Background: Active surveillance (AS) has emerged as a viable management strategy for low-risk papillary thyroid microcarcinoma (PTMC), following pioneering trials at Kuma Hospital and the Cancer Institute Hospital in Japan. Numerous prospective cohort studies have since validated AS as a management option for low-risk PTMC, leading to its inclusion in thyroid cancer guidelines across various countries. From 2016 to 2020, the Multicenter Prospective Cohort Study of Active Surveillance on Papillary Thyroid Microcarcinoma (MAeSTro) enrolled 1,177 patients, providing comprehensive data on PTMC progression, sonographic predictors of progression, quality of life, surgical outcomes, and cost-effectiveness when comparing AS to immediate surgery. The second phase of MAeSTro (MAeSTro-EXP) expands AS to low-risk papillary thyroid carcinoma (PTC) tumors larger than 1 cm, driven by the hypothesis that overall risk assessment outweighs absolute tumor size in surgical decision-making. Methods: This protocol aims to address whether limiting AS to tumors smaller than 1 cm may result in unnecessary surgeries for low-risk PTCs detected during their rapid initial growth phase. By expanding the AS criteria to include tumors up to 1.5 cm, while simultaneously refining and standardizing the criteria for risk assessment and disease progression, we aim to minimize overtreatment and maintain rigorous monitoring to improve patient outcomes. Conclusion This study will contribute to optimizing AS guidelines and enhance our understanding of the natural course and appropriate management of low-risk PTCs. Additionally, MAeSTro-EXP involves a multinational collaboration between South Korea and Australia. This cross-country study aims to identify cultural and racial differences in the management of low-risk PTC, thereby enriching the global understanding of AS practices and their applicability across diverse populations.

Background/Aims: Elevated gamma-glutamyl transferase (GGT) levels indicate hepatic dysfunction and have been linked to an increased risk of pancreatobiliary cancers. However, this association, particularly in individuals with diabetes mellitus (DM), requires elucidation. We aimed to examine the association between elevated serum GGT levels and pancreatobiliary cancer risk in patients with diabetes. Methods: Our study included data from the National Health Insurance Service (NHIS) database for 2,459,966 adults aged >20 years diagnosed with DM between 2009 and 2012. We examined the association between serum GGT levels and pancreatobiliary cancer risk, considering DMrelated factors. Serum GGT levels were categorized into quartiles, and Cox proportional hazards analysis was performed to evaluate the association between serum GGT levels and pancreatobiliary cancer risk. Results: Over a median follow-up period of 7.2 years, 21,795 patients (0.89%) were newly diagnosed with pancreatobiliary cancer. The adjusted hazard ratio for pancreatobiliary cancer in quartiles 2–4 compared with that in quartile 1 was 1.091, 1.223, and 1.554, respectively, demonstrating a significant upward trend (p<0.001). This association remained consistent across all cancer types and was independent of the DM duration or treatment regimen. Conclusions Elevated serum GGT levels were independently associated with an increased risk of pancreatobiliary cancer, regardless of the duration of DM or the use of oral hypoglycemic agents and insulin. While these findings suggest the potential utility of serum GGT as a biomarker for identifying individuals at higher risk of pancreatobiliary cancer within the diabetic population, further research is needed to validate its clinical applicability.

Background/Aims: The Korean guidelines for Helicobacter pylori treatment were revised in 2020, however, the extent of adherence to these guidelines in clinical practice remains unclear. Herein, we initiated a prospective, nationwide, multicenter registry study in 2021 to evaluate the current management of H.pylori infection in Korea. Methods: This interim report describes the adherence to the revised guidelines and their impact on firstline eradication rates. Data on patient demographics, diagnoses, treatments, and eradication outcomes were collected using a web-based electronic case report form. Results: A total of 7,261 patients from 66 hospitals who received first-line treatment were analyzed.The modified intention-to-treat eradication rate for first-line treatment was 81.0%, with 80.4% of the prescriptions adhering to the revised guidelines. The most commonly prescribed regimen was the 14-day clarithromycin-based triple therapy (CTT; 42.0%), followed by tailored therapy (TT; 21.2%), 7-day CTT (14.1%), and 10-day concomitant therapy (CT; 10.1%). Time-trend analysis demonstrated significant increases in guideline adherence and the use of 10-day CT and TT, along with a decrease in the use of 7-day CTT (all p<0.001). Multivariate logistic regression analysis revealed that guideline adherence was significantly associated with first-line eradication success (odds ratio, 2.03; 95% confidence interval, 1.61 to 2.56; p<0.001). Conclusions The revised guidelines for the treatment of H. pylori infection have been increasingly adopted in routine clinical practice in Korea, which may have contributed to improved first-line eradication rates. Notably, the 14-day CTT, 10-day CT, and TT regimens are emerging as the preferred first-line treatment options among Korean physicians.

