Chronic obstructive pulmonary disease and cancer risk: a Danish nationwide cohort study.

Introduction: Little is known about the risk of cancer in patients with chronic obstructive pulmonary disease (COPD), including which cancer sites are most affected. We examined the short- and long-term risk of lung and extrapulmonary cancer in a nationwide cohort of COPD patients.
Methods: We linked the Danish National Registry of Patients and the nationwide cancer registry, and examined the incidence of various cancers in 236,494 individuals with a first incident hospital contact with COPD during 1980-2008. The observed cancer incidence in this cohort was compared with the expected incidence in the general population on the basis of national age-, sex-, and site-specific incidence rates.
Results: Median follow-up was 3.5 years. During the first year of follow-up, 9434 cancers were diagnosed in COPD patients [standardized incidence ratio (SIR) = 3.1; 95% CI 3.0 to 3.2]. The 1-year SIR was 8.5 (8.2-8.9) for lung cancer, 5.1 (5.0-5.2) for all tobacco-related cancers, and 1.9 (1.9-2.0) for other cancers. In the following years, cancer incidence was increased 1.4-fold (1.4-1.5) in COPD patients. These patients had an increased risk of developing tobacco-related cancers (SIR = 2.1; 95% CI 2.0-2.1), including cancers of the lung, larynx, tongue, oral cavity, pharynx, esophagus, stomach, liver, pancreas, cervix uteri, and urinary tract (with SIRs ranging between 1.3 and 2.8).
Conclusions: Patients with first-time hospital-diagnosed COPD are at considerably increased risk of developing both lung cancer and extrapulmonary cancers. Physicians should be aware of cancer in COPD patients.
(Copyright © 2011 Elsevier Ltd. All rights reserved.)