From the Guidelines
Yes, polycythemia vera is considered a type of blood cancer. It is classified as a myeloproliferative neoplasm, which is a group of slow-growing blood cancers where the bone marrow makes too many abnormal blood cells. In polycythemia vera specifically, the bone marrow produces too many red blood cells, and often elevated white blood cells and platelets as well. This occurs due to a genetic mutation, most commonly in the JAK2 gene, which causes the bone marrow stem cells to produce blood cells uncontrollably. Some key points to consider in the management of polycythemia vera include:
- Risk stratification, with high-risk patients defined as those aged greater than 60 years or with a history of previous thrombosis, as outlined in the European LeukemiaNet guidelines 1
- Treatment typically includes phlebotomy (blood removal) to reduce blood thickness, low-dose aspirin to prevent blood clots, and medications like hydroxyurea, ruxolitinib, or interferon to reduce blood cell production, as recommended by the NCCN guidelines 1
- Monitoring response and signs/symptoms of disease progression every 3–6 months or more frequently as clinically indicated, with bone marrow aspirate and biopsy performed to rule out disease progression to myelofibrosis prior to the initiation of cytoreductive therapy 1 While polycythemia vera progresses slowly and many patients have a near-normal life expectancy with proper management, it is still a cancer because it involves the uncontrolled growth of abnormal cells that can interfere with normal body functions and potentially transform into more aggressive blood cancers like myelofibrosis or acute leukemia in some patients. The most recent and highest quality study, published in 2018 by the European LeukemiaNet, provides updated recommendations on the management of Philadelphia-negative classical myeloproliferative neoplasms, including polycythemia vera 1. This study used a Delphi process and consensus conferences to produce recommendations, and provides a comprehensive overview of the current state of knowledge on the management of polycythemia vera. Overall, the management of polycythemia vera requires a comprehensive approach that takes into account the patient's individual risk factors and disease characteristics, and involves a combination of pharmacological and non-pharmacological interventions to reduce the risk of thrombosis and disease progression.
From the Research
Definition and Classification of Polycythemia Vera
- Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis 2.
- It is one of three stem-cell-derived myeloid malignancies commonly known as myeloproliferative neoplasms 3.
- PV is classified as a cancer due to its clonal nature and potential for progression to more aggressive diseases such as myelofibrosis or acute myeloid leukemia 4, 5, 6.
Characteristics and Diagnostic Criteria
- PV is characterized by erythrocytosis, often with associated leukocytosis and thrombocytosis 3.
- The World Health Organization's major diagnostic criteria include an elevated hemoglobin or hematocrit level, abnormal results on bone marrow biopsy, and presence of the Janus kinase 2 genetic mutation, which is present in approximately 98% of cases 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 6.
Treatment and Management
- The current goal of therapy is to prevent thrombosis, with periodic phlebotomy and once- or twice-daily aspirin therapy being the backbone of treatment in all patients, regardless of risk category 6.
- Cytoreductive therapy is reserved for high-risk disease, with first-line drugs of choice being hydroxyurea and pegylated interferon-α, and second-line busulfan and ruxolitinib 4, 6.
- Treatment strategies may vary depending on the clinical scenario, including pregnancy, splanchnic vein thrombosis, pruritus, perioperative care, and post-PV myelofibrosis 6.