Pleural plaques as risk indicators for malignant pleural mesothelioma: a necropsy-based study

Our plain-English summary of Pleural plaques as risk indicators for malignant pleural mesothelioma: a necropsy-based study, by C. Bianchi, A. Brollo, L. Ramani, et al (American Journal of Industrial Medicine, 1997).

The study

• Authors: C. Bianchi, A. Brollo, L. Ramani, C. Zuch
• Journal: American Journal of Industrial Medicine
• Published: 1997;32(5):445-9
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Pleural plaque is recognized as a reliable marker of previous exposure to asbestos. However, it is controversial whether pleural plaque is a risk indicator for asbestos-related malignancies. In the present study, the thoracic cavities were examined for pleural plaques in 3,005 necropsies performed at the Monfalcone Hospital in people aged 15 years or older. Plaques were classified into three classes: 1, small (plaques measuring 1-4 cm in major diameter); 3, large (plaques involving a major part of a hemithorax); and 2, moderate (intermediate conditions). The prevalences of pleural plaques were 70.9% among men, and 24.0% among women. The prevalences of plaques (total plaques, various classes) among subjects with pleural mesothelioma were compared with those observed in the remaining cases. The series included 92 subjects with malignant pleural mesothelioma (82 men and 10 women). Mesothelioma cases showed higher prevalences of total plaques as well as higher prevalences of classes 1, 2, and 3, when compared with controls. These differences reached the statistical significance for total plaques, and classes 2, 3. The present data are consistent with the idea that pleural plaque is a risk indicator for pleural mesothelioma.

In plain English

This necropsy-based study from the Monfalcone Hospital in northeastern Italy, an industrial area with large shipyards, examined the chest cavity for pleural plaques in all 3,005 necropsies on people aged 15 or older performed between October 1979 and March 1995 (1,878 men and 1,127 women). Plaques were graded as small, moderate or large. Plaques were found in 70.9% of men and 24.0% of women. The 92 people with malignant pleural mesothelioma (82 men, 10 women) were compared with the remaining cases. In men, the age-adjusted odds ratio for having any plaques was 3.43 (95% confidence interval 1.71 to 7.94), and for large plaques it was 5.73 (2.65 to 13.8). The small-plaque result in men (2.34, 0.97 to 6.04) did not reach statistical significance. In women, the odds ratio for any plaques was 7.58 (1.71 to 45.62). The authors reported significant differences for total plaques and for moderate and large plaques, and a significant trend with plaque size. They concluded that the data are consistent with pleural plaque being a risk indicator for pleural mesothelioma. They noted that necropsy studies are biased by selection factors.

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: Necropsy-based study comparing the prevalence of pleural plaques in people with malignant pleural mesothelioma against the remaining necropsy cases (controls)
• Who was studied: 3,005 necropsies on people aged 15 years or older at the Monfalcone Hospital, Monfalcone area, northeastern Italy, from October 1, 1979 to March 31, 1995. The series comprised 1,878 men and 1,127 women.
• Exposure: Pleural plaques found at necropsy, used as a marker of past asbestos exposure and graded by size: class 1 small (1 to 4 cm in major diameter), class 2 moderate (intermediate), class 3 large (involving the majority of a hemithorax). Fiber types were not specified in this study.
• Main results:
  • Pleural plaques were present in 70.9% of men and 24.0% of women in the whole necropsy series.
  • The series included 92 people with malignant pleural mesothelioma: 82 men and 10 women.
  • Among the 82 men with mesothelioma, plaques were absent in 11.0%, small in 20.7%, moderate in 28.0% and large in 40.2%. Among the 10 women with mesothelioma, plaques were absent in 30.0%, small in 40.0%, moderate in 20.0% and large in 10.0%.
  • Men, mesothelioma versus controls, any plaques present: age-stratified Mantel-Haenszel odds ratio 3.43, P 0.0004, 95% CI 1.71 to 7.94.
  • Men, small plaques: odds ratio 2.34, P 0.06, 95% CI 0.97 to 6.04.
  • Men, moderate plaques: odds ratio 2.70, P 0.015, 95% CI 1.20 to 6.78.
  • Men, large plaques: odds ratio 5.73, P less than 0.0001, 95% CI 2.65 to 13.8.
  • Women, mesothelioma versus controls, any plaques present: odds ratio 7.58 (without age stratification), Fisher exact P 0.0026, exact 95% CI 1.71 to 45.62.
  • Women, small plaques: odds ratio 5.45, Fisher exact P 0.032, exact 95% CI 0.91 to 37.39.
  • Women, moderate and large plaques combined: odds ratio 15.81, Fisher exact P 0.0040, exact 95% CI 2.1 to 119.9.
  • The authors stated that the differences between mesothelioma cases and controls were significant for total plaques and for classes 2 and 3.
  • The chi-square test for linear trend across plaque classes was 24.95 in men and 16.539 in women, both with P less than 0.0001.
• The authors' conclusion: The authors concluded that their data are consistent with the idea that pleural plaque is a risk indicator for pleural mesothelioma.
• Limitations the authors state:
  • Necropsy studies are not considered ideal in epidemiology and are biased by selection factors.
  • The best way to evaluate plaques, measuring the total area of parietal pleura involved, is difficult to apply in routine necropsies, so a rougher size classification was used.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Pleural Mesothelioma, Autopsy, Hemithorax, Mesothelioma, Statistical Significance.

Related studies

• Pleural plaques and exposure to mineral fibres in a male urban necropsy population — A. Karjalainen, P.J. Karhunen, et al. (1994)
• Asbestos exposure in lung carcinoma: a necropsy-based study of 414 cases — C. Bianchi, A. Brollo, et al. (1999)
• Asbestos exposure in a shipyard area, northeastern Italy — C. Bianchi, A. Brollo, et al. (2000)
• 'Black Spots' and hyaline pleural plaques on the parietal pleura of 150 urban necropsy cases — K. Mitchev, P. Dumortier, et al. (2002)
• Asbestos bodies and pleural plaques in human lungs at necropsy — I. Hägerstrand, B. Seifert (1973)
• Relationship between pleural plaques and biomarkers of cumulative asbestos dose. A necropsy study — P.G. Barbieri, D. Consonni, et al. (2019)

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