Cancer-associated thrombosis: Where do we stand?

Venous thromboembolism (VTE) is a major cause of morbidity and mortality in cancer patients. Cancer patients have a four to sevenfold increased risk of VTE compared with non-cancer patients and approximately 20%-30% of all VTE occurs in patients with cancer. Numerous clinical and biologic risk factors predispose cancer patients to VTE, including cancer-directed treatments, tumor site of origin, and circulating mediators produced by tumor cells. Along with clinical risk factors, measurable markers of increased risk such as elevations of the platelet or leukocyte counts, soluble P-selectin, and D-dimer have been integrated to develop numerous risk stratification scores to predict those patients at high risk for cancer-associated VTE. Utilizing risk stratification models, recent studies have examined the use of direct oral anticoagulants (DOACs) for primary thromboprophylaxis of VTE, with promising results. Treatment of cancer-associated VTE is currently evolving. The long-accepted standard of care, low molecular weight heparin (LMWH), is currently being compared with the DOACs in clinical trials. Trials to date using edoxaban and rivaroxaban have found that DOACs are non-inferior to LMWH for the secondary prevention of cancer-associated VTE but may result in an increased rate of bleeding, especially in certain patient groups. Additional studies are ongoing and will be necessary to further define optimal VTE treatment for many cancer patient subpopulations.