LOW-DOSE SPLENIC IRRADIATION IN THE TREATMENT OF IMMUNE THROMBOCYTOPENIA IN HIV-INFECTED PATIENTS

Purpose: To determine the effect of low-dose splenic irradiation on se vere Zidovudine-resistant, HIV-1-associated thrombocytopenia (HAT). Me thods and Materials: Between September 1994 and October 1996, 17 patie nts were included in a prospective study, The patients met the followi ng criteria for inclusion: hemorrhagic symptoms or a platelet count be low or equal to 50 x 10(9)/l and normal numbers of megakaryocytes on b one aspiration. The mean baseline platelet count was 20.3 (+/- 14.4) x 10(9)/l; four patients had a platelet count inferior to 10 x 10(9)/l. Splenic volume was defined by ultrasonography, A total dose of 9 Gy w as given using an isocentric parallel pair field technique. Results: O ne month after the end of treatment six patients had a significant ris e in their platelet count. Clinically, hemorrhagic symptoms stopped fo r all patients that were symptomatic. Unfortunately, duration of respo nse was short because for one patient only the platelet count remains stable with a follow-up of 6 months. All patients are alive and in rec ent evaluation, with four out of eight patients receiving a combinatio n of antiretroviral therapy had a platelet count above 50 x 10(9)/l. C onclusion: Our results are disappointing concerning the duration of re sponse, especially comparatively to those reported in autoimmune throm bocytopenia. Mechanisms of HAT are more complex, and megakaryocytes' i nfection may play an important role. Splenic irradiation should be con sidered as palliative treatment for the minority of patients with seve re bleeding that does not respond to standard medical treatment. (C) 1 998 Elsevier Science Inc.