A study published in Thorax found that patients with chronic obstructive pulmonary disease (COPD) who have never smoked have a higher risk of lung cancer than smokers without COPD. Specifically, never smokers with COPD had more than 2.6 times the incidence of lung cancer compared with never smokers without COPD.
The observational cohort study included 338,548 Korean citizens aged 40 to 84 years with no history of lung cancer at baseline who were enrolled in the National Health Insurance Service National Sample Cohort who had at least one health check between 2002 and 2013.
Greater incidence of lung cancer among never smokers with COPD
During a median follow-up of seven years, 1,834 patients developed lung cancer (primary endpoint), with incidence rates of 4.9 per 1,000 person-years among patients with COPD and 0.7 per 1,000 person-years among those who did not have COPD. Compared with participants without COPD, those with COPD were older, more likely to be male, were smokers, and had a lower income and more comorbidities
The risk of disease in never smokers with COPD was higher than that in ever smokers without COPD, and patients with COPD who had never smoked had more than double the risk of developing lung cancer than those without COPD who had never smoked. Compared with never smokers without COPD, fully adjusted hazard ratios for lung cancer were 2.67 (95% CI, 2.09-3.40) in never smokers with COPD, 1.97 (95% CI, 1.75-2.21) in ever smokers without COPD, and 6.19 (95% CI, 5.04-7.61) in ever smokers with COPD.
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,” the authors concluded.
The study is limited because it did not include data on COPD severity and its impact on lung cancer risk.