Interstitial lung diseases in a lung cancer screening trial

Purpose: To determine the prevalence and the evolution of interstitial lung disease (ILD) in a population of smokers included in a lung cancer screening trial. Methods and Materials: Two observers, blinded to any information, independently reviewed for the presence of ILD the low-dose thin-section CT scans of 692 consecutive heavy smokers (age ≥ 49 yrs, with ≥ 20 pack-years of smoking history) recruited by the Multicentric Italian Lung Detection (MILD) trial. The observers recorded the CT abnormalities and assigned a CT diagnosis of the disease. Subsequently, the observers evaluated the evolution of the abnormalities in the available CT scans obtained after three years. Results: In 158 out of 692 (22.8%) cases were recorded the presence of CT abnormalities consistent with ILD. In these cases, the CT diagnoses were respiratory bronchiolitis (RB)-like (109/692, 15.7%), nonspecific interstitial pneumonia (NSIP)-like (26/692, 3.8%), usual interstitial pneumonia (UIP)-like (2/698, 0.3%), and indeterminate (21/698, 3%). After three years, 40/44 (90.1%), 2/44 (4.5%), 2/44 (4.5%) RB-like cases and 9/14 (64.3%), 3/14 (21.4%), 2/14 (14.3%) NSIPlike cases showed no changes, an increase and a decrease in the extent of the abnormalities, respectively. Among the indeterminate CT diagnoses, the abnormalities remained stable, resolved and increased in 8/14 (57.2%), 4/14 (28.5%), 2/14 (14.3%) cases at follow‑up. Conclusion: Thin-section CT features of ILD, probably representing smokingrelated ILD, are not uncommon in a lung cancer screening population and should not be overlooked.