Purpose: Although gastric cancer (GC) exhibits significant genomic heterogeneity, the clinical implications of its immune microenvironment remain poorly understood. Materials and Methods: We retrospectively evaluated patients with GC who underwent gastrectomies between 2011 and 2014. The tumors were analyzed for Epstein–Barr virus (EBV), microsatellite instability-high (MSI-H), tumor-infiltrating lymphocytes (CD3), tumor-associated macrophages (CD68 and CD163), and programmed death-ligand 1 (PD-L1) expression. Tumors were classified using the modified The Cancer Genome Atlas scheme, and their clinical characteristics were compared. Results: A total of 567 patients were classified into EBV (6%), MSI-H (10%), chromosomal instability-like (36%), and genomically stable-like (48%) subtypes. EBV tumors exhibited the highest PD-L1 expression (85%) and immune infiltration by CD3+ T cells (86%), CD68+ macrophages (58%), and CD163+ macrophages (40%). High CD68+ macrophage tumors were associated with advanced stages and worse 5-year disease-free survival (83% vs. 95%; P<0.001);however, this association was not independently significant after adjusting for the tumor-nodemetastasis stage. PD-L1 expression did not significantly affect the survival outcomes. Conclusions GC subtypes have distinct immune microenvironments that influence prognosis. Our findings highlight the prognostic and therapeutic potential of immune profiling in GC.

Purpose: Endoscopic submucosal dissection (ESD) has become a standard minimally invasive treatment for selected patients with early gastric cancer (EGC). This study presents the first nationwide survey of patients with EGC treated with ESD in 2023, conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research. Materials and Methods: Data were retrospectively collected from participating referral centers across Korea using a standardized case report form covering patient characteristics, tumor features, procedural details, histopathological findings, and clinical outcomes.Descriptive and comparative analyses were conducted to summarize nationwide ESD practice patterns and outcomes. Results: Data from 5,460 ESD cases from 5,250 patients across 27 institutions were analyzed. The mean age was 67.4 years, with 74.1% males. Multiple synchronous lesions were identified in 3.7%. Most lesions were located in the lower third of the stomach (64.0%), and differentiated-type adenocarcinomas accounted for 87.8%. The en bloc and complete resection rates were 99.2% and 91.4%, respectively. Curative resection was achieved in 80.5%, whereas local non-curative resection (L-NCR) and surgical non-curative resection (S-NCR) were identified in 2.8% and 16.7%, respectively. Additional surgery was performed more frequently in patients with S-NCR than in those with L-NCR (59.3% vs. 24.7%). The bleeding and perforation rates were 3.6% and 0.9%, respectively, and were mostly managed conservatively or endoscopically. The median length of hospitalization was 4.0 days. Conclusions This first nationwide survey provides a comprehensive overview of the current practice of EGC treatment using ESD in Korea, demonstrating high technical success and safety, and establishing a baseline dataset for future longitudinal research.

This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Background: In the era of nucleoside analogs (NA), we investigated the safety of using hepatitis B surface antigen (HBsAg)-positive grafts in liver transplantation (LT) using nationwide KOTRY data. Methods: Among 4,265 adult LTs in the KOTRY registry (April 2014–January 2020), 20 (0.5%) used HBsAg(+) grafts. The S(+) group was compared with HBsAg-nega-tive groups, both HBcAb(+) (C[+]) and HBcAb(−) (SC[−]), using 1:1 propensity scorematching. Patient and graft survival were evaluated using Kaplan–Meier analysis.Cox regression was used to identify prognostic factors. Results: No significant differences were observed in patient or graft survival be-tween S(+) and C(+) or SC(−) groups. Key prognostic factors for patient survivalincluded age, HCC, MELD score, ascites, and encephalopathy. For graft survival, HCC, preoperative HCC treatment, MELD score, ascites, and encephalopathy were significant. HBV recurrence occurred in the S(+) group, but did not compromise outcomes. Conclusion In HBV-endemic regions, HBsAg(+) liver grafts can be safely used to expand the donor pool without compromising LT outcomes when combined with appropriate prophylaxis.

