The impact of previous pulmonary tuberculosis on lung cancer development in never smoker with COPD

<b>Background:</b> Chronic obstructive pulmonary disease (COPD) is associated with increased lung cancer incidence irrespective of smoking status. While previous pulmonary tuberculosis (PTB) is risk factor of developing both COPD and lung cancer, it remains unclear whether previous PTB affects lung cancer development in COPD patients. Thus, we aimed to impact of PTB on lung cancer development in COPD patients differently based on smoking status. <b>Methods:</b> This is a cohort study of nationally representative sample followed for up to 13 years (January 1, 2002 to December 31, 2015). A total of 14,948 men and women with COPD, 40 to 84 years of age with no history of lung cancer at baseline and having at least one health screening examination with chest radiograph and questionnaires for smoking status were included. The study endpoint was lung cancer incidence and the study exposure was previous PTB on chest radiograph according to smoking status. <b>Results:</b> During 111,972 person-years (PY) of follow-up (median follow-up 7.3 years), we observed 440 incident cases of lung cancer in COPD subjects without previous PTB (incidence rate 466 per 100,000 PY) and 149 cases in COPD subjects with previous PTB (incidence rate 852 per 100,000 PY). Compared to COPD subjects without previous PTB, the fully-adjusted hazard ratios (95% CI) for lung cancer in those with previous PTB was 1.40 (1.03, 1.90) among never smokers. However, there was no significant differences between non-PTB and PTB among COPD with smoking history. <b>Conclusion:</b> In this large national cohort study, previous PTB was associated with lung cancer development in COPD patients, which was evident in never smokers.