Of note, apixaban, rivaroxaban, and LMWH have not received approval from the US Food and Drug Administration (FDA) for thromboprophylaxis in patients with cancer treated in the outpatient setting, making the use of these agents off label.

Another recommendation concerns patients undergoing perioperative VTE prophylaxis for surgery. According to the guidelines, all patients with cancer undergoing a major surgical intervention should be offered pharmacologic thromboprophylaxis with either unfractionated heparin (UFH) or LMWH unless there is contraindication such as active bleeding, a high risk of bleeding, or other issues. In eligible patients, prophylaxis should be initiated prior to surgery. Mechanical methods may be added to pharmacologic thromboprophylaxis but should not be used as monotherapy for VTE prevention unless pharmacologic methods are contraindicated because of active bleeding or high bleeding risk).

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For patients with cancer who have already experienced a VTE, the guidelines recommend initial anticoagulation treatment with LMWH, UFH, fondaparinux, or rivaroxaban. LMWH is the preferred choice for initiation of treatment with parenteral anticoagulation compared with UFH for the initial 5 to 10 days of treatment in patients with newly diagnosed VTE who do not have severe renal impairment (defined as creatinine clearance < 30 mL/min). For long-term anticoagulation in this setting, the preferred agent is LMWH, edoxaban, or rivaroxaban for a duration of at least 6 months, as these agents have demonstrated superior efficacy compared with vitamin K antagonists (VKAs). Although VKAs are inferior, they may be used if LMWH or DOACs are not readily available. The guidelines caution that there is an elevated risk for major bleeding risk with DOACs, and this has been observed in particular in patients with gastrointestinal cancers and possibly genitourinary cancers.

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However, ASCO does not recommend using anticoagulants in the absence of established VTE as a means of improving survival.

The final recommendation focuses on patient knowledge and education about VTEs. There is substantial variation in VTE risk among individual patients with cancer and within various treatment settings. All patients with cancer should be initially evaluated for VTE risk and then assessed periodically afterwards, particularly when beginning any systemic therapy or at the time of hospitalization. Individual risk factors, including biomarkers or cancer site, are not completely reliable in identifying patients who are at the highest risk, and in the ambulatory setting, patients with solid tumors can be assessed with a validated risk assessment tool.


1.     Key NS, Khorana AA, Kuderer NM, et al. Venous thromboembolism prophylaxis and treatment in patients with cancer: ASCO clinical practice guideline update [published online August 5, 2019]. J Clin Oncol. doi:10.1200/jco.19.01461