Low molecular weight heparin versus rivaroxaban in the treatment of venous thromboembolism in gastrointestinal malignancies.

: Due to their ease of use, the direct oral anticoagulants (DOACs) are an attractive treatment option for cancer-associated venous thromboembolism (VTE) and have been readily adopted by many clinicians. A recent published study comparing a DOAC (edoxaban) to the current standard-of-care low molecular weight heparin dalteparin for the treatment of cancer-associated thrombosis showed that edoxaban was noninferior to dalteparin for recurrent VTE, but the risk of major bleeding was higher. We present three patients with high-risk gastrointestinal malignancies complicated by cancer-associated VTE with progression of thrombosis while treated with the oral direct Xa inhibitor rivaroxaban. Upon switching therapy to low molecular weight heparin, we found that these patients had clinical and radiologic improvement of VTE. More studies are needed to evaluate the efficacy of rivaroxaban in high-risk gastrointestinal-VTE. We suggest that in some patients, DOACs may not be sufficient for the treatment of VTEs related to high-risk gastrointestinal malignancies.