A 52-year-old female with past medical history of diabetes, hypertension, and stage 4 lung cancer on palliative chemotherapy presents with acute-onset dyspnea, pleuritic chest pain, and cough. Her exam is notable for tachycardia, hypoxemia, and diminished breath sounds. A CT pulmonary embolism study shows new left segmental thrombus. What is her preferred method of anticoagulation?
Brief overview of the issue
Venous thromboembolism (VTE) including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a significant concern in the context of malignancy and is associated with higher rates of mortality at 1 year.
The standard of care in the recent past has relied on low-molecular-weight heparin (LMWH) after several trials showed decreased VTE recurrence in cancer patients, compared with vitamin K antagonist (VKA) treatment.1,2 LMWH has been recommended as a first-line treatment by clinical guidelines for cancer-related VTE given lower drug-drug interactions between LMWH and chemotherapy regimens, as compared with traditional VKAs, and it does not rely on intestinal absorption.3
In more recent years, the focus has shifted to direct oral anticoagulants (DOACs) as potential treatment options for cancer-related VTE given their ease of administration, low side-effect profile, and decreased cost. Until recently, studies have mainly been small and largely retrospective, however, several larger randomized control studies have recently been published.
Overview of the data
Several retrospective trials have investigated the use of DOACs in cancer-associated VTE. One study looking at VTE recurrence rates showed a trend towards lower rates with rivaroxaban, compared with LMWH at 6 months (13% vs. 17%) that was significantly lower at 12 months (16.5 % vs. 22%). Similar results were found when comparing rivaroxaban to warfarin. Major bleeding rates were similar among cohorts.4
Several other retrospective cohort studies looking at treatment of cancer-associated VTE treated with LMWH vs. DOACs found that overall patients treated with DOACs had cancers with lower risk for VTE and had lower burden of metastatic disease. When this was adjusted for, there was no significant difference in the rate of recurrent cancer-associated thrombosis or major bleeding.5,6
Recently several prospective studies have corroborated the noninferiority or slight superiority of DOACs when compared with LMWH in treatment of cancer-associated VTE, while showing similar rates of bleeding. These are summarized as follows: a prospective, open-label, randomized controlled (RCT), noninferiority trial of 1,046 patients with malignancy-related VTE assigned to either LMWH for at least 5 days, followed by oral edoxaban vs. subcutaneous dalteparin for at least 6 months and up to 12 months. Investigators found no significant difference in the rate of recurrent VTE in the edoxaban group (12.8%), as compared to the dalteparin group (13.5%, P = .006 for noninferiority). Risk of major bleeding was not significantly different between the groups.7
A small RCT of 203 patients comparing recurrent VTE rates with rivaroxaban vs. dalteparin found significantly fewer recurrent clots in the rivaroxaban group compared to the dalteparin group (11% vs 4%) with no significant difference in the 6-month cumulative rate of major bleeding, 4% in the dalteparin group and 6% for the rivaroxaban group.8 Preliminary results from the ADAM VTE trial comparing apixaban to dalteparin found significantly fewer recurrent VTE in the apixaban group (3.4% vs. 14.1%) with no significant difference in major bleeding events (0% vs 2.1%).9 The Caravaggio study is a large multinational randomized, controlled, open-label, noninferiority trial looking at apixaban vs. dalteparin with endpoints being 6-month recurrent VTE and bleeding risk that will likely report results soon.
Risk of bleeding is also a major consideration in VTE treatment as studies suggest that patients with metastatic cancer are at sixfold higher risk for anticoagulant-associated bleeding.3 Subgroup analysis of Hokusai VTE cancer study found that major bleeding occurred in 32 of 522 patients given edoxaban and 16 of 524 patients treated with dalteparin. Excess of major bleeding with edoxaban was confined to patients with GI cancer. However, rates of severe major bleeding at presentation were similar.10
Overall, the existing data suggests that DOACs may be a viable option in the treatment of malignancy-associated VTE given its similar efficacy in preventing recurrent VTE without significant increased risk of major bleeding. The 2018 International Society on Thrombosis and Haemostasis VTE in cancer guidelines have been updated to include rivaroxaban and edoxaban for use in patients at low risk of bleeding, but recommend an informed discussion between patients and clinicians in deciding between DOAC and LMWH.11 The Chest VTE guidelines have not been updated since 2016, prior to when the above mentioned DOAC studies were published.