(C-235) Safety and Effectiveness of Anticoagulation in Cancer Patients with Venous Thromboembolism: A Population-based Cohort Study

Background: Venous thromboembolism (VTE) is a significant complication in cancer patients, driven by malignancy-related hypercoagulability and treatment-induced risks. While novel oral anticoagulants are increasingly used for cancer-associated VTE, critical knowledge gaps persist. Direct comparisons of anticoagulant safety and effectiveness between cancer and non-cancer patients remain limited, leaving clinicians without clear guidance on optimal anticoagulation strategies for this high-risk population.

Objectives: To evaluate the safety and effectiveness of anticoagulant therapy in cancer patients with VTE compared to non-cancer patients.

Methods: This population-based cohort study utilized data from the Taiwan National Health Insurance Database and the Taiwan Cancer Registry. Patients newly diagnosed with VTE between 2016 and 2020 who initiated anticoagulant therapy within 90 days of diagnosis were included. Patients under 40 years of age, those on dialysis, pregnant women, and those who died on the same day as anticoagulant initiation were excluded. The index date was defined as the date of the first anticoagulant prescription. A propensity score matching (PSM) approach was applied to balance baseline characteristics between the cancer and non-cancer groups. The primary outcome was VTE recurrence, while secondary outcomes included intracranial hemorrhage, gastrointestinal bleeding, and major organ bleeding. The Fine–Gray subdistribution hazard model was used to account for competing risks, considering death as a competing event.

Results: A total of 8,147 cancer patients and 19,794 non-cancer patients met the inclusion criteria. After PSM, 7,935 patients remained in each group. The incidence of VTE recurrence was significantly higher in the cancer group than in the non-cancer group (20.26 vs. 6.99 per 100 person-years), with an adjusted subdistribution hazard ratio (aSHR) of 1.85 (95% CI: 1.76–1.94). For secondary outcomes, cancer patients had a 1.31-fold increased risk of gastrointestinal bleeding compared to non-cancer patients (aSHR: 1.31, 95% CI: 1.22–1.41). In contrast, the risk of intracranial hemorrhage was significantly lower in the cancer group (aSHR: 0.71, 95% CI: 0.63–0.80). Sensitivity analyses consistently supported these findings.

Conclusions: Cancer patients face a significantly higher risk of VTE recurrence and gastrointestinal bleeding compared to non-cancer patients. These findings underscore the need for personalized anticoagulation strategies that balance thrombotic risk with bleeding complications in cancer-associated VTE. Our future research will focus on optimizing anticoagulant management to improve outcomes for this high-risk population.