Leucemias agudas na infância

As leucemias constituem a neoplasia mais frequente na infância. Sao responsaveis por cerca de um terco dos cânceres pediatricos. A leucemia linfocitica aguda (LLA) representa cerca de 75% dos casos de leucemias infantis. As leucemias mieloides agudas (LMA) representam 15% a 20% das leucemias em pacientes com idade inferior a 15 anos. As manifestacoes clinicas das leucemias agudas sao decorrentes da inibicao da hematopoiese pelas celulas leucemicas e dos efeitos da infiltracao leucemica em diversos orgaos e sistemas. Observa-se anemia devido a diminuicao dos eritrocitos, sangramentos decorrentes da trombocitopenia e infeccoes consequentes a neutropenia. A infiltracao dos diferentes tecidos resulta em hepatomegalia, esplenomegalia e linfadenomegalia. O diagnostico das leucemias e firmado pela presenca de mais de 25% de celulas leucemicas na puncao aspirativa de medula ossea (mielograma). O tratamento da LLA e feito com regimes quimioterapicos de longa duracao. A indicacao do trans- plante de medula ossea durante uma primeira remissao permanece controversa. A probabilidade de cura da LLA pode chegar a 80%. Na LMA, com o uso exclusivo de quimioterapia, a probabi- lidade de sobrevida livre de doenca (SLD) por periodos prolonga- dos e de 30% a 40%. Quando se emprega o transplante de medula ossea alogenico, a probabilidade estimada de SLD a longo prazo e de 50% a 60%...(AU) The leukemias are the most common malignant neoplasm in child- represents 15% to 20% of cases in patients less than 15 years old. The clinical manifestations of acute leukemias are secondary to inhibition of hematopoiesis by leukemic cells and to the effects of leukemic infiltration in different organs and systems. Anemia is caused by reduction of erythrocytes, bleeding is secondary to thrombocytopenia, and infections are related to neutropenie. The infiltration of tissues results in hepatomegaly, splenomegaly and lymphadenopathy Acute leukemias are diagnosed by abone mar- row aspirate that demonstrates more than 25% of the bone mar- row cells as a relatively homogeneous population of blasts. The treatment of ALL consists of prolonged chemotherapy regimens. The role of allogeneic bone marrow transplantation during first remission remains controversiet. The probability of cure in ALL reaches 80%, In AML, with chemotherapy alone, the probability of long term disease free survival is from 30% to 40%. When bone marrow transplantation is used the estimated probability of prolonged disease free survival is 50% to 60%...