Clinical and genetic characteristics of acute myeloid leukemia with t(8;21) in children and results of therapy according to protocol AML-MM-2000

A t(8;21) is the most frequent abnormality in AML in children. Patients with this genetic abnormality are traditionally expected favorable prognosis with a probability of cure up to 80 %. Known additional cytogenetic abnormalities in AML with t(8;21) not affecting prognosis. These include loss of one sex chromosome and del(9q-). Prognosis impact of additional abnormalities involving chromosomes 7 and 11 in patients with t(8;21) is unknown. The purpose of this study was to analyse of additional anomalies, that occur in patients with t(8;21), and their influence on prognosis. During the study period 173 children with AML have received AML-MM-2000 treatment protocol in Russia and Belarus. Of these, in 33 patients (11 girls and 22 boys, median age — 10.5 years) t(8;21) was detected by chromosome banding or molecular-genetic analysis. In group with t(8;21) CNS leukemia in 8 patients was detected, extramedullary lesion — in 8 patients. In 4 patients CNS leukemia combined with presence of extramedullary lesions. These factors did not influence on therapy outcome. Overall survival of AML patients with t(8;21) was 0,67 ± 0,08 compared to 0,44 ± 0,04 in patients with AML without this translocation (p = 0,04). Special subgroup consist of 5 patients with t(8;21) and identified chromosomal abnormalities affecting chromosome 7 and 11, which were a poor prognostic factor: event-free survival in this subgroup of patients (n = 5) was 0,0 ± 0,0, compared to 0,34 ± 0,16 in patients with t(8;21) without additional anomalies (n = 28) (p = 0,027).