Purpose: This study aimed to report the real-world outcomes of intravesical gemcitabine for bacillus Calmette–Guérin (BCG)–unresponsive, high-risk, non–muscle-invasive bladder cancer (HR-NMIBC) in Korean patients who were unable or unwilling to undergo radical cystectomy (RC). Materials and Methods: This retrospective study included 131 patients (median age, 69 years; 88.5% men) treated with intravesical gemcitabine for BCG-unresponsive HR-NMIBC at nine centers between May 2019 and April 2022. The primary endpoint was 1-year recurrence-free survival (RFS). The secondary endpoints included factors influencing RFS, progression-free survival (PFS), cystectomy- free survival, cancer-specific survival (CSS), overall survival (OS), and safety. Survival analysis was performed using the Kaplan-Meier method, and risk factors for recurrence were assessed using Cox regression models. Results: Patients were followed up for a median duration of 25 months, with carcinoma in situ (CIS) in 41.9% of the patients. The 1-year and 2-year RFS rates were 68% and 42%, while the 1-year and 2-year PFS rates were 87% and 77%, respectively. No significant factors influencing RFS were identified. Seventeen patients underwent RC during a median follow-up of 16 months, with the condition in three patients progressing to muscle-invasive disease on final pathological analysis. The 2-year CSS and OS rates were 98% and 97%, respectively. Intravesical gemcitabine was well-tolerated, with only seven patients (5.3%) unable to complete the full induction course. Conclusion Our research highlights the potential of intravesical gemcitabine as a viable bladder-sparing treatment option for BCG-unresponsive HR-NMIBC, providing real-world evidence on its safety, efficacy, and tolerability.

The COVID-19 pandemic has adversely affected the mental health of the global population. This study aimed to assess the acute and persistent symptoms of depression, as well as factors related to their manifestation, through a longitudinal study design. A total of 1,492 community-dwelling adults from an online public panel across three regions were evaluated at baseline, with 908 adults (60.9%) followed up after six months. Depression symptoms were evaluated using Patient Health Questionnaire-9 (PHQ-9). Participants also completed self-administered questionnaires on sociodemographic information, psychosocial experiences related to COVID-19, the UCLA Loneliness Scale, and the Korean version of the Gratitude Questionnaire (K-GQ-6).The prevalence of acute and persistent depression symptoms was 8.4% and 12.0%, respectively. Multivariate logistic regression analysis identified changes in predictors of depression over time, with younger age and self-isolation experience found to be associated with acute depression. Factors such as underlying mental illness, eating and sleeping disturbances, loneliness, and COVID-19-related stress emerged as significant risk factors for persistent depression. A disposition toward gratitude was identified as a protective factor for persistent depressive symptoms. These findings suggest that during any long-term pandemic crisis such as COVID-19, timely support and attention are essential for vulnerable populations, including young people and individuals with mental health conditions, to prevent depression. Specifically, promoting daily routines such as regular eating and sleeping patterns, and managing COVID-19-related stress may be critical in preventing persistent depression. Additionally, psychological support that reduces loneliness and fosters gratitude may help mitigate depression risk.

Objectives: This study aimed to investigate the impact of behavioral and psychological symptoms (BPS), assessed by the neuropsychiatric inventory (NPI) total score, on instrumental activities of daily living (IADL) performance in patients with mild cognitive impairment. Methods: Ninety-two patients diagnosed with mild cognitive impairment who visited a university hospital dementia clinic were recruited. Assessments included the Korean version-Mini Mental State Examination, NPI, Korean-IADL (KIADL), and Short Form of Geriatric Depression Scale-Korean version. Correlation and hierarchical multiple regression analyses were performed to analyze the relationship between BPS and IADL. Results: The mean age of participants was 74.61±5.86 years. K-IADL scores significantly correlated with age (r=0.347, p<0.001) and NPI total score (r=0.265, p<0.05). Hierarchical regression analysis showed that the addition of the NPI total score significantly increased the explained variance of functional decline (R 2 =0.197, F=5.332, p<0.001), with age (β=0.354, p<0.001) and NPI total score (β=0.248, p<0.05) identified as independent predictors in patients with mild cognitive impairment. Conclusions The overall severity of BPS exerts a detrimental effect on IADL function in mild cognitive impairment patients, independent of age and cognitive status. These results underscore the clinical importance of evaluating the cumulative burden of BPS to predict functional prognosis and implement early interventions.

