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

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.

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.

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).

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.