Leukemia and myelodysplasia effect of multiple cytotoxic therapy in essential thrombocythemia

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder cha racterized by increased risk of thrombosis and/or hemorrhages. Cytotoxic dr ugs are mostly used in patients at high risk for thrombotic complications, while their use is still debated in low risk patients because of the risk o f leukemia or secondary neoplasm. We discuss the leukemic risk of available treatment strategies in a large cohort of patients. Over a 12 years period we treated 23 patients with busulfan (BU), 1 with pipobroman (Pi), 6 with P-32, 48 with hydroxyurea (HU) in 62 cases associated with acetyl salicylic acid (ASA) while 77 patients received ASA alone and 33 did not receive any therapy. We observed 2 cases of acute leukemia (AL) and 1 of myelodysplast ic syndrome (MDS). One of these patients had been treated with SLP and Pi t hese after with and the other two with BU and HU. They represented 23% of a ll patients treated with more than 1 cytotoxic agent, 16.6% of P-32 treated subjects, 4% of those with HU and 6.4% of those with BU. The case of MDS o ccurred in a 81 years old female and represents 4% of cases of ET over the 70 years of age. No cases of AL or MDS were observed in patients not receiving cytotoxic the rapy (with or without ASA). According to our experience the use of more tha n one cytotoxic agent in ET confirms the increase in the risk of leukemia i n these cases. However, none of the patients treated with HU alone, even fo r more than 10 years (12 cases) developed AL. No treatment or therapy with ASA alone may be the best choice in young patients with ET with a low risk of thrombotic complications.