Improving outcomes of hematopoietic stem cell transplant for pediatric acute lymphoblastic leukemia in Hong Kong

Abstract

PURPOSE/OBJECTIVE: Our unit is one of the two pediatric hematopoietic stem cell transplant (HSCT) centres in Hong Kong. We started to perform HSCT for children with acute lymphoblastic leukemia (ALL) in 1993. We aimed to review their outcomes in the past 20 years. MATERIALS AND METHODS: This is a retrospective review of the patient and transplant characteristics and transplant outcomes of children with ALL who underwent HSCT in our unit in 1993-2012. RESULTS: We have performed allogeneic HSCT for 35 children (26 males and 9 females) with ALL. The median age at HSCT was 7.6 years (range, 0.8 to 17.0 years). Twelve children were transplanted in first complete remission, 17 in second remission, 4 in third remission, and 2 with non-remission. Donors were matched sibling (n ? 14), 1-antigen mismatched parent (n ? 3), matched unrelated donor (n ? 8), or unrelated cord blood (n ? 10). Conditioning employed total body irradiation plus etoposide and/or cyclophosphamide in children above 3 years old, and busulfan, cyclophosphamide and melphalan in children below 3 years. Five year overall survival (OS) and relapse-free survival (RFS) were better after year 2000 (OS:75.7% vs. 50.0%; RFS: 76.7% vs. 50.0%). The differences in OS and RFS in different eras were statistically significant after adjusting for age, gender, remission status, and type of donors (p ? 0.035 for OS and p ? 0.016 for RFS). Transplant-related mortalities were 33.3% before 2000 and 13.0% after 2000. CONCLUSIONS: Transplant outcomes for pediatric ALL steadily improved in Hong Kong in the past 20 years. This was likely attributable to improvement in supportive care with reduction in transplant-related mortality.