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.

Background: This study aimed to evaluate the effects of kombucha on the surface of composite resins and to examine thedegradation-inhibiting effect of adding calcium to kombucha. Methods: Six experimental groups were established, with three types of liquid kombucha: one with 3% added calcium,carbonated water as a positive control, and mineral water as a negative control. The pH and titratable acidity values of the experimental groups were measured. The samples were filled with condensed composite resin and placed in the experimental drinks for 5, 15, 30, and 60 minutes. The Vickers microhardness of the surface was measured before and after immersion, and the changes were compared. Results: The pH values of the experimental group were I’m alive (2.87±0.02), Hollys (2.95±0.01), Ediya (2.99±0.01), I’m alive +3% Ca (4.09±0.01), carbonated water (4.66±0.01), and mineral water (7.67±0.02). I’m alive (–12.35) showed the largest reduction in surface hardness, followed by Hollys (–9.78), carbonated water (–7.97), I’m alive +3% Ca (–7.82), Ediya (–7.60), and mineral water (–1.56). In the Vickers microhardness measurements, all experimental groups, except for the mineral water group, showed significant differences (p＜0.05). The scanning electron microscope results showed that the experimental group and positive control had rough surfaces and micropores. Conclusion The surface hardness was significantly reduced in all experimental groups except for water. In particular, in the caseof kombucha with low pH, the reduction rate increased, weakening the physical properties of the material. In addition, the reduction rate of surface hardness was lower in kombucha with added calcium, and it is believed that drinking kombucha containing calcium can minimize the erosion of dental materials.

Background: This study aimed to evaluate the effects of kombucha on the surface of composite resins and to examine thedegradation-inhibiting effect of adding calcium to kombucha. Methods: Six experimental groups were established, with three types of liquid kombucha: one with 3% added calcium,carbonated water as a positive control, and mineral water as a negative control. The pH and titratable acidity values of the experimental groups were measured. The samples were filled with condensed composite resin and placed in the experimental drinks for 5, 15, 30, and 60 minutes. The Vickers microhardness of the surface was measured before and after immersion, and the changes were compared. Results: The pH values of the experimental group were I’m alive (2.87±0.02), Hollys (2.95±0.01), Ediya (2.99±0.01), I’m alive +3% Ca (4.09±0.01), carbonated water (4.66±0.01), and mineral water (7.67±0.02). I’m alive (–12.35) showed the largest reduction in surface hardness, followed by Hollys (–9.78), carbonated water (–7.97), I’m alive +3% Ca (–7.82), Ediya (–7.60), and mineral water (–1.56). In the Vickers microhardness measurements, all experimental groups, except for the mineral water group, showed significant differences (p＜0.05). The scanning electron microscope results showed that the experimental group and positive control had rough surfaces and micropores. Conclusion The surface hardness was significantly reduced in all experimental groups except for water. In particular, in the caseof kombucha with low pH, the reduction rate increased, weakening the physical properties of the material. In addition, the reduction rate of surface hardness was lower in kombucha with added calcium, and it is believed that drinking kombucha containing calcium can minimize the erosion of dental materials.

Background: This study aimed to evaluate the effects of kombucha on the surface of composite resins and to examine thedegradation-inhibiting effect of adding calcium to kombucha. Methods: Six experimental groups were established, with three types of liquid kombucha: one with 3% added calcium,carbonated water as a positive control, and mineral water as a negative control. The pH and titratable acidity values of the experimental groups were measured. The samples were filled with condensed composite resin and placed in the experimental drinks for 5, 15, 30, and 60 minutes. The Vickers microhardness of the surface was measured before and after immersion, and the changes were compared. Results: The pH values of the experimental group were I’m alive (2.87±0.02), Hollys (2.95±0.01), Ediya (2.99±0.01), I’m alive +3% Ca (4.09±0.01), carbonated water (4.66±0.01), and mineral water (7.67±0.02). I’m alive (–12.35) showed the largest reduction in surface hardness, followed by Hollys (–9.78), carbonated water (–7.97), I’m alive +3% Ca (–7.82), Ediya (–7.60), and mineral water (–1.56). In the Vickers microhardness measurements, all experimental groups, except for the mineral water group, showed significant differences (p＜0.05). The scanning electron microscope results showed that the experimental group and positive control had rough surfaces and micropores. Conclusion The surface hardness was significantly reduced in all experimental groups except for water. In particular, in the caseof kombucha with low pH, the reduction rate increased, weakening the physical properties of the material. In addition, the reduction rate of surface hardness was lower in kombucha with added calcium, and it is believed that drinking kombucha containing calcium can minimize the erosion of dental materials.

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.

The selected treatment for a nodule that is diagnosed as thyroid cancer is surgery. Imaging and blood tests are performed prior to surgery to determine the extent of the surgery. An Ultrasound (US) of the thyroid and neck should be performed to evaluate the size of the cancer, whether it is multifocal and has invaded surrounding tissues, and the status of the cervical lymph nodes (LNs). In addition to US, contrast-enhanced computed tomography may help detect cervical LN metastasis and evaluate patients suspected with invasive thyroid cancer.Generally, routine preoperative measurement of serum thyroglobulin and thyroglobulin antibody concentrations is not recommended. Integrated 18F-fluorodeoxyglucose positron-emission/computed tomography may be helpful either in patients with suspected lateral cervical LNs or distant metastasis or in patients with aggressive histology.

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.