- Venous thromboembolism (VTE) is common in oncology and is increasing over time.
- Risk stratification is essential to balance the risks and benefits of primary thromboprophylaxis.
- The management of cancer-associated thrombosis (CAT) is specific at different times in the course of cancer.
- The benefit-risk analysis of anticoagulant therapy should be conducted regularly.
Prevention
Venous thromboembolic complications are common in cancer patients.The cumulative incidence of CAT is increasing over time for various reasons, including longer patient survival, more frequent accidental outcomes and the introduction of new therapies, explained Marc Carrier, Head of the Division of Hematology at The Ottawa Hospital (Canada) during a Special Interest Session held at the 2022 ASH Annual Congress. It presented a summary of the clinical relevance of VTE in cancer patients and the evidence of efficacy and safety of anticoagulant regimens for the primary prevention of CAT.
VTE is associated with morbidity and mortality and can be a traumatic and stressful experience for patients. Most CATs (up to 80%) occur in outpatients. «We need to think about how to educate patients about signs and symptoms and to seek assistance if they have them,» Dr. Carrier recommended. Primary thromboprophylaxis is safe and effective in outpatients with cancer, but requires proper risk stratification using a validated score (i.e. the Khorana score) in addition to clinical judgment and experience.
In outpatients undergoing systemic therapy, ASH guidelines recommend:
- low risk of thrombosis, no thromboprophylaxis;
- intermediate risk, thromboprophylaxis with a direct oral anticoagulant (DOAC) or no thromboprophylaxis;
- high risk, thromboprophylaxis with a DOAC or low-molecular weight (LMWH) heparin; Thromboprophylaxis should be used with caution in individuals at high risk of bleeding.
Secondary treatment and prevention
» What distinguishes these guidelines is that the committee considered domains of the process that leads from evidence to additional evidence-to-decision domains such as resource utilization, cost-effectiveness, healthcare equity, acceptability and feasibility,» said Radhika Gangaraju, Assistant Professor at the University of Alabama at Birmingham (AL, USA), who described the ASH guidelines for CAT management.Recommendations are given for three specific points: initial management (first 5–10 days after diagnosis of VTE), short-term treatment (3–6 months), and long-term treatment (>6 months).
Anticoagulant therapy algorithm for CAT:
- evaluate whether there is any bleeding risk or any contraindication to anticoagulant therapy;
- evaluate drug interactions with DOACs
- no interaction, prefer DOACs
- interactions with DOAC, prefer LMWH (LMWH is also preferable for patients with intraluminal or genitourinary gastrointestinal tumors [GI] who have not undergone resection, with impaired GI absorption, and for the treatment of extended VTE);
- perform the normal benefit-risk analysis of anticoagulant therapy at each clinical visit;
- Continue anticoagulant therapy in case of evidence of active cancer, metastatic disease and in patients receiving chemotherapy (observational studies recommend discontinuation of antithrombotic drugs in patients with end-stage tumors due to the high risk of clinically relevant bleeding in the last weeks of life).
Adoption of guidelines
The second part of the session was devoted to strategies for the adoption of VTE guidelines in cancer patients.Despite recommendations, outpatient drug prophylaxis is rarely adopted in the United States. Obstacles to its adoption include:
- lack of accuracy/unavailability of risk stratification tools;
- lack of time;
- lack of awareness.
Two strategies have been presented to address these shortcomings. Ang Li, Assistant Professor at Baylor College of Medicine (Houston, TX), presented an overview of the potential uses of optimized clinical informatics in modern electronic health record (EHR) systems to aid adherence to CAT guidelines, while Katy Toale, clinical pharmacy specialist at MD Anderson Cancer Center (Houston, TX), described the anticoagulant therapy management program that is directing, aimed at ensuring the safe and effective use of these drugs.
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