Characteristics and Therapeutic Outcomes of Acute Promyelocytic Leukemia in Children and Adolescents / 임상소아혈액종양

ABSTRACT

BACKGROUND: Acute promyelocytic leukemia (APL) is rare in children, accounting for 5-7% of all acute myeloid leukemia (AML) cases. This study aimed to review clinical and laboratory characteristics of pediatric APL patients, and to analyze the therapeutic outcomes. METHODS: Twenty pediatric patients with APL, diagnosed from January 1998 to April 2016, were retrospectively reviewed. Clinical and laboratory findings were collected, and morphologic, immunophenotypic, cytogenetic and molecular characteristics were evaluated. Therapeutic outcomes and prognostic factors of patients were analyzed. RESULTS: The number of pediatric APL patients was 20, which was 18.5% of all the cases of AML. The 5-year overall survival (OS) and event-free survival (EFS) were 88.5±7.6% and 83.0±9.0%, respectively. As compared to typical APL patients, patients with microgranular variants (M3v) (n=4, 20%) showed a tendency for a younger age, low white blood cell counts, and a shorter prothrombin time (P=0.045), but their 5-year OS and EFS were not significantly different. Better survival was observed in ATRA plus chemotherapy group both for 5-year OS (100% vs. 60.0±21.9%, P=0.018), and for 5-year EFS (60.0±21.9% vs. 91.7±8.0%, P=0.080) than ATRA only group. Stem cell transplantations were given to 3 patients and they are alive without disease for 8.3-16.5 years of follow-up. One death after relapse, another death in remission and development of secondary leukemia were encountered during the study period. CONCLUSION: This study analyzed clinical characteristics of pediatric APL and demonstrated very good outcome with the combination of ATRA and chemotherapy.