Rectal cancer, which accounts for approximately 40% of colorectal cancers, remains a major clinical concern. Recent advances in diagnostic imaging, surgical techniques, radiotherapy, and systemic treatment have steadily improved rectal cancer outcomes. Considering this, the Korean Rectal Cancer Multidisciplinary (KRCM) Committee has aimed to provide clinicians and policymakers with up-to-date, evidence-based clinical practice guidelines to support optimal decision-making, reflecting current evidence, the Korean healthcare context, and patient values and preferences. The Clinical Practice Guidelines for Rectal Cancer version 2.0 were developed through multidisciplinary collaboration with related academic societies, building upon and updating the KRCM Clinical Practice Guidelines version 1.0 (titled “Multidisciplinary guidelines for the management of rectal cancer”). These consensus guidelines of the KRCM were established based on a comprehensive literature review, evidence synthesis, with recommendation development guided by the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, and consideration of applicability in real-world clinical practice under the national health insurance system. Each recommendation has been presented with its strength and level of evidence.

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: Seborrheic dermatitis (SD) is a chronic inflammatory scalp disorder associated with Malassezia dysbiosis and increased sebum production. AMPamide has been suggested to have anti-inflammatory and sebum-regulating effects, but its clinical efficacy and microbiome-modulating effects in SD remain unclear. Objective: To evaluate the clinical efficacy and scalp microbiome changes following 4 weeks of use of an AMPamide-containing shampoo in patients with SD. Methods: In this observational study, 30 patients with SD applied an AMPamide-containing shampoo for 4 consecutive weeks. Clinical outcomes, including sebum levels and overall severity scores, were assessed. Scalp bacterial and fungal communities were analyzed to evaluate α- and β-diversity and changes in Malassezia composition. Results: Treatment resulted in significant reductions in sebum levels and clinical severity scores, particularly in erythema, dandruff, and pruritus. Bacterial community composition remained largely stable, while fungal α-diversity increased, and β-diversity analysis revealed a decrease in the ratio of Malassezia restricta to Malassezia globosa. Conclusion AMPamide-containing shampoo was associated with improved clinical symptoms and a shift toward a more balanced fungal community composition in patients with SD, supporting its potential as a non-steroidal therapeutic option for SD.

Purpose: Current guidelines recommend vaccination at least 2 weeks before chemotherapy initiation to optimize the immune response despite limited evidence. Our previous study indicated no differences in short-term immune response for the 13-valent pneumococcal conjugate vaccine (PCV13) according to the vaccination timing. This study aims to investigate the long-term efficacy of PCV13 and clinical factors associated with the respective antibody response. Materials and Methods: Patients with gastric or colorectal cancer who received adjuvant chemotherapy were enrolled and divided into two groups: vaccinated 2 weeks before chemotherapy (arm A) and vaccinated concurrently with chemotherapy (arm B). Serum samples were collected before vaccination and in one month, 3 years, and 5 years. Immune responses were measured using enzyme-linked immunosorbent assay and multiplex opsonophagocytosis assay. Results: Including 63 patients, both groups showed an initial increase in the geometric mean titers of opsonophagocytic activity and the geometric mean concentrations of serotype-specific IgG levels after one month, followed by a decline at 3 and 5 years, particularly for serotypes 1, 14, 18C, and 19A. Despite the decline, global protection was maintained for 5 years, although global response decreased. The two arms did not show significant differences in immunogenicity nor in factors such as vaccination timing, age, cancer type, or chemotherapy regimen. Conclusion Vaccination timing is not a significant factor for the immunogenicity of PCV13 in cancer patients undergoing adjuvant chemotherapy. Global protection against pneumococcal infection was sustained for > 5 years, and global response remained in over half of patients.

Background: In vitro and animal studies have demonstrated that bone morphogenetic protein-7 (BMP-7), renowned for its osteogenic properties, also exerts beneficial effects on muscle metabolism by enhancing myogenesis and reversing muscle atrophy. Despite being proposed as a common regulatory factor for both muscle and bone, the impact of BMP-7 on human muscle health has not been thoroughly investigated. Methods: This cross-sectional study involved 182 community-dwelling older adults who underwent a comprehensive geriatric assessment in South Korea. Sarcopenia was diagnosed using Asian-specific cutoffs, and serum BMP-7 levels were quantified via enzyme immunoassay. Results: The mean age of the participants was 72.2±7.3 years, with 62.6% being female. After adjustments for confounders, serum BMP-7 levels were not significantly different between individuals with and without sarcopenia, nor were there differences based on skeletal muscle mass, strength, or physical performance levels (p=0.423 to 0.681). Likewise, no correlations were detected between circulating BMP-7 levels and any sarcopenia assessment metrics such as skeletal muscle index, grip strength, gait speed, or chair stand completion times (p=0.127 to 0.577). No significant associations were observed between increases in serum BMP-7 concentrations and the risk of sarcopenia or poor muscle phenotypes (p=0.431 to 0.712). Stratifying participants into quartiles based on serum BMP-7 levels also indicated no differences in sarcopenia-related parameters (p=0.663 to 0.996). Conclusion Despite experimental evidence supporting BMP-7’s role in muscle metabolism, this study found no significant association between serum BMP-7 levels and clinical indicators of muscle health in older adults. These findings challenge the utility of serum BMP-7 as a biomarker for sarcopenia in this demographic.

