TREATMENT STRATEGIES IN ESSENTIAL THROMBOCYTHEMIA - A CRITICAL-APPRAISAL OF VARIOUS EXPERIENCES IN DIFFERENT CENTERS

The therapeutic strategy in patients with Essential Thrombocythemia (E T) is a difficult balance between the prevention of bleeding and throm botic complications and the risks of drug side effects and toxicity. M ajor bleeding is rare and seem to be related to higher platelet counts : therefore, a platelet count over 1500 x 10(9)/L is generally regarde d as an indication for cytoreduction. Thrombotic complications include microvascular occlusive symptoms, which are reversible with low-dose aspirin, and large vessels thrombosis. The risk of major thrombosis is higher in ET patients aged more than 60 ys. and with previous occlusi ve event. In this high-risk group, the non-alkylating agent hydroxyure a (HU) significantly reduces the rate of vascular complications and ha s emerged as the treatment of choice. However, the long-term risk/bene fit of HU remains disputed because its leukemogenic potential has not been ruled out. This holds also for other myelosuppressive agents, suc h as busulphan and pipobroman. Other drugs of particular interest for young patients include recombinant alpha-interferon (IFN) and Anagreli de. Both of them are effective in lowering platelet count, but their e fficacy in reducing clinical complications remains to be demonstrated. However, both IFN and Anagrelide have shown to have frequent and clin ically important side effects. Thus, further clinical studies are requ ired to establish their role in the strategy of ET patient treatment.