Prevalence of lung cancer in chronic obstructive pulmonary disease: A systematic review

Background There are similar risk factors for the development of chronic obstructive pulmonary disease (COPD) and lung cancer. It is recognized that COPD is common in patients with lung cancer. However, the prevalence of lung cancer in the COPD population remains unclear. We performed a systematic review and meta-analysis to determine the prevalence of lung cancer in COPD. Methods Four databases (MEDLINE, EMBASE, PubMed, CINAHL) examining the prevalence of lung cancer in COPD were searched for studies published between 1997 and 2018. Meta-analysis with a random effects model was used to calculate pooled prevalence for the included studies. A sub-group analysis was performed for studies of similar population and design. Odds ratios were calculated for case-control studies. Results Twenty-one studies that examined the prevalence of lung cancer in a population of 1,682,908 individuals with COPD were included. The pooled prevalence for lung cancer in COPD was 2.79% (95% CI: 1.88–3.88). Results are confounded by significant heterogeneity among studies (Q = 12,622, I2 = 100%), particularly related to the large variation in sample size and study design. Seven studies compared lung cancer prevalence in COPD to controls without COPD with an odds ratio of 6.35 (95% CI: 3.98–10.15). Conclusions Although the prevalence of lung cancer in individuals with COPD is low, it is greater than the prevalence of lung cancer in the general population. Knowledge of the co-occurrence of lung cancer in COPD will inform the screening of lung cancer for patients who have COPD.