Additional advantages of CT scanning are that it can help differentiate between structural abnormalities that cause airflow limitation (e.g. emphysema, bronchiolitis and bronchiectasis), identify abnormalities that are associated with clinically significant features (i.e. phenotypes), and detect both pulmonary comorbidities (e.g. lung cancer, interstitial lung disease and pulmonary hypertension) and nonpulmonary comorbidities (e.g. coronary artery calcifications, heart failure and diseases of the mediastinum) [23]. The risk of lung cancer is increased among patients with COPD, but it is inversely related to the degree of airflow obstruction [24]. The presence of airflow obstruction should raise awareness of the risk for lung cancer; indeed, patients with COPD are considered good candidates to be screened for lung cancer, especially if they have radiological emphysema or a low diffusion capacity for carbon monoxide (DLCO) [24].