ARTICLE
COPD prevalence is increased in lung cancer independent of age, gender and smoking history.
Eur Respir J. 2009 Feb 5. Young RP, Hopkins RJ, Christmas T, Black PN, Metcalf P, Gamble GD. University of Auckland, New Zealand.
Chronic obstructive pulmonary disease (COPD) is a common co-morbid disease in lung cancer, estimated to affect between 40-70% depending on diagnostic criteria. As smoking exposure is found in 85-90% of those diagnosed with either COPD or lung cancer, co-existing disease could merely reflect a shared smoking exposure.
Potential confounding by age, gender and pack year history and/or the possible effects of lung cancer on spirometry, may result in "over-diagnosis" of COPD prevalence. In this study the prevalence of COPD (pre-bronchodilator GOLD 2+ criteria) in patients diagnosed with lung cancer was 50% compared to 8% in a randomly recruited community control group, matched for age, gender, and pack year exposure (n=602, OR=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 non-significant increase in COPD prevalence following diagnosis (56% to 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 and this is much greater than previously reported. We conclude that COPD is both a common and important independent risk factor for lung cancer.
