[Treatment of essential thrombocythemia]

Essential thrombocythemia (ET) is a myeloproliferative syndrome that rises many therapeutic problems. This affection is rarely life threatening, but hemorrhagic and thrombotic complications must be prevented when possible. The rarity of these complications makes difficult the assessment of treatment efficiency. Few randomised clinical trials were done, and treatment often rests on retrospective studies. The potential toxicity of treatments, their leukemogenicity in particular, rises a decisional problem for young patients. We propose to review available data in order to propose the most rational treatment for each patient.

After numerous years when we only disposed of retrospective studies, non-randomised prospective studies or isolated case-reports, two randomised trials allows us to more precisely define ET treatment. The first trial proved the efficiency of the hydroxyurea-aspirin association in the prevention of thrombotic events in high-risk patients. The second trial signalled to our attention the increased risk of bleeding of the association anagrelide-aspirin, with also the possibility of increased appearance of myelofibrosis.

New perspectives in the treatment of ET will require to get more insights in the role of hydroxyurea and anagrelide in particular by longer follow-up. But not less important is a better definition of the thrombosis risks (who has to be treated?) and also of the diagnostic groups since ET can, in some particular cases, be misdiagnosed with polycythemia vera or idiopathic myelofibrosis.