Incidence and clinical characteristics of lung cancer in patients with COPD - From Hokkaido COPD cohort study

Introduction: COPD is known to be associated with increased risk of lung cancer; however, it is unclear how patients with COPD should be followed up to detect the development of lung cancer. Aim: To investigate incidence and clinical characteristics of lung cancer in patients with COPD, using data from a 10-year prospective observational cohort study. Methods: A total of 279 subjects with COPD (GOLD 1, 26%; GOLD 2, 45%; GOLD 3, 24%; GOLD 4, 5%) participated in the Hokkaido COPD cohort study. Chest CT scans were taken every year during the first 5 years for all subjects and for another 5 years for those who agreed. Results: 39 subjects (14%) were newly diagnosed with primary lung cancer (stage I, 48%; stage II, 6%; stage III, 26%; stage IV, 19%) during 10 years (incidence density of 17.0 cases per 1,000 person-years). Median time to diagnosis was 3.3 years (IQR 2.8-5.7 years) and the highest annual incidence rate was observed during the 4th year (4.4%). In 23 subjects (59%), scheduled annual CT scans of the cohort study were clues to the diagnosis, and their clinical stages of lung cancer were significantly earlier than others (p Conclusion: 14% of subjects with COPD developed lung cancer during 10 years and the degree of emphysema was associated with time to its diagnosis. Regular check-up by CT scans may be useful for early detection of lung cancer, especially for those with apparent emphysema.