Polycythemia vera is one of several types of blood cancer called myeloproliferative neoplasms, or MPN. The common factor in these diseases is that immature cells in the bone marrow (called stem cells) that are supposed to mature into different kinds of blood cells experience mistakes in their genes that cause them to malfunction. Instead of multiplying and functioning normally, the irregular cells begin to grow uncontrollably, crowding out the normal blood cells that keep our bodies healthy. The different varieties of MPN depend on the type of cells that are affected.1
The stem cells in our bone marrow produce three main types of blood cells:1
Red blood cells, which carry oxygen to nourish our cells
White blood cells, which fight infection
Platelets, which cause our blood to clot and stop bleeding1
Polycythemia vera is a type of MPN in which the bone marrow produces too many red blood cells. In many cases, patients with polycythemia vera have excess white blood cells and platelets, as well.2,3
How does polycythemia vera develop?
Polycythemia vera begins when a stem cell in the bone marrow undergoes a mistake, or mutation, in its genes. Genes exist in every cell and serve as an instruction manual for the cell’s functioning and reproduction.3 Nobody understands exactly what causes the initial stem cell to mutate. When the mutated cell copies itself and divides, the mistake is passed onto the daughter cells, which themselves begin to divide and grow without stopping. The result is that the body produces too many red blood cells.
The extra cells cause the blood to thicken and slow, becoming prone to clotting, or clumping together. When clots form in the blood, you are at higher risk of more serious complications, such as stroke, heart attack, or pulmonary embolism, which happens when an artery in the lungs becomes blocked. With polythycemia vera, abnormal bleeding can occur, as well.2,3
Polycythemia vera is a rare disease. Its exact cause is not known, but certain risk factors may increase your risk of developing the disease. These include:
Sex: Men are slightly more likely than women are to develop this condition.
Age: Polycythemia vera is more common among people over 60, but it may occur at any age.
Environmental exposure: Exposure to high levels of radiation or certain toxins may increase the risk for this condition.
Mutation: About 95% of all patients with polythycemia vera have a mutation in the JAK2 gene in their blood-forming cells. This mutation causes the body to make too many blood cells.4
Polycythemia vera develops slowly and often does not cause symptoms in early stages. Many times it is diagnosed only from a routine blood test that shows high levels of red blood cells. Sometimes the disease is diagnosed when a patient sees a doctor because of symptoms.
Although there is no cure for polycythemia vera, most people with the disease live a normal life expectancy if they are treated and their disease is tracked carefully by an experienced doctor. Left untreated, polycythemia vera can be life-threatening.3,4
Treatment for this condition focuses on reducing the number of blood cells. Common therapies include:
Removing blood from your veins (phlebotomy)
Low-dose aspirin to thin the blood
Medicines that reduce blood cell formation
Medicines that relieve itching
Medicines that destroy cancer cells6
Patients are considered low risk if they are under 60 and have no history of blood clots. Patients are higher risk if they are over 60 or have ever had blood clots. 7
MPN Facts. Seattle Cancer Care Alliance. Available at: https://www.seattlecca.org/diseases/myeloproliferative-neoplasms-mpn/mpn-facts Accessed June 7, 2019.
Polycythemia vera. Seattle Cancer Care Alliance. Available at: https://www.seattlecca.org/diseases/polycythemia-vera Accessed June 28, 2019.
Polycythemia vera. Leukemia & Lymphoma Society. Available at: https://www.lls.org/myeloproliferative-neoplasms/polycythemia-vera?src1=20084&src2= Accessed June 28, 2019.
Polycythemia vera. MPN Research Foundation. Available at: http://www.mpnresearchfoundation.org/Polycythemia-Vera-28PV-29 Accessed June 28, 2019.
Polycythemia vera. Symptoms and causes. February 8, 2017. Available at: https://www.mayoclinic.org/diseases-conditions/polycythemia-vera/symptoms-causes/syc-20355850 Accessed June 28, 2019.
Polycythemia vera. Diagnosis and Treatment. Mayo Clinic. February 8, 2017. Available at: https://www.mayoclinic.org/diseases-conditions/polycythemia-vera/symptoms-causes/syc-20355850 Accessed June 28, 2019.
Polycythemia vera Treatment. Leukemia & Lymphoma Society. Available at: https://www.lls.org/myeloproliferative-neoplasms/polycythemia-vera/treatment Accessed June 28, 2019.