The 2024 Korean Thyroid Association (KTA) Clinical Practice Guidelines for Differentiated Thyroid Cancer (DTC) introduce updated recommendations based on recent advancements and clinical evidence. These guidelines encompass a broad spectrum of DTC cases, from localized thyroid cancer to advanced, treatment-resistant cases, covering both diagnostic and therapeutic approaches. Given the extensive content, careful organization was essential to effectively communicate these updates to KTA members. This article reviews the key changes in the 2024 guidelines, with a focus on revised diagnostic criteria, risk stratification, and initial treatment protocols for DTC. Updates include improved approaches to risk assessment, refinements in surgical intervention guidelines.Additionally, the new guidelines emphasize personalized management strategies that account for individual patient risk profiles and molecular characteristics. These updates aim to enhance diagnostic accuracy, optimize treatment outcomes, and minimize overtreatment for low-risk patients, aligning Korean practices with global standards.

The main goal of thyroid cancer treatment is to completely remove the lesion and minimize recurrence. However, given the very favorable prognosis and the quality of life following the extended lifespan after surgery, completing the surgery without complications is just as important as the complete removal of the cancer. Preventing surgical complications is very important, and the experience of the thyroid surgeon is the most critical factor. Therefore, overcoming the occurrence of complications is a necessary step that a novice must take to become a competent thyroid surgeon. With this background in mind, the author believes that ‘thyroid surgery is a battle with the laryngeal nerves, parathyroid, and blood vessels.’ This review aims to describe methods to minimize postoperative bleeding and hypoparathyroidism based on the author’s experience.

Calcitonin is an important tumor marker for medullary thyroid carcinoma. Serum calcitonin is increased in most cases of medullary thyroid carcinoma. However, medullary thyroid carcinoma with normal calcitonin level has been reported very rarely. 1.2 cm sized solid thyroid nodule was suspicious for medullary thyroid carcinoma in fine needle aspiration cytology, but serum calcitonin was within the normal range. The final pathology after surgery was medullary thyroid carcinoma with positive calcitonin immunohistochemical staining. The authors present a case of calcitonin-negative medullary thyroid cancer with reviews of the mechanism, diagnosis, treatment, prognosis and follow-up of this case.

Background and Objectives: Thyroid nodules can cause dysphagia by direct esophageal compression. Diagnosis of esophageal compression during thyroid ultrasound (US) has not been described. Materials and Methods: We present a case series of four patients who presented with dysphagia due to compressive thyroid nodules. Thyroid US demonstrated esophageal compression due to the culprit nodules, which were subsequently treated with radiofrequency ablation (RFA). Two benign biopsies were confirmed for each before ablation. Symptom scoring was used to assess the severity of dysphagia before and one month after the procedure. Results: All patients reported improvement in their dysphagia and a decline in symptom scores a month after the procedure. Thyroid US also demonstrated improvement in esophageal compression at that time. Conclusion Thyroid US can be a valuable tool in diagnosing dysphagia due to esophageal compression caused by thyroid nodules.

Insulin autoimmune syndrome (IAS) is rare. Herein, we report a case of methimazole-induced IAS successfully treated with propylthiouracil (PTU) and review related literature on Korean cases. A 48-year-old woman visited our hospital due to a hypoglycemic mental alteration. She had been taking medications for Graves’ disease including methimazole. Laboratory tests revealed a low serum glucose, high insulin, C-peptide, and anti-insulin antibody titer level. Abdominal computed tomography was negative for pancreatic tumors. Therefore, the patient was diagnosed with methimazole-induced IAS. After methimazole discontinuation and frequent diet, her hypoglycemic symptoms improved. She was treated with PTU for Graves’ disease. Previously, six cases of methimazole-induced IAS have been reported in Korea. Our case was the first in Korea to respond well to medical therapy (PTU) without other hypoglycemic treatments, such as steroids. PTU, which does not contain a sulfhydryl group, can be an option for the treatment of Graves’ disease and methimazole-induced IAS.

Background and Objectives: Monocarboxylate transporter 4 (MCT4) transmembrane proteins are encoded by SLC16A3 and control lactate metabolism to promote tumor growth. Materials and Methods: Gene expression of SLC16A3 encoding MCT4 was analyzed in the database of Gene Expression Omnibus. Protein expression of MCT4 was evaluated using immunohistochemical staining in 138 papillary thyroid carcinomas (PTCs) and 21 anaplastic thyroid carcinomas (ATCs). Results: The mRNA expression of SLC16A3 was significantly higher in ATCs compared with PTCs and normal thyroid tissue (p＜0.01, and p＜0.001, respectively). Normal thyroid tissue did not express MCT4 in immunohistochemical staining compared with ATC that was 100% positive for MCT4 protein expression. The MCT4 expression in ATCs was significantly enhanced compared with that in PTC (p＜0.001). Conclusion MCT4 expression is associated with de-differentiation and might be helpful as a biomarker and therapeutic target for thyroid cancer.

