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.

Changes in tuberculosis risk after transplantation in the setting of decreased community tuberculosis incidence: a national population-based study, 2008-2020.

BACKGROUND: Transplant recipients are immunocompromised and vulnerable to developing tuberculosis. However, active tuberculosis incidence is rapidly declining in South Korea, but the trend of tuberculosis infection among transplant recipients has not been elucidated. This study aimed to evaluate the risk of active tuberculosis after transplantation, including risk factors for tuberculosis and standardized incidence ratios, compared with that in the general population. METHODS: This retrospective study was conducted based on the South Korean health insurance review and assessment database among those who underwent transplantation (62,484 recipients) between 2008 and 2020. Tuberculosis incidence was compared in recipients treated during higher- (2010-2012) and lower-disease burden (2016-2018) periods. Standardized incidence ratios were analyzed using the Korean Tuberculosis Surveillance System. The primary outcome was the number of new tuberculosis cases after transplantation. RESULTS: Of 57,103 recipients analyzed, the overall cumulative incidence rate 1 year after transplantation was 0.8% (95% confidence interval [CI]: 0.7-0.8), significantly higher in the higher-burden period than in the lower-burden period (1.7% vs. 1.0% 3 years after transplantation, P < 0.001). Individuals who underwent allogeneic hematopoietic stem cell transplantation had the highest tuberculosis incidence, followed by those who underwent solid organ transplantation and autologous hematopoietic stem cell transplantation (P < 0.001). The overall standardized incidence ratio was 3.9 (95% CI 3.7-4.2) and was the highest in children aged 0-19 years, at 9.0 (95% CI 5.7-13.5). Male sex, older age, tuberculosis history, liver transplantation, and allogeneic hematopoietic stem cell transplantation were risk factors for tuberculosis. CONCLUSIONS: Transplant recipients are vulnerable to developing tuberculosis, possibly influenced by their immunocompromised status, solid organ transplant type, age, and community prevalence of tuberculosis. Tuberculosis prevalence by country, transplant type, and age should be considered to establish an appropriate tuberculosis prevention strategy for high-risk groups.

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.

Paediatric palliative screening scale as a useful tool for clinicians' assessment of palliative care needs of pediatric patients: a retrospective cohort study.

BACKGROUND: Although the importance of palliative care in pediatric patients has been emphasized, many health care providers have difficulty determining when patients should be referred to the palliative care team. The Paediatric Palliative Screening Scale (PaPaS) was developed as a tool for screening pediatric patients for palliative care needs. The study aimed to evaluate the PaPaS as a reliable tool for primary care clinicians unfamiliar with palliative care. METHODS: This was a retrospective cohort study of patients referred to the pediatric palliative care teams in two tertiary hospitals in the Republic of Korea between July 2018 and October 2019. RESULTS: The primary clinical and pediatric palliative care teams assessed the PaPaS scores of 109 patients, and both teams reported a good agreement for the sum of the PaPaS score. Furthermore, the PaPaS scores correlated with those obtained using the Lansky performance scale. Although the mean PaPaS score was higher in the pediatric palliative care team, the scores were higher than the cut-off score for referral in both groups. CONCLUSION: The PaPaS can be a useful tool for primary care clinicians to assess the palliative care needs of patients and their families.

Erratum: Correction of Affiliations in the Article "Clinical Characteristics and Treatment Outcomes in Children, Adolescents, and Young-adults with Hodgkin's Lymphoma: a KPHOG Lymphoma Working-party, Multicenter, Retrospective Study".

This corrects the article on p. e393 in vol. 35, PMID: 33258329.

Clinical Characteristics and Treatment Outcomes in Children, Adolescents, and Young-adults with Hodgkin's Lymphoma: a KPHOG Lymphoma Working-party, Multicenter, Retrospective Study.

