Background: Patients with chronic obstructive pulmonary disease (COPD) are liable to develop significant comorbidities, including lung cancer. Whether they are at a higher risk for cancer of other types remains debatable, especially for Asians. We studied the risk of incident cancer in COPD patients using a nationwide representative database, the Taiwan National Health Insurance Research Database.
Methods: From 1995 to 2008, 50,875 COPD patients who were free of antecedent malignancy were identified and followed up to development of malignancy, death or end of 2008, whichever came first. The risk of cancer was determined with the standardized incidence ratio (SIR), which is based on comparison to the national cancer incidence among the general population.
Results: During a median follow-up period of 5.61 years, 3623 (7.02 %) patients developed cancer and the SIR was 1.2 [95 % confidence interval (CI) 1.16-1.24, p < 0.001]. The risk remained higher at <1, 1-5, and even ≥5 years after the diagnosis of COPD (SIR 1.83, 1.07, and 1.11, respectively). Furthermore, the risk was significantly higher for some specific types of cancer, including head and neck cancer (SIR 1.23, 95 % CI 1.08-1.39, p = 0.002), esophageal cancer (SIR 1.35, 95 % CI 1.08-1.67, p = 0.010), lung and mediastinal cancer (SIR 1.86, 95 % CI 1.74-1.99, p < 0.001), breast cancer (SIR 1.19, 95 % CI 1.01-1.4, p = 0.041), prostate cancer (SIR 1.20, 95 % CI 1.06-1.35, p < 0.001), cancer of the central nervous system (SIR 1.58, 95 % CI 1.05-2.28, p = 0.030), lymphoma (SIR 1.53, 95 % CI 1.22-1.90, p < 0.001), and multiple myeloma (SIR 1.95, 95 % CI 1.31-2.80, p = 0.001).
Conclusion: COPD patients had increased risk for incident cancers, including lung cancer and several extrapulmonary cancers.
Keywords: Chronic obstructive pulmonary disease; Extrapulmonary cancer; Incident cancer; Lung cancer.