Management of Polycythemia Vera

Introduction to Thrombotic Complications

• Polycythemia vera is characterized by a high risk of thrombotic complications, with a pooled prevalence of overall thrombosis of 28.6% in newly diagnosed patients, and the National Comprehensive Cancer Network recommends low-dose aspirin (81-100 mg daily) for all patients to reduce this risk, regardless of risk stratification 1, 2

Aspirin Therapy

• Low-dose aspirin (81-100 mg daily) reduces the risk of thrombotic events, particularly effective for microvascular symptoms like erythromelalgia, as recommended by the NCCN and the American Society of Hematology, with a relative risk reduction of 0.40 (95% CI, 0.18–0.91; P=0.03) in the European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) trial 3, 2, 4, 5, 1
• Aspirin should be used with caution in patients with acquired von Willebrand disease or platelet count >1,500 × 10^9/L due to increased bleeding risk, and enteric-coated aspirin preparations may have lower bioavailability and inadequate platelet inhibition, particularly in heavier patients 2, 6

Cytoreductive Therapy and Hematocrit Management

• The target hematocrit for all polycythemia vera (PV) patients is <45%, regardless of gender, based on the CYTO-PV study which demonstrated reduced thrombotic events when hematocrit was maintained below 45%, and phlebotomy is recommended for patients with hematocrit >50% who have symptoms of hyperviscosity, or for patients with polycythemia vera to maintain hematocrit <45% 2, 7, 2, 8, 9
• Hydroxyurea is the preferred first-line option for most high-risk patients, especially those over 40 years old, according to the European LeukemiaNet (ELN) criteria and the National Comprehensive Cancer Network, while Interferon-α is preferred in younger patients and women of childbearing age 3, 2, 3, 4
• Busulfan may be considered as a second-line option in elderly patients (>70 years) with polycythemia vera, and Ruxolitinib is a second-line option for patients intolerant or resistant to hydroxyurea, as recommended by the National Comprehensive Cancer Network 3

Risk Stratification and Management

• The risk categories are defined as follows:

• Low-risk PV patients should undergo phlebotomy to maintain hematocrit <45% plus low-dose aspirin (81-100 mg/day), while high-risk PV patients should undergo phlebotomy to maintain hematocrit <45% plus low-dose aspirin and cytoreductive therapy, as recommended by the National Comprehensive Cancer Network 2

Monitoring and Disease Progression

• Patients should be monitored for signs of disease progression to myelofibrosis or acute myeloid leukemia, according to the National Comprehensive Cancer Network, and for thrombotic or bleeding complications, with aggressive management of cardiovascular risk factors recommended, including control of hypertension, hyperlipidemia, and diabetes, as well as smoking cessation 2, 3, 10, 2, 8
• Allogeneic stem cell transplantation should be considered for eligible intermediate-2 or high-risk patients, as recommended by the NCCN and the European Society for Medical Oncology 1, 3, 5
• Regular assessment of complete blood counts and monitoring for resistance or intolerance to hydroxyurea using ELN criteria is essential for proper management of polycythemia vera, as recommended by the European LeukemiaNet (ELN) criteria, and iron status monitoring is critical, with treatment with iron supplementation recommended for transferrin saturation <20% 3, 7