-up). That study found a significantly elevated HR of 2.41 (95% confidence interval 1.21 to 4.85) for pleural plaques and lung cancer, adjusted for smoking and cumulative asbestos exposure.
  • The author suggested the difference between the French and Australian results might be due to lower cumulative exposure in the French study or to the French study not adjusting for asbestosis
  • The editorial cites a meta-analysis (not this article's finding) reporting similar baseline cancer prevalence in asbestos workers and heavy smokers screened by CT, about 1%
• The authors' conclusion: The author concluded that the Brims study shows exposure rather than plaque determines risk, so people with known moderate to heavy exposure should not be denied screening for lacking plaques. In general populations, where exposure is less certain, the author wrote that finding bilateral plaques should prompt a detailed exposure history.
• Limitations the authors state:
  • The fiber types differed between the two cohorts in the Brims study
  • The exposure measure used in the regression analyses (log-linear or dichotomous) may not have been the best one
  • Complex interactions among exposure, asbestosis, plaques, cancer, age and smoking limit mechanistic conclusions
  • The finding depends on accurate cumulative exposure estimates, which limits its application to groups whose exposure is less well characterized
  • The CT screening studies of exposed workers that the editorial cites are small, mostly limited to initial tests, and have not examined population mortality

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Lung Cancer.

Related studies

• Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data — C. Paris, S. Thierry, et al. (2009)
• Relationship between number of asbestos bodies in autopsy lung and pleural plaques on chest X-ray film — T. Kishimoto, T. Ono, et al. (1989)
• Significant relationship between the extent of pleural plaques and pulmonary asbestos body concentration in lung cancer patients with occupational asbestos exposure — T. Yusa, K. Hiroshima, et al. (2015)
• Relationship between pleural plaques and biomarkers of cumulative asbestos dose. A necropsy study — P.G. Barbieri, D. Consonni, et al. (2019)
• Relationships between asbestos exposure and pleural plaques: dose and time effects using fractional polynomials — M. Menant, I. Benlala, et al. (2024)
• Pleural effusion during bromocriptine exposure in two patients with pre-existing asbestos pleural plaques: a relationship? — C. Knoop, M. Mairesse, et al. (1997)

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