Risk of Recurrent Venous Thromboembolism and Bleeding in Patients with Cancer Associated Thrombosis

Background: The treatment paradigm for cancer associated thrombosis (CAT) has evolved over recent years from using low molecular weight heparin (LMWH) to direct oral anticoagulants (DOACs). Some randomized trials suggest decreased rates of recurrent venous thromboembolism (VTE) in CAT patients treated with DOACs compared to LMWH but also reported increased rates of bleeding. The Cleveland Clinic Taussig Cancer Center has been treating cancer thrombosis in a centralized CAT clinic since 2014. Here we report our rates of bleeding and recurrent VTE in cancer patients treated with anticoagulation.

Methods: We prospectively followed cancer patients referred to our clinic from 8/2014-10/2019. A total of 1548 patients were referred to the clinic, of whom 462 were diagnosed with an acute VTE. VTE events, including deep venous thrombosis, pulmonary embolism, and visceral thrombosis, were noted. The comparison of bleeding rates (defined using ISTH criteria for major and clinically relevant non major bleeding, CRNMB) among treatment groups (LMWH vs DOACs) was examined using chi-square test. Rate of recurrent VTE was analyzed using a competing model in which death was treated as a competing risk.

Results: The study population comprised 462 patients with acute VTE with a mean age of 62.67±12.23 and 51.8 % males. Of these, 234 (52.9%) received LMWH, 161(36.4%) received DOACs, and 47 (10.6%) received other agents including warfarin for initial anticoagulation. Overall, the 6-month, 1 year, and 2-year VTE recurrence rate was 5.9%, 6.6%, 7.9%, respectively. Recurrent VTE rates were similar for LMWHs, DOACs and other agents (P>0.05). Of 368 patients for whom follow-up data was available, 74 (16.7%) had bleeding event , of which 25 (33.8%) had major bleeding and 49 (66.4%) had CRNMB at 6 month follow-up with no difference across three treatment groups (p=0.56).

Conclusion: In this real-world practice setting, rates of recurrent VTE and bleeding were similar for DOACs and LMWH suggesting that with careful patient selection the concern for higher bleeding with DOACs in cancer patients can be safely overcome.