Pulmonary Tuberculosis and the Incidence of Lung Cancer among Patients with Chronic Obstructive Pulmonary Disease

Rationale: Although a history of pulmonary tuberculosis (PTB) is a risk factor for developing both chronic obstructive pulmonary disease (COPD) and lung cancer, it remains unclear whether a history of PTB affects lung cancer development in patients with COPD. Objectives: To investigate whether a history of PTB is associated with an increased risk of lung cancer development in a population with COPD. Methods: This cohort study included a nationwide representative sample of 13,165 Korean men and women with COPD, aged between 50 and 84 years. In addition, to assess whether the relationship between PTB and lung cancer risk differs between participants with and without COPD, a matched cohort without COPD was included. Participants were matched 1:3 for age, sex, smoking history, and PTB status based on the index health screening examination of corresponding participants with COPD. The two cohorts were followed up for 13 years (January 1, 2003, to December 31, 2015). PTB was diagnosed on the basis of the results of chest radiography, and incident lung cancer was identified from hospitalization and outpatient visit claims (International Classification of Diseases, Tenth Revision diagnosis code C33 or C34). Results: During 370,617 person-years (PY) of follow-up (median follow-up, 7.7 yr) in the COPD group, we observed 430 incident cases of lung cancer in participants without a history of PTB (incidence rate, 524 per 100,000 PY) and 148 cases in those with a history of PTB (incidence rate, 931 per 100,000 PY). Compared with participants without a PTB history, the fully adjusted subdistribution hazard ratio (95% confidence interval [CI]) for lung cancer in those with a history of PTB was 1.24 (1.03-1.50). The association of PTB history and lung cancer development was more evident in never-smokers with COPD. In contrast, among participants without COPD, the corresponding hazard ratio (95% CI) was 0.98 (0.78-1.22). There was no interaction among PTB, smoking status, and COPD. Conclusions: A history of PTB was associated with an increased risk of developing lung cancer among patients with COPD in our country with an intermediate tuberculosis burden. Patients with COPD with a history of PTB, particularly never-smokers, might benefit from periodic screening or assessment for lung cancer development.