Objective: Revision surgery for recurrent cervical radiculopathy or myelopathy after posterior decompression is technically challenging because of epidural adhesions, altered anatomy, and the risk of postoperative instability. Although anterior cervical discectomy and fusion is commonly performed, it sacrifices segmental motion and is associated with fusion-related morbidity. This technical report describes the surgical technique and early clinical outcomes of unilateral biportal endoscopic (UBE) posterior cervical revision as a motion-preserving alternative. Methods: Five patients underwent UBE-assisted posterior cervical revision surgery for recurrent cervical disc herniation, foraminal stenosis, or central canal stenosis. Procedures included inclinatory foraminotomy or unilateral laminotomy with bilateral decompression, depending on pathology. Clinical outcomes were evaluated using visual analogue scale (VAS) scores for neck and arm pain, motor strength assessment, radiographic evaluation, and modified MacNab criteria. All patients were followed for at least 1 year. Results: All procedures were completed without conversion to open surgery or the need for fusion. Adequate neural decompression was achieved in all cases, with preservation of facet joint integrity and cervical alignment. Neck pain VAS scores improved from 4–8 preoperatively to 0–1 at 1 year postoperatively, while arm pain VAS scores improved from 7–9 to 0–2. Motor weakness improved in all patients who presented with preoperative deficits. No intraoperative or postoperative complications were observed during the follow-up period. Conclusion UBE-assisted posterior cervical revision surgery appears to be a feasible and effective minimally invasive option for selected patients. This technique allows sufficient decompression while preserving cervical motion and avoiding fusion-related morbidity.

To demonstrate the feasibility and highlight key technical nuances of a unilateral biportal endoscopic (UBE) transforaminal approach for resecting chronic, centrally calcified thoracic disc herniation (TDH). Central TDH is a rare and technically demanding condition due to the narrow thoracic canal, proximity to the spinal cord, and frequent calcification in chronic cases. Minimally invasive techniques that reduce spinal cord manipulation and preserve posterior stabilizing structures are therefore preferred. A 74-year-old woman presented with lower back and left leg pain, sensory disturbance, and gait impairment. Magnetic resonance imaging revealed a centrally calcified TDH at T10–11 with significant spinal cord compression. The lesion was approached via a transforaminal UBE route under continuous irrigation, providing a direct lateral working corridor for optimal visualization and controlled decompression. The calcified and adherent disc was progressively thinned and delicately dissected from the dura using an angled sharp hook and fine endoscopic instruments, minimizing cord manipulation. Postoperative imaging confirmed complete decompression, and the patient showed marked neurological recovery without complications. For centrally located, calcified TDH, the transforaminal UBE approach enables effective decompression while minimizing spinal cord retraction and preserving posterior elements. The accompanying video provides a detailed step-by-step demonstration of the procedure to enhance its safety and reproducibility.

Osteoid osteoma is a benign bone-forming tumor that rarely occurs in the cervical spine. Surgical removal is indicated when symptoms persist despite conservative management. Although open excision or radiofrequency ablation has traditionally been performed, these approaches may be associated with extensive tissue disruption or postoperative spinal instability. Recently, minimally invasive techniques, including unilateral biportal endoscopy (UBE), have been introduced for spinal tumor resection. We report the case of a 50-year-old man with persistent left-sided neck pain lasting 6 months. Imaging studies revealed a 15-mm nidus in the left lamina of C3, consistent with osteoid osteoma. The lesion was completely excised using the UBE technique, with preservation of the facet joint and surrounding structures. Histopathologic examination confirmed the diagnosis of osteoid osteoma. The patient’s symptoms improved immediately after surgery, and no perioperative complications occurred. Follow-up computed tomography and magnetic resonance imaging demonstrated complete lesion removal, with no evidence of recurrence at the 7-month follow-up. UBE-assisted resection represents an effective and minimally invasive surgical option for cervical osteoid osteoma. This approach enables adequate visualization, precise lesion excision, and preservation of spinal stability, resulting in favorable clinical and radiologic outcomes.

Purpose: Recent development in perioperative treatment of resectable non–small cell lung cancer (NSCLC) have changed the landscape of early lung cancer management. The ADAURA trial has demonstrated the efficacy of adjuvant osimertinib treatment in resectable NSCLC patients; however, studies are required to show which subgroup of patients are at a high risk of relapse and require adjuvant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor treatment. This study evaluated risk factors for postoperative relapse among patients who underwent complete resection. Materials and Methods: Data were obtained from the Korean Association for Lung Cancer Registry (KALC-R), a database created using a retrospective sampling survey by the Korean Central Cancer Registry (KCCR) and the Lung Cancer Registration Committee. Results: A total of 3,176 patients who underwent curative resection was evaluated. The mean observation time was approximately 35.4 months. Among stage I to IIIA NSCLC patients, the EGFR-mutant subgroup included 867 patients, and 75.2%, 11.2%, and 11.8% were classified as stage I, stage II, and stage III, respectively. Within the EGFR-mutant subgroup, 44 (5.1%) and 121 (14.0%) patients showed early and late recurrence, respectively. Multivariate analysis on association with postoperative relapse among the EGFR-mutant subgroup showed that age, pathologic N and TNM stages, pleural invasion status, and surgery type were independent significant factors. Conclusion Among the population that underwent complete resection for early NSCLC with EGFR mutation, patients with advanced stage, pleural invasion, or limited resection are more likely to show postoperative relapse.