BACKGROUND: Hodgkin's lymphoma (HL) constitutes 10%-20% of all malignant lymphomas and has a high cure rate (5-year survival, around 90%). Recently, interest has increased concerning preventing secondary complications (secondary cancer, endocrine disorders) in long-term survivors. We aimed to study the epidemiologic features and therapeutic outcomes of HL in children, adolescents, and young adults in Korea. METHODS: We performed a multicenter, retrospective study of 224 patients aged < 25 years diagnosed with HL at 22 participating institutes in Korea from January 2007 to August 2016. RESULTS: A higher percentage of males was diagnosed at a younger age. Nodular sclerosis histopathological HL subtype was most common, followed by mixed cellularity subtype. Eighty-one (36.2%), 101 (45.1%), and 42 (18.8%) patients were classified into low, intermediate, and high-risk groups, respectively. Doxorubicin, bleomycin, vinblastine, dacarbazine was the most common protocol (n = 102, 45.5%). Event-free survival rate was 86.0% ± 2.4%, while five-year overall survival (OS) rate was 96.1% ± 1.4%: 98.7% ± 1.3%, 97.7% ± 1.6%, and 86.5% ± 5.6% in the low, intermediate, and high-risk groups, respectively (P = 0.021). Five-year OS was worse in patients with B-symptoms, stage IV disease, high-risk, splenic involvement, extra-nodal lymphoma, and elevated lactate dehydrogenase level. In multivariate analysis, B-symptoms and extra-nodal involvement were prognostic factors for poor OS. Late complications of endocrine disorders and secondary malignancy were observed in 17 and 6 patients, respectively. CONCLUSION: This is the first study on the epidemiology and treatment outcomes of HL in children, adolescents, and young adults in Korea. Future prospective studies are indicated to develop therapies that minimize treatment toxicity while maximizing cure rates in children, adolescents, and young adults with HL.

Development and validation of self- and caregiver-report of a distress screening tool for pediatric cancer survivors.

PURPOSE: To develop and validate the Distress Screening Tool (DST) for child and adolescent cancer survivors. METHODS: In part 1, items of the DST were generated through literature search and group interviews. Initially, the DST was tested on pediatric cancer survivors and their caregivers. In part 2, the modified version of the DST was retested with a different set of participants. Lastly, the psychometric properties and cutoff scores of the DST were evaluated on a separate set of survivors and caregivers. RESULTS: In part 1, six items of the DST self- and caregiver-report versions were generated. The initial 6 DST items of both versions showed acceptable internal consistency, but low inter-item correlation. Following the item modification, both versions of the DST showed improved inter-item correlation. In part 2, the modified DST had acceptable internal consistency and convergent validity, with acceptable psychometric properties. Cutoff scores were also generated. CONCLUSIONS: The DST could be a useful tool for pediatric cancer survivors.

Combined intravitreal melphalan and intravenous/intra-arterial chemotherapy for retinoblastoma with vitreous seeds.

PURPOSE: We aimed to evaluate the therapeutic effect and complications of combined intravitreal melphalan and intravenous/intra-arterial chemotherapy as a primary approach for retinoblastoma with vitreous seeds. METHODS: In this retrospective case series, eight eyes from eight retinoblastoma patients with vitreous seeds were included. All eyes received 20-30 µg of intravitreal melphalan accompanied by intravenous and intra-arterial chemotherapy. Triple freeze-thaw cryotherapy was performed when withdrawing the needle from the eye to prevent tumor dissemination. RESULTS: Tumors and vitreous seeds regressed in all eyes. The mean number of intravitreal melphalan injections was 3.25 (median 3.50, range 2-4). Globe salvage was attained in seven of eight eyes (87.5 %). Enucleation was performed in one case, in which the pathologic section showed no residual tumor and tumor-free resection margins. Serous retinal detachment was observed in four eyes (50 %), and vitreous hemorrhage developed in two (25 %). Retinal pigment epithelium atrophy or mottling was found in three eyes (37.5 %). There were no cases of extraocular tumor extension or remote metastasis. CONCLUSIONS: Combined intravitreal melphalan and intravenous/intra-arterial chemotherapy was effective for tumor and vitreous seeding control, but vision-threatening complications such as vitreous hemorrhage or serous retinal detachment occurred in half the cases.

