COPD prevalence in lung cancer patients – Is COPD a risk factor for lung cancer?

Background and aim: Chronic obstructive pulmonary disease (COPD) is a common comorbid disease in lung cancer, estimated to affect 40–70% of lung cancer patients. As smoking exposure is found in 85–90% of those diagnosed with either COPD or lung cancer, coexisting disease could reflect a shared smoking exposure. We aimed to investigate the prevalence of COPD in patients diagnosed with lung cancer. Methods: We analysed 1173 patients diagnosed with lung cancer in Internal Medicine Department between 2000 and 2010 for the presence of lung cancer risk factors. Results: A number of 1046 patients (89.17%; p<0.0001) were former smokers/actively smoking. Preexisting disease was diagnosed in a number of 442 cases (37.68%): COPD in 257 cases, and other etiologic factors in 185 cases (58.14% versus 41.85%; p<0.0001). Histopathological results were avaible in 131 cases and showed: scuamos carcinoma (n=78; 59.54%), adenocarcinoma (n=24; 18.32%), large cell undifferentiated carcinoma (n=11; 8.39%), and small cell carcinoma (n=18; 13.74%). Smokers versus non-smokers and COPD prevalence according to histopathologic types were the following: 71 versus 7 (p<0.0001), and 14 cases of COPD (17.94%) for scuamos carcinoma; 15 versus 9 (p=0.1482), and 2 cases of COPD (13.33%) for adenocarcinoma; 8 versus 3 (p=0.0861), and 1 case of COPD (9.09%) for large cell undifferentiated carcinoma; and 14 versus 4 (p=0.0022), and 3 cases of COPD (16.66%) for small cell carcinoma. Conclusions: Our study showes a high prevalence of COPD in lung cancer patients. COPD was the second most important risk factor for lung cancer, after smoking. The most important relationship of COPD was with the scuamos type lung cancer.