Purpose: Radical cystectomy (RC) is associated with substantial postoperative morbidity, and unplanned readmission remains common despite advances in perioperative management. However, the association between postoperative readmission due to complications and oncologic outcomes after RC for bladder cancer has not been clearly defined. We evaluated the impact of postoperative readmission on overall survival (OS) and cancer-specific survival (CSS) after RC for bladder cancer. Materials and Methods: We retrospectively analyzed 3,972 patients who underwent RC for bladder cancer in a multicenter cohort. Postoperative readmission was defined as unplanned hospitalization within 90 days postsurgery due to surgery-related complications. Survival outcomes were assessed using the Kaplan-Meier method and compared using the log-rank test. Univariable and multivariable Cox proportional hazards regression analyses were performed to identify independent predictors of OS and CSS. Results: Among the study population, 916 patients (23.1%) experienced postoperative readmission. Baseline and perioperative characteristics were generally comparable between patients with and without readmission. Kaplan-Meier analyses demonstrated significantly worse OS and CSS among patients who experienced postoperative readmission (both log-rank p<0.001). In multivariable analyses adjusting for clinicopathological factors, postoperative readmission remained independently associated with worse OS (hazard ratio [HR], 1.654; 95% confidence interval [CI], 1.464–1.868; p<0.001) and CSS (HR, 1.761; 95% CI, 1.509–2.055; p<0.001). Conclusion Postoperative readmission within 90 days after RC was independently associated with inferior long-term oncologic outcomes. These findings suggest the importance of strategies aimed at preventing postoperative complications and subsequent readmission.

Objective: To characterize toxin gene profiles and antimicrobial resistance among Clostridium perfringens isolated from diarrheic piglets in Korea. Methods: Fecal samples (n = 1,627) were collected from 286 farms in 2023–2024. Clostridium perfringens isolates (n = 410) were recovered under anaerobic conditions. Toxin genes (cpa, cpb, cpb2, cpe, etx, and iap) were detected by multiplex real-time polymerase chain reaction.Susceptibility to 18 antimicrobials was assessed by disc diffusion. Results: Type A strains (cpa alone [24.6%] or cpa+cpb2 [46.8%]) predominated; cpb2 and cpe were detected in 73.4% and 19.0% of isolates, respectively. Resistance was highest to bacitracin (94.9%), amoxicillin/clavulanic acid (79.8%), and florfenicol (81.5%). Conclusions and Relevance: In 2023–2024, type A isolates carrying cpb2 were the predominant toxinotype among Clostridium perfringens recovered from diarrheic piglets in Korea. The high prevalence of resistance to several commonly used agents supports strengthened antimicrobial stewardship and evaluation of alternative control strategies.

Objective: This study examined whether baseline levels of 14 serum biomarkers predicted antidepressant remission differently by sex at 12 weeks and 12 months. Methods: In a prospective cohort, 1,086 outpatients with depressive disorders received stepwise antidepressant treatment following a naturalistic protocol. Baseline serum samples were analyzed for biomarkers from six systems: immune (high-sensitivity C-reactive protein, tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, interleukin-4, interleukin-10), metabolic (leptin, ghrelin, total cholesterol), neurotrophic (brain-derived neurotrophic factor), neurotransmitter (serotonin), endocrine (cortisol), and nutritional (folate, homocysteine). Remission, defined as a Hamilton Depression Rating Scale scores ≤ 7, was assessed at 12 weeks and 12 months. Logistic regression models with biomarker-by-sex interaction and stratified analyses were used, adjusting for clinical covariates. Results: Higher baseline serotonin predicted 12-week remission in males but not in females. At 12 months, lower leptin and higher folate predicted remission only in males, while lower cortisol predicted remission only in females. These showed significant biomarker-sex interactions. No sex-specific interactions were found for immune markers. Conclusion Baseline serum biomarkers across biological systems showed sex-specific associations with treatment outcomes. Neurotransmitter, metabolic, endocrine, and nutritional markers may offer predictive value for sex-tailored, biomarker-informed treatment strategies in depression.