New and old prognostic factors in polycythemia vera.

Polycythemia vera is a chronic myeloproliferative disorder affecting people in the sixth decade of life. The disease is considered long-lasting; median survival exceeds 18 years. As thrombosis is the main complication during follow-up, scoring systems have focused on the risk of thrombosis. Age over 60 years and prior thrombosis are considered the standard risk factors for thrombosis and represent the state of the art for risk stratification in decision making regarding treatment. However, new disease-based risk factors-leukocytosis and the JAK2V617F mutation burden-seem to be emerging as indicators of prognosis in polycythemia vera. Leukocytosis, as a marker of disease proliferation, seems to have an impact on thrombosis, post-polycythemia vera myelofibrosis, leukemia, and survival. The role of the JAK2V617F mutation as a prognostic factor requires further validation, but it may have a dominant role in disease progression and in the activation of platelets and leukocytes.