Introduction
The AML1-ETO (RUNX1-RUNX1T1; AE) fusion protein generated from translocation at chromosome 8 and 21 represents one of the most common cytogenetic abnormalities in acute myeloid leukemia (AML), accounting for 5~10% of all cases [1-2]. Although the AML1-ETO-positive AML (AE-AML) is considered a subtype with favorable prognosis, studies have shown that the AE-AML is highly heterogenous, shown as up to 6-31% of AE-AML patients carrying a c-KIT mutation and 15-26.7% presenting with extramedullary leukemia (EML) [1, 3-4], also the long term survival ranging from 28 to 70% [4-6]. While most research report both c-KIT mutations and EML are associated with higher risk of relapse and worse survival in AE-AML [3-4, 7], some studies, especially in children, show neither seems to impact the disease outcome [8-9], which in turn further supports the heterogeneity of this subtype leukemia. Taking together, it suggests AML1-ETO fusion protein might behave heterogenously in different subgroups, might be age-dependent. However, the different clinical significance of c-KIT mutation and EML between pediatric and adult patients with AE-AML remains unsure. Further study is needed to reveal the different phenotype of AE-AML in pediatric and adult patients, which is good for better understanding of the heterogeneity of AML1-ETO fusion protein.
In this multi-center retrospective study, we analyzed the demographic features of pediatric vs. adult patients in AE-AML, and demonstrated the different phenotype of c-KIT mutation and EML with age-dependence.