Low-dose chest computed tomography screening of subjects exposed to asbestos

Abstract

Objectives: The primary aim was to reveal the prevalence of lung cancer (LC) and malignant pleural mesothelioma (MPM) in subjects with past asbestos exposure (AE). We also examined pulmonary or pleural changes correlated with the development of LC.

Materials and methods: This was a prospective, multicenter, cross-sectional study. There were 2132 subjects enrolled between 2010 and 2012. They included 96.2% men and 3.8% women, with a mean age of 76.1 years; 78.8% former or current smokers; and 21.2% never smokers. We screened subjects using low-dose computed tomography (CT). The CT images were taken with a CT dose Index of 2.7 mGy. The evaluated CT findings included subpleural curvilinear shadow/subpleural dots, ground glass opacity or interlobular reticular opacity, traction bronchiectasia, honeycombing change, parenchymal band, emphysema changes, pleural effusion, diffuse pleural thickening, rounded atelectasis, pleural plaques (PQs), and tumor formation.

Results: The PQs were detected in most of subjects (89.4%) and emphysema changes were seen in 46.0%. Fibrotic changes were detected in 565 cases (26.5%). A pathological diagnosis of LC was confirmed in 45 cases (2.1%) and MPM was confirmed in 7 cases (0.3%). The prevalence of LC was 2.5% in patients with a smoking history, which was significantly higher than that in never smokers (0.7%, p = 0.027). The prevalence of LC was 2.8% in subjects with emphysema changes, which was higher than that of subjects without those findings (1.6%); although, the difference was not statistically significant (p = 0.056). The prevalence of LC in subjects with both fibrotic plus emphysema changes was 4.0%, which was significantly higher than that of subjects with neither of those findings (1.8%, p = 0.011). Logistic regression analysis revealed smoking history, fibrotic plus emphysema changes, and pleural effusion as significant explanatory variables.

Conclusions: Smoking history, fibrotic plus emphysema changes, and pleural effusion were correlated with the prevalence of LC.

Keywords: Asbestos; Low-dose CT; Lung cancer; Mesothelioma; Screening.