A retrospective review of recurrent venous thromboembolism in patients with cancer with direct factor Xa inhibitors.
Authors: Fitzgerald Shane , Dean Andrew Peter , Das Adarsh , O'Donnell Iarla , Ibraheem Mark , Farrell Dermot , Robinson Maclain , de Beer Vincent 
Published: July 2024

e24136 Background: Venous thromboembolism (VTE) in cancer patients is a significant cause of morbidity and mortality. People with malignancies are at an increased risk of thrombosis compared to the normal population. Regimens that include platinum-based agents and vascular endothelial growth factor (VEGF) inhibitors have a higher risk of thromboembolism1. The recent ASCO 2023 guidelines for VTE prophylaxis and treatment have advised that direct factor Xa inhibitors are a suitable option for initial and long-term treatment for VTE, given patient preference of oral over subcutaneous administration of anti coagulation2. In our retrospective review of a single centre in Western Australia, we have identified twelve patients who have developed thromboembolic events whilst on direct oral anticoagulation. Methods: Electronic patient records were reviewed for oncology patients attending between 2016 and 2023 at a single centre in Western Australia.Diagnosis of VTE and subsequent treatment was confirmed from radiology and medication records. Twelve patients were identified, and data was recorded and analysed. Results: 12 patients were identified with recurrent VTE whilst on direct factor Xa inhibitors. The median age was 59.5 years (range 50-71). The most common associated malignancies were pancreatic, ovarian and lung cancer. Others include breast, vulval, colon and gastroesophageal cancer. Two thirds of patients were metastatic at diagnosis (n = 8). Common sites of thrombosis include the lower limbs at both initial [n = 6] and recurrent [n = 4] presentation. All patients were treated with therapeutic doses of rivaroxaban (n = 8) or apixaban (n = 4) at the time of of initial or recurrent thrombotic event. Median time to initial thrombotic event was 4.5 months from diagnosis compared to recurrent VTE [5 months]. All patients were changed to either LMWH (n = 10) or unfractionated heparin (n = 2). Ten patients [83.3%] did not have further thrombosis post switching to heparin. One patient had recurrent pulmonary emboli on imaging despite heparin administration, and the other had an IVC filter insertion. Conclusions: VTE is a common complication for oncology patients. Given our results, clinicians should be suspicious for recurrent VTE for patients on direct factor Xa inhibitors. There is an argument for enoxaparin or dalteparin to be better options, particularly in those high risk. Whilst patient preference for an oral option is desirable, further investigation is needed to directly compare the differing direct factor Xa inhibitors and the rates of VTE recurrence. References: Abdol Razak, N. et al. (2018) ‘Cancer-associated thrombosis: An overview of mechanisms, risk factors, and treatment’, Cancers, 10(10), p. 380 Key, N.S. et al. (2023) ‘Venous thromboembolism prophylaxis and treatment in patients with cancer: ASCO guideline update’, Journal of Clinical Oncology, 41(16), pp. 3063–3071.