The increasing detection of papillary thyroid microcarcinoma (PTMC) has raised concerns about overtreatment.For low-risk PTMC, either immediate surgery or active surveillance (AS) can be considered. To support AS implementation, the Korean Thyroid Association convened a multidisciplinary panel and developed the first Korean guideline. AS is recommended to adults with pathologically proven Bethesda V-VI PTMC without clinical evidence of lymph node or distant metastasis, gross extrathyroidal extension, tracheal or recurrent laryngeal nerve invasion, or aggressive histology. Baseline assessment requires high‑resolution cervical ultrasound by experienced operators to rule out extrathyroidal extension, tracheal or recurrent laryngeal nerve invasion, and lymph node metastasis;contrast‑enhanced neck computed tomography is optional. Patient characteristics such as age, comorbidities, and capacity for long-term follow-up should be assessed. Shared decision-making should weigh the benefits and risks of surgery and AS, expected oncologic outcomes, complications, quality of life, anxiety, medical cost, and patient preference. Follow-up includes cervical ultrasound and thyroid function test every six months for two years, then annually. Disease progression, defined as significant tumor growth or newly detected nodal or distant metastasis, warrants surgery. Despite remaining uncertainties, this guideline offers a framework to ensure oncologic safety and support patient-centered active surveillance.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Notable effectiveness of trastuzumab deruxtecan in patients with human epidermal growth factor receptor 2 (HER2)–low advanced breast cancer (BC) has focused pathologists’ attention. We studied the incidence and clinicopathologic characteristics of HER2-low BC, and the effects of immunohistochemistry (IHC) associated factors on HER2 IHC results. Materials and Methods: The Breast Pathology Study Group of the Korean Society of Pathologists conducted a nationwide study using real-world data on HER2 status generated between January 2022 and December 2022. Information on HER2 IHC protocols at each participating institution was also collected. Results: Total 11,416 patients from 25 institutions included in this study. Of these patients, 40.7% (range, 6.0% to 76.3%) were classified as HER2-zero, 41.7% (range, 10.5% to 69.1%) as HER2-low, and 17.5% (range, 6.7% to 34.0%) as HER2-positive. HER2-low tumors were associated with positive estrogen receptor and progesterone receptor statuses (p < 0.001 and p < 0.001, respectively). Antigen retrieval times (≥ 36 minutes vs. < 36 minutes) and antibody incubation times (≥ 12 minutes vs. < 12 minutes) affected on the frequency of HER2 IHC 1+ BC at institutions using the PATHWAY HER2 (4B5) IHC assay and BenchMark XT or Ultra staining instruments. Furthermore, discordant results between core needle biopsy and subsequent resection specimen HER2 statuses were observed in 24.1% (787/3,259) of the patients. Conclusion The overall incidence of HER2-low BC in South Korea concurs with those reported in previously published studies. Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

These guidelines aim to establish the standard practice for diagnosing and treating patients with differentiated thyroid cancer (DTC). Based on the Korean Thyroid Association (KTA) Guidelines on DTC management, the “Treatment of Advanced DTC” section was revised in 2024 and has been provided through this chapter. Especially, this chapter covers surgical and nonsurgical treatments for the local (previous surgery site) or regional (cervical lymph node metastasis) recurrences. After drafting the guidelines, it was finalized by collecting opinions from KTA members and related societies. Surgical resection is the preferred treatment for local or regional recurrence of advanced DTC. If surgical resection is not possible, nonsurgical resection treatment under ultrasonography guidance may be considered as an alternative treatment for local or regional recurrence of DTC. Furthermore, if residual lesions are suspected even after surgical resection or respiratory-digestive organ invasion, additional radioactive iodine and external radiation treatments are considered.

Thyroid nodules represent a prevalent condition that is detectable via palpation or ultrasound. In recent years, there has been a paradigm shift toward enhanced diagnostic precision and less aggressive therapeutic approaches, highlighting the growing necessity for tailored clinical recommendations to optimize patient outcomes. The Korean Thyroid Association (KTA) has developed guidelines for managing patients with thyroid nodules, following a comprehensive review by task force members of the relevant literature identified via electronic database searches. The recommendations are provided with a level of recommendation for each section. The guidelines encompass thyroid cancer screening in high-risk groups, appropriate diagnostic methods for thyroid nodules, role of pathologic and molecular marker testing in making a diagnosis, long-term follow-up and treatment of benign thyroid nodules, and special considerations for pregnant women. The major revisions that were made in the 2023 guidelines were the definition of high-risk groups for thyroid cancer screening, application of the revised Korean Thyroid Imaging Reporting and Data System (K-TIRADS), addition of the role of core needle biopsy and molecular marker tests, application of active surveillance in patients with low-risk papillary thyroid microcarcinoma, and updated indications for nonsurgical treatment of benign thyroid nodules. In the 2024 revision of the KTA guidelines for thyroid cancer, the evidence for some recommendations has been updated to address the tumor size in the context of active surveillance in patients with low-risk thyroid cancer and the surgical size cutoff. These evidence-based recommendations serve to inform clinical decision-making in the management of thyroid nodules, thereby facilitating the delivery of optimal and efficacious treatments to patients.

Differentiated thyroid cancer demonstrates a wide range of clinical presentations, from very indolent cases to those with an aggressive prognosis. Therefore, diagnosing and treating each cancer appropriately based on its risk status is important. The Korean Thyroid Association (KTA) has provided and amended the clinical guidelines for thyroid cancer management since 2007. The main changes in this revised 2024 guideline include 1) individualization of surgical extent according to pathological tests and clinical findings, 2) application of active surveillance in low-risk papillary thyroid microcarcinoma, 3) indications for minimally invasive surgery, 4) adoption of World Health Organization pathological diagnostic criteria and definition of terminology in Korean, 5) update on literature evidence of recurrence risk for initial risk stratification, 6) addition of the role of molecular testing, 7) addition of definition of initial risk stratification and targeting thyroid stimulating hormone (TSH) concentrations according to ongoing risk stratification (ORS), 8) addition of treatment of perioperative hypoparathyroidism, 9) update on systemic chemotherapy, and 10) addition of treatment for pediatric patients with thyroid cancer.