RT Journal Article SR Electronic T1 COPD prevalence is increased in lung cancer, independent of age, sex and smoking history JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 380 OP 386 DO 10.1183/09031936.00144208 VO 34 IS 2 A1 R. P. Young A1 R. J. Hopkins A1 T. Christmas A1 P. N. Black A1 P. Metcalf A1 G. D. Gamble YR 2009 UL http://erj.ersjournals.com/content/34/2/380.abstract AB Chronic obstructive pulmonary disease (COPD) is a common comorbid disease in lung cancer, estimated to affect 40–70% of lung cancer patients, depending on diagnostic criteria. As smoking exposure is found in 85–90% of those diagnosed with either COPD or lung cancer, coexisting disease could merely reflect a shared smoking exposure. Potential confounding by age, sex and pack-yr smoking history, and/or by the possible effects of lung cancer on spirometry, may result in over-diagnosis of COPD prevalence. In the present study, the prevalence of COPD (pre-bronchodilator Global Initiative for Chronic Obstructive Lung Disease 2+ criteria) in patients diagnosed with lung cancer was 50% compared with 8% in a randomly recruited community control group, matched for age, sex and pack-yr smoking exposure (n = 602, odds ratio 11.6; p<0.0001). In a subgroup analysis of those with lung cancer and lung function measured prior to the diagnosis of lung cancer (n = 127), we found a nonsignificant increase in COPD prevalence following diagnosis (56–61%; p = 0.45). After controlling for important variables, the prevalence of COPD in newly diagnosed lung cancer cases was six-fold greater than in matched smokers; this is much greater than previously reported. We conclude that COPD is both a common and important independent risk factor for lung cancer.