Background: Immunocompromised patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection often have prolonged viral shedding, and some are clinically suspected of reinfection with different SARSCoV-2 variants. However, data on this issue are limited. This study investigated the SARS-CoV-2 variants in serially collected respiratory samples from immunocompromised patients with prolonged viral shedding for over 12 weeks or relapsed viral shedding after at least 2 weeks of viral clearance. Materials and Methods: From February 2022 to September 2023, we prospectively enrolled immunocompromised patients with coronavirus disease 2019 who had hematologic malignancies or had undergone transplantation and were admitted to a tertiary hospital. Weekly saliva or nasopharyngeal swabs were collected from enrolled patients for at least 12 weeks after diagnosis. Genomic RNA polymerase chain reaction (PCR) was performed on samples, and those testing positive underwent viral culture to isolate the live virus. Spike gene full sequencing via Sanger sequencing and real-time reverse transcription-PCR for detecting mutation genes were conducted to identify SARSCoV-2 variants. Results: Among 116 enrolled patients, 20 with prolonged or relapsed viral shedding were screened to identify the variants. Of these 20 patients, 7 (35%) exhibited evidence of re-infection; one of 8 patients with prolonged viral shedding and 6 of 12 with relapsed viral shedding were reinfected with SARS-CoV-2. Conclusion Our data suggest that approximately one-third of immunocompromised patients with persistent or relapsed viral shedding had reinfection with different variants of SARS-CoV-2.

Background: and Purpose The risk factors for developing epilepsy following febrile convulsion (FC) have been studied extensively, but the underlying genetic components remain largely unexplored. Our objective here was to identify the risk loci related to FC through a genomewide association study of Korean epilepsy patients. Methods: We examined associations between a history of FC and single-nucleotide polymorphisms (SNPs) in data obtained from 125 patients with focal epilepsy: 28 with an FC history and 97 without an FC history. Results: Among 288,394 SNPs, 5 candidate SNPs showed p<1×10-4 . Regional association plots of these SNPs identified a novel locus adjacent to PROX1 that is implicated in hippocampal neurogenesis and epileptogenesis. The allele frequencies of the SNPs upstream of PROX1 including two candidate SNPs (rs1159179 and rs7554295 on chromosome 1) differed significantly between the groups with and without an FC history. In contrast, the allele frequencies of the SNPs inside PROX1 showed no differences, indicating dysregulated expression of PROX1 rather than a functional alteration in the PROX1 protein. Conclusions This novel discovery of SNPs upstream of PROX1 suggests that the dysregulated expression of PROX1 contributes to the development of focal epilepsy following FC. We propose that these SNPs are potential genetic markers for focal epilepsy following FC, and that PROX1 represents a potential therapeutic target of antiseizure medications.

Objective: This study aimed to identify factors associated with the recovery of mandibular nerve disturbance and to predict the possibility of recovery tailored to individual patients. Materials and Methods: Patients who visited the dental hospital with symptoms of mandibular nerve disturbance from April 2015 to September 2020 were studied. Patients were divided into two groups based on treatment outcomes: recovered or non-recovered. Variables related to recovery included age, sex, onset event of the nerve disturbance, affected area, imaging findings, and treatment methods. The correlation between recovery and these variables was analyzed using the Chi-square test and Fisher’s exact test. Results: A total of 328 patients were included in the study.Among the variables associated with recovery, the onset event of the symptom (P-value=0.02) and imaging findings (P-value=0.04) were statistically significant. Among the significant variables, the highest proportion of patients (77.78%) recovered without symptoms of onset event, while implant surgery showed the lowest recovery rate (34.25%). Regarding imaging findings, the recovery rate was highest in cases of suspected canal damage (58.82%), while no patients recovered from compression of the canal (0.00%). Conclusion This study highlights the importance of large-scale data analysis and a thorough evaluation of clinical variables to understand mandibular nerve disturbances. The findings provide a basis for improving treatment strategies and reducing the impact of nerve disturbances on patients’ quality of life.

Background: Group B Streptococcus (GBS) is one of the leading causes of neonatal earlyonset sepsis, resulting in high mortality and significant comorbidity. Intrapartum penicillin prophylaxis is recommended for pregnant women with GBS colonization to prevent vertical transmission. For pregnant women at high risk of anaphylaxis to penicillin, clindamycin is recommended only if the susceptibility of GBS isolates has been identified. We retrospectively examined the GBS detection rate and clindamycin resistance among Korean women of reproductive age over the last 20 years. Methods: Microbiologic studies using vaginal, vaginal–rectal or vaginal–perianal swabs from female patients 15–49 years of age during 2003–2022 were reviewed. Annual GBS detection rates and clindamycin resistance rates were calculated. The study period was divided into two periods (period 1, 2003–2015; period 2, 2016–2022) based on the introduction of universal culture-based GBS screening in our center in 2016. GBS detection rates and clindamycin resistance rates were compared between the periods using χ2 tests. Results: A total of 14,571 women were tested 16,879 times and GBS was isolated in 1,054 tests (6.2%), with 423 clindamycin-resistant isolates (40.1%). The GBS detection rate increased from 3.4% (301/8,869) in period 1 to 9.4% (2,753/8,010) in period 2 (P < 0.001). Even during period 1, the GBS detection rate was higher in 2009–2015 compared to 2003–2008 (P < 0.001). Clindamycin resistance rates have remained at similar levels since 2009, which were 39.5% (199/301) in period 1 and 40.2% (303/753) in period 2 (P = 0.833). Conclusion This study demonstrated that GBS detection rates in Korean women of reproductive age significantly increased almost three times during the twenty years of the study period, with a persistently high clindamycin resistance rate of up to 40%.