Purpose: Recent development in perioperative treatment of resectable non–small cell lung cancer (NSCLC) have changed the landscape of early lung cancer management. The ADAURA trial has demonstrated the efficacy of adjuvant osimertinib treatment in resectable NSCLC patients; however, studies are required to show which subgroup of patients are at a high risk of relapse and require adjuvant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor treatment. This study evaluated risk factors for postoperative relapse among patients who underwent complete resection. Materials and Methods: Data were obtained from the Korean Association for Lung Cancer Registry (KALC-R), a database created using a retrospective sampling survey by the Korean Central Cancer Registry (KCCR) and the Lung Cancer Registration Committee. Results: A total of 3,176 patients who underwent curative resection was evaluated. The mean observation time was approximately 35.4 months. Among stage I to IIIA NSCLC patients, the EGFR-mutant subgroup included 867 patients, and 75.2%, 11.2%, and 11.8% were classified as stage I, stage II, and stage III, respectively. Within the EGFR-mutant subgroup, 44 (5.1%) and 121 (14.0%) patients showed early and late recurrence, respectively. Multivariate analysis on association with postoperative relapse among the EGFR-mutant subgroup showed that age, pathologic N and TNM stages, pleural invasion status, and surgery type were independent significant factors. Conclusion Among the population that underwent complete resection for early NSCLC with EGFR mutation, patients with advanced stage, pleural invasion, or limited resection are more likely to show postoperative relapse.

Purpose: Recent development in perioperative treatment of resectable non–small cell lung cancer (NSCLC) have changed the landscape of early lung cancer management. The ADAURA trial has demonstrated the efficacy of adjuvant osimertinib treatment in resectable NSCLC patients; however, studies are required to show which subgroup of patients are at a high risk of relapse and require adjuvant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor treatment. This study evaluated risk factors for postoperative relapse among patients who underwent complete resection. Materials and Methods: Data were obtained from the Korean Association for Lung Cancer Registry (KALC-R), a database created using a retrospective sampling survey by the Korean Central Cancer Registry (KCCR) and the Lung Cancer Registration Committee. Results: A total of 3,176 patients who underwent curative resection was evaluated. The mean observation time was approximately 35.4 months. Among stage I to IIIA NSCLC patients, the EGFR-mutant subgroup included 867 patients, and 75.2%, 11.2%, and 11.8% were classified as stage I, stage II, and stage III, respectively. Within the EGFR-mutant subgroup, 44 (5.1%) and 121 (14.0%) patients showed early and late recurrence, respectively. Multivariate analysis on association with postoperative relapse among the EGFR-mutant subgroup showed that age, pathologic N and TNM stages, pleural invasion status, and surgery type were independent significant factors. Conclusion Among the population that underwent complete resection for early NSCLC with EGFR mutation, patients with advanced stage, pleural invasion, or limited resection are more likely to show postoperative relapse.

Objective: Endoscopic surgery is gaining popularity as a minimally invasive option for adjacent segment degeneration (ASD). However, most of the previous literature has focused on transforaminal endoscopic techniques. This study aimed to assess the outcomes of decompressive laminectomy (unilateral laminectomy and bilateral decompression) with unilateral biportal endoscopic (UBE) in patients with lumbar ASD presenting with spinal stenosis. Methods: Thirty-nine ASD patients presenting with spinal stenosis who underwent UBE decompressive surgery between June 2018 and November 2022 at 4 different institutions were enrolled. The postoperative decompression amount and spinal instability were assessed using magnetic resonance images and dynamic radiographs. All patients were followed for at least 1 year, and clinical outcomes were assessed. Results: In the 39 patients, the cross-sectional area of the dural sac (0.55±0.21 cm2 to 1.11±0.41 cm2, p<0.001) indicated significant spinal decompression. Dynamic radiographs did not demonstrate significant occurrence of instability in operated segment. Three patients experienced complications, with one case each of hematoma, dural tear, and neurologic deficit. Visual analogue scale scores of the back (6.4±2.4 to 2.1±1.2, p<0.001) and leg (7.5±1.5 to 1.6±1.6, p<0.001), and Oswestry Disability Index scores (47.5±16.3 to 19.8±9.7, p<0.001) indicated significant clinical improvement that was sustained over 1 year. During the average follow-up period of 2 years, 2 patients underwent revision surgery due to failure and relapse. Conclusion UBE decompressive surgery had satisfactory outcomes in ASD patients, without significant failure or relapse.

