Treatment of children with acute lymphoblastic leukemia with risk group based intensification and omission of cranial irradiation: A Korean study of 295 patients.

Background: Recent studies indicate 70-80% event-free survival (EFS) for pediatric acute lymphoblastic leukemia (ALL). In this study, we report the outcome of 295 children and adolescents treated at our institution, with stratification into four risk groups, and omission of cranial irradiation in all patients. Procedure: Patients were diagnosed from January 2005 to December 2011 and classified and treated as low, standard, high, and very high risk groups. A delayed intensification phase was given twice for high and very high risk groups. None of the patients received cranial irradiation for central nervous system (CNS) prophylaxis. Results: The 10-year EFS and overall survival (OS) were 78.5 +/- 2.5% and 81.9 +/- 2.7%, respectively. EFS according to risk group was as follows: low risk 91.2 +/- 3.7%, standard risk 98.1 +/-+/- 1.9%, high risk 81.5 +/- 4.3%, very high risk 59.4 +/- 5.3%. In a multivariate analysis, high hyperdiploidy and infant ALL were significant predictors of EFS. Cumulative incidence of any relapse, isolated CNS relapse, and any CNS relapse were 17.1 +/- 2.3%, 1.5 +/- 0.7%, and 2.3 +/- 0.9%, respectively. Other events included infection-related deaths during remission induction chemotherapy (3), primary refractory disease (2), and treatment-related deaths in first complete remission (8). Conclusions: In this single-institution study of Korean pediatric ALL patients, risk group based intensification with omission of cranial irradiation resulted in EFS comparable to previous studies, excellent survival of low-and standard-risk patients, and a low rate of CNS relapse.