South Korea’s current vaccination policies leave a surveillance gap for non-National Immunization Program (NIP) vaccines. In this study, we proposed a sentinel surveillance approach for monitoring the safety of non-NIP vaccines. Vaccination data were collected retrospectively among patients hospitalized with pre-defined adverse events of special interest (AESI) by reviewing electronic medical records in five university hospitals. This approach incorporates expert assessment to determine the causal relationship. We confirmed that 16 patients had received non-NIP vaccines among 860 patients diagnosed with AESI.We concluded one case of preeclampsia was possibly related to tetanus-diphtheria-pertussis vaccination. We propose a multi-hospital-based, retrospective assessment system for predefined AESIs as an alternative to active vaccine safety monitoring method. These efforts are expected to enhance both the accuracy and timeliness of safety monitoring in South Korea.

Background: While the clinical course of radiation-induced meningioma (RIM) is considered to be more aggressive than that of sporadic meningioma (SM), the genetic predisposition for RIM is not established well. The present study aimed to analyze the clinical and genetic characteristics of RIMs to increase understanding of the tumorigenesis and prognosis of RIMs. Methods: We investigated a database of 24 patients who met the RIM criteria between January 2000 and April 2023. Genetic analysis through next-generation sequencing with a targeted gene panel was performed on 10 RIM samples. Clinical, radiological, and pathological parameters were evaluated with genetic analyses. Results: The median ages for receiving radiotherapy (RT) and RIM diagnosis were 8.0 and 27.5 years, respectively, with an interval of 17.5 years between RT and RIM diagnosis. RIMs tended to develop in non-skull bases and multifocal locations. Most primary pathologies included germ cell tumors and medulloblastoma. The tumor growth rate was 3.83 cm 3 per year, and the median doubling time was 0.8 years. All patients underwent surgical resection of RIMs. The histological grade of RIMs was World Health Organization grade 1 (64%) or 2 (36%). RIMs showed higher incidences in young-age (63%), high-dose (75%), and extendedfield (79%) RT groups. The recurrence rate was 21%. Genetic analysis revealed NF2 one copy loss in 90% of the patients, with truncating NF2 mutations and additional copy number aberrations in grade 2 RIMs. TERT promoter mutation and CDKN2A/B deletion were not identified. Notably, loss of H3K27me3 was identified in 26% of RIMs. H3K27me3 loss was associated with a higher prevalence of grade 2 RIMs (67%) and high recurrence rates (33%). Conclusion The study reveals a higher prevalence of high-grade tumors among RIMs with more rapid growth and higher recurrences than SMs. Genetically, RIMs are primarily associated with NF-2 alterations with chromosomal abnormalities in grade 2 tumors, along with a higher proportion of H3K27me3 loss.

Background/Aims: Globus is often linked with gastroesophageal reflux disease, which influences its treatment strategies. This study aims to investigate clinical characteristics of patients with refractory proton pump inhibitor (PPI) globus to better understand its etiology. Methods: Between 2017 and 2023, 122 out of 592 patients with globus from the Samsung Medical Center outpatient clinic who were unresponsive to 8 weeks of PPI treatment were analyzed. Patients underwent 24-hour esophageal pH monitoring and high-resolution manometry (HRM). They were divided into acid reflux, non-acid reflux, and no reflux groups, with basal impedance (BI) measurements taken at 3, 9, and 15 cm along the esophagus. These values were compared against data of healthy volunteers to identify significant differences across groups. Results: The acid reflux group displayed a median impedance of 1152 Ω at 3 cm, which was significantly lower than the median impedance of the non-acid reflux group (2644 Ω) and the no-reflux group (3083 Ω) (P = 0.015). Most patients in non-acid reflux and no-reflux groups showed higher impedance levels at both 3 cm and 15 cm compared to the first quartile of healthy individuals with significant differences (P = 0.032 and P = 0.029, respectively). Proximal BI was significantly lower than distal BI in both groups: 2278 Ω vs 2644 Ω in the non-acid reflux group (P = 0.035) and 2387 Ω vs 3083 Ω in the no-reflux group (P < 0.001). Conclusions Reduced proximal BI values compared to distal BI values suggest increased permeability in globus patients. Further studies with a larger cohort of refractory PPI patients and healthy volunteers are needed to explore these findings and their implications on globus etiology.