Purpose: Radiotherapy (RT) remains a cornerstone of curative treatment for localized and locally advanced prostate cancer. However, dose escalation to improve tumor control is often constrained by the proximity of the rectum, which increases the risk of gastrointestinal (GI) and genitourinary toxicities. Biodegradable rectal spacers inserted between the prostate and rectum have emerged as an effective approach to reduce rectal radiation exposure. This guideline provides evidence-based recommendations on indications, contraindications, procedural standards, and clinical management for biodegradable rectal spacer insertion during prostate cancer RT. Materials and Methods: This guideline was developed by a multidisciplinary expert panel through a systematic review of the literature, analysis of international guidelines (National Comprehensive Cancer Network, European Association of Urology, American Society for Radiation Oncology), and expert consensus among radiation oncologists, radiologists, and urologists with clinical experience in spacer insertion. The strength of each recommendation and the level of evidence were classified according to the modified GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system. Results: Spacer insertion is conditionally recommended (Grade C, Level I) for patients receiving definitive external-beam RT without rectal invasion. It reduces the high-dose rectal irradiation volume (V70–75) by >50%, decreases acute GI toxicity, and helps maintain bowel-related quality of life. However, the benefit for late severe toxicity (grade 2 or higher) remains debated in recent meta-analyses. Contraindications include rectal invasion, anatomical inaccessibility, infection, and material hypersensitivity. Procedures should be performed under local anesthesia in a sterile environment by trained physicians. Short-course antibiotics and simulator-based training, including completion of multiple supervised cases, are advised. Conclusion Biodegradable rectal spacer insertion is clinically validated and effective in reducing acute rectal toxicity. Although pivotal trials demonstrated a favorable procedural safety profile, real-world postmarket data include reports of rare but severe procedural complications. This guideline provides standardized recommendations tailored to Korean clinical practice while remaining consistent with international standards, emphasizing the importance of operator training and careful patient selection.

Purpose: Tandem autologous stem cell transplantation (tASCT) is a viable option for high-risk multiple myeloma (MM) patients. Minimal residual disease (MRD), a real-time surrogate marker of disease burden, serves as a valuable measure of treatment response. This study evaluated the impact of tASCT on MRD dynamics in MM patients. Methods: We analyzed data from a multicenter registry of 28 patients who underwent tASCT as frontline treatment between January 2019 and October 2024. Eligibility criteria included undergoing two ASCTs within one year, having MRD positivity before tASCT, and completing follow-up MRD assessment. Patients were stratified into two groups:extensive MRD clearance (≥ 50% reduction, n = 18) and modest MRD clearance (< 50% reduction, n = 10). Results: Across the entire cohort, mean MRD decreased from 0.111% pre-tASCT to 0.056% post-tASCT. Three patients achieved MRD negativity, 20 had reductions without negativity, and five experienced increases. The extensive clear‑ ance group showed significant MRD reduction (0.152% to 0.017%) and longer progression-free survival (PFS: 37.7 vs.16.3 months, p = 0.013) compared with the modest clearance group, in which MRD increased (0.175% to 0.830%).Overall survival did not differ significantly. Conclusions tASCT provides clinical benefit for MRD-positive MM patients, particularly those achieving significant MRD reduction. These findings support tASCT as a feasible approach for MRD-positive patients following initial ASCT.

Purpose: This postmarketing surveillance (PMS) study aimed to evaluate real-world data on the effectiveness and safety of abiraterone acetate plus prednisone (AAP) in patients with metastatic hormone-sensitive prostate cancer (mHSPC). Materials and Methods: This prospective, multicenter observational study was conducted at 27 centers in South Korea between June 2018 and April 2021. Among 117 enrolled patients, 108 were included in the final analysis. Median follow-up period was 40.4 weeks (interquartile range, 22.8–49.2 weeks). Patients aged ≥18 years with mHSPC treated with AAP were included. Effectiveness endpoints included radiographic progression-free survival (rPFS), time to prostate-specific antigen (PSA) progression (TTPP), and PSA response (≥50%, ≥90% reduction). Adverse events (AEs) were assessed and graded based on severity. Results: A total of 108 patients were included in the analysis. Radiographic and PSA progression were observed in 13 (12.0%) and 26 patients (24.1 %), respectively. In the Kaplan-Meier analysis, the median rPFS and TTPP were not reached. The PSA response rates were 85.2% (≥50% reduction) and 75.9% (≥90% reduction) during the study period. AEs were reported in 31 patients (28.7%), with grade 3 or 4 AEs reported in 6 patients (5.6%). The most frequently observed AE was elevated aspartate aminotransferase level (5.6%). Conclusion This PMS study found that AAP is effective and well-tolerated in the real-world management of mHSPC.