Purpose: This study aimed to provide the clinical characteristics, prognostic factors, and 5-year relative survival rates of lung cancer diagnosed in 2015. Materials and Methods: The demographic risk factors of lung cancer were calculated using the KALC-R (Korean Association of Lung Cancer Registry) cohort in 2015, with survival follow-up until December 31, 2020. The 5-year relative survival rates were estimated using Ederer II methods, and the general population data used the death rate adjusted for sex and age published by the Korea Statistical Information Service from 2015 to 2020. Results: We enrolled 2,657 patients with lung cancer who were diagnosed in South Korea in 2015. Of all patients, 2,098 (79.0%) were diagnosed with non–small cell lung cancer (NSCLC) and 345 (13.0%) were diagnosed with small cell lung cancer (SCLC), respectively. Old age, poor performance status, and advanced clinical stage were independent risk factors for both NSCLC and SCLC. In addition, the 5-year relative survival rate declined with advanced stage in both NSCLC (82%, 59%, 16%, 10% as the stage progressed) and SCLC (16%, 4% as the stage progressed). In patients with stage IV adenocarcinoma, the 5-year relative survival rate was higher in the presence of epidermal growth factor receptor (EGFR) mutation (19% vs. 11%) or anaplastic lymphoma kinase (ALK) translocation (38% vs. 11%). Conclusion In this Korean nationwide survey, the 5-year relative survival rates of NSCLC were 82% at stage I, 59% at stage II, 16% at stage III, and 10% at stage IV, and the 5-year relative survival rates of SCLC were 16% in cases with limited disease, and 4% in cases with extensive disease.

Purpose: The purpose of this study was to investigate the clinical outcomes of postoperative radiotherapy (PORT) patients who underwent radical prostatectomy for localized prostate cancer. Materials and Methods: Localized prostate cancer patients who received PORT after radical prostatectomy between 2001 and 2012 were identified retrospectively in a multi-institutional database. In total, 1,117 patients in 19 institutions were included. Biochemical failure after PORT was defined as prostate-specific antigen (PSA) ≥ nadir+2 after PORT or initiation of androgen deprivation therapy (ADT) for increasing PSA regardless of its value. Results: Ten-year biochemical failure-free survival, clinical failure-free survival, distant metastasisfree survival, overall survival (OS), and cause-specific survival were 60.5%, 76.2%, 84.4%, 91.1%, and 96.6%, respectively, at a median of 84 months after PORT. Pre-PORT PSA ≤ 0.5 ng/ml and Gleason’s score ≤ 7 predicted favorable clinical outcomes, with 10-year OS rates of 92.5% and 94.1%, respectively. The 10-year OS rate was 82.7% for patients with a PSA > 1.0 ng/mL and 86.0% for patients with a Gleason score of 8-10. The addition of longterm ADT (≥ 12 months) to PORT improved OS, particularly in those with a Gleason score of 8-10 or ≥ T3b. Conclusion Clinical outcomes of PORT in a Korean prostate cancer population were very similar to those in Western countries. Lower Gleason score and serum PSA level at the time of PORT were significantly associated with favorable outcomes. Addition of long-term ADT (≥ 12 months) to PORT should be considered, particularly in unfavorable risk patients with Gleason scores of 8-10 or ≥ T3b.

The molecular mechanism underlying the initiation of somatic cell reprogramming into induced pluripotent stem cells (iPSCs) has not been well described. Thus, we generated single-cell-derived clones by using a combination of drug-inducible vectors encoding transcription factors (Oct4, Sox2, Klf4 and Myc) and a single-cell expansion strategy. This system achieved a high reprogramming efficiency after metabolic and epigenetic remodeling. Functional analyses of the cloned cells revealed that extracellular signal-regulated kinase (ERK) signaling was downregulated at an early stage of reprogramming and that its inhibition was a driving force for iPSC formation. Among the reprogramming factors, Myc predominantly induced ERK suppression. ERK inhibition upregulated the conversion of somatic cells into iPSCs through concomitant suppression of serum response factor (SRF). Conversely, SRF activation suppressed the reprogramming induced by ERK inhibition and negatively regulated embryonic pluripotency by inducing differentiation via upregulation of immediate early genes, such as c-Jun, c-Fos and EGR1. These data reveal that suppression of the ERK-SRF axis is an initial molecular event that facilitates iPSC formation and may be a useful surrogate marker for cellular reprogramming.