Polycythemia vera (PV) is a type of blood cancer known as a myeloproliferative neoplasm. It involves the abnormal development and function of bone marrow cells that produce blood cells, and leads to the overproduction of red blood cells. White blood cells and platelets may also be overproduced. There is currently no cure for PV, but the condition can often be managed for many years. In rare cases, PV may progress to myelofibrosis (scarring of the bone marrow) or acute myeloid leukemia (AML).
The following is a general overview of the diagnosis and treatment of PV. Each person with PV is different, and the specific characteristics of your condition will determine how it is managed. The information on this Web site is intended to help educate you about treatment options and to facilitate a shared decision-making process with your treating physician.
At its early stages, PV may not cause any symptoms. Symptoms that may develop as the condition progresses include the following1:
Overproduction of blood cells and changes to blood flow increase the risk of serious blood clots in people with PV. This can lead to life-threatening conditions such as heart attack, stroke, or pulmonary embolism. Treatment of PV can reduce this risk while also helping to manage bothersome PV symptoms. PV can cause pregnancy complications, and women who are pregnant or considering becoming pregnant may wish to talk with their doctor about how to manage their health.
Blood tests provide the primary information necessary to diagnosis PV. Patients may also undergo a bone marrow examination. PV typically involves a high concentration of red blood cells and the presence of certain gene mutations in blood cells.2 These gene mutations, which involve the Janus kinase 2 (JAK2) gene, are identified in almost all people with PV. JAK2 mutations are thought to contribute to the growth of PV and some other myeloproliferative neoplasms, but the exact role of this gene continues to be studied.
Another common characteristic of PV is lower-than-normal blood levels of a protein known as erythropoietin. People with PV may also have elevated levels of platelets and/or white blood cells.
Treatment of PV can improve symptoms and and reduce the risk of complications. Choice of treatment depends in part on a patient’s risk of blood clots.3 Patients who are older or who have history of blood clots are considered high-risk and may require more extensive treatment than patients who are low-risk. Treatment of low-risk patients often involves phlebotomy (removal of some blood) and low-dose aspirin.
Phlebotomy: Periodic removal of blood from a vein (using the same technique as blood donation) reduces the concentration of red blood cells.
Low-dose aspirin: Reduces the risk of blood clots.
Hydroxyurea: May be used for the treatment of high-risk patients or patients who have not responded adequately to phlebotomy and low-dose aspirin. Hydroxyurea suppresses blood cell production in the bone marrow.
Other drugs that may be used (particularly if patients don’t respond to hydroxyurea) include interferon alfa and busulfan. Once again, the goal is to manage blood cell concentrations.
In rare cases, PV progresses to myelofibrosis (scarring of the bone marrow) or acute myeloid leukemia (AML). Among people with PV, the 10-year risk of myelofibrosis is less than 10% and the 10-year risk of AML is less than 5%.2 For information about the management of these conditions, click on one of the following:
The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. Future progress in the treatment of polycythemia vera will result from the continued evaluation of new treatments in clinical trials. Participation in a clinical trial may offer patients access to better treatments and advance the existing knowledge about treatment of this cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. Areas of active investigation aimed at improving the treatment of polycythemia vera include the following:
JAK inhibitors: Targeted drugs known as JAK inhibitors may change the way in which myeloproliferative neoplasms are treated. These drugs target abnormal cell signaling that is through to contribute to the growth of myeloproliferative neoplasms. The JAK1 and JAK2 inhibitor Jakafi® (ruxolitinib) has been approved for the treatment of myelofibrosis, and is also being studied in Phase III clinical trials for the treatment of PV.
HDAC inhibitors: Other targeted drugs that are being evaluated for PV include histone deacetylase (HDAC) inhibitors. These drugs—which include givinostat, vorinistat, pabinostat, and others—interfere with enzymes that may contribute to cancer growth.
1 National Cancer Institute: PDQ® Chronic Myeloproliferative Disorders Treatment. Bethesda, MD: National Cancer Institute. Date last modified 08/07/2013. Available at: http://cancer.gov/cancertopics/pdq/treatment/myeloproliferative/Patient. Accessed 10/11/2013.
2 Tefferi A. Polycythemia vera and essential thrombocythemia: 2013 update on diagnosis, risk-stratification, and management. American Journal of Hematology. 2013;88:508-516.
3 Hensley B, Geyer H, Mesa R. Polycythemia vera: current pharmacotherapy and future directions. Expert Opinion in Pharmacotherapy. 2013;14:609-617.