Comparison of two consecutive cohorts of childhood acute myeloid leukemia in Hong Kong

Abstract

PURPOSE/OBJECTIVE: To review the clinical data and outcome of two consecutive cohorts of pediatric patients with acute myeloid leukemia (AML) treated with two different protocols prospectively at 5 oncology units under coordination of Hong Kong Paediatric Haematology & Oncology Study Group (HKPHOSG) MATERIALS AND METHODS: Cohort 1 was treated with modified UKAML XII regimen from 1995 to 2007 (13 years). We treated Cohort 2 from 2008 to 2012 (5 years) with NOPHO AML 2004 protocol as a collaborating group. Main differences with the latter protocol were D15 marrow blast count as risk factor, use of idarubicin instead of daunorubicin, higher cumulative dose of cytarabine, indication for transplant and donor selection. Acute promyelocytic leukemia and myeloid leukemia of Down syndrome were excluded. RESULTS: There are 104 cases in Cohort 1 and 53 in Cohort 2. Age distribution and median age (9.5 yr) are similar in the two cohorts. There are more female in Cohort 1 (53.8%) than Cohort 2 (37.7%). The FAB subtype distribution shows no obvious difference, but the number of patients with t(8;21) or AML1-ETO is higher in Cohort 1 (17.3%) than Cohort 2 (9.4%). There is no significant difference in induction death (Cohort 1: 2.9%; Cohort 2: 3.8%) and Complete Remission (CR) rate after induction (Cohort 1: 92.3%; Cohort 2: 94.3%). Relapse rates for Cohort 1 and 2 are 46.1% and 37.7% while total transplant rates are 55.8% and 45.3% respectively. The 5-yr event-free survival (Cohort 1:43.3%; Cohort 2: 46.7%) and overall survival (Cohort 1: 64.65%; Cohort 2: 64.6%) show no significant difference. The median follow up is 112.2 months for Cohort 1, and is 30.7 months for Cohort 2. CONCLUSIONS: The recent protocol (NOPHO AML 2004) has been able to achieve similar survival rates as the last protocol with fewer transplants and less daunorubicin. Different strategies to improve treatment outcome are needed in future.