Interstitial lung diseases in a lung cancer screening trial.

We assessed the prevalence of interstitial lung disease (ILD) in a cohort of smokers included in a lung cancer screening trial. Two observers independently reviewed for the presence of the CT findings consistent with ILD the CT examinations of 692 heavy smokers recruited by the Multicentric Italian Lung Detection (MILD) trial. Four CT patterns were considered: usual interstitial pneumonia (UIP), other chronic interstitial pneumonia (OCIP), respiratory bronchiolitis (RB) and indeterminate. Subsequently, the evolution of ILD in those subjects undergone a repeat CT examination after three years was assessed. The UIP pattern and the OCIP pattern were identified in 2/692 (0.3\%) and 26/692 (3.8\%) patients, respectively; 109/692 (15.7\%) patients showed CT abnormalities consistent with RB, while an indeterminate CT pattern was reported in 21/692 (3\%) subjects Age, male sex and current smoking status were factors associated with the presence of OCIP and UIP (combined) pattern, although such relationship did not attain statistical significance. A progression of the disease was observed in 3/12 (25\%) subjects with OCIP undergone repeat CT after three years. Thin-section CT features of ILD, probably representing smoking-related ILD, are not uncommon in a lung cancer screening population and should not be overlooked.