Comprehensive insights into AML relapse: genetic mutations, clonal evolution, and clinical outcomes.

INTRODUCTION: Acute myeloid leukemia (AML) is a complex hematologic malignancy characterized by uncontrolled proliferation of myeloid precursor cells within bone marrow. Despite advances in understanding of its molecular underpinnings, AML remains a therapeutic challenge due to its high relapse rate and clonal evolution. METHODS: In this retrospective study, we analyzed data from 24 AML patients diagnosed at a single institution between January 2017 and August 2023. Comprehensive genetic analyses, including chromosomal karyotyping, next-generation sequencing, and gene fusion assays, were performed on bone marrow samples obtained at initial diagnosis and relapse. Clinical data, treatment regimens, and patient outcomes were also documented. RESULTS: Mutations in core genes of FLT3, NPM1, DNMT3A, and IDH2 were frequently discovered in diagnostic sample and remained in relapse sample. FLT3-ITD, TP53, KIT, RUNX1, and WT1 mutation were acquired at relapse in one patient each. Gene fusion assays revealed stable patterns, while chromosomal karyotype analyses indicated a greater diversity of mutations in relapsed patients. Clonal evolution patterns varied, with some cases showing linear or branching evolution and others exhibiting no substantial change in core mutations between diagnosis and relapse. CONCLUSIONS: Our study integrates karyotype, gene rearrangements, and gene mutation results to provide a further understanding of AML heterogeneity and evolution. We demonstrate the clinical relevance of specific mutations and clonal evolution patterns, emphasizing the need for personalized therapies and measurable residual disease monitoring in AML management. By bridging the gap between genetics and clinical outcome, we move closer to tailored AML therapies and improved patient prognoses.

Unraveling trajectories from aplastic anemia to hematologic malignancies: genetic and molecular insights.

Background: Aplastic anemia (AA), characterized by hematopoietic stem cell deficiency, can evolve into different hematologic malignancies. Our understanding of the genetic basis and mechanisms of this progression remains limited. Methods: We retrospectively studied 9 acquired AA patients who later developed hematologic malignancies. Data encompassed clinical, laboratory, karyotype, and next-generation sequencing (NGS) information. We explored chromosomal alterations and mutation profiles to uncover genetic changes underlying the transition. Results: Nine AA patients developed myelodysplastic syndrome (seven patients), acute myeloid leukemia (one patient), or chronic myelomonocytic leukemia (one patient). Among eight patients with karyotype results at secondary malignancy diagnosis, monosomy 7 was detected in three. Trisomy 1, der(1;7), del(6q), trisomy 8, and del(12p) were detected in one patient each. Among three patients with NGS results at secondary malignancy diagnosis, KMT2C mutation was detected in two patients. Acquisition of a PTPN11 mutation was observed in one patient who underwent follow-up NGS testing during progression from chronic myelomonocytic leukemia to acute myeloid leukemia. Conclusion: This study highlights the genetic dynamics in the progression from AA to hematologic malignancy. Monosomy 7's prevalence and the occurrence of PTPN11 mutations suggest predictive and prognostic significance. Clonal evolution underscores the complexity of disease progression.

Long-term Outcomes of Protocol-Based Treatment for Newly Diagnosed Medulloblastoma.

PURPOSE: The Korean Society of Pediatric Neuro-Oncology (KSPNO) conducted treatment strategies for children with medulloblastoma (MB) by using alkylating agents for maintenance chemotherapy or tandem high-dose chemotherapy (HDC) with autologous stem cell rescue (ASCR) according to the risk stratification. The purpose of the study was to assess treatment outcomes and complications based on risk-adapted treatment and HDC. MATERIALS AND METHODS: Fifty-nine patients diagnosed with MB were enrolled in this study. Patients in the standard-risk (SR) group received radiotherapy (RT) after surgery and chemotherapy using the KSPNO M051 regimen. Patients in the high-risk (HR) group received two and four chemotherapy cycles according to the KSPNO S081 protocol before and after reduced RT for age following surgery and two cycles of tandem HDC with ASCR consolidation treatment. RESULTS: In the SR group, 24 patients showed 5-year event-free survival (EFS) and overall survival (OS) estimates of 86.7% (95% confidence interval [CI], 73.6 to 100) and 95.8% (95% CI, 88.2 to 100), respectively. In the HR group, more infectious complications and mortality occurred during the second HDC than during the first. In the HR group, the 5-year EFS and OS estimates were 65.5% (95% CI, 51.4 to 83.4) and 72.3% (95% CI, 58.4 to 89.6), respectively. CONCLUSION: High intensity of alkylating agents for SR resulted in similar outcomes but with a high incidence of hematologic toxicity. Tandem HDC with ASCR for HR induced favorable EFS and OS estimates compared to those reported previously. However, infectious complications and treatment-related mortalities suggest that a reduced chemotherapy dose is necessary, especially for the second HDC.

