From the Guidelines
All patients with polycythemia vera should be managed with phlebotomy to maintain the hematocrit at less than 45% and low-dose aspirin, with cytoreduction indicated in high-risk patients. The treatment of polycythemia vera (PV) is focused on reducing the risk of thrombotic events and improving quality of life. According to the most recent and highest quality study, the CYTO-PV trial 1, intensive phlebotomy treatment targeting a hematocrit of less than 45% significantly reduces the risk of cardiovascular death or major thrombotic events compared to less intensive phlebotomy.
Key Components of Treatment
- Phlebotomy: removing 300-500 mL of blood every 2-3 days until the hematocrit is below 45% for men and 42% for women
- Low-dose aspirin (81-100 mg daily) to reduce thrombotic risk
- Cytoreductive therapy with hydroxyurea or interferon alpha for high-risk patients
- Management of generic cardiovascular risk factors and cessation of smoking
High-Risk Patients
High-risk patients, defined by factors such as poor tolerance of phlebotomy, symptomatic or progressive splenomegaly, severe disease-related symptoms, platelet counts greater than 1,500 10^9/L, and progressive leukocytosis, require cytoreductive therapy. Either hydroxyurea or interferon alpha is recommended as first-line cytoreductive therapy at any age, with hydroxyurea used with caution in young patients and busulphan considered in elderly patients 1.
Monitoring and Adjustment
Regular monitoring of blood counts is necessary to adjust treatment and prevent complications like thrombosis, bleeding, and cardiovascular events. Adequate hydration is also important to reduce blood viscosity and improve circulation. The European LeukemiaNet recommendations 1 provide a framework for the management of PV, emphasizing the importance of individualized treatment approaches based on patient risk factors and response to therapy.
From the Research
Definition and Diagnosis of Polycythemia Vera
- Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis 2.
- The diagnosis of PV is based on the presence of a JAK2 gene variant, which is found in more than 95% of patients, and erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) 2.
- Other common features of PV include thrombocytosis (53%), leukocytosis (49%), pruritus (33%), erythromelalgia (5.3%), transient visual changes (14%), and splenomegaly (36%) with abdominal discomfort 2.
Risk Factors and Complications
- Patients with PV are at increased risk of arterial and venous thrombosis, with a median survival from diagnosis of 14.1 to 27.6 years 2.
- Prior to or at the time of PV diagnosis, arterial thrombosis occurred in 16% of patients and 7% had venous thrombotic events, which could involve unusual sites, such as splanchnic veins 2.
- PV is also associated with an increased bleeding risk, especially in patients with acquired von Willebrand disease, which can occur with extreme thrombocytosis (platelet count, ≥1000 × 10^9/L) 2.
- About 12.7% of patients with PV develop myelofibrosis and 6.8% develop acute myeloid leukemia 2.
Treatment and Management
- All patients with PV should receive therapeutic phlebotomy (goal hematocrit, <45%) and low-dose aspirin (if no contraindications) 2, 3.
- Patients who are at higher risk of thrombosis, including those aged 60 years or older or with a prior thrombosis, may benefit from cytoreductive therapy with hydroxyurea or interferon to lower thrombosis risk and decrease symptoms 2, 3.
- Ruxolitinib, a Janus kinase inhibitor, can alleviate pruritus and decrease splenomegaly in patients who are intolerant of or resistant to hydroxyurea 2, 4.
- The current goal of therapy is to prevent thrombosis, and periodic phlebotomy, with a hematocrit target of <45%, combined with once- or twice-daily aspirin (81 mg) therapy, is the backbone of treatment in all patients, regardless of risk category 3.