Well-differentiated thyroid cancer is managed with surgical resection, and adjuvant radioactive iodine (RAI) treatment reserved for moderate to high-risk patients. However, some patients with locally advanced disease are not candidates for upfront surgical resection. Within this rare patient population, VEGF tyrosine kinase inhibitors (TKI) and BRAF inhibitors have shown to successfully control and even reduce the size of RAI resistant thyroid cancers. In this case report, we elucidate the efficacy of a tumor agnostic strategy in facilitating the surgical resection of a locally advanced papillary thyroid cancer (PTC) with carotid involvement. A 60-year-old female presented with a large right sided papillary thyroid carcinoma with a BRAFV600E mutation. Initial stability was achieved through the use of Lenvatinib and subsequent use of dabrafenib and trametinib resulted in significant partial response. Following the aforementioned treatments, the patient successfully advanced to definitive surgery and RAI. BRAF/MEK inhibitors can be used in the neo-adjuvant setting to ensure resection in patients with locally advanced/unresectable well-differentiated thyroid cancer.

Background and Objectives: Surgical decision-making for papillary thyroid cancer (PTC) relies on accurate preoperative staging, where ultrasonography plays a crucial role in predicting outcomes. We aimed to analyze the predictive effects of preoperative sonographic findings on pathological characteristics. Materials and Methods: Retrospective study was performed using ultrasonographic images and clinico-pathologic data of papillary thyroid cancer patients who underwent total thyroidectomy or lobectomy between March 2016 and May 2020. Finally, 152 patients and 169 tumors were analyzed. Results: Mean age of patients was 54.2±14.2 years and the proportion of female was 75.7%. Tumor size was 13.6±10.3 mm and the proportions of extrathyroidal extension (ETE) and lymph node (LN) involvement were 52.2% and 23.0%, respectively. Preoperative sonographic findings, including ETE, tumor margin, echogenicity, and K-TIRDAS, were significantly associated with pathological ETE.Other pathological characteristics, including LN involvement, lymphovascular invasion, and resection margin positivity, were more observed in patients with more aggressive findings on preoperative sonography; however, we could not find statistical significances. Conclusion This study showed that preoperative sonographic characteristics, such as sonographic ETE, tumor margin, echogenicity, and K-TIRADS, can provide valuable insights into predicting pathological ETE in PTC patients.

Background and Objectives: To analyze the clinical trends and treatment patterns of thyroid cancer in the recent decade in South Korea. Materials and Methods: Two distinctive datasets, a single institutional database from 2009 to 2021 of differentiated thyroid cancer (DTC) patients (n=3145) and a nationwide database of the Korean Cancer Center Registry (KCCR) from 2005 to 2019 for patients (n=414,828) with all types of thyroid cancer, were analyzed. Annual incidence, the extent of thyroidectomy and neck dissection, T and N stages, and postoperative radioactive iodine (RAI) were investigated and descriptively presented. Results: The institutional database demonstrated that the annual cases of DTC surgeries suddenly dropped in 2014, coinciding with a social debate on overdiagnosis in South Korea. Due to changes in the staging manual and management guidelines during the study period, lobectomy has been preferred more than total thyroidectomy and the number of anterior compartment neck dissections has decreased. However, cases with lateral neck dissection and T4 stage gradually increased, suggesting that social issue did not influence the incidence of advanced thyroid diseases. The KCCR database also supported a similar phenomenon that showed a recent increase in localized and regional disease after a shock from social controversy. Conclusion Our institutional and KCCR data findings collectively indicate a steady incidence in localized and regional thyroid cancer after the initial drop triggered by the 2014 controversy in South Korea.

Background and Objectives: Telomerase reverse transcriptase (TERT) promoter mutations are a poor prognostic factor in differentiated thyroid carcinoma (DTC). However, their prognostic value in anaplastic thyroid carcinoma (ATC) is unclear. Therefore, we investigated whether TERT promoter mutations also act as an independent poor prognostic factor in ATC. Materials and Methods: We reviewed the medical records of 41 patients with ATC who underwent the TERT promoter mutations test at Samsung Medical Center between November 1995 and December 2022. The aggressive treatment group was defined as patients who underwent surgery, external radiotherapy, and systemic therapy. Results: Among 41 patients, 15 (36.6%) showed TERT promoter mutations. There only differences in the clinicopathological characteristics between the TERT-mutant and wild-type groups were tumor size and coexistence of DTC. Median tumor size in the TERT-mutant group was 5.1 cm (3.0-11.0), which was significantly larger than that in the wild-type group (4.1 cm, 0.8-8.0, p=0.010). Nevertheless, the TERT-mutant group received relatively more aggressive treatment (53.3% vs. 19.2%, p=0.056), and the overall survival of the TERT-mutant group was longer than that of the wild-type group (9.4 months [0.4-51.5] vs. 7.1 months [0.4-49.5]), but its difference was not significant (p=0.458). In multiple regression analysis, distant metastasis was a significant prognostic factor, but TERT promoter mutation was not. Conclusion Unlike in DTC, TERT promoter mutations were not an independent poor prognostic factor in ATC.