A population pharmacokinetic model of methotrexate in Korean patients with haematologic malignancy.

AIMS: This study was conducted to develop a population pharmacokinetic (PK) model of methotrexate in Korean patients with haematologic malignancy, identify factors affecting methotrexate PK, and propose an optimal dosage regimen for the Korean population. METHODS: Data were retrospectively collected from 188 patients with acute leukaemia or non-Hodgkin's lymphoma who were admitted to Severance Hospital during the period from November 2005 to January 2016. Using demographic factors and laboratory results as potential covariates for PK parameters, model development was performed using NONMEM and optimal dosing regimens were developed using the final PK model. RESULTS: A two-compartment model incorporating body weight via allometry best described the data, yielding typical parameter values of 25.09 L for central volume of distribution ( V 1 ), 17.65 L for peripheral volume of distribution ( V 2 ), 12.89 L/h for clearance (CL) and 0.655 L/h for inter-compartmental clearance in a 50 kg patient. Covariate analyses showed that, at the weight of 50 kg, CL decreased by 0.11 L/h for each 1-year increase in age above 14 years old and decreased 0.8-fold when serum creatinine level doubled, indicating the importance of age-specific dose individualization in methotrexate treatment. Volume of distribution at steady state derived from PK parameters (= V 1 + V 2 ) was 0.85 L/kg, which was similar to those in the Western or Chinese populations. Optimal doses simulated from the final model successfully produced the PK measures close to the target chosen. CONCLUSIONS: The population PK model and optimal dosage regimens developed in this study can be used as a basis to achieve precision dosing in Korean patients with haematologic malignancy.

Diagnostic yield of targeted next-generation sequencing for pediatric hereditary hemolytic anemia.

BACKGROUND: Hereditary hemolytic anemia (HHA) refers to a heterogeneous group of genetic disorders that share one common feature: destruction of circulating red blood cells (RBCs). The destruction of RBCs may be due to membranopathies, enzymopathies, or hemoglobinopathies. Because these are genetic disorders, incorporation of next-generation sequencing (NGS) has facilitated the diagnostic process of HHA. METHOD: Genetic data from 29 patients with suspected hereditary anemia in a tertiary hospital were retrospectively reviewed to evaluate the efficacy of NGS on hereditary anemia diagnosis. Targeted NGS was performed with custom probes for 497 genes associated with hematologic disorders. After genomic DNA was extracted from peripheral blood, prepared libraries were hybridized with capture probes and sequenced using NextSeq 550Dx (Illumina, San Diego, CA, USA). RESULT: Among the 29 patients, ANK1 variants were detected in five, four of which were pathogenic or likely pathogenic variants. SPTB variants were detected in six patients, five of which were classified as pathogenic or likely pathogenic variants. We detected g6pd pathogenic and spta1 likely pathogenic variants in two patients and one patient, respectively. Whole-gene deletions in both HBA1 and HBA2 were detected in two patients, while only HBA2 deletion was detected in one patient. One likely pathogenic variant in PLKR was detected in one patient, and one likely pathogenic variant in ALAS2 was detected in another. CONCLUSION: Here, NGS played a critical role in definitive diagnosis in 18 out of 29 patients (62.07%) with suspected HHA. Thus, its incorporation into the diagnostic workflow is crucial.

Development and psychometric properties of the social adjustment scale for youth cancer survivors in South Korea.

Objective: We developed a new scale-the Social Adjustment Scale for Youth Cancer Survivors-and examined its psychometric properties. Methods: In the scale's development stage, preliminary items were constructed based on the results of a concept analysis of the hybrid model, literature review, and interviews. These items were then reviewed through content validity and cognitive interviews. In the validation stage, 136 survivors were recruited from two children's cancer centers in Seoul, South Korea. An exploratory factor analysis was performed to identify a set of constructs, and validity and reliability were tested. Results: Starting with 70 items constructed through literature review and interviews with youth survivors, the final scale comprised 32 items. The exploratory factor analysis identified four domains-namely, role achievement in one's present position, harmony in relationships, disclosure and acceptance of cancer history, and preparation and expectation for future roles. Correlations with quality of life indicated good convergent validity (r â€‹= â€‹0.82, P â€‹< â€‹0.001). The Cronbach's α of the overall scale was 0.95, indicating excellent internal consistency; and the intraclass correlation coefficient was 0.94 (P â€‹< â€‹0.001), suggesting high test-retest reliability. Conclusions: The Social Adjustment Scale for Youth Cancer Survivors exhibited acceptable psychometric properties in measuring the social adjustment of youth cancer survivors. It can be used to identify youths facing difficulty in adjusting to society after treatment and to investigate the effect of interventions implemented to promote social adjustment among youth cancer survivors. Future research is needed to examine the applicability of the scale in patients across diverse cultural backgrounds and healthcare systems.