Purpose: This study aimed to report the overall national trends in the rates of cancer screening based on recommendations and provide insights into the changing trends of these rates across different demographics. Materials and Methods: This study used data from the Korean National Cancer Screening Survey (KNCSS), which surveys nationwide cancer-screening rates and includes 4,500 individuals meeting the Korean National Cancer Screening Program (NCSP) protocol age criteria. Cancer-screening rates were assessed using structured questionnaires; yearly trends were analyzed for both lifetime cancer-screening rates and rates of screening based on recommendations, and subgroup analyses were performed based on age and sex. Results: The rates of cancer screening based on recommendations showed significant increments: the stomach cancer-screening rate increased from 39.2% in 2004 to 77.5% in 2023 (3.50% per year), the liver cancer-screening rate increased from 20.0% to 48.8% (4.30% per year), and the colorectal cancer, increased from 19.9% to 70.7% (5.15% per year). The breast cancer-screening rate increased from 33.2% to 72.7% (2.88% per year), and the cervical cancer, increased from 58.3% to 70.2% (1.08% per year). Despite some differences, particularly in relation to sociodemographic factors, screening rates increased significantly for all cancer types. Conclusion Cancer-screening rates in Korea increased consistently from 2004 to 2023, demonstrating the effectiveness of the national cancer-screening program. However, the increments in breast, cervical and lung cancer-screening rates were relatively lower, indicating the need for additional efforts and strategies.

Background: Patients with diabetes are known to be at high risk for end-stage kidney disease (ESKD), but the accurate annual risk data for new-onset ESKD is still limited. In South Korea, the prevalence and incidence of ESKD are increasing more rapidly compared to the global average. This study aimed to determine the incidence rate (IR) of ESKD by diabetes status from 2012 to 2022. Methods: Using data from the Korean National Health Insurance Service, we calculated the IR and hazard ratio (HR) for newonset ESKD in the general population. Individuals were categorized based on diabetes status into nondiabetes, impaired fasting glucose (IFG), diabetes duration <5 and ≥5 years. Results: Among the participants, 67.6% were nondiabetic, 22.3% had IFG, and 10% had diabetes. In Korea, the IRs of ESKD were 139 per million population (pmp) for nondiabetes, 188 pmp for IFG, 632 pmp for diabetes <5 years, and 3,403 pmp for diabetes ≥5 years. An advanced estimated glomerular filtration rate (eGFR) category was the strongest risk factor for ESKD development. However, even in patients with normal renal function, those with long-standing diabetes had a 14-fold higher risk of ESKD compared to nondiabetic individuals. The risk of ESKD associated with diabetes increased exponentially with declining renal function. Notably, IFG showed an increasing tendency for ESKD in younger patients (<65 years) with early-stage chronic kidney disease (CKD; eGFR ≥60 mL/min/1.73 m²). Conclusion Longer diabetes duration amplifies ESKD risk, particularly as renal function declines. Even in patients with normal renal function, long-standing diabetes significantly increases ESKD risk, while IFG is associated with elevated risk only in younger individuals with early-stage CKD.

Background: Dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, reduces hyperglycemia and obesity by inhibiting renal glucose reabsorption. This post hoc study evaluated clinical factors influencing patient response to dapagliflozin. Methods: The analysis focused on patients treated with dapagliflozin (10 mg/day for 52 weeks) within the randomized, double-blind, parallel-group BEYOND trial. Adequate glycemic control (GC) was defined as a reduction in glycated hemoglobin (HbA1c) of ≥ 1.0% or the achievement of an HbA1c level <7.0% at week 52. Significant weight loss (WL) referred to a reduction in body weight of ≥3.0% at week 52. Participants were classified into four groups based on their GC and WL responses: GC+/WL+, GC+/WL−, GC−/WL+, and GC−/WL−. Results: Among dapagliflozin recipients (n=56), at 52 weeks, HbA1c had decreased by 1.0%±0.8% from baseline, while body weight had declined by 2.4±3.1 kg. Overall, 69.6% of participants achieved GC+, and 57.1% achieved WL+. Male sex and shorter diabetes duration were significantly associated with achieving GC+. Conversely, higher estimated glomerular filtration rate was significantly linked to WL+. The only factor significantly associated with both GC+ and WL+ was shorter diabetes duration (odds ratio, 0.81; 95% confidence interval, 0.68 to 0.97; P=0.023). The GC+ and WL+ groups exhibited favorable responses beginning soon after dapagliflozin therapy was initiated. Furthermore, HbA1c decline was more strongly associated with reduction in visceral fat than with WL. Conclusion A short duration of diabetes and early response to treatment appear to represent key factors in maximizing the benefits of dapagliflozin for blood glucose and weight management.

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: Sclerostin, initially recognized for its pivotal role in bone metabolism, has gained attention for its multifaceted impact on overall human health. However, its influence on frailty—a condition that best reflects biological age—has not been thoroughly investigated. Methods: We collected blood samples from 244 older adults who underwent comprehensive geriatric assessments. Sclerostin levels were quantified using an enzyme-linked immunosorbent assay. Frailty was assessed using two validated approaches: the phenotypic model by Fried and the deficit accumulation frailty index (FI) by Rockwood. Results: After controlling for sex, age, and body mass index, we found that serum sclerostin levels were significantly elevated in frail individuals compared to their robust counterparts (P<0.001). There was a positive correlation between serum sclerostin concentrations and the FI (P<0.001). Each standard deviation increase in serum sclerostin was associated with an odds ratio of 1.87 for frailty (P=0.003). Moreover, participants in the highest quartile of sclerostin levels had a significantly higher FI and a 9.91-fold increased odds of frailty compared to those in the lowest quartile (P=0.003 and P=0.039, respectively). Conclusion These findings, which for the first time explore the association between circulating sclerostin levels and frailty, have significant clinical implications, positioning sclerostin as one of potential blood-based biomarkers for frailty that captures the comprehensive physical, mental, and social aspects of the elderly, extending beyond its traditional role in bone metabolism.