Cancer development in COPD patients: retrospective analysis of the National Health Insurance Service-National Sample Cohort in Korea

Abstract Background COPD is a well-known risk factor for lung cancer, independent of smoking behavior. By investigating the retrospective National Health Insurance Service-National Sample Cohort (NHIS-NSC) in Korea, this study attempted to prove our hypothesis that COPD is a risk factor for major cancers developing outside of the lungs. We also aimed to investigate the environmental factors associated with the development of lung cancer in COPD patients. Methods This study analyzed data from the NHIS-NSC over a 12-year period. Among the 514,795 subjects in the NHIS-NSC, 20,837 patients who were diagnosed with any cancer from 2002 to 2003 were excluded. Finally, this cohort enrolled four arms, the healthy control group (N=127,884), never-smokers with COPD (N=29,799), former smokers with COPD (N=3,267), and smokers with COPD (N=8,335). Results Over a 12-year period, lung cancer developed in 1.27% of the never-smokers with COPD, 2.97% of the former smokers with COPD, and 4.79% of smokers with COPD much higher than in 0.63% of the healthy control group (p < 0.001). Multivariate analyses showed that COPD, regardless of smoking status, contributed to the development of lung cancer but was not linked with any other major cancers, including stomach cancer, colorectal cancer, liver cancer and acute myeloid leukemia (p < 0.01). Age, male gender, lower BMI, low exercise level, smoking, and COPD were independent factors associated with the development of lung cancer (p< 0.01) Conclusion Our data suggest that COPD was an independent risk factor for the development of lung cancer in the Korean population, regardless of smoking status but other major cancers were not linked with COPD.