Patients and methods
We retrospectively studied 307 newly diagnosed non-M3 AML patients at our center over ten years from October 2005 to September 2015. The follow-up period ranged from 1 to 176 months, with a median follow-up time of 35 months. AML patients ≤15 years old were consecutively enrolled, and acute promyelocytic leukemia patients were excluded. The diagnosis and morphologic subtype of AML was based on the French-American-British (FAB) classification.13 All patients were classified into two groups according to the WBC count at diagnosis: those without hyperleukocytosis (WBC count <50×109/L group) versus those with hyperleukocytosis (WBC count ≥50×109/L group). Moreover, patients in the hyperleukocytosis group were divided into two subgroups: 32 patients with WBC count 50-100×109/L and 49 with WBC count ≥100×109/L. Cytogenetic risk category accorded to 2017 European leukemia net(ELN) .14
Chemotherapyregimen
All patient in this study received Chinese Academy of Medical Science (CAMS)-2009 regimen, referred to the AML99 program for chemotherapy.15 The standard induction treatment regimen consisted of etoposide,150 mg/m2with a 2-hour infusion on days 1-5, 3 days of idarubicin ,8 mg/m2 iv on days 6-8, and seven days of cytarabine, 200 mg/m2 on days 6-12. A second course of induction therapy was given if not achieved CR. The five courses of consolidation treatment consisted of high-dose cytarabine combined with etoposide or idarubicin.16 Patients with high risk or secondary remission after recurrence recommended to receive allogeneic hematopoietic stem cell transplantation(HSCT). If there was no condition to perform HSCT, consolidation and strengthen treatment should be continued. The patients received prophylactic treatment for central nervous system through intrathecal multi-drug chemotherapy at once per course of treatment.