Risk of Cancer After a Hospital Contact for Dyspnea: A Nationwide Danish Cohort Study.

Purpose: Dyspnea may be a symptom of undiagnosed cancer, but this association remains poorly understood. We examined cancer incidence among patients with a hospital contact for dyspnea compared with the general population. Patients and Methods: Using nationwide Danish registries, we identified all patients with a hospital contact for dyspnea during 1994-2022 and followed them until a cancer diagnosis, emigration, death, or December 31, 2022. We computed cumulative cancer incidence treating death as a competing event, and standardized incidence ratios (SIR) with 95% confidence intervals (CIs), as the observed number of cancers relative to the expected number based on national cancer incidence rates. Results: Among 266,044 patients with dyspnea, 27,884 subsequent cancers were observed. The 1-year cumulative incidence of any cancer was 3.8%, rising to 12.7% at 10 years. At one year, cumulative incidence was highest for lung (1.4%), gastrointestinal (0.6%), hematological (0.5%), and prostate (0.5%) cancers. The 1-year SIR for any cancer was 3.17 (95% CI, 3.11-3.23), elevated across all cancer types, and highest for pleural (17.57; 95% CI, 15.32-20.05), lung (9.34; 95% CI, 9.05-9.64), and hematological (4.17; 95% CI, 3.94-4.41) cancers. Beyond one year, cancer incidence remained elevated (SIR, 1.14; 95% CI, 1.12-1.16), particularly for lung cancer (SIR, 1.56; 95% CI, 1.50-1.61). Conclusion: Patients with a hospital contact for dyspnea had a markedly higher incidence of thoracic and non-thoracic cancers than the general population, particularly during the first year of follow-up. These findings support consideration of an underlying cancer across organ systems as part of the diagnostic evaluation of patients presenting with dyspnea.