Real-world data of long-term survival in patients with T-cell lymphoma who underwent stem cell transplantation.

This study aimed to identify the benefits of autologous-stem cell transplantation (auto-SCT) and allogeneic-SCT (allo-SCT) in patients with aggressive T-cell lymphomas to aid in the selection of transplantation type in clinical practice. This study retrospectively analyzed data from 598 patients who underwent transplantation for T-cell lymphomas from 2010 to 2020. In total, 317 patients underwent up-front SCT as consolidation therapy. The 3-year progression-free survival (PFS) and overall survival (OS) were 68.7% and 76.1%, respectively. Patients who underwent auto-SCT had significantly better OS (p = 0.026) than those who underwent allo-SCT; however, no statistical difference in PFS was found. Transplantation was used as a salvage therapy in 188 patients who had relapsed/refractory disease. Overall, 96 (51.1%) patients underwent auto-SCT and 92 (48.9%) patients underwent allo-SCT. Auto-SCT improved long-term survival in patients with complete remission (CR). Allo-SCT demonstrated better 3-year PFS in patients with partial remission and relapsed/refractory disease status. However, >50% of patients died within 1 year of allo-SCT. As a consolidative therapy, up-front auto-SCT demonstrated a survival benefit. Auto-SCT was also effective in patients who achieved CR after salvage therapy. If the disease persists or cannot be controlled, allo-SCT may be considered with reduced intensity conditioning.

Development and effects of an internet-based family resilience-promoting program for parents of children with cancer: A randomized controlled trial.

PURPOSE: The diagnosis of cancer in children can negatively impact their parents, owing to the complex treatment processes. Families with high levels of resilience can overcome these difficulties and thus perform higher family functions. We aimed to develop an internet-based family resilience-promoting program for parents of children with cancer and evaluate its effect on the levels of family resilience, depression, and family function. METHODS: This prospective, parallel-group, randomized-controlled study that was conducted at Yonsei Cancer Center from June to October 2021 included 41 parents of children with cancer. In total, four sessions of the internet-based family resilience-promoting program, led by a nurse, were conducted individually for parents. Levels of family resilience, depression, and family function were measured before, immediately after, and 4 weeks after the program. The data were analyzed using the linear mixed-effect model, and program satisfaction was evaluated through an internet-based questionnaire and interview. RESULTS: The experimental group (the family resilience-promoting program participants) differed more significantly from the control group in the level of change in family resilience (ß = 13.214, p = 0.003, effect size = 0.374) and family function (ß = 1.256, p = 0.018, effect size = 0.394). However, there was no significant difference between the groups in the level of depression (ß = 2.133, p = 0.187, effect size = 0.416). All the program participants showed a high program satisfaction score of 4.75 out of 5.00 points overall. CONCLUSIONS: The applicability of the internet-based family resilience-promoting program as an appropriate nursing intervention was verified. Its application can help the families of children with cancer adapt to the stressful situation of their children's cancer diagnosis and treatment.

Epidemiologic and Clinical Outcomes of Pediatric Renal Tumors in Korea: A Retrospective Analysis of The Korean Pediatric Hematology and Oncology Group (KPHOG) Data.