Purpose: To evaluate whether extended pelvic lymph node dissection (PLND) improves survival outcomes compared with standard PLND in patients with bladder cancer (BCa) undergoing radical cystectomy (RC), and to assess its potential benefits in patients with prior or concurrent radical nephroureterectomy (p/cRNU). Materials and Methods: A multicenter analysis included 2202 patients with BCa undergoing RC with standard or extended PLND at 11 tertiary centers from 2003 to 2023. Following propensity score matching, 659 pairs (n=1,318), including 128 patients with p/cRNU, were analyzed. Recurrence-free survival (RFS) was the primary outcome, while overall survival (OS), cancer-specific survival (CSS), and readmission rates were secondary outcomes. Survival analyses performed using Kaplan-Meier methods and clustered Cox models. Results: Extended PLND yielded significantly more lymph nodes than standard PLND (median: 27.0 vs. 17.0, p<0.001) but did not improve RFS, CSS, or OS in the overall cohort (all p>0.05). Extended PLND increased readmission rates (28.4% vs. 20.2%, p=0.001) and readmission risk (odds ratio, 1.57; 95% confidence interval [CI], 1.15–2.16, p=0.005). However, subgroup analysis revealed extended PLND significantly improved RFS in patients with p/cRNU (hazard ratio, 0.54; 95% CI, 0.38–0.77; p<0.001). Conclusion Extended PLND does not provide survival benefits for overall patient population and increases readmission risk but significantly improves RFS in patients with p/cRNU. Tailoring PLND extent based on upper tract disease status is recommended.

Endoscopic retrograde cholangiopancreatography (ERCP) is a procedure that requires abundant clinical experience and endoscopic skills, and can lead to various complications, some of which may progress to life-threatening conditions. With expanding indications and technological advancements, ERCP is widely utilized, enhancing procedural accessibility. However, without proper quality management, the procedure can pose significant risks. Quality management in ERCP is essential to ensure safe and successful procedures and meet societal demands for improved healthcare competitiveness. To address these concerns, the Korean Pancreatobiliary Association has developed a Korean-specific ERCP quality indicator reflecting domestic medical environments and realities. Initially, based on a review of foreign ERCP quality indicators and related literatures, key questions were formulated for five preprocedural items, three intra-procedural items, and four post-procedural items. Descriptions and recommendations for each item were selected through peer evaluation. The developed Korean-specific ERCP quality indicator was reviewed by external experts based on the latest evidence and consensus in this fields. This Korean-specific indicator is expected to significantly contribute to improving ERCP quality in Korea, as it is tailored to local needs.

Endoscopic retrograde cholangiopancreatography (ERCP) is a procedure that requires abundant clinical experience and endoscopic skills, and can lead to various complications, some of which may progress to life-threatening conditions. With expanding indications and technological advancements, ERCP is widely utilized, enhancing procedural accessibility. However, without proper quality management, the procedure can pose significant risks. Quality management in ERCP is essential to ensure safe and successful procedures and meet societal demands for improved healthcare competitiveness. To address these concerns, the Korean Society of Pancreatobiliary Endoscopy has developed a Korean-specific ERCP quality indicator reflecting domestic medical environments and realities. Initially, based on a review of foreign ERCP quality indicators and related literatures, key questions were formulated for five pre-procedural items, three intra-procedural items, and four post-procedural items. Descriptions and recommendations for each item were selected through peer evaluation. The developed Korean-specific ERCP quality indicator was reviewed by external experts based on the latest evidence and consensus in this fields. This Korean-specific indicator is expected to significantly contribute to improving ERCP quality in Korea, as it is tailored to local needs.

