This study introduces a novel biportal endoscopic foraminal decompression technique that minimizes bone removal while ensuring safe and effective nerve root decompression. Leveraging the accessory process as a key surgical landmark, this technique enables precise navigation and controlled turn-down of the ligamentum flavum (LF). A key advantage of this technique is its reduced requirement for bone resection, differing from traditional microscopic or uniportal endoscopic surgeries that often necessitate resection of the lateral isthmus or superior articular process. This technique is particularly beneficial for foraminal and extraforaminal herniated nucleus pulposus cases, where bony decompression needs are relatively lower compared to foraminal stenosis. Using the accessory process as a landmark also enhances surgical precision and reduces the risk of nerve root injury, providing a valuable advantage for less experienced surgeons. Despite these advantages, challenges exist, particularly at the L5–S1 level, where the less prominent accessory process and limited workspace due to anatomical constraints can pose difficulties. In cases of severe bony compression, additional bone removal may be necessary to achieve adequate decompression. In conclusion, the Non-facetectomy LF turn-down technique (non-facetectomy foraminal decompression) offers a safe and effective minimally invasive alternative for treating various foraminal pathologies.

This study introduces a novel biportal endoscopic foraminal decompression technique that minimizes bone removal while ensuring safe and effective nerve root decompression. Leveraging the accessory process as a key surgical landmark, this technique enables precise navigation and controlled turn-down of the ligamentum flavum (LF). A key advantage of this technique is its reduced requirement for bone resection, differing from traditional microscopic or uniportal endoscopic surgeries that often necessitate resection of the lateral isthmus or superior articular process. This technique is particularly beneficial for foraminal and extraforaminal herniated nucleus pulposus cases, where bony decompression needs are relatively lower compared to foraminal stenosis. Using the accessory process as a landmark also enhances surgical precision and reduces the risk of nerve root injury, providing a valuable advantage for less experienced surgeons. Despite these advantages, challenges exist, particularly at the L5–S1 level, where the less prominent accessory process and limited workspace due to anatomical constraints can pose difficulties. In cases of severe bony compression, additional bone removal may be necessary to achieve adequate decompression. In conclusion, the Non-facetectomy LF turn-down technique (non-facetectomy foraminal decompression) offers a safe and effective minimally invasive alternative for treating various foraminal pathologies.

This study introduces a novel biportal endoscopic foraminal decompression technique that minimizes bone removal while ensuring safe and effective nerve root decompression. Leveraging the accessory process as a key surgical landmark, this technique enables precise navigation and controlled turn-down of the ligamentum flavum (LF). A key advantage of this technique is its reduced requirement for bone resection, differing from traditional microscopic or uniportal endoscopic surgeries that often necessitate resection of the lateral isthmus or superior articular process. This technique is particularly beneficial for foraminal and extraforaminal herniated nucleus pulposus cases, where bony decompression needs are relatively lower compared to foraminal stenosis. Using the accessory process as a landmark also enhances surgical precision and reduces the risk of nerve root injury, providing a valuable advantage for less experienced surgeons. Despite these advantages, challenges exist, particularly at the L5–S1 level, where the less prominent accessory process and limited workspace due to anatomical constraints can pose difficulties. In cases of severe bony compression, additional bone removal may be necessary to achieve adequate decompression. In conclusion, the Non-facetectomy LF turn-down technique (non-facetectomy foraminal decompression) offers a safe and effective minimally invasive alternative for treating various foraminal pathologies.

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.

Background: The risk of device thrombosis and device-oriented clinical outcomes with bioresorbable vascular scaffold (BVS) was reported to be significantly higher than with contemporary drug-eluting stents (DESs). However, optimal device implantation may improve clinical outcomes in patients receiving BVS. The current study evaluated mid-term safety and efficacy of Absorb BVS with meticulous device optimization under intravascular imaging guidance. Methods: The SMART-REWARD and PERSPECTIVE-PCI registries in Korea prospectively enrolled 390 patients with BVS and 675 patients with DES, respectively. The primary endpoint was target vessel failure (TVF) at 2 years and the secondary major endpoint was patientoriented composite outcome (POCO) at 2 years. Results: Patient-level pooled analysis evaluated 1,003 patients (377 patients with BVS and 626 patients with DES). Mean scaffold diameter per lesion was 3.24 ± 0.30 mm in BVS group.Most BVSs were implanted with pre-dilatation (90.9%), intravascular imaging guidance (74.9%), and post-dilatation (73.1%) at proximal to mid segment (81.9%) in target vessel.Patients treated with BVS showed comparable risks of 2-year TVF (2.9% vs. 3.7%, adjusted hazard ratio [HR], 1.283, 95% confidence interval [CI], 0.487–3.378, P = 0.615) and 2-year POCO (4.5% vs. 5.9%, adjusted HR, 1.413, 95% CI, 0.663–3.012,P = 0.370) than those with DES. The rate of 2-year definite or probable device thrombosis (0.3% vs. 0.5%, P = 0.424) was also similar. The sensitivity analyses consistently showed comparable risk of TVF and POCO between the 2 groups. Conclusion With meticulous device optimization under imaging guidance and avoidance of implantation in small vessels, BVS showed comparable risks of 2-year TVF and device thrombosis with DES.

