Venous Thrombo-embolism Prophylaxis in the Outpatient Oncology Setting
Further investigation of VTE and data collection on this topic is warranted.
Patients with cancer who are admitted into the hospital are frequently placed on venous thromboembolism (VTE) prophylaxis. These patients are up to seven times more likely to develop a VTE, which significantly increases mortality.1
VTE is the second most common cause of death in patients with cancer and has consequently become an increasingly scrutinized inpatient diagnosis with respect to patient therapeutic and safety outcomes as well as financial reimbursement.1,2 Therefore, inpatient VTE prophylaxis has become a main priority when admitting patients with cancer.
Patients are typically started on pharmacologic agents such as enoxaparin, fondaparinux, and unfractionated heparin. Choice of pharmacologic VTE prophylaxis can be somewhat complicated and is typically based on a multitude of factors including (but not limited to) clinician preference, degree of liver or renal dysfunction, recent surgeries, risk of or history of bleeding (gastrointestinal, intracranial, etc), degree of thrombocytopenia, allergy history, and cost.
When patients are discharged home, whether or not to include pharmacologic VTE prophylaxis is a less frequently discussed and often challenging topic. Many patients are relatively immobile at home making the pathophysiology behind the increased risk of VTE still present. In order to help aid patients and clinicians with this decision, the Khorana score was developed.3
The Khorana score evaluates a patient's VTE risk based on the site of the primary tumor, hemoglobin levels, prechemotherapy white blood cells and platelet counts and body mass index. Based on their Khorana score, patients are stratified into low- (score of 0), intermediate- (score of 1 to 2), and high-risk (score of 3 or more) groups. At 2.5 months, VTE risk is approximately 0.3% in the low-, 2% in the intermediate-, and 6.7% in the high-risk groups.3
Although scales such as the Khorana score are available, many clinicians do not frequently use them and typically do not recommend using pharmacologic VTE in the outpatient setting.
The data behind this common recommendation is based on several clinical trials including the Prophylaxis of Thromboembolism during Chemotherapy (PROTECHT) trial and the Semuloparin in the Prevention of Venous Thromboembolism in Cancer Patients Undergoing Chemotherapy (SAVE-ONCO) trial which both showed a less than 2% absolute risk reduction in VTE.4 In addition to PROTECHT and SAVE-ONCO, most other clinical trials have shown less than a 5% absolute risk reduction in symptomatic VTE.4
Current guidelines from major societies such as the National Comprehensive Cancer Network (NCCN), American Society of Clinical Oncology (ASCO), and American College of Chest Physicians (ACCP) all recommend against the routine use of VTE prophylaxis in outpatient patients with cancer with the exception of certain clinical scenarios.1
The scenarios that warrant a more detailed consideration for outpatient VTE prophylaxis include patients with multiple myeloma receiving thalidomide or lenalidomide with chemotherapy or dexamethasone, primary cancers with high risk of VTE (pancreatic, gastric, lung) and a high Khorana score, as well as patients with other malignancies and high-risk Khorana scores.1,4
An interesting area of future research may be the use of the novel oral anticoagulants (NOACs) including direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban, apixiban) to prevent VTE in outpatient patients with cancer. There is currently a lack of data comparing these medications with agents such as enoxaparin and heparin; however, future studies may help further characterize their role, if any, in such a commonly encountered clinical scenario.
As with most medical decisions encountered during the care of patients with cancer, the decision to use outpatient pharmacologic VTE prophylaxis is multifactorial and still accumulating clinical data. It is one of many important discussions to be considered between a patient and clinician upon discharge from the hospital.
- Connors JM. Prophylaxis against venous thromboembolism in ambulatory patients with cancer. N Engl J Med. 2014;370(26):2515-2519.
- Khorana AA, Francis CW, Culakova E, et al. Thromboembolism is a leading cause of death in cancer patients receiving outpatient chemotherapy. J Thromb Haemost. 2007;5(3):632-634.
- Khorana AA, Kuderer NM, Culakova E, et al. Development and validation of a predictive model for chemotherapy-associated thrombosis. Blood. 2008;111(10):4902-4907.
- Lyman GH, Khorana AA, Kuderer NM, et al. Venous thromboembolism prophylaxis and treatment in patients with cancer: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol. 2013;31(17):2189-2204.