PURPOSE: Renal tumors account for approximately 7% of all childhood cancers. These include Wilms tumor (WT), clear cell sarcoma of the kidney (CCSK), malignant rhabdoid tumor of the kidney (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea. MATERIALS AND METHODS: From January 2001 to December 2015, data of pediatric patients (0-18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed. RESULTS: Among 439 patients (male, 240), the most common tumor was WT (n=342, 77.9%), followed by RCC (n=36, 8.2%), CCSK (n=24, 5.5%), MRTK (n=16, 3.6%), CMN (n=12, 2.7%), and others (n=9, 2.1%). Median age at diagnosis was 27.1 months (range 0-225.5) and median follow-up duration was 88.5 months (range 0-211.6). Overall, 32 patients died, of whom 17, 11, 1, and 3 died of relapse, progressive disease, second malignant neoplasm, and treatment-related mortality. Five-year overall survival and event free survival were 97.2% and 84.8% in WT, 90.6% and 82.1% in RCC, 81.1% and 63.6% in CCSK, 60.3% and 56.2% in MRTK, and 100% and 91.7% in CMN, respectively (p < 0.001). CONCLUSION: The pediatric renal tumor types in Korea are similar to those previously reported in other countries. WT accounted for a large proportion and survival was excellent. Non-Wilms renal tumors included a variety of tumors and showed inferior outcome, especially MRTK. Further efforts are necessary to optimize the treatment and analyze the genetic characteristics of pediatric renal tumors in Korea.

Care Needs of Adolescents and Young Adults with Cancer Undergoing Active Treatment in South Korea: A Mixed Methods Study.

Purpose: Adolescents and young adults (AYAs) with cancer have special care needs that are different from those of children and older adults with cancer. This study assessed the perspective and experience of AYAs with cancer in South Korea to identify their care needs. Methods: This study used a convergent mixed-methods design. From July 2020 to November 2021, AYAs with cancer (N = 77; 15-39 years of age) participated in a quantitative cross-sectional study, using a tool developed by our study team. In May 2021, a qualitative focus group was conducted with 10 AYAs with cancer. Integrated analyses were conducted concurrently by reporting the quantitative and qualitative findings together. Results: Quantitative findings revealed that the highest care need domains were communication and information, whereas the highest care priority item was the management of pain and symptoms occurring during the treatment. Qualitative findings revealed 12 themes across 5 domains. Comparing and merging of the quantitative and qualitative data resulted in eight confirmed themes and four expanded findings, including knowing people who overcame similar illnesses, fear of death, dedicated space, and a program for AYAs with cancer. Conclusion: When developing and implementing programs and health care services, especially in countries with no established program or cancer specialty unit for AYAs with cancer, it is important to consider the special care needs and priorities of AYAs with cancer. This mixed methods study provided empirical evidence to help understand and prioritize the needs of AYAs with cancer undergoing active treatment in South Korea.

The Efficacy of Alternate Systemic Intravenous Chemotherapy and Intra-arterial Chemotherapy Approach for Eye Globe Salvage in Retinoblastoma.

PURPOSE: The advances in the treatment of retinoblastoma have enabled salvaging the globe in advanced stages with intra-arterial chemotherapy (IAC). We developed a strategy of alternate application of systemic intravenous chemotherapy (IVC) and IAC (referred to as alternate systemic IVC and IAC; ASIAC) to reduce central nervous metastases during IAC and examined its efficacy and safety in eye globe salvage in this study. MATERIALS AND METHODS: Between January 2010 and February 2021, 43 eyes of 40 patients received ASIAC treatment for retinoblastoma at the Yonsei Cancer Center, Yonsei University Health System. Their medical records were reviewed retrospectively to evaluate the eye salvage rate (ESR), defined from diagnosis to enucleation. High-risk retinoblastoma was defined as group D or E by the International Classification of Retinoblastoma. RESULTS: The study enrolled 38 and five cases of high-risk and low-risk retinoblastoma, respectively. In total, 178 IAC and 410 IVC courses were administered, with a median of 4 (interquartile range [IQR], 3.0 to 5.0) IAC and 9 (IQR, 6.0 to 11) IVC courses per eye, respectively. The 5-year ESR was 60.4%±8.7% for the whole cohort, 100% for low-risk retinoblastoma, and 53.6%±9.8% for high-risk retinoblastoma. Among those diagnosed since 2015, the 5-year ESR for high-risk retinoblastoma was 63.5%±14.0%. Fifteen eyes underwent enucleation; no viable tumor was found in three enucleated eyes. There were no deaths in this cohort. CONCLUSION: Primary IAC-IVC (i.e., ASIAC) for patients with retinoblastoma was tolerable and effective in salvaging the eye and maintaining survival.

Factors influencing perceived communication quality for successful fertility preservation counseling for adolescent and young adult cancer patients and their caregivers in Korea.

