Evaluating lung cancer risk factors in adults with interstitial lung disease

Adults with interstitial lung disease (ILD) have a higher risk of developing lung cancer compared to the general population. We aimed to identify ILD-specific risk factors that can be used to improve lung cancer detection in this high-risk population.

Adults ≥21 years who received at least two chest CT scans at an academic medical center between 2005 and 2020 and were found to have ILD were studied retrospectively. Lung cancer diagnoses were adjudicated based on pathology reports from lung biopsies. Logistic regression was used to evaluate associations of clinical variables with comorbid lung cancer.

Among 1,366 adults with ILD, the mean age was 67.2 ± 12.4 years and 639 (46.8 %) were men. In total, 227 adults (16.6 %) had a lung nodule on CT imaging, of whom 55 (24.3 %) were diagnosed with lung cancer. Radiographic usual interstitial pneumonia (UIP) (OR 3.00, 95 % CI 1.43-6.33) was independently associated with increased odds of lung cancer. Risk factors including age, sex, smoking status, pack-years, use of immunosuppression, and radiographic fibrosis pattern collectively demonstrated high discriminative accuracy in predicting comorbid lung cancer, even among adults who would not have qualified for lung cancer screening based on current guidelines (AUC 0.80, 95 % CI 0.72-0.88).

In a large study of adults with ILD, radiographic UIP was independently associated with comorbid lung cancer even after adjusting for established risk factors. Our results suggest radiographic UIP is an independent lung cancer risk factor and support the development of targeted lung cancer screening guidelines in adults with UIP.