Lung function predicts lung cancer.

Recently, we and others have shown that between 50 and 80% of patients diagnosed with lung cancer had pre-existing chronic obstructive pulmonary disease (COPD) [2–4] consistent with the findings of CALABRO et al. [1]. In our series of 446 lung cancer patients, we reported that 60–65% had prebronchodilator Global Initiative for Obstructive Lung Disease (GOLD) 1+ spirometric criteria for COPD [2] consistent with other published studies [3, 4]. This compared with a prevalence of only 15% in a randomly selected population of smokers matched for pack-yrs, sex, ethnicity and smoking exposure [2]. This suggests that the association between COPD and lung cancer is strongly independent of smoking exposure dose. Indeed, the risk of lung cancer conferred by a reduced forced expiratory volume in 1 s (FEV1) has been shown to be greater than that conferred by smoking dose (pack-yrs) [5]. When chest CT scan evidence of emphysema is included in the COPD (spirometric) criteria, the proportion of those with lung cancer showing signs of airway disease (small airways disease and/or emphysema) may even be higher than 80% [3]. Of interest, the study by CALABRO et al. [1] confirmed that even mild reductions in FEV1 (,90% predicted) are associated with lung cancer. In our series of nonscreened lung cancer cases [2], 80% had FEV1 ,90% pred (unpublished data).