PURPOSE: Although relatively new in Asian countries, fertility preservation (FP) discussions are crucial for adolescent and young adult (AYA) cancer patients. This study highlights patients' and their caregivers' perceptions of communications quality during FP discussions in Korea. METHODS: Participants were AYA patients and their caregivers (each: n = 34). The study examined the clinical pathways for FP and used surveys to collect details on discussion characteristics and satisfaction levels during FP discussions at the Yonsei Cancer Center, Seoul, Korea. Quality and degree of satisfaction with FP discussions were measured on a scale ranging from 1 to 7. RESULTS: Two caregivers did not complete the survey. All respondents reported high overall satisfaction; however, several factors were related to low satisfaction with information quality. Caregivers who received both verbal communication and nonverbal communication tools (e.g., pamphlets, Internet resources) were more satisfied with the information quality than those who only received verbal communication. Regarding provider type, both respondent groups reported high overall satisfaction with physicians, rather than other types of care providers. Regarding the number of discussion sessions, respondents reported an improved understanding of FP and better communication and information quality if they participated in more than one discussion session. CONCLUSION: The FP process for AYA cancer patients can be improved by adjusting the type of provider, number of discussion sessions, and types of information. This will form the cornerstone of effective FP communication in Korea.

Outcomes of intracranial non-germinomatous germ cell tumors: a retrospective Asian multinational study on treatment strategies and prognostic factors.

PURPOSE: Non-germinomatous germ cell tumors (NGGCTs) are rare pediatric conditions. This multicenter study using Asian multinational patient data investigated treatment outcomes and prognostic factors for NGGCTs. METHODS: Medical records of 251 patients with NGGCTs treated from 1995 to 2015 were retrospectively analyzed from participating centers in Asian countries (Korea, Taiwan, Singapore, and Japan). RESULTS: The median follow up was 8.5 years (95% CI 7.8-9.9). In the total cohort, 5-year event-free survival (EFS) and overall survival (OS) rates were 78.2% and 85.4%, respectively. In 17.9% of the patients, diagnosis was determined by tumor markers alone (alpha-fetoprotein ≥ 10 ng/mL (Korea) or > 25 ng/mL (Taiwan and Singapore), and/or ß-human chorionic gonadotropin (ß-hCG) ≥ 50 mIU/mL). Patients with immature teratomas and mature teratomas comprised 12.0% and 8.4%, respectively. The 5-year EFS rate was higher in patients with histologically confirmed germinoma with elevated ß-hCG (n = 28) than those in patients with malignant NGGCTs (n = 127). Among malignant NGGCTs, patients with choriocarcinoma showed the highest 5-year OS of 87.6%, while yolk sac tumors showed the lowest OS (68.8%). For malignant NGGCT subgroups, an increase in serum ß-hCG levels by 100 mIU/mL was identified as a significant prognostic factor associated with the EFS and OS. CONCLUSION: Our result shows excellent survival outcomes of overall CNS NGGCT. However, treatment outcome varied widely across the histopathologic subgroup of NGGCT. Hence, this study suggests the necessity for accurate diagnosis by surgical biopsy and further optimization of diagnosis and treatment according to the histopathology of NGGCTs. Future clinical trials should be designed for individualized treatments for different NGGCTs subsets.

Comparison of blood collection tubes for 29 biochemical analytes in pediatric patients with central venous catheters.

BACKGROUND: Pediatric cancer patients undergoing chemotherapy or radiation therapy generally require a central venous catheter (CVC). However, serum drawn from CVCs has several drawbacks for use in routine chemistry tests. Biochemical analytes were evaluated using heparin plasma instead of serum to maintain turnaround time and to prevent problems caused by micro-clot formation or delayed clotting time. METHODS: Venous blood samples from 52 pediatric oncology patients with chemoports or Hickman catheters were collected in serum separating tubes (SSTs) and lithium heparin tubes (LHTs). A total of 29 parameters were analyzed on a Cobas c702 (Roche Diagnostics, Mannheim, Germany). Passing-Bablok regression and Bland-Altman difference plots were used for statistical analyses. RESULTS: When the mean value of each analyte measured from LHT was compared with those from SST, percentage bias was within the desirable bias limit in most of the analytes. However, albumin, potassium, and inorganic phosphorus showed a negative constant bias of -3.0%, -5.3%, and -1.6%, respectively, and total protein showed a positive constant bias of + 3.8%. CONCLUSIONS: The use of LHTs for sample collection from pediatric patients with CVCs could be helpful for routine chemistry analyses. The results of potassium and total protein should be interpreted with consideration of the difference between serum and plasma samples.

Avelumab in paediatric patients with refractory or relapsed solid tumours: dose-escalation results from an open-label, single-arm, phase 1/2 trial.

