Variation in Venous Thromboembolism Outcomes Based on Primary Cancer Site: A RIETE Registry Analysis

Patients with cancer-associated venous thromboembolism (VTE) are at increased risk of both recurrent VTE and bleeding. These risks may vary by cancer site, but the magnitude of this variation remains unclear.

The aim of the study was to compare 90-day risks of recurrent VTE or VTE-related death (composite outcome) and major bleeding across different cancer sites.

We analyzed 18,660 patients with active cancer and VTE and 88,162 without cancer in the RIETE (Registro Informatizado de la Enfermedad Tromboembólica) registry. Multivariable Cox models and Fine-Gray competing risk analyses were used. Sensitivity analyses included propensity score matching and subgroup stratification by cancer site.

Within 90 days, 4.0% of cancer-associated thrombosis patients experienced the composite outcome (fatal pulmonary embolism: 1.4%; VTE recurrence: 3.0%), and 3.4% had major bleeding. Compared to noncancer patients, cancer-associated thrombosis patients had higher risks of the composite outcome (adjusted HR [aHR]: 2.54; 95% CI: 2.21 to 2.93) and major bleeding (aHR: 1.40; 95% CI: 1.22-1.61). The highest thrombotic risk was found in lung (aHR: 4.03; 95% CI: 3.38-4.81) and pancreatic cancers (aHR: 3.85; 95% CI: 3.04-4.88), followed by gastrointestinal (aHR: 1.95; 95% CI: 1.53-2.48) and breast (aHR: 1.63; 95% CI: 1.27-2.09) cancers. Major bleeding risk was highest in gastrointestinal (aHR: 1.66; 95% CI: 1.37-2.00), genitourinary (aHR: 1.66; 95% CI: 1.38-2.00), and pancreatic cancers (aHR: 1.43; 95% CI: 1.05-1.95). Results were consistent in the propensity-matched cohort.

VTE and bleeding risks in cancer-associated thrombosis vary substantially by cancer site. These findings support a personalized approach to anticoagulation in cancer patients with VTE.