Favorable outcome of alternate systemic and intra-arterial chemotherapy for retinoblastoma.

The recent trend of treatment for retinoblastoma is to salvage the eye globes as well as achieving patients' survival. Intra-arterial chemotherapy (IAC) is one of the current standard treatment; however, it cannot exclude the risk of occult micrometastases in the central nervous system in advanced-stage retinoblastoma. Alternate fashion of intravenous chemotherapy (IVC) and IAC strategy was developed to increase the eye salvage rate and to reduce the metastatic risk. Between January 2012 and December 2014, 13 eyes of 12 patients with newly diagnosed retinoblastoma received alternate chemotherapy using IVC and IAC in Yonsei Cancer Center. Eye salvage rate was assessed by the eye preservation time, which was defined as the duration from the diagnosis to the time of enucleation. Total 13 eyes were classified according to the International Classification of Retinoblastoma (ICRB) as group B (n = 1, 7.7%), group C (n = 2, 15.4%), group D (n = 5, 38.5%), or group E (n = 5, 38.5%). IAC was performed, 3 to 5 times (median: 4 times) for each eye, total 54 times. Five to 15 courses (median: 8 courses) of systemic chemotherapy were performed in the patients. During the median follow-up period of 30.4 months, overall eye salvage rate was 63.9 ± 14.7%. All patients survived. The treatment was tolerable without significant complications. These results showed that primary alternate IVC-IAC was tolerable and effective for retinoblastoma.

Poor bone health at the end of puberty in childhood cancer survivors.

BACKGROUND: Although the survival rate following childhood cancer is >80%, late effects are a major concern. We aimed to determine the clinical factors affecting bone health after puberty in childhood cancer survivors at risk for low bone mineral density (BMD). PROCEDURES: We performed dual-energy X-ray absorptiometry at the lumbar spine, femoral neck, and total hip regions for survivors with the following bone densitometry indications (BDIXs): brain or nasopharyngeal cancer, head or neck area radiotherapy, or corticosteroid treatment (N = 92). Additionally, we evaluated 16 survivors without these BDIXs but with other clinical factors that could affect bone health. We assessed the effects of these factors on BMD using univariate and logistic regression analyses. Moderate BMD deficit was defined as a Z-score of <-1.0 and ≥-2.0, and severe BMD deficit was defined as <-2.0. RESULTS: Severe BMD deficits were found in 18 survivors (16.7%) and moderate BMD deficits were in 39 (36.1%) in at least one bone region. BMD deficits tended to increase as the number of BDIXs increased (P < 0.010). There were no severe BMD deficits in survivors without BDIXs. The duration since cancer treatment completion was correlated with higher BMD (P < 0.05). Endocrine dysfunction was a significant risk factor for decreased BMD in univariate and multivariate analyses (P < 0.05 for both). CONCLUSIONS: Decreased BMD was prevalent in our study cohort. Endocrine dysfunction was found to be a significant risk factor, and it should be managed in survivors to ensure future bone health.

Incidence and Features of Lymphoid Proliferation and Lymphomas after Solid Organ or Hematopoietic Stem Cell Transplantation in a National Database Cohort.

PURPOSE: Post-transplantation lymphoproliferative disorders (PTLDs) after hematopoietic stem transplantation (HCT) or solid organ transplantation (SOT) result in poorer outcomes, including death. There are limited large cohort data on the incidence and natural course of PTLD in Asians. MATERIALS AND METHODS: We investigated PTLD using Korean national health insurance claims data of 47,518 patients who underwent HCT or SOT in 2008-2020. Patient demographics, time and type of PTLD diagnosis, type of PTLD treatment, and death data were collected. We used Fine and Gray subdistribution hazard models to calculate the cumulative incidence and risk factors for PTLD. RESULTS: During median follow-up of 5.32 years, PTLD occurred in 294 of 36,945 SOT patients (0.79%) and 235 of 10,573 HCT patients (2.22%). Cumulative incidence of PTLD were 0.49% at 1 year, 1.02% at 5 years, and 1.50% at 10 years post-transplantation. Age < 20 years (subdistribution hazard ratio [SHR] of 1.67 in age 10-19, SHR 1.51 in age 0-9), HCT (SHR 3.02), heart transplantation (SHR 2.27), and liver transplantation (SHR 1.47) were significant risk factors for PTLD. The presence of PTLD was associated with an increased risk of death (hazard ratio of 2.84). Overall, 5-year survival of PTLD patients was 68.9% (95% confidence interval, 64.9 to 73.2). CONCLUSION: We observed a steady increase in PTLD over 10 years after HCT or SOT in this large cohort study. Pediatric age group, HCT, liver transplantation, and heart transplantation were suggested to be risk factors for PTLD, and PTLD was associated with a higher risk of death.

