Optimal treatment intensity in children with Down syndrome and myeloid leukaemia: data from 56 children treated on NOPHO-AML protocols and a review of the literature.

Children with Down syndrome (DS) and myeloid leukaemia have a significantly higher survival rate than other children, but they also experience considerable treatment-related toxicity. We analysed data on 56 children with DS who were treated on the Nordic Society for Paediatric Haematology and Oncology-acute myeloid leukaemia (NOPHO-AML)88 and NOPHO-AML93 protocols and reviewed the literature. In the dose-intensive NOPHO-AML88 protocol, 8 out of 15 patients (53%) experienced an event. In the less dose-intensive NOPHO-AML93 protocol, 7 out of 41 patients (17%) had an event. Therapy was reduced in 29 patients (52%) with in average 75% and 67% of the scheduled dose of anthracycline and cytarabine, respectively. Treatment-related death occurred in seven who all received full treatment. Relapse and resistant disease occurred at a similar rate in those receiving full and reduced treatment. Review of major series of myeloid leukaemia of DS showed no clear relationship between dose and survival; however, it appears that both a reduction in treatment dose and a less intensively timed treatment regimen improved the outcome. Further studies are needed to define the optimal regimen for treating myeloid leukaemia of DS.