There has been limited evidence for the association between chronic obstructive pulmonary disease (COPD) and the incidence of lung cancer among never smokers. We aimed to estimate the risk of lung cancer incidence in never smokers with COPD, and to compare it with the risk associated with smoking. This cohort study involved 338 548 subjects, 40 to 84 years of age with no history of lung cancer at baseline, enrolled in the National Health Insurance Service National Sample Cohort. During 2 355 005 person-years of follow-up (median follow-up 7.0 years), 1834 participants developed lung cancer. Compared with never smokers without COPD, the fully-adjusted hazard ratios (95% CI) for lung cancer in never smokers with COPD, ever smokers without COPD, and ever smokers with COPD were 2.67 (2.09 to 3.40), 1.97 (1.75 to 2.21), and 6.19 (5.04 to 7.61), respectively. In this large national cohort study, COPD was also a strong independent risk factor for lung cancer incidence in never smokers, implying that COPD patients are at high risk of lung cancer, irrespective of smoking status.
- lung cancer
- never smokers
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HYP and DK contributed equally.
JC and OJK contributed equally.
Contributors Author contributions: Conception and design: HYP, DK, EG, JC, OJK. Data analysis: DK, EG, JC. Data interpretation and manuscript writing: HYP, DK, SHS, K-HY, CKR, GYS, HK, YMS, EG, JC, OJK. Revision of the manuscript and contribution to intellectual content: HYP, DK, SHS, KHY, CKR, GYS, HK, YMS, EG, JC, OJK.
Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (no. 2017R1A2B2006435).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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