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.

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.

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.

Allogeneic hematopoietic cell transplantation in patients with juvenile myelomonocytic leukemia in Korea: a report of the Korean Pediatric Hematology-Oncology Group.

Juvenile myelomonocytic leukemia (JMML) is a life-threatening myeloproliferative neoplasm. This multicenter study evaluated the characteristics, outcomes, and prognostic factors of allogeneic hematopoietic cell transplantation (HCT) in recipients with JMML who were diagnosed between 2000 and 2019 in Korea. Sixty-eight patients were retrospectively enrolled-28 patients (41.2%) received HCT during 2000-2010 and 40 patients (58.8%) during 2011-2020. The proportion of familial mismatched donors increased from 3.6 to 37.5%. The most common conditioning therapy was changed from Busulfan/Cyclophosphamide-based to Busulfan/Fludarabine-based therapy. The 5-year probabilities of event-free survival (EFS) and overall survival (OS) were 52.6% and 62.3%, respectively. The 5-year incidence of transplant-related mortality was 30.1%. Multivariate analysis revealed that the proportion of hemoglobin F ≥ 40%, abnormal cytogenetics, and matched sibling donors were independent risk factors for a higher relapse rate. Patients whose donor chimerism was below 99% had a significantly higher relapse rate. Better OS and lower treatment-related mortality were observed in patients with chronic graft-versus-host disease (GVHD), whereas grade III or IV acute GVHD was associated with worse EFS. In conclusion, the number of transplant increased along with the increase in alternative donor transplants, nevertheless, similar results were maintained. Alternative donor transplantation should be encouraged.

Response to chemotherapy in juvenile myelomonocytic leukemia and its clinical implications for survival: A retrospective registry-based study of the Korean Pediatric Hematology-Oncology Group.

Juvenile myelomonocytic leukemia (JMML) is a life-threatening myeloproliferative neoplasm. The chemotherapeutic effect on survival remains unclear, and feasible standardized response criteria are yet to be established. We aimed to evaluate the chemotherapeutic response and its effect on survival in patients with JMML. A retrospective registry was reviewed for children diagnosed with JMML between 2000 and 2019. Response was assessed according to the criteria proposed by the International JMML Symposium in 2007 (criteria I) and the updated version in 2013 with its modifications (criteria II). A total of 73 patients were included in this study. Complete response (CR) rates were 46.6% and 28.8% using the criteria I and criteria II, respectively. A platelet count ≥ 40 × 109/L at diagnosis was associated with higher CR rates using the criteria II. Patients with criteria I-based CR had a better overall survival (OS) than those without CR (81.1% vs. 49.1% at 5 years). Patients with criteria II-based CR showed better OS (85.7% vs. 55.5% at 5 years) and event-free survival (EFS) (71.1% vs. 44.7% at 5 years) than those without CR. Additionally, a trend toward better EFS was observed in patients with criteria II-based CR than in those with criteria I-based CR but without criteria II-based CR (71.1% vs. 53.8% at 5 years). Chemotherapeutic response is associated with better survival outcomes. Along with splenomegaly, the addition of platelet count recovery, existence of extramedullary leukemic infiltration, and more stringent leukocyte counts to the response criteria allows for a more sensitive prediction of survival outcomes.

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.

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.