Background: Data on the status of long-term follow-up (LTFU) care for childhood cancer survivors (CCSs) in Korea is lacking. This study was conducted to evaluate the current status of LTFU care for CCSs and relevant physicians’ perspectives. Methods: A nationwide online survey of pediatric hematologists/oncologists in the Republic of Korea was undertaken. Results: Overall, 47 of the 74 board-certified Korean pediatric hematologists/oncologists currently providing pediatric hematology/oncology care participated in the survey (response rate = 63.5%). Forty-five of the 47 respondents provided LTFU care for CCSs five years after the completion of primary cancer treatment. However, some of the 45 respondents provided LTFU care only for CCS with late complications or CCSs who requested LTFU care. Twenty of the 45 respondents oversaw LTFU care for adult CCSs, although pediatric hematologists/ oncologists experienced more difficulties managing adult CCSs. Many pediatric hematologists/oncologists did not perform the necessary screening test, although CCSs had risk factors for late complications, mostly because of insurance coverage issues and the lack of Korean LTFU guidelines. Regarding a desirable LTFU care system for CCSs in Korea, 27 of the 46 respondents (58.7%) answered that it is desirable to establish a multidisciplinary CCSs care system in which pediatric hematologists/oncologists and adult physicians cooperate. Conclusion The LTFU care system for CCS is underdeveloped in the Republic of Korea. It is urgent to establish an LTFU care system to meet the growing needs of Korean CCSs, which should include Korean CCSs care guidelines, provider education plans, the establishment of multidisciplinary care systems, and a supportive national healthcare policy.

Purpose: Acute promyelocytic leukemia (APL) is a rare disease in children and there are some different characteristics between children and adult. We aimed to evaluate incidence, clinical characteristics and treatment outcomes of pediatric APL in Korea. Materials and Methods: Seventy-nine pediatric APL patients diagnosed from January 2009 to December 2016 in 16 tertiary medical centers in Korea were reviewed retrospectively. Results: Of 801 acute myeloid leukemia children, 79 (9.9%) were diagnosed with APL. The median age at diagnosis was 10.6 years (range, 1.3 to 18.0). Male and female ratio was 1:0.93. Thirty patients (38.0%) had white blood cell (WBC) count greater than 10×109/L at diagnosis. All patients received induction therapy consisting of all-trans retinoic acid and chemotherapy. Five patients (6.6%) died during induction chemotherapy and 66 patients (86.8%) achieved complete remission (CR) after induction chemotherapy. The causes of death were three intracranial hemorrhage, one cerebral infarction, and one sepsis. Five patients (7.1%) suffered a relapse during or after maintenance chemotherapy. The estimated 4-year event-free survival and overall survival (OS) rates were 82.1%±4.4%, 89.7%±5.1%, respectively. The 4-year OS was significantly higher in patients with initial WBC < 10×109/L than in those with initial WBC ≥ 10×109/L (p=0.020). Conclusion This study showed that the CR rates and survival outcomes in Korean pediatric APL patients were relatively good. The initial WBC count was the most important prognostic factor and most causes of death were related to serious bleeding in the early stage of treatment.

Purpose: Effectiveness and safety of clofarabine (one of the treatment mainstays in pediatric patients with relapsed/refractory acute lymphoblastic leukemia [ALL]) was assessed in Korean pediatric patients with ALL to facilitate conditional coverage with evidence development. Materials and Methods: In this multicenter, prospective, observational study, patients receiving clofarabine as mono/combination therapy were followed up every 4-6 weeks for 6 months or until hematopoietic stem cell transplantation (HSCT). Response rates, survival outcomes, and adverse events were assessed. Results: Sixty patients (2-26 years old; 65% B-cell ALL, received prior ≥ 2 regimen, 68.3% refractory to previous regimen) were enrolled and treated with at least one dose of clofarabine; of whom 26 (43.3%) completed 6 months of follow-up after the last dose of clofarabine. Fifty-eight patients (96.7%) received clofarabine combination therapy. Overall remission rate (complete remission [CR] or CR without platelet recovery [CRp]) was 45.0% (27/60; 95% confidence interval [CI], 32.4 to 57.6) and the overall response rate (CR, CRp, or partial remission [PR]) was 46.7% (28/60; 95% CI, 34.0 to 59.3), with 11 (18.3%), 16 (26.7%), and one (1.7%) patients achieving CR, CRp, and PR, respectively. The median time to remission was 5.1 weeks (95% CI, 4.7 to 6.1). Median duration of remission was 16.6 weeks (range, 2.0 to 167.6 weeks). Sixteen patients (26.7%) proceeded to HSCT. There were 24 deaths; 14 due to treatment-emergent adverse events. Conclusion Remission with clofarabine was observed in approximately half of the study patients who had overall expected safety profile; however, there was no favorable long-term survival outcome in this 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, highrisk, 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.