590: Anticoagulation Post-Ivc Thrombectomy in Renal Cell Carcinoma With Tumor Thrombus

Introduction: Tumor thrombus (TT) can manifest in different cancers but is most common in renal cell carcinoma (RCC). Tumor burden can extend to the inferior vena cava (IVC) and is thought to disrupt vascular integrity, increasing the risk of a venous thromboembolism (VTE). It remains unknown whether anticoagulation improves survival in these patients. The amount of literature comparing the safety and efficacy of different anticoagulants is sparse. Our objective was to evaluate the bleeding and clotting rates in patients with RCC-associated TT status post IVC thrombectomy and assess the impact of anticoagulation on these rates. Methods: We reviewed the charts of adult patients that were diagnosed with RCC, presented with TT and underwent IVC thrombectomy from 2014 to 2023. Our primary outcome was to evaluate the rate of VTE events in patients with RCC-associated TT post IVC thrombectomy in those that are on therapeutic anticoagulation compared to those that are not. Secondary outcomes included mortality, arterial thromboembolisms, and a composite of clinically relevant non-major and major bleeds. The 12-month cumulative incidences of VTE, ATE, all thrombosis, major bleeding, minor bleeding, all bleeding events, and mortality were calculated, considering all outcomes as competing risks. Cox proportional hazard models were used to calculate hazard ratios (HR) with 95% CIs for outcomes with a univariable analysis, followed by a multivariable analysis adjusted for age, sex, tumor grade, and anticoagulation use. Results: Statistical analysis did not indicate a significant association between therapeutic anticoagulation and VTE event rate. Adjusted HR for VTE in our therapeutically anticoagulated group was 0.8 (95% CI: 0.3 - 2.5). aHR for major bleeding in the therapeutically anticoagulated group was 3.9 (95% CI: 1.1 - 13.4), while aHR for minor bleeding was 4.4 (95% CI: 1.1 - 17), and aHR for all bleeding was 3.8 (95% CI: 1.6 - 9.2). Conclusions: This study found no definitive evidence that anticoagulation therapy improves thrombosis outcomes in TT patients and found that the use of therapeutic anticoagulation in these patients increases bleeding risk. An increased VTE risk might justify therapeutic anticoagulation in selected patients, but this risk should be weighed against potential bleeding risk.