BACKGROUND: We report dose-escalation results from an open-label, phase 1/2 trial evaluating avelumab (anti-PD-L1) in paediatric patients with refractory/relapsed solid tumours. METHODS: In phase 1, patients aged < 18 years with solid (including central nervous system [CNS]) tumours for which standard therapy did not exist or had failed were enrolled in sequential cohorts of 3-6 patients. Patients received avelumab 10 or 20 mg/kg intravenously every 2 weeks. Primary endpoints were dose-limiting toxicities (DLTs) and grade ≥ 3 treatment-emergent adverse events (AEs). RESULTS: At data cut-off (27 July 2021), 21 patients aged 3-17 years had received avelumab 10 mg/kg (n = 6) or 20 mg/kg (n = 15). One patient had three events that were classified as a DLT (fatigue with hemiparesis and muscular weakness associated with pseudoprogression; 20 mg/kg cohort). Grade ≥ 3 AEs occurred in five (83%) and 11 (73%) patients in the 10 and 20 mg/kg cohorts, respectively, and were treatment-related in one patient (7%; grade 3 [DLT]) in the 20 mg/kg cohort. Avelumab exposure in paediatric patients receiving 20 mg/kg dosing, but not 10 mg/kg, was comparable or higher compared with approved adult dosing (10 mg/kg or 800 mg flat dose). No objective responses were observed. Four patients with CNS tumours (20 mg/kg cohort) achieved stable disease, which was ongoing in two patients with astrocytoma at cut-off (for 24.7 and 30.3 months). CONCLUSION: In paediatric patients with refractory/relapsed solid tumours, avelumab monotherapy showed a safety profile consistent with previous adult studies, but clinical benefits were limited.

Noma disease (cancrum oris, orofacial gangrene) in an acute myeloid leukemia patient: a case report.

BACKGROUND: Noma is a rare disease that occurs mainly in malnourished patients in developing countries. Noma starts as facial swelling and gingival necrosis that eventually necrotizes underlying tissues including the jaw bone, leaving severe disfigurement. It is reported extremely rarely in patients with severe immunosuppression or blood dyscrasia. CASE PRESENTATION: The gingivitis that occurred in a 12-year-old Asian female patient with acute myeloid leukemia was getting increasingly worse. Although the proper treatment was done, the patient's condition did not improve, and eventually, a large full-thickness defect was left in the maxillofacial part. CONCLUSIONS: Early diagnosis and management is the only way to prevent the progression, which leads to facial disfigurement. We present a case of noma in a pediatric acute myeloid leukemia patient, in which oral function was restored through surgical intervention.

Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) System for Pediatric Patients with Hepatoblastoma: A Retrospective, Hospital-Based Cohort Study in South Korea.

PURPOSE: In 2017, the Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) system was introduced. We aimed to evaluate the accuracy of CHIC-HS System for the prediction of event-free survival (EFS) in Korean pediatric patients with hepatoblastoma. MATERIALS AND METHODS: This two-center retrospective study included consecutive Korean pediatric patients with histopathologically confirmed hepatoblastoma from March 1988 through September 2019. We compared EFS among four risk groups according to the CHIC-HS system. Discriminatory ability of CHIC-HS system was also evaluated using optimism-corrected C-statistics. Factors associated with EFS were explored using multivariable Cox regression analysis. RESULTS: We included 129 patients (mean age, 2.6±3.3 years; female:male, 63:66). The 5-year EFS rates in the very low, low, intermediate, and high-risk groups, according to the CHIC-HS system were 90.0%, 82.8%, 73.5%, and 51.3%, respectively. The CHIC-HS system aligned significantly well with EFS outcomes (p=0.004). The optimism-corrected C index of CHIC-HS was 0.644 (95% confidence interval [CI], 0.561 to 0.727). Age ≥ 8 (vs. age ≤ 2; hazard ratio [HR], 2.781; 95% CI, 1.187 to 6.512; p=0.018), PRE-Treatment EXTent of tumor (PRETEXT) stage IV (vs. PRETEXT I or II; HR, 2.774; 95% CI, 1.228 to 5.974; p=0.009), and presence of metastasis (HR, 2.886; 95% CI, 1.457 to 5.719; p=0.002), which are incorporated as the first three nodes in the CHIC-HS system, were independently associated with EFS. CONCLUSION: The CHIC-HS system aligned significantly well with EFS outcomes in Korean pediatric patients with hepatoblastoma. Age group, PRETEXT stage, and presence of metastasis were independently associated with EFS.