Thrombocytopenia in patients with acute promyelocytic leukemia

Fatal bleeding is still the main cause of early death in patients with acute promyelocytic leukemia (APL). The severe bleeding disorder arises from thrombocytopenia and, obviously, from complex coagulopathy typical for APL. The extend of thrombocytopenia is related to the severity of coagulopathy, and this was the reason why thrombocytopenia was considered when the three risk groups (low, intermediate, high risk) for APL were made by Sanz et al. Contrary to leukocyte concentration in time of diagnosis which increases the probability of relapse, thrombocytopenia mirrors more likely the risk of early death. Risk of bleeding is inversely related to the concentration of thrombocytes and, therefore, thrombocytopenia during the first days in APL should be considered in a different way than in other hematological malignancies. Platelet transfusions are the principal treatment of coagulopathy and thrombocytopenia in APL, because despite the progress in diagnostics and complex therapy of APL there is no clear and unambiguous recommendation for treatment of APL coagulopathy using either heparin nor antifibrinolytics or plasma coagulation factors substitution etc. Mistakes often originate from certain misunderstanding of recommendations for transfusion policy in APL, when satisfactory prophylactic treatment means that thrombocyte concentration never decreases under the recommended level (typically 30-50 × 10⁹/l). Analysis of the data from centers which cooperate with CELL (the Czech leukemia study group for life) showed that patients with APL were sending to those centers sooner, and the diagnostics were faster in last four years in the Czech Republic. This fact improved the distribution of patient in the risk groups. Moreover, the early mortality meaningfully decreased, undoubtedly thanks to the more intensive substitution therapy of thrombocytopenia and coagulopathy. Between 1989 and 2006, the distribution of patients diagnosed with APL in the Czech Republic was 33 % high risk, 46 % intermediate risk, and 22 % low risk, and only 69 % of patients reached complete remission after induction therapy. In the last years, between 2006 and 2009, the distribution of patients with APL diagnosed and in CELL cooperating centers changed to 17 % high risk, 45 % intermediate risk, and 38 % low risk, and 93 % of the patients reached complete remission after induction. These newer results are fully comparable with countries, where the results of diagnostics and treatment of APL are the best - and we can conclude, that this is the best message for the Czech hematology.

Keywords: acute promyelocytic leukemia; thrombocytopenia; coagulopathy