Asbestos exposure, pleural plaques, and the risk of death from lung cancer

Our plain-English summary of Asbestos exposure, pleural plaques, and the risk of death from lung cancer, by J.C. Pairon, P. Andujar, M. Rinaldo, et al (American Journal of Respiratory and Critical Care Medicine, 2014).

The study

• Authors: J.C. Pairon, P. Andujar, M. Rinaldo, J. Ameille, P. Brochard, S. Chamming's, B. Clin, G. Ferretti, A. Gislard, F. Laurent, A. Luc, P. Wild, C. Paris
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 2014;190(12):1413-20
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Rationale: Although asbestos is a well-known lung carcinogen, the pleural plaque-lung cancer link remains controversial.

Objectives: This study was designed to examine this link in asbestos-exposed workers.

Methods: A 6-year follow-up was conducted to study lung cancer mortality in the 5,402 male subjects participating in an asbestos-related disease screening program conducted from October 2003 to December 2005 in four French regions. Chest computed tomography (CT) scan was performed in all subjects with randomized, independent, double reading of CT scans focusing on benign asbestos-related abnormalities. Cox model survival regression analysis was used to model lung cancer mortality according to the presence of pleural plaques, with age as the main time variable, adjusting for smoking and asbestos cumulative exposure index. All statistical tests were two-sided.

Measurements And Main Results: Thirty-six deaths from lung cancer were recorded. Lung cancer mortality was significantly associated with pleural plaques in the follow-up study in terms of both the unadjusted hazard ratio of 2.91 (95% confidence interval = 1.49-5.70) and the adjusted hazard ratio of 2.41 (95% confidence interval = 1.21-4.85) after adjustment for smoking and asbestos cumulative exposure index.

Conclusions: Pleural plaques may be an independent risk factor for lung cancer death in asbestos-exposed workers and could be used as an additional criterion in the definition of high-risk populations eligible for CT screening.

In plain English

This French study followed 5,402 men from an asbestos-related disease screening program run in four regions between October 2003 and December 2005. The men were retired or unemployed workers with past occupational asbestos exposure, which industrial hygienists estimated from work histories. All had a chest CT scan, and 1,118 (20.7%) had pleural plaques. Death certificates up to 31 December 2010 showed 36 lung cancer deaths: 17 among the 1,118 men with plaques and 19 among the 4,284 without. Men with plaques had a higher risk of lung cancer death (hazard ratio 2.91, 95% confidence interval 1.49 to 5.70). The link remained after adjusting for smoking and cumulative asbestos exposure (hazard ratio 2.41, 1.21 to 4.85). None of the men who died of lung cancer had asbestosis on CT. The authors noted that lung cancer deaths were fewer than expected, pointing to selection of participants, and that other workplace carcinogens were not taken into account. They concluded that pleural plaques may be an independent risk factor for lung cancer death and could help define groups eligible for CT screening.

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: Cohort follow-up study: mortality follow-up of about 6 years of men screened by chest CT, analysed with Cox proportional hazards regression
• Who was studied: 5,402 men (retired or unemployed workers with a history of occupational asbestos exposure) who took part in a screening program in four French regions from October 2003 to December 2005. Women, men with uninterpretable CT scans, and men judged unexposed were excluded.
• Exposure: Occupational asbestos exposure, with fiber types not specified. Industrial hygienists assessed it from each man's full work history and expressed it as duration of exposure, a cumulative exposure index, and time since first exposure. 23.8% had worked in the construction industry at some point. The factor compared between groups was the presence of pleural plaques on CT.
• Main results:
  • 1,118 of the 5,402 men (20.7%) had parietal pleural plaques, with or without diaphragmatic pleural plaques, on CT.
  • 36 lung cancer deaths were recorded between the CT scan and 31 December 2010. None occurred in the year after the CT scan.
  • 17 lung cancer deaths occurred among the 1,118 men with pleural plaques and 19 among the 4,284 men without.
  • Compared with men without plaques, men with pleural plaques had a higher risk of lung cancer death: unadjusted hazard ratio 2.91 (95% CI 1.49 to 5.70), and 2.41 (95% CI 1.21 to 4.85) after adjustment for smoking and cumulative asbestos exposure index.
  • Compared with never smokers, the hazard ratio for lung cancer death was 2.31 (95% CI 0.80 to 6.71) in ex-smokers and 5.96 (95% CI 1.58 to 22.5) in current smokers.
  • None of the men who died of lung cancer had interstitial abnormalities compatible with asbestosis on CT.
• The authors' conclusion: The authors concluded that pleural plaques may be an independent risk factor for lung cancer death in asbestos-exposed workers and could be used as an additional criterion in defining high-risk populations eligible for CT screening.
• Limitations the authors state:
  • Lung cancer mortality in the cohort was lower than expected from national rates. The authors attributed this to voluntary participation and a healthy worker effect.
  • Among 1,269 men whose CT scans were not sent to the coordinating centers, there were 17 lung cancer deaths. The authors took this to suggest a selection bias, though they judged its effect on the plaque comparison fairly limited.
  • Causes of death came from death certificates, and the authors had no access to the medical files of men recorded as dying of lung cancer.
  • Only asbestos exposure was assessed, so a role for co-exposure to other occupational lung carcinogens cannot be ruled out.
  • Only 37 men had asbestosis on CT, too few for a specific analysis. The authors saw this as further evidence of selection.
  • Pulmonary nodules were not systematically examined at the expert CT reading, so not all lung cancer deaths can be assumed to be new cases arising after the scan.

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: Asbestos Exposure, Pleural Plaques, Lung Cancer, CT Scan, Cumulative Exposure, Hazard Ratio, confidence interval.

Related studies

• Pleural plaques and the risk of pleural mesothelioma — J.C. Pairon, F. Laurent, et al. (2013)
• Asbestos exposure, pleural plaques and digestive cancers — B. Clin, C. Gramond, et al. (2025)
• Inter-reader agreement in HRCT detection of pleural plaques and asbestosis in participants with previous occupational exposure to asbestos — F. Laurent, C. Paris, et al. (2014)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)
• Relationships between asbestos exposure and pleural plaques: dose and time effects using fractional polynomials — M. Menant, I. Benlala, et al. (2024)
• Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data — C. Paris, S. Thierry, et al. (2009)

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