Survival of Children with Acute Lymphoblastic Leukemia with Risk Group-Based Protocol Changes: A Single Center Experience with 460 Patients over a 20-Year Period.

Purpose: Recent treatments for pediatric acute lymphoblastic leukemia (ALL) are founded on risk stratification. We examined the survival rates and prognostic factors of patients over a 20-year period at a single institution.

Materials and methods: This study analyzed patients diagnosed with ALL and treated at the Pediatric Department of Samsung Medical Center (SMC). Patients were categorized into standard-risk (SR), high-risk (HR), and very high-risk (VHR) groups. The SMC protocol for the HR group underwent two changes during the study period: A modified Children's Cancer Group (CCG)-1882 protocol was used from 2000 to 2005, the Korean multicenter HR ALL-0601 protocol from 2006 to 2014, and the Korean multicenter HR ALL-1501 protocol from 2015 to 2019.

Results: Of the 460 patients, complete remission was achieved in 436 patients (94.8%). The 10-year overall survival rate (OS) was 83.8±1.9% for all patients. OS according to the SMC risk group was as follows: 95.9±1.4% in the SR group, 83.8±3.6% in the HR group, and 66.2±6.9% in the VHR group. The 5-year OS within the HR group varied according to the treatment protocol: 73.9±7.5%, in the modified CCG-1882 protocol, 83.0±3.9%, in the 0601 protocol, and 96.2±2.6%, in the 1501 protocol. For those aged 15 years and older, the OS was only 56.5±13.1%. Relapse occurred in 71 patients (15.4%), and the OS after relapse was 37.7±6.0%.

Conclusion: The treatment outcomes of patients with ALL improved markedly. However, there is a need to further characterize adolescents and young adult patients, as well as those who have experienced relapses.