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Background: Changes in thyrotropin receptor antibody (TRAb) levels are associated with the clinical outcomes of Graves' hyperthyroidism. However, the effects of the patterns of TRAb changes on patient prognosis according to the treatment duration of antithyroid drugs (ATDs) are not well established. Methods: In this retrospective cohort study, 1,235 patients with Graves' hyperthyroidism who were treated with ATDs for more than 12 months were included. Patients were divided into two groups according to treatment duration: group 1 (12-24 months) and group 2 (>24 months). Risk prediction models comprising age, sex, and either TRAb levels at ATD withdrawal (model A) or patterns of TRAb changes (model B) were compared. Results: The median treatment duration in groups 1 (n=667, 54%) and 2 (n=568, 46%) was 17.3 and 37.1 months, respectively. The recurrence rate was significantly higher in group 2 (47.9%) than in group 1 (41.4%, P=0.025). Group 2 had significantly more goiter, thyroid eye disease, and fluctuating and smoldering type of TRAb pattern compared with group 1 (all P<0.001). The patterns of TRAb changes were an independent risk factor for recurrence after adjusting for other confounding factors in all patients, except in group 1. Integrated discrimination improvement and net reclassification improvement analyses showed that model B performed better than model A in all patients, except in group 1. Conclusion: The dynamic risk model, including the patterns of TRAb changes, was more suitable for predicting prognosis in patients with Graves' hyperthyroidism who underwent longer ATD treatment duration. [ABSTRACT FROM AUTHOR]

Background: We aimed to evaluate the utility of repeat biopsy of thyroid nodules classified as atypia of undetermined significance with architectural atypia (IIIB) on core-needle biopsy (CNB). Methods: This retrospective study evaluated patients with thyroid nodules categorized as IIIB on CNB between 2013 and 2015. Demographic characteristics, subsequent biopsy results, and ultrasound (US) images were evaluated. The malignancy rates of nodules according to number of CNBs and the number of IIIB diagnoses was compared. Demographic and US features were evaluated to determine factors predictive of malignancy. Results: Of 1,003 IIIB nodules on CNB, the final diagnosis was determined for 328 (32.7%) nodules, with 121 of them confirmed as malignant, resulting in a malignancy rate of 36.9% (95% confidence interval, 31.7% to 42.1%). Repeat CNB was performed in 248 nodules (24.7%), with 75 (30.2%), 131 (52.8%), 13 (5.2%), 26 (10.5%), one (0.4%), and two (0.8%) reclassified into categories II, IIIB, IIIA, IV, V, and VI, respectively. Malignancy rates were not significantly affected by the number of CNBs (P=0.291) or the number of IIIB diagnoses (P=0.473). None of the nodules confirmed as category II on repeat CNB was malignant. US features significantly associated with malignancy (P<0.003) included solid composition, irregular margins, microcalcifications, and high suspicion on the US risk stratification system. Conclusion: Repeat biopsy of nodules diagnosed with IIIB on CNB did not increase the detection of malignancy but can potentially reduce unnecessary surgery. Repeat biopsy should be performed selectively, with US features guiding the choice between repeat biopsy and diagnostic surgery. [ABSTRACT FROM AUTHOR]

Background: Thyroid cancer mortality has been largely overlooked as relatively stable given the large gap between thyroid cancer incidence and mortality. This study evaluated long-term trends in age-standardized mortality rates (ASMRs) throughout Korea and compared them with mortality data reported by the Surveillance, Epidemiology, and End Results (SEER). Methods: Cancer-specific mortality data from 1985 to 2020 were obtained from Statistics Korea. ASMRs from thyroid cancer were calculated based on the Korean mid-year resident registration population of 2005. We assessed SEER*Explorer and downloaded the mortality data. Results: The ASMR increased from 0.19 to 0.77/100,000 between 1985 and 2002 but decreased continuously to 0.36/100,000 in 2020. The annual percent change (APC) in the ASMR between 1985 and 2003 and between 2003 and 2020 was 6.204 and -4.218, respectively, with similar patterns observed in both men and women. The ASMR of the SEER showed a modest increase from 1988 to 2016 and then stabilized. In subgroup analysis, the ASMR of the old age group (=55 years) increased significantly from 0.82 in 1985 to 3.92/100,000 in 2002 (APC 6.917) but then decreased again to 1.86/100,000 in 2020 (APC -4.136). ASMRs according to the age group in the SEER showed a relatively stable trend even in the elderly group. Conclusion: The ASMR of thyroid cancer in Korea had increased from 1985 to 2002 but has since been steadily decreasing. This trend was mainly attributed to elderly people aged 55 or over. The absolute APC value of Korea was much higher than that of the SEER. [ABSTRACT FROM AUTHOR]

Background: In this study, we evaluated the recent changes in the standardized, age-specific, stage-specific incidence rates (IRs) of thyroid cancer in Korea and compared them with the incidence data reported by the Surveillance, Epidemiology, and End Results Program. Methods: The analysis was conducted using the incidence data (2005 to 2018) from the Statistics Korea and Korea Central Cancer Registry. Results: The age-standardized IR (SIR) of thyroid cancer increased from 24.09 per 100,000 in 2005 to 74.83 in 2012 (annual percent change [APC], 14.5). From 2012 to 2015, the SIR decreased to 42.52 (APC, -17.9) and then remained stable until 2018 (APC, 2.1). This trend was similar in both men and women. Regarding age-specific IRs, the IRs for ages of 30 years and older showed a trend similar to that of the SIR; however, for ages below 30 years, no significant reduction was observed from the vertex of IR in 2015. Regarding stage-specific IRs, the increase was more prominent in those with regional disease (APC, 17.4) than in those with localized disease until 2012; then, the IR decreased until 2015 (APC, -16.1). The average APC from 2005 to 2018 increased in men, those under the age of 30 years, and those with regional disease. Conclusion: The SIR in Korea peaked in 2012 and decreased until 2015 and then remained stable until 2018. However, in young individuals under the age of 30 years, the IR did not significantly decrease but tended to increase again. In terms of stage-specific IRs, the sharpest increase was seen among those with regional disease. [ABSTRACT FROM AUTHOR]

Background: Hürthle cell carcinoma (HCC), a type of thyroid carcinoma, is rare in South Korea, and few studies have investigated its prognosis. Methods: This long-term multicenter retrospective cohort study evaluated the clinicopathological features and clinical outcomes in patients with HCC who underwent thyroid surgery between 1996 and 2009. Results: The mean age of the 97 patients included in the study was 50.3 years, and 26.8% were male. The mean size of the primary tumor was 3.2±1.8 cm, and three (3.1%) patients had distant metastasis at initial diagnosis. Ultrasonographic findings were available for 73 patients; the number of nodules with low-, intermediate-, and high suspicion was 28 (38.4%), 27 (37.0%), and 18 (24.7%), respectively, based on the Korean-Thyroid Imaging Reporting and Data System. Preoperatively, follicular neoplasm (FN) or suspicion for FN accounted for 65.2% of the cases according to the Bethesda category, and 13% had malignancy or suspicious for malignancy. During a median follow-up of 8.5 years, eight (8.2%) patients had persistent/recurrent disease, and none died of HCC. Older age, gross extrathyroidal extension (ETE), and widely invasive types of tumors were significantly associated with distant metastasis (all P<0.01). Gross ETE (hazard ratio [HR], 27.7; 95% confidence interval [CI], 2.2 to 346.4; P=0.01) and widely invasive classification (HR, 6.5; 95% CI, 1.1 to 39.4; P=0.04) were independent risk factors for poor disease-free survival (DFS). Conclusion: The long-term prognosis of HCC is relatively favorable in South Korea from this study, although this is not a nationwide data, and gross ETE and widely invasive cancer are significant prognostic factors for DFS. The diagnosis of HCC by ultrasonography and cytopathology remains challenging. [ABSTRACT FROM AUTHOR]

Active surveillance (AS) for low-risk papillary thyroid microcarcinoma (PTMC) has been accepted worldwide as safe and effective. Despite the growing acceptance of AS in the management of low-risk PTMCs, there are barriers to AS in real clinical settings, and it is important to understand and establish appropriate AS protocol from initial evaluation to follow-up. PTMC management strategies should be decided upon after careful consideration of patient and tumor characteristics by a multidisciplinary team of thyroid cancer specialists. Patients should understand the risks and benefits of AS, participate in decision-making and follow structured monitoring strategies. In this review, we discuss clinical outcomes of AS from previous studies, optimal indications and follow-up strategies for AS, and unresolved questions about AS. [ABSTRACT FROM AUTHOR]

Background: Serum calcitonin measurement contains various clinical and methodological aspects. Its reference level is wide and unclear despite sensitive calcitonin kits are available. This study aimed to identify the specific reference range in the healthy Korean adults. Methods: Subjects were ≥20 years with available calcitonin (measured by a two-site immunoradiometric assay) data by a routine health checkup. Three groups were defined as all eligible subjects (group 1, n=10,566); subjects without self or family history of thyroid disease (group 2, n=5,152); and subjects without chronic kidney disease, autoimmune thyroid disease, medication of proton pump inhibitor/H2 blocker/steroid, or other malignancies (group 3, n=4,638). Results: This study included 6,341 male and 4,225 female subjects. Males had higher mean calcitonin than females (2.3 pg/mL vs. 1.9 pg/mL, P<0.001) in group 1. This gender difference remained similar in groups 2 and 3. Calcitonin according to age or body mass index was not significant in both genders. Higher calcitonin in smoking than nonsmoking men was observed but not in women. Sixty-nine subjects had calcitonin higher than the upper reference limit (10 pg/mL) and 64 of them had factors associated with hypercalcitoninemia besides medullary thyroid cancer. Our study suggests the reference intervals for men who were non, ex-, current smokers, and women (irrespective of smoking status) as <5.7, <7.1, <7.9, and <3.6 pg/mL, respectively. Conclusion: Specific calcitonin reference range should be provided considering for sex and smoking status. Taking account for several factors known to induce hypercalcitoninemia can help interpret the gray zone of moderately elevated calcitonin. [ABSTRACT FROM AUTHOR]

Background: The clinical outcomes of delayed radioiodine remnant ablation (RRA) therapy in patients with low-risk papillary thyroid carcinoma (PTC) are unclear. We aimed to evaluate the clinical impact of the interval between total thyroidectomy (TT) and RRA therapy in patients with low-risk PTC. Methods: We included 526 patients who underwent TT and RRA for low-risk PTC with a primary tumor size of >1 cm between 2000 and 2012. Patients were divided into the early (<90 days) and the delayed (≥90 days) RRA groups based on the interval between TT and RRA. The results of diagnostic whole-body scan (DxWBS), ongoing risk stratification (ORS; response to therapy), and disease-free survival (DFS) were evaluated before and after propensity score matching (PSM). Results: Among the 526 patients, 75 (14.3%) patients underwent delayed RRA; they had more cervical lymph node metastasis and received a higher RRA dose than those who underwent early RRA. The median follow-up period was 9.1 years after initial therapy, and the structural recurrence rate was 1.9%. In DxWBS, 60 patients had focal iodine uptake limited in operative bed, with no significant difference between groups. According to ORS, 78%, 20%, 1%, and 1% patients were classified into excellent, indeterminate, biochemical incomplete, and structural incomplete response groups, respectively. There was no significant difference in ORS or DFS between groups before and after PSM. Conclusion: The timing of the first RRA had no clinical impact in patients with low-risk PTC. Thus, the clinical decision for RRA can be determined >3 months after TT considering other prognostic factors. [ABSTRACT FROM AUTHOR]

Background: The study aimed to compare the prognostic value of the 4th edition of World Health Organization classification (WHO-2017) with the previous WHO classification (WHO-2004) for follicular thyroid carcinoma (FTC). Methods: This multicenter retrospective cohort study included 318 patients with FTC from five tertiary centers who underwent thyroid surgery between 1996 and 2009. We evaluated the prognosis of patients with minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTC according to WHO-2017. Further, we evaluated the proportion of variation explained (PVE) and Harrell's C-index to compare the predictability of disease-free survival (DFS) and disease-specific survival (DSS). Results: In total, 227, 58, and 33 patients had MI-, EA-, and WI-FTC, respectively. During a median follow-up of 10.6 years, 46 (14.5%) patients had disease recurrence and 20 (6.3%) patients died from FTC. The 10-year DFS rates of patients with MI-, EA-, and WI-FTC were 91.1%, 78.2%, and 54.9%, respectively (P<0.001, PVE=7.1%, C-index=0.649). The corresponding 10-year DSS rates were 95.9%, 93.5%, and 73.5%, respectively (P<0.001, PVE=2.6%, C-index=0.624). The PVE and C-index values were higher using WHO-2017 than using WHO-2004 for the prediction of DFS, but not for DSS. In multivariate analysis, older age (P=0.02), gross extrathyroidal extension (ETE) (P=0.003), and distant metastasis (P<0.001) were independent risk factors for DSS. Conclusion: WHO-2017 improves the predictability of DFS, but not DSS, in patients with FTC. Distant metastasis, gross ETE and older age (≥55 years) were independent risk factors for DSS. [ABSTRACT FROM AUTHOR]

Background: Vandetanib is the most widely used tyrosine kinase inhibitor for the treatment of patients with advanced medullary thyroid cancer (MTC). However, only limited data regarding its use outside clinical trials are available. We aimed to evaluate the efficacy and safety of vandetanib in patients with advanced MTC in routine clinical practice. Methods: In this multicenter retrospective study, 12 patients with locally advanced or metastatic MTC treated with vandetanib at four tertiary hospitals were included. The primary outcome was the objective response rate (ORR) based on the Response Evaluation Criteria in Solid Tumors. The progression-free survival (PFS), overall survival (OS), and toxicities were also evaluated. Results: Eleven patients (92%) had distant metastasis and 10 (83%) had disease progression at enrollment. Partial response was observed in five patients (ORR, 42%) and stable disease lasting ≥24 weeks was reported in an additional five patients (83%). During the median 31.7 months of follow-up, disease progression was seen in five patients (42%); of these, two died due to disease progression. The median PFS was 25.9 months, while the median OS was not reached. All patients experienced adverse events (AEs) which were generally consistent with the known safety profile of vandetanib. Vandetanib was discontinued in two patients due to skin toxicity. Conclusion: Consistent with the phase III trial, this study confirmed the efficacy of vandetanib for advanced MTC in terms of both ORR and PFS in the real-world setting. Vandetanib was well tolerated in the majority of patients, and there were no fatal AEs. [ABSTRACT FROM AUTHOR]

Background: The optimal dose of radioactive iodine (RAI) therapy for N1b papillary thyroid carcinoma (PTC) is controversial. We evaluated the clinical outcome of N1b PTC patients treated with either 100 or 150 mCi of RAI. Methods: We retrospectively analyzed N1b PTC patients who underwent total thyroidectomy and postoperative RAI therapy at a tertiary referral center between 2012 and 2017. As the baseline characteristics differed between treatment groups, we performed exact matching for various pathological factors according to RAI dose. We evaluated the response to therapy and recurrence-free survival (RFS) in the matched patients. Structural recurrent/persistent disease was defined as new structural disease detected after initial therapy, which was confirmed by cytology or pathology. Results: Of the total 436 patients, 37 (8.5%) received 100 mCi of RAI and 399 (91.5%) received 150 mCi of RAI. After an exact 1:3 matching, 34 patients in the 100 mCi group and 100 patients in the 150 mCi group remained. There was no significant difference in response to therapy between the groups in the matched population (P=0.63). An excellent response was achieved in 70.6% (n=24) of patients in the 100 mCi group and 76.0% (n=76) in the 150 mCi group. Two (5.9%) patients in the 100 mCi group and four (4.0%) in the 150 mCi group had recurrence and there was no significant difference in RFS between the groups in the matched population (P=0.351). Conclusion: There were no differences in response to therapy and RFS in N1b PTC patients according to RAI dose. [ABSTRACT FROM AUTHOR]

Background: Although radiofrequency ablation (RFA) is a safe treatment for thyroid tumors, nerve damage is a frequent complication. A previous retrospective study suggested that an injection of cold 5% dextrose in water (5% DW) can reduce nerve damage during RFA. This study validated the efficacy of injecting cold 5% DW for management of nerve damage during RFA. Methods: Between November 2017 and December 2018, 242 patients underwent 291 RFA sessions for treatment of benign thyroid nodules or recurrent thyroid cancers. Using a standardized technique, cold (0°C to 4°C) 5% DW was immediately injected around the damaged nerve into patients with any symptoms suggesting nerve damage. The incidence of nerve damage, the volume of 5% DW injected, symptom recovery time and the incidence of permanent nerve damage were evaluated. Results: Nineteen patients experienced nerve damage symptoms related to 21 RFA sessions, including 17 patients during 19 sessions and two patients on the day after two sessions. Patients with nerve damage symptoms detected during RFA were treated by injection of a mean 41 mL (range, 3 to 260) cold 5% DW, but the two patients who experienced symptoms the next day did not receive cold 5% DW injections. Immediate recovery was observed after 15 RFA sessions in 14 patients. No patient experienced permanent nerve damage. Conclusion: Injection of cold 5% DW is effective in managing nerve damage during RFA of thyroid lesions. [ABSTRACT FROM AUTHOR]

Background: Concerns have arisen about the classification of extra-thyroidal extension (ETE) and lateral cervical lymph node metastasis (N1b) in the 8th edition of the tumor-node-metastasis staging system (TNM-8). This study evaluated the prognostic validity of a modified-TNM staging system, focusing on ETE and N1b, in differentiated thyroid carcinoma (DTC) patients. Methods: This multicenter retrospective cohort study included 4,878 DTC patients from five tertiary hospitals. In the modified- TNM, T3b in TNM-8 was down-staged to T2, and stage II was subdivided into stages IIA and IIB. Older patients with N1b were reclassified as stage IIB. Results: The modified-TNM resulted in staging migration in 540 patients (11%) classified as stage II according to the TNM-8, with 75 (14%), 381 (71%), and 84 patients (16%) classified as stages I, IIA, and IIB, respectively. The 10-year disease-specific survival (DSS) rates in patients classified as stages I, