High-flow nasal cannula (HFNC) is a noninvasive respiratory support system that delivers air that is heated at 31°C−38°C, humidified 100%, and oxygen-enriched at a constant high flow rate of 15−60 L/min. Because of its numerous physiological benefits, convenience, and minimal side effects, HFNC has been increasingly used over the past decade in patients with acute hypoxemic respiratory failure, yet the clinical benefits of long-term HFNC remain uncertain. Several studies have suggested its potential use as an alternative home oxygen therapy for patients with chronic stable lung diseases, such as chronic obstructive pulmonary disease (COPD), interstitial lung disease, and bronchiectasis. The use of long-term home HFNC in patients with chronic respiratory failure is an emerging area with promising potential. Despite limited clinical research, this review aims to describe the physiology of HFNC use and summarize the current evidence on its long-term application, to provide healthcare providers with insights and perspectives on the potential role of long-term home HFNC.

Purpose: This study assessed the reproducibility and clinical value of the vascular index (VI), derived from superb microvascular imaging (SMI) using Doppler ultrasonography, for evaluating renal function in transplanted kidneys. Methods: This retrospective study included 63 renal transplant patients who underwent grayscale and Doppler ultrasonography with SMI from January 2022 to February 2023. The VI of the transplanted kidneys was measured using three methods (VI_box, VI_F1, VI_F2). The VI was compared across chronic kidney disease (CKD) groups categorized by estimated glomerular filtration rate (eGFR) and Kidney Disease: Improving Global Outcomes (KDIGO) CKD risk groups based on eGFR and albuminuria. The correlation between VI and renal function was evaluated. Univariate and multivariate linear regression analyses were used to identify predictors of eGFR. Results: Significant differences in VI were observed among CKD groups based on eGFR (VI_box, P=0.001; VI_F1, P<0.001; VI_F2, P<0.001) and KDIGO CKD groups based on eGFR and albuminuria (VI_box, P=0.039; VI_F1, P=0.001; VI_F2, P<0.001). VI_F1 and VI_F2 demonstrated moderate/high correlations with eGFR (r=0.627, P<0.001 and r=0.657, P<0.001, respectively) and serum creatinine (r=-0.626, P<0.001 and r=-0.649, P<0.001, respectively). VI_box moderately correlated with eGFR (r=0.445, P<0.001). Multivariate regression identified the urine albumincreatinine ratio (ACR) (adjusted odds ratio [aOR], 1.122; 95% confidence interval [CI], -0.007 to, 0.000; P=0.030) and VI_F2 (aOR, 1.114; 95% CI, 0.466 to 1.235; P<0.001) were independently associated with eGFR. Conclusion The VI measured by drawing a region of interest along the border of the transplanted kidney in SMI (VI_F2) is highly reproducible and correlates well with eGFR. Both VI_F2 and ACR independently predict eGFR.

Purpose: Sarcopenia is a poor prognostic factor in non–small cell lung cancer (NSCLC). However, its prognostic significance in patients with NSCLC receiving immune checkpoint inhibitors (ICIs) and its relationship with lymphopenia remain unclear. We aimed to investigate the prognostic role of sarcopenia and its effect on lymphocyte recovery in patients with stage III NSCLC treated with concurrent chemoradiotherapy (CCRT) followed by ICI. Materials and Methods: We retrospectively evaluated 151 patients with stage III NSCLC who received definitive CCRT followed by maintenance ICI between January 2016 and June 2022. Sarcopenia was evaluated by measuring the skeletal muscle area at the L3 vertebra level using computed tomography scans. Lymphocyte level changes were assessed based on measurements taken before and during CCRT and at 1, 2, 3, 6, and 12 months post-CCRT completion. Results: Even after adjusting for baseline absolute lymphocyte count through propensity score-matching, patients with pre-radiotherapy (RT) sarcopenia (n=86) exhibited poor lymphocyte recovery and a significantly high incidence of grade ≥ 3 lymphopenia during CCRT. Pre-RT sarcopenia and grade ≥ 3 lymphopenia during CCRT emerged as prognostic factors for overall survival and progression-free survival, respectively. Concurrent chemotherapy dose adjustments, objective response after CCRT, and discontinuation of maintenance ICI were also analyzed as independent prognostic factors. Conclusion Our results demonstrated an association between pre-RT sarcopenia and poor survival, concurrent chemotherapy dose adjustments, and impaired lymphocyte recovery after definitive CCRT. Moreover, CCRT-induced lymphopenia not only contributed to poor prognosis but may have also impaired the therapeutic efficacy of subsequent maintenance ICI, ultimately worsening treatment outcomes.

Purpose: This study aims to evaluate the treatment approaches and locoregional patterns for adenoid cystic carcinoma (ACC) in the breast, which is an uncommon malignant tumor with limited clinical data. Materials and Methods: A total of 93 patients diagnosed with primary ACC in the breast between 1992 and 2022 were collected from multi-institutions. All patients underwent surgical resection, including breast-conserving surgery (BCS) or total mastectomy (TM). Recurrence patterns and locoregional recurrence-free survival (LRFS) were assessed. Results: Seventy-five patients (80.7%) underwent BCS, and 71 of them (94.7%) received post-operative radiation therapy (PORT). Eighteen patients (19.3%) underwent TM, with five of them (27.8%) also receiving PORT. With a median follow-up of 50 months, the LRFS rate was 84.2% at 5 years. Local recurrence (LR) was observed in five patients (5.4%) and four cases (80%) of the LR occurred in the tumor bed. Three of LR (3/75, 4.0%) had a history of BCS and PORT, meanwhile, two of LR (2/18, 11.1%) had a history of mastectomy. Regional recurrence occurred in two patients (2.2%), and both cases had a history of PORT with (n=1) and without (n=1) irradiation of the regional lymph nodes. Partial breast irradiation (p=0.35), BCS (p=0.96) and PORT in BCS group (p=0.33) had no significant association with LRFS. Conclusion BCS followed by PORT was the predominant treatment approach for ACC of the breast and LR mostly occurred in the tumor bed. The findings of this study suggest that partial breast irradiation might be considered for PORT in primary breast ACC.

Background/Aims: Direct-acting antivirals (DAAs) effectively eradicate hepatitis C virus. This study investigated whether metabolic dysfunction influences the likelihood of fibrosis regression after DAA treatment in patients with chronic hepatitis C (CHC). Methods: This multicenter, retrospective study included 8,819 patients diagnosed with CHC who were treated with DAAs and achieved a sustained virological response (SVR) between January 2014 and December 2022. Fibrosis regression was defined as a 20% reduction in noninvasive surrogates for liver fibrosis, such as liver stiffness (LS) measured by vibration-controlled transient elastography (VCTE) and the fibrosis-4 (FIB-4) score. Hypercholesterolemia (h-TC) was defined as >200 mg/dL. Results: The median age of the study population was 59.6 years, with a predominance of male patients (n=4,713, 57.3%). Genotypes 1, 2, and others were confirmed in 3,872 (46.2%), 3,487 (41.6%), and 1,024 (12.2%) patients, respectively. Diabetes mellitus (DM) was present in 1,442 (17.2%) patients and the median LS was 7.50 kPa (interquartile range, 5.30–12.50). Multivariate analysis revealed that the presence of DM and pre-DAA h-TC were independently associated with a decreased probability of fibrosis regression by VCTE. Additionally, pre-DAA h-TC was independently associated with a decreased probability of fibrosis regression by the FIB-4. Conclusions Metabolic dysfunction has an unfavorable influence on fibrosis regression in patients with CHC who achieve SVR after DAA treatment.

Background: Allograft is predominantly used interbody spacers for anterior cervical discectomy and fusion (ACDF). The corticocancellous allograft has weaker mechanical strength as it is an artificial composite of the cancellous and cortical parts. Additionally, whether utilizing a firmer allograft, such as the cortical ring, leads to better outcomes is unclear. Therefore, we aimed to compare the surgical outcomes of cortical ring and cortico-cancellous allografts in ACDF. Methods: Patients who underwent ACDF using allograft and were followed up for > 1 year were retrospectively reviewed. Patient characteristics, including fusion rates (assessed by interspinous motion [ISM], intra-graft bone bridging, and extra-graft bone bridging), subsidence, allograft complications (e.g., allograft fracture and resorption), and patient-reported outcome measures (neck pain visual analog scale [VAS], arm pain VAS, and neck disability index), were assessed. Patients were divided into 2 groups based on the allograft used: cortical ring and cortico-cancellous allograft groups. Subgroup analysis was subsequently conducted in singleand multi-level operation groups. Results: A total of 227 patients were included. Of them, 134 (59.0%) and 93 (41.0%) underwent ACDF using cortical ring and corticocancellous allograft, respectively. In single-level operations, the cortico-cancellous allograft significantly frequented allograft resorption (24 / 66, 36.4%) than the cortical ring allograft (1 / 28, 3.7%) (p = 0.001). The cortico-cancellous allograft group demonstrated significantly greater subsidence. However, the fusion rates did not significantly differ between the 2 groups. In multi-level operations, the cortico-cancellous allograft (5 / 27, 18.5%) resulted in a significantly higher fracture rate than the cortical ring allograft (5 / 105, 4.7%) (p = 0.030). The fusion rate at 1-year postoperative assessed using ISM (63.2% vs. 55.5%) and intra-graft bone bridging (66.7% vs. 40.7%) was higher in the cortical ring group; however, the difference was not significant. The patient-reported outcomes at 1-year postoperative did not demonstrate significant intergroup differences both in single- and multi-level operations. Conclusions Allograft resorption or fracture occurs more frequently with cortico-cancellous than cortical ring allografts. Despite the frequent occurrence of allograft-related complications with cortico-cancellous allografts, the fusion rate was not significantly affected. Due to the higher rate of allograft resorption or fractures and greater subsidence with cortico-cancellous allografts, cortical ring allografts might yield more stable results in ACDF.

Background: A 24-item early-onset scoliosis questionnaire (EOSQ-24) has been developed as a valid tool for assessing the physical and emotional function of patients with early-onset scoliosis (EOS). Previous studies that conducted transcultural adaptation of the original EOSQ-24 into other languages have demonstrated the high reliability of the questionnaire. However, a Korean version of the EOSQ-24 is not available, limiting optimal patient assessment in this nation. Therefore, this study was conducted to develop and validate a Korean version of EOSQ-24. Methods: The original English version of the EOSQ-24 was cross-culturally adapted following standard guidelines. The final version of the Korean EOSQ-24 was prospectively applied to a group of patients who were native Korean speakers. Internal consistency was evaluated using the Cronbach α coefficient and item-total correlations. The mean, standard deviation, floor effect, and ceiling effect of each item were also assessed. Results: A total of 102 caregivers of patients with EOS (45 males and 57 females) completed the Korean EOSQ-24. The patients’ average age was 6.39 ± 2.16 years. The Cronbach α coefficient for the 24-item scale was 0.942, indicating excellent reliability. The corrected item-total correlation coefficients ranged between 0.449 and 0.788. The mean value of the EOSQ-24 questionnaire was 3.19. Floor and ceiling effects for all questionnaires were below 30%, which could be considered acceptable. Conclusions Our study successfully developed and validated the Korean version of the EOSQ-24, providing a reliable instrument for assessing the physical and emotional well-being of patients with EOS and their caregivers in the Korean context. The widespread adoption of the Korean EOSQ-24 in clinical practice and research settings can enhance the quality of care and improve outcomes for individuals affected by EOS in Korea.

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: The incidence of steatotic liver disease (SLD) is increasing across all age groups as the incidence of obesity increases worldwide. The existing noninvasive prediction models for SLD require laboratory tests or imaging and perform poorly in the early diagnosis of infrequently screened populations such as young adults and individuals with healthcare disparities. We developed a machine learning-based point-of-care prediction model for SLD that is readily available to the broader population with the aim of facilitating early detection and timely intervention and ultimately reducing the burden of SLD. Methods: We retrospectively analyzed the clinical data of 28,506 adults who had routine health check-ups in South Korea from January to December 2022. A total of 229,162 individuals were included in the external validation study. Data were analyzed and predictions were made using a logistic regression model with machine learning algorithms. Results: A total of 20,094 individuals were categorized into SLD and non-SLD groups on the basis of the presence of fatty liver disease. We developed three prediction models: SLD model 1, which included age and body mass index (BMI); SLD model 2, which included BMI and body fat per muscle mass; and SLD model 3, which included BMI and visceral fat per muscle mass. In the derivation cohort, the area under the receiver operating characteristic curve (AUROC) was 0.817 for model 1, 0.821 for model 2, and 0.820 for model 3. In the internal validation cohort, 86.9% of individuals were correctly classified by the SLD models. The external validation study revealed an AUROC above 0.84 for all the models. Conclusions As our three novel SLD prediction models are cost-effective, noninvasive, and accessible, they could serve as validated clinical tools for mass screening of SLD.

Background/Aims: We previously reported that patients with moderate-to-severe ulcerative colitis (UC) often experience common mental disorders (CMDs) such as anxiety and depression, necessitating immediate psychological interventions within the first 4 weeks of diagnosis. In this 3-year follow-up study of the MOSAIK cohort in Korea, we examined the effects of CMDs at initial diagnosis on clinical outcomes and health-related quality of life (HRQoL). Methods: We examined differences in clinical outcomes (evaluated based on clinical response, relapse, hospitalization, and medication use) and HRQoL (assessed using the Inflammatory Bowel Disease Questionnaire [IBDQ] and Short Form 12 [SF-12]) according to Hospital Anxiety and Depression Scale (HADS) scores at diagnosis. Results: In a study involving 199 UC patients, 47.7% exhibited significant psychological distress (anxiety and/or depression) at diagnosis. Clinical follow-up showed no major differences in outcomes, including remission rates, response rates, or hospitalization rates, between patients with anxiety or depression at diagnosis and patients without anxiety or depression at diagnosis. The HRQoL at the end of follow-up was notably lower in those with baseline CMDs, particularly anxiety, across all domains of the IBDQ and SF-12. Linear mixed-effect models revealed that higher HADS scores, as well as higher Mayo scores, were independently associated with lower IBDQ scores and both summary domains of the SF-12. Additionally, regular attendance at follow-up visits during the study period was also related to improvements in HRQoL (all p<0.05). Conclusions While CMDs present at the time of UC diagnosis did not influence long-term clinical outcomes, they persistently impaired HRQoL. Our findings support the routine incorporation of psychological interventions into the long-term management of moderate-to-severe UC.