COMBINED PLATELETPHERESIS AND CYTOTOXIC CHEMOTHERAPY FOR SYMPTOMATIC THROMBOCYTOSIS IN MYELOPROLIFERATIVE DISORDERS

Background. Patients with myeloproliferative disorders (MPD) may have symptomatic thrombocytosis develop that requires prompt and sustained lowering of platelet counts to avert serious thrombotic or hemorrhagic sequelae. Methods. The authors retrospectively studied the short- and long-term effects of plateletpheresis combined with three different c hemotherapy regimens (busulfan, hydroxyurea, or busulfan/hydroxyurea) in 30 patients with MPD with symptomatic thrombocytosis. Results. Twen ty-nine patients entered first remission (FR) with initial treatment. The average number of plateletphereses to FR was three (standard devia tion [SD], +/-3). Average total dose of busulfan (216 mg) and time to FR (1.6 months) were less than for previously reported patients treate d without plateletphereses. Addition of hydroxyurea to busulfan decrea sed the number of plateletpheresis needed (P = 0.02) but did not addit ionally reduce the amount of busulfan needed or the time to FR. The sh ortest time to FR was in the hydroxyurea group (mean, 0.6 +/- 0.3 mont hs), but unmaintained remission could be achieved only in the busulfan -treated groups. With median follow-up of 68 months, median survival w as 53 months for the busulfan group, 55 months for the hydroxyurea gro up, and was undefined with no deaths for the busulfan/hydroxyurea grou p. Neither fatal complications of recurrent symptomatic thrombocytosis nor development of acute leukemia has occurred, except for progressio n to blast crisis in two patients with chronic myelogenous leukemia. C onclusion. Combined plateletpheresis and chemotherapy is a rapidly eff ective initial treatment for patients with MPD with symptomatic thromb ocytosis. With maintenance therapy or prompt treatment at relapse of d isease, prolonged good quality survival can be expected.