Background/Aims: Renal relapse has known to be a poor prognostic factor in patients with lupus nephritis (LN), but there were few studies that identified the risk factors of renal relapse in real world. We conducted this study based on 35-years of experience at a single center to find out predictors of renal relapse in Korean patients with LN after achieving complete response (CR). Methods: We retrospectively analyzed the clinical, laboratory, pathologic and therapeutic parameters in 296 patients of LN who reached CR. The cumulative risk and the independent risk factors for renal relapse were examined by Kaplan-Meier methods and Cox proportional hazards regression analyses, respectively. Results: The median follow-up period from CR was 123 months. Renal relapse had occurred in 157 patients. Renal relapse occurred in 38.2%, 57.6% and 67.9% of patients within 5-, 10-, and 20-year, respectively. The age at diagnosis of SLE and LN were significantly younger, and the proportions of severe proteinuria and serum hypoalbuminemia were higher in patients with renal relapse. Interestingly, the proportion of receiving cytotoxic maintenance treatment was higher in patients with renal relapse. In Cox proportional hazards regression analyses, only young-age onset of LN (by 10 years, HR = 0.779, p = 0.007) was identified to independent predictor of renal relapse. Conclusions Young-age onset of LN was only independent predictor and the patients with severe proteinuria and serum hypoalbuminemia also tended to relapse more, despite of sufficient maintenance treatment. Studies on more effective maintenance treatment regimens and duration are needed to reduce renal relapse.

Purpose: This study aimed to compare the short-term outcomes and safety profiles of androgen-deprivation therapy (ADT)+abiraterone/prednisone with those of ADT+docetaxel in patients with de novo metastatic hormone-sensitive prostate cancer (mHSPC). Materials and Methods: A web-based database system was established to collect prospective cohort data for patients with mHSPC in Korea. From May 2019 to November 2022, 928 patients with mHSPC from 15 institutions were enrolled. Among these patients, data from 122 patients who received ADT+abiraterone/prednisone or ADT+docetaxel as the primary systemic treatment for mHSPC were collected. The patients were divided into two groups: ADT+abiraterone/prednisone group (n=102) and ADT+docetaxel group (n=20). We compared the demographic characteristics, medical histories, baseline cancer status, initial laboratory tests, metastatic burden, oncological outcomes for mHSPC, progression after mHSPC treatment, adverse effects, follow-up, and survival data between the two groups. Results: No significant differences in the demographic characteristics, medical histories, metastatic burden, and baseline cancer status were observed between the two groups. The ADT+abiraterone/prednisone group had a lower prostate-specific antigen (PSA) progression rate (7.8% vs. 30.0%; p=0.011) and lower systemic treatment discontinuation rate (22.5% vs. 45.0%; p=0.037). No significant differences in adverse effects, oncological outcomes, and total follow-up period were observed between the two groups. Conclusions ADT+abiraterone/prednisone had lower PSA progression and systemic treatment discontinuation rates than ADT+docetaxel. In conclusion, further studies involving larger, double-blinded randomized trials with extended follow-up periods are necessary.

Purpose: In men with metastatic castration-resistant prostate cancer (mCRPC), new bone lesions are sometimes not properly categorized through a confirmatory bone scan, and clinical significance of the test itself remains unclear. This study aimed to demonstrate the performance rate of confirmatory bone scans in a real-world setting and their prognostic impact in enzalutamide-treated mCRPC. Materials and Methods: Patients who received oral enzalutamide for mCRPC during 2014-2017 at 14 tertiary centers in Korea were included. Patients lacking imaging assessment data or insufficient drug exposure were excluded. The primary outcome was overall survival (OS). Secondary outcomes included performance rate of confirmatory bone scans in a real-world setting. Kaplan-Meier analysis and multivariate Cox regression analysis were performed. Results: Overall, 520 patients with mCRPC were enrolled (240 [26.2%] chemotherapy-naïve and 280 [53.2%] after chemotherapy). Among 352 responders, 92 patients (26.1%) showed new bone lesions in their early bone scan. Confirmatory bone scan was performed in 41 patients (44.6%), and it was associated with prolonged OS in the entire population (median, 30.9 vs. 19.7 months; p < 0.001), as well as in the chemotherapy-naïve (median, 47.2 vs. 20.5 months; p=0.011) and post-chemotherapy sub-groups (median, 25.5 vs. 18.0 months; p=0.006). Multivariate Cox regression showed that confirmatory bone scan performance was an independent prognostic factor for OS (hazard ratio 0.35, 95% confidence interval, 0.18 to 0.69; p=0.002). Conclusion Confirmatory bone scan performance was associated with prolonged OS. Thus, the premature discontinuation of enzalutamide without confirmatory bone scans should be discouraged.