Polycythemia vera (PV) is a malignant disease, one of the chronic myeloproliferative syndromes (CMPS), or myeloproliferative neoplasms. These diseases have a common characteristic, the stem cells in the bone marrow, responsible for producing all the blood cells, have a defect which makes them produce one of the myeloid lineage blood cells in an uncontrolled manner.

In the case of polycythemia vera, due to a mutation in a cell that produces the red blood cells, the blood becomes thicker on account of a considerable increase in the number of red blood cells.

In our country the incidence of polycythemia vera is 4-6 cases per million, per year. The average age at diagnosis is 60. This disease is rare before the age of 40.

In the majority of cases the disease does not present any symptoms and is generally diagnosed as a result of a routine blood test. If there are any clinical manifestations they can include: non-specific symptoms (50%) (asthenia, night sweats, weight loss, attacks of gout, epigastric pain, generalised pruritus [itch]); thrombotic phenomena (50%) (stroke, angina, infarction, intermittent claudication of the lower limbs and abdominal venous thrombosis [portal, splenic, hepatic]); peripheral venous insufficiency (reddening and pain/burning sensation in the fingers and soles of the feet, which is accentuated with heat, such as taking a shower, and ameliorated when exposed to cold). Hemorrhages (nose bleeds, bleeding gums, gastrointestinal bleeding) are not infrequent (15-30%), nor are neurological manifestations (60%) (migraine, tingling sensation in the hands and feet, dizziness, visual alterations).

Three measurements of red blood cell concentrations may be used to diagnose polycythemia vera: the hematocrit level (greater than 51% in men and 48% in women), the concentration of hemoglobin (greater than 185 g/l in men and 165 g/l in women) and a red blood cell count (values greater than 5-6 million). These measurements form part of a standard blood test, a hemogram blood test, and if PV is suspected, it is relatively simple to confirm so and, furthermore, the test frequently demonstrates an increase in the values for white blood cells (leucocytosis) and platelets (thrombocytosis).

To complete the study and establish the definitive diagnosis there must also be, at least, a molecular study (to detect the presence of a specific mutation of the JAK2 gene), a bone marrow biopsy, and a quantification of serum erythropoietin concentration (always low).

Treatment for PV must be based on bloodletting, acetylsalicylic acid (aspirin), and hydroxyurea or radioactive phosphorus.

Bloodletting is the treatment of choice in most cases for patients with a history of thrombosis. It is performed every three or four days and 400 ml of blood is extracted to reduce the hematocrit level (up to 45% for men and 42% for women). The procedure includes regular monitoring of the patient.

For patients with a risk of thrombosis, the treatment of choice is with hydroxyurea, although, with patients of advanced age the use of radioactive phosphorus is preferred.

Unless contraindicated, all patients must take 100 mg of aspirin per day. Many patients also require allopurinol to reduce the values for uric acid.

For patients with marked thrombocytosis the administration of anagrelide may be indicated.

Although it is not a curable disease, it is, because of its chronic nature, usually effectively managed over long periods of time. Nevertheless, an increase in the number of red blood cells and platelets can lead to the hemorrhagic/thrombotic complications mentioned earlier. Over years patients with PV may evolve to myelofibrosis with bone marrow exhaustion (deficit of all the normal elements of the blood). Similarly, and especially after many years of treatment with hydroxyurea, there may be an evolution to acute myeloblastic leukaemia.

In spite of all this, well treated patients have an average expectation of survival that exceeds 15 years.

For more quality information about polycythemia vera, you can consult the following websites:

 

• Polycythemia Vera. Leukemia and Lymphoma Society
• Polycythemia Vera treatment. Leukemia and Lymphoma Society
  
  
• Myeloproliferative neoplasms treatment. Leukemia and Lymphona Society
  
  
• Chronic myeloproliferative neoplasms treatment. National Cáncer Institute

There are other resources and links (in Spanish) of interest that may be of use to polycythemia vera patients

• Recomendaciones generales sobre la alimentación durante el tratamiento del cáncer. ICO