Association Between Chronic Obstructive Pulmonary Disease and Survival in Patients with Lung Cancer: A Nationwide Cohort Study.

Purpose: Chronic obstructive pulmonary disease (COPD) frequently co-occurs with lung cancer and may adversely influence survival through reduced respiratory reserve, systemic inflammation, immune dysregulation, and impaired treatment tolerance. However, its independent prognostic impact in large real-world lung cancer populations remains uncertain. This nationwide cohort study examined the association between pre-existing COPD and four-year all-cause mortality among patients with newly diagnosed lung cancer. Methods: We conducted a nationwide retrospective cohort study using linked data from Taiwan's National Health Insurance Research Database, Cancer Registry, and Death Registry. Adults newly diagnosed with lung cancer between 2011 and 2019 were included and followed until death or the end of 2023. COPD was defined using diagnostic codes recorded before or at cancer diagnosis. Propensity score matching at a 1:3 ratio was used to balance baseline characteristics. Survival was assessed using Kaplan-Meier methods and Cox proportional hazards models. Results: The matched cohort included 34,832 patients, including 8,708 with COPD and 26,124 without COPD. Four-year survival was lower among patients with COPD than among those without COPD, 31.6% versus 36.8%, respectively; log-rank Conclusion: Using nationwide linked claims, cancer registry, and mortality data, this study provides population-level evidence that pre-existing COPD is an independent host-related prognostic factor for poorer four-year survival among patients with newly diagnosed lung cancer. Integrating COPD identification, pulmonary optimization, and multidisciplinary pulmonary-oncology care into routine lung cancer management may support risk stratification and improve long-term outcomes.