Low-dose computed tomography (LDCT) in workers previously exposed to asbestos: detection of parenchymal lung disease

Our plain-English summary of Low-dose computed tomography (LDCT) in workers previously exposed to asbestos: detection of parenchymal lung disease, by M.C. Carrillo, S. Alturkistany, H. Roberts, et al (Journal of Computer Assisted Tomography, 2013).

The study

• Authors: M.C. Carrillo, S. Alturkistany, H. Roberts, E. Nguyen, T.B. Chung, N. Paul, S. Herman, G. Weisbrod, D. Patsios
• Journal: Journal of Computer Assisted Tomography
• Published: 2013;37(4):626-30
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To evaluate the lungs of asymptomatic asbestos-exposed workers who were screened for lung cancer and mesothelioma using low-dose computed tomography (LDCT) for parenchymal abnormalities.

Methods: Three hundred fifteen baseline LDCT studies of the chest of participants with at least 20 years' exposure to asbestos or presence of pleural plaques before enrollment on chest radiographs were analyzed.

Results: Three hundred fifteen subjects were studied. The mean age was 61.7 years, and the mean exposure to asbestos was 26.9 years. One hundred seventy-five (56%) participants had absence of parenchymal findings with a mean age of 58.7 years, mean exposure of 24.6 years, and a mean smoking pack years of 19. One hundred forty subjects (44%) had parenchymal findings (138 men and 2 women) with a mean age of 65.3 years, mean exposure of 29.73 years, and a mean smoking pack years of 21.5 years. Participants who had parenchymal manifestations were more likely to be older and have longer exposure to asbestos compared to participants who had no relevant parenchymal findings. There was no statistical difference in the mean smoking pack years between the groups with and without parenchymal findings.

Conclusions: Low-dose CT could demonstrate parenchymal lung manifestations in this higher-risk asymptomatic group with prior exposure to asbestos in the setting of screening for lung cancer and mesothelioma. Individuals with longer exposure to asbestos and of higher age have more pulmonary abnormalities. The age and the latency of exposure play an important role given that the asbestos-related parenchymal abnormalities on LDCT were more prevalent in the elderly participants and with longer periods of exposure.

In plain English

This University of Toronto study reviewed the baseline low-dose CT chest scans of 315 consecutive asbestos workers (311 men, 4 women) in a screening program for early lung cancer and mesothelioma, from March 2005 to August 2006. Participants had asbestos exposure more than 20 years earlier or pleural plaques on a chest X-ray. Fiber types were not reported. Readers, who were blinded to each worker's time of asbestos exposure and smoking history, looked for changes in the lung tissue. Pleural disease and cancer were analyzed separately. Of the 315 workers, 140 (44%) had lung tissue findings related to asbestos exposure and 175 (56%) had no such findings. Those with findings were older on average (65.3 vs 58.8 years) and had longer exposure (29.7 vs 24.6 years). Both differences were statistically significant. Mean smoking pack-years did not differ significantly between the groups. The most common findings were parenchymal bands (70 of 140) and septal thickening (53 of 140). The authors concluded that age and latency of exposure play a role. They noted that no lung function tests were done and that the scans were designed to find nodules, not interstitial lung disease.

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: Analysis of baseline low-dose CT scans from a lung cancer and mesothelioma screening study, comparing participants with and without lung parenchymal findings
• Who was studied: 315 consecutive asymptomatic asbestos workers (311 males, 4 females; mean age 61.7 years, range 39 to 83) in a screening study at the University of Toronto, Canada, March 2005 to August 2006
• Exposure: Occupational asbestos exposure more than 20 years before participation, or pleural plaques on chest radiograph. Mean exposure 26.9 years (range 0 to 58). Fiber types not specified.
• Main results:
  • 140 of 315 participants (44%) had abnormal parenchymal findings on low-dose CT
  • 175 of 315 participants (56%) had no abnormal parenchymal findings related to asbestos exposure
  • Participants with findings were older (mean age 65.3 vs 58.8 years, P less than 0.0001) and had longer asbestos exposure (mean 29.7 vs 24.6 years, P less than 0.0001) than those without findings
  • No statistically significant difference in mean smoking pack-years between groups (21.5 with findings vs 19.1 without; P = 0.44)
  • Among the 140 with findings, parenchymal bands were present in 50% (70/140)
  • Among the 140 with findings, intralobular and interlobular septal thickening was present in 37.9% (53/140)
  • Among the 140 with findings, subpleural ground-glass opacities were present in 33.6% (47/140)
  • Among the 140 with findings, rounded atelectasis was present in 15.7% (22/140)
  • Among the 140 with findings, honeycomb lung and architectural distortion was present in 6.4% (9/140). The discussion gives this as 2.9% of the whole study population.
  • Among the 140 with findings, curvilinear subpleural bands were present in 4.3% (6/140)
• The authors' conclusion: The authors concluded that age and latency of exposure play a role, since asbestos-related parenchymal abnormalities on low-dose CT were more prevalent in older participants and those with longer exposure. They also reported a low rate (2.9%) of a usual interstitial pneumonia pattern of fibrosis in this screening population.
• Limitations the authors state:
  • No pulmonary function tests to correlate with the radiologic findings
  • Not all participants had high-resolution CT or prone-position images to confirm parenchymal abnormalities
  • The imaging protocol was designed to detect nodules, not interstitial lung disease

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Low-Dose CT Screening, Lung Cancer, Mesothelioma, Pleural Plaques, Chest X-Ray, Latency.

Related studies

• Low-dose chest computed tomography screening of subjects exposed to asbestos — K. Kato, K. Gemba, et al. (2018)
• Relationships (I) of International Classification of High-resolution Computed Tomography for Occupational and Environmental Respiratory Diseases with the ILO International Classification of Radiographs of Pneumoconioses for parenchymal abnormalities — T. Tamura, N. Suganuma, et al. (2015)
• Impact of low-dose computed tomography screening on lung cancer mortality among asbestos-exposed workers — F. Barbone, F. Barbiero, et al. (2018)
• Ultra-low-dose chest computer tomography screening of an asbestos-exposed population in Western Australia — F.J. Brims, C.P. Murray, et al. (2015)
• Yield of Low-Dose Computerized Tomography Screening for Lung Cancer in High-Risk Workers: The Case of 7189 US Nuclear Weapons Workers — S.B. Markowitz, A. Manowitz, et al. (2018)
• Is it useful to combine sputum cytology and low-dose spiral computed tomography for early detection of lung cancer in formerly asbestos-exposed power industry workers? — M.K. Felten, L. Knoll, et al. (2014)

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