Management of polycythemia vera and essential thrombocythemia.

The optimal management of patients with polycythemia vera (PV) and essential thrombocythemia (ET) continues to be controversial. Both diseases present diagnostic challenges and there is a paucity of data from randomized clinical trials to guide therapeutic decisions. However, the past two years have seen major advances in our understanding of these myeloproliferative disorders (MPD). First, the ECLAP study demonstrated the anti-thrombotic efficacy of aspirin in patients with PV. Second, the PT-1 trial, the largest randomized study of any MPD, has provided much needed guidance on the optimal management of patients with ET. Third, the identification of a single JAK2 mutation in most patients with PV, and in some of those with ET, illuminates the pathogenesis of these diseases and raises questions about the boundary between them. For the purpose of management decisions, it remains appropriate to consider them as separate entities for the time being. However, as we learn more about the clinical significance of the JAK2 mutation, it seems likely that the coming years will see major changes in the way we classify and manage these disorders.