From the Guidelines

Venous Thromboembolism (VTE) prophylaxis in outpatients is not routinely recommended, except in highly selected cases.

No routine pharmacologic thromboprophylaxis is recommended for cancer outpatients, according to the American Society of Clinical Oncology (ASCO) guidelines 1.
Highly selected outpatients with solid tumors receiving chemotherapy may be considered for Low Molecular Weight Heparin (LMWH) prophylaxis on a case-by-case basis, with a discussion about the uncertainty of benefits and harms 1.
Patients with multiple myeloma receiving thalidomide- or lenalidomide-based regimens with chemotherapy and/or dexamethasone should receive pharmacologic thromboprophylaxis with either aspirin or LMWH 1.
The National Comprehensive Cancer Network (NCCN) guidelines suggest that outpatients at high risk for VTE, based on the Khorana risk assessment score, could be considered for VTE prophylaxis on an individual basis 1.

Risk assessment is crucial in determining the need for VTE prophylaxis in outpatients, with the Khorana risk assessment score being a useful tool 1.
Individualized discussion with patients about the potential risks and benefits of VTE prophylaxis is essential, particularly in cases where the benefits are uncertain 1.
Clinical trials are needed to further evaluate the efficacy of risk-adjusted thromboprophylaxis in outpatients with cancer 1.

From the Research

The majority of fatal cases of pulmonary embolism in hospitalized patients occur in acutely ill, medically treated patients, and current guidelines recommend using VTE prophylaxis in this population 2.
However, there are no clinical trials evaluating VTE prophylaxis for medical outpatients that have been published, making it challenging to establish guidelines for this specific group 2.
Identification of patients at risk of developing VTE enables appropriate thromboprophylaxis to be implemented, and clinical trials have demonstrated the effectiveness of thromboprophylaxis in various medical settings 3.
Guidelines recommend VTE risk assessment in outpatients with cancer and pharmacologic thromboprophylaxis in selected patients at high risk for VTE, with the use of validated risk stratification tools such as the Khorana and Protecht scores 4.

The implementation of decision-making tools based on risk factor assessment improves the prescription of appropriate VTE prophylaxis 3.
Patients should undergo thrombosis- and bleeding-risk assessment as part of their preoperative evaluation, using validated risk-assessment models such as the Caprini score 5.
Patients at high risk of VTE should receive pharmacologic thromboprophylaxis, either alone or combined with mechanical prophylaxis, while those at high risk of bleeding should receive mechanical prophylaxis until their risk of bleeding is reduced 5.

A systems-based program that uses the electronic health record and offers personalized VTE prophylaxis recommendations can increase VTE risk assessment rates in patients initiating outpatient chemotherapy 4.
The use of novel oral anticoagulants, which have a wide therapeutic window and predictable pharmacodynamics and pharmacokinetics, may be an effective option for VTE prophylaxis in outpatients 3.