A review of central nervous system leukaemia in paediatric acute myeloid leukaemia

The treatment of pediatric acute myeloid leukemia (AML) is the subject of many studies by collaborative groups around the world. These studies have examined both variations in the timing of chemotherapy agents being given, as well as the addition or omission of specific chemotherapeutic agents. In cooperative group studies, the methods utilized for the treatment of central nervous system (CNS) leukemia have remained relatively stable over the years. However, there are significant differences among the different cooperative groups as to the therapy used to treat both overt CNS leukemia and the therapy used for the prevention of CNS leukemia. Similarly, the criterion used to define the presence of CNS leukemia differs among the groups. The majority of cooperative groups classify CNS findings in a similar manner, specifically CNS1 status is less than 5 white blood cells in the cerebrospinal fluid (CSF) with no blasts present, CNS2 status is less than 5 white blood cells in the CSF with the presence of blasts, and CNS3 status is 5 or more white blood cells in the CSF with the presence of blasts (all in an atraumatic tap). This manuscript will examine both the definition and therapy of CNS leukemia in pediatric AML cooperative group trials as well as the incidence of CNS relapse in these trials, with recommendations for therapy based on these studies