What is Polycythemia vera (PV)?

From the Guidelines

Polycythemia vera (PV) is a Philadelphia-negative classical myeloproliferative neoplasm characterized by excessive production of red blood cells, white blood cells, and platelets, requiring management with phlebotomy and low-dose aspirin to reduce the risk of thrombotic events and improve quality of life. The diagnosis of PV is often confirmed by the presence of the JAK2 V617F mutation, which is found in the majority of patients 1. Key features of PV include:

• Increased blood viscosity due to excessive red blood cell production
• Elevated white blood cell and platelet counts
• Risk of thrombotic events, such as stroke and myocardial infarction
• Potential transformation to myelofibrosis or acute leukemia Treatment of PV depends on risk stratification, with all patients requiring phlebotomy to maintain a hematocrit below 45% and low-dose aspirin to prevent thrombotic events 1. High-risk patients, such as those with a history of thrombosis or advanced age, may require cytoreductive therapy with hydroxyurea or interferon-alpha to reduce the risk of thrombotic events and improve survival 1. Regular monitoring of blood counts and symptom management are also essential to improve quality of life and reduce the risk of complications. It is also important to note that hydroxyurea should be used with caution in young patients, and busulphan may be considered in elderly patients 1. Overall, the management of PV requires a comprehensive approach that includes phlebotomy, aspirin, cytoreductive therapy, and regular monitoring to reduce the risk of thrombotic events and improve quality of life.

From the Research

Definition and Characteristics of Polycythemia Vera (PV)

• Polycythemia vera (PV) is a chronic myeloproliferative neoplasm characterized by exuberant red cell production leading to a broad range of symptoms that compromise quality of life and productivity of patients 2.
• PV is associated with an increased red blood cell mass and increased risk of thrombosis, affecting approximately 65 000 people in the US, with an annual incidence of 0.5 to 4.0 cases per 100 000 persons 3.
• The disease is almost universally associated with a JAK2 gene variant, which helps distinguish PV from secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea 3.

Clinical Features and Diagnosis

• Erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) is a required diagnostic criterion, although thrombocytosis (53%) and leukocytosis (49%) are common 3.
• Patients may have pruritus (33%), erythromelalgia (5.3%), transient visual changes (14%), and splenomegaly (36%) with abdominal discomfort 3.
• A working diagnosis is considered in the presence of a JAK2 mutation associated with hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women; morphologic confirmation by bone marrow examination is advised but not mandated 4.

Treatment and Management

• Current therapeutic first line recommendations based on risk adapted classification divided patients into two groups, according to age (< or >60 years) and presence of prior thrombotic events 2.
• All patients with PV should receive therapeutic phlebotomy (goal hematocrit, <45%) and low-dose aspirin (if no contraindications) 3, 4.
• Cytoreductive therapy with hydroxyurea or interferon is recommended for patients at high risk of thrombosis, including those aged 60 years or older or with a prior thrombosis 2, 3, 4.
• Ruxolitinib is a Janus kinase inhibitor that can alleviate pruritus and decrease splenomegaly in patients who are intolerant of or resistant to hydroxyurea 2, 3, 5.