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: 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: 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: 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.

Purpose: This study aimed to evaluate the feasibility of measuring liver fat using the volumetric measurement method (Fatvol) by comparing it with the conventional 27-regions of interest drawing method (Fatroi). Materials and Methods: This retrospective study included 67 patients who underwent liver magnetic resonance imaging with fat quantification in August or September 2020.Two experienced abdominal radiologists measured the proton density fat fraction (PDFF) of the liver using the mDIXON-Quant sequence for each of two methods. The PDFF was measured twice with each method at intervals of at least 4 weeks to avoid recall bias. Measurement times were recorded. The intra-class correlation coefficient (ICC) was calculated for intra-exam repeatability, inter-reviewer reproducibility, and inter-exam agreement. Results: Measurement times for Fatvol were significantly shorter than for Fatroi. Measurement times for Fatroi and Fatvol, respectively, for reviewer A were 209.4 ± 55.1 s and 137.2 ± 51.5 s in session 1, and 180.9 ± 37.3 s and 127.0 ± 46.1 s in session 2. For reviewer B, the times were 190.7 ± 30.1 s and 74.8 ± 27.4 s in session 1, and 174.6 ± 21.8 s and 64.1 ± 17.5 s in session 2. In all cases, p < 0.001. The mean PDFF values were 7.2% ± 6.4% and 7.2% ± 6.5% (sessions 1 and 2, respectively) for Fatroi and 7.4% ± 6.0% and 7.3% ± 6.1% for Fatvol for reviewer A. For reviewer B, they were 7.1% ± 6.6% and 7.1% ± 6.6% for Fatroi and 7.4% ± 5.8% and 7.4% ± 5.8% for Fatvol. The ICCs between measurement methods (0.998 and 0.995 for reviewers A and B, respectively), for Fatvol within each reviewer (0.999 and 1.000 in sessions 1 and 2, respectively), and between reviewers (0.999) were excellent. Conclusion The measurement time could be significantly reduced using Fatvol compared to Fatroi while maintaining the consistency of the liver fat measurement values.

Purpose: We compared the surgical outcomes of radical nephrectomy (RN) and partial nephrectomy (PN) in adult patients with clinical T2 stage (cT2) renal cell carcinoma (RCC) by utilizing data from the Korean Renal Cell Carcinoma (KORCC) database. Materials and Methods: We retrospectively analyzed adult patients with cT2 RCC from 8 tertiary hospitals who were registered in the KORCC between 2003 and 2023. Patients with a solitary kidney or bilateral tumors were excluded. The patient cohort was divided into RN and PN arms, and propensity score matching (PSM) was conducted with a 1:3 ratio. Perioperative and survival outcomes were compared between arms. Results: After PSM, the PN and RN arms included 44 and 132 patients, respectively. No significant differences were observed in baseline characteristics, apart from laterality, following PSM. Regarding perioperative outcomes, complications of Clavien-Dindo classification grade III or higher (11.4%, p<0.001) and urological complications (9.1%, p=0.045) were more common in the PN arm than in the RN arm. Postoperative renal function was superior in the PN arm, whereas the incidence of de novo chronic kidney disease (CKD) at 6 months was higher among the recipients of RN (37.6%, p<0.001). Pathological examination indicated a higher pathological T stage in the RN arm. Overall, cancer-specific, and recurrence-free survival rates did not differ significantly between arms. Based on Cox regression analysis, the use of PN was not a significant predictor of recurrence-free survival (hazard ratio, 0.675; p=0.474). Conclusions In cT2 RCC, PN was associated with a lower incidence of de novo CKD than RN. No significant differences in survival outcomes were noted. PN may represent a viable alternative to RN for certain patients with cT2 RCC. Further research is warranted to explore the management of advanced RCC.

Background/Aims: Although an association between achalasia and esophageal cancer has been reported, whether achalasia confers a substantial increase in mortality is unknown. Moreover, the causes of death related to achalasia have not been investigated. We performed this nationwide, population-based cohort study on achalasia because no such study has been performed since the introduction of high-resolution manometry in 2008. Methods: This study was performed using data extracted from the Korean National Health Insurance Service database, covering a 9-year period from 2009 to 2017. Control participants without a diagnostic code for achalasia were randomly selected and matched by sex and birth year at a case-to-control ratio of 1:4. Data on the cause of death from Statistics Korea were also analyzed. Results: The overall incidence of achalasia was 0.68 per 100,000 person-years, and the prevalence was 6.46 per 100,000 population. Patients with achalasia (n=3,063) had significantly higher adjusted hazard ratio (aHR) for esophageal cancer (aHR, 3.40; 95% confidence interval [CI], 1.25 to 9.22; p=0.017), pneumonia (aHR, 2.30; 95% CI, 1.89 to 2.81; p<0.001), aspiration pneumonia (aHR, 3.92; 95% CI, 2.38 to 6.48; p<0.001), and mortality (aHR, 1.68; 95% CI, 1.44 to 1.94; p<0.001). Esophageal cancer carried the highest mortality risk (aHR, 8.82; 95% CI, 2.35 to 33.16; p=0.001), while pneumonia had the highest non-cancer mortality risk (aHR, 2.28; 95% CI, 1.31 to 3.96; p=0.004). Conclusions In this nationwide study, achalasia was associated with increased risk of mortality.Esophageal cancer and pneumonia were the most common comorbidities and the major causes of death in patients with achalasia.

Purpose: We aimed to identify the risk factors for salvage procedure (SP) required for refractory adenomatous tissue resistant to morcellation during holmium laser enucleation of the prostate (HoLEP). Methods: Patients who underwent HoLEP between January 2010 and April 2020 at Seoul National University Hospital were analyzed. SPs were defined as cases of conversion to resection of the prostatic tissue using an electrosurgical loop after morcellation or secondary morcellation a few days after surgery or conversion to open cystotomy. Results: Among a total of 2,427 patients, 260 were identified as having SP (SP group) (transurethral resection-nodule [n = 250, 96.1%], secondary morcellation a few days after surgery [n = 9, 3.5%], and conversion to open cystotomy [n = 1, 0.4%]). Patients in the SP group were older and had higher 5-α reductase inhibitors use, higher prostate-specific antigen, larger total prostate volume, and larger transition zone volume (TZV) than those in the non-SP group. In the multivariable logistic regression analysis, only age and TZV were associated with SP. Compared to 40s and 50s, the odds ratios (ORs) were 3.84 in 60s (95% confidence interval [CI] 1.37–10.78, P = 0.011), 4.53 in 70s (95% CI, 1.62–12.62, P = 0.004), and 6.59 in 80s or older (95% CI, 2.23–19.46, P = 0.001). The ORs of the SP were analyzed per TZV quartile. Compared to TZV ≤ 20.3 mL, the OR was 3.75 in 32.0 mL < TZV ≤ 50.4 mL (95% CI, 2.00–7.04, P < 0.001) and 8.25 in 50.4 mL < TZV (95% CI, 4.06–16.77, P < 0.001). Conclusions The risk of refractory morcellation increased in patients aged > 60 years or those with TZV > 32 mL. In order to more efficiently remove these resistant adenomas, it is necessary to develop more efficient morcellators in the future.

Background: Tenofovir disoproxil fumarate (TDF, Viread® ) had been used as a standard treatment option of chronic hepatitis B (CHB). This clinical trial was conducted to evaluate the efficacy and safety of DA-2802 (tenofovir disoproxil orotate) compared to TDF. Methods: The present study was a double blind randomized controlled trial. Patients with CHB were recruited from 25 hospitals in Korea and given DA-2802 at a dose of 319 mg once daily or Viread® at a dose of 300 mg once daily for 48 weeks from March 2017 to January 2019. Change in hepatitis B virus (HBV) DNA level at week 48 after dosing compared to baseline was the primary efficacy endpoint. Secondary efficacy endpoints were proportions of subjects with undetectable HBV DNA, those with normal alanine aminotransferase (ALT) levels, and those with loss of hepatitis B envelop antigen (HBeAg), those with loss of hepatitis B surface antigen (HBsAg). Adverse events (AEs) were also investigated. Results: A total of 122 patients (DA-2802 group: n = 61, Viread® group: n = 61) were used as full analysis set for efficacy analysis. Mean age, proportion of males, laboratory results and virologic characteristics were not different between the two groups. The change in HBV DNA level at week 48 from baseline was −5.13 ± 1.40 in the DA-2802 group and −4.97 ± 1.40 log 10 copies/mL in the Viread® group. The analysis of primary endpoint using the nonparametric analysis of covariance showed statistically significant results (P < 0.001), which confirmed non-inferiority of DA-2802 to Viread® by a prespecified noninferiority margin of 1. The proportion of undetectable HBV DNA was 78.7% in the DA-2802 group and 75.4% in the Viread® group (P = 0.698). The proportion of subjects who had normal ALT levels was 75.4% in the DA-2802 group and 73.3% in the Viread® group (P = 0.795). The proportion of those with HBeAg loss was 8.1% in the DA-2802 group and 10.8% in the Viread® group (P = 1.000). No subject showed HBsAg loss. The frequency of AEs during treatment was similar between the two groups. Most AEs were mild to moderate in severity. Conclusion DA-2802 is considered an effective and safe treatment for patients with CHB.

Background: Coronavirus disease 2019 (COVID-19) is generally asymptomatic or mild in otherwise healthy children, however, severe cases may occur. In this study, we report the clinical characteristics of children classified as critical COVID-19 in Korea to provide further insights into risk factors and management in children. Methods: This study was a retrospective case series of children < 18 years of age classified as critical COVID-19. Cases were identified by the Korea Disease Control and Prevention Agency surveillance system and medical records were reviewed. Critical COVID-19 was defined as cases with severe illness requiring noninvasive (high flow nasal cannula, continuous positive airway pressure, or bilevel positive airway pressure) or invasive mechanical ventilation, extracorporeal membrane oxygenation (ECMO) or continuous renal replacement therapy (CRRT), between January 20, 2020 and October 7, 2021. Results: Among 39,146 cases diagnosed with COVID-19 in subjects < 18 years of age, eight cases (0.02%) were identified as critical COVID-19. The median age was 13 years (range 10 month–17 years) and male-to-female ratio was 1:1. Three children had underlying diseases; one child has asthma and major depressive disorder, one child had LennoxGastaut syndrome and one child had mental retardation and was newly diagnosed with type 2 diabetes mellitus with the diagnosis of COVID-19. Among the eight children, seven were obese (body mass index range [BMI] median 29.3, range 25.9–38.2, weight-for-length > 97% for infant) and one was overweight (BMI 21.3). All patients had fever, six patients had dyspnea or cough and other accompanied symptoms included sore throat, headache, lethargy and myalgia. Radiologic findings showed pneumonia within 1–8 days after symptom onset. Pneumonia progressed in these children for 2–6 days and was improved within 5–32 days after diagnosis. Among the eight critical cases, remdesivir was administered in six cases.Steroids were provided for all cases. Inotropics were administered in one case. Six cases were treated with noninvasive mechanical ventilator and three required mechanical ventilator. One case required ECMO due to acute respiratory distress syndrome. All cases were admitted to the intensive care unit and admission period ranged from 9–39 days. Among all critical COVID-19 cases < 18 years of age, there were no fatal cases. Conclusion To develop appropriate policies for children in the COVID-19 pandemic, it is important to monitor and assess the clinical burden in this population.