Outcome after relapse in childhood acute lymphoblastic leukemia

Among 157 children with acute lymphoblastic leukemia (ALL) who experienced relapse at 54 institutes participating in the Japan Association of Childhood Leukemia Study, we analyzed the outcomes after relapse in 103 and 30 eligible cases with bone marrow (BM) and central nervous system (CNS) relapse, respectively. Reinduction rates in BM and CNS relapse cases were 72.3% and 83.3%, respectively. High reinduction rates were observed in B-precursor (B-pre) phenotype ALL in both relapse groups and in late (more than 24 months from onset) BM-relapse patients. After BM relapse, the overall 5-year survival rate was superior in the allogeneic stem cell transplantation (SCT) group compared to the non-SCT group (41.9%+/-8.2% versus 13.6%+/-6.5%, P < .0001). In contrast, the 4-year overall survival rate was not significantly different between the SCT (allogeneic plus autologous) and non-SCT groups after CNS relapse (26.8%+/-14.2% versus 61.9%+/-12.3%, P = .252). The late BM-relapse patients showed a significantly higher survival rate than did early-relapse patients, and survival rates were similar between the allogeneic and autologous group when the patients underwent SCT during a second complete remission. Moreover, B-pre ALL patients classified in the standard-risk group according to National Cancer Institute/Rome's criteria at onset had a good prognosis after allogeneic SCT. Improving the cure rate in relapsed ALL patients requires more intensive reinduction therapy and efforts to succeed with SCT in early BM-relapse patients as well as the establishment of a treatment strategy including indications of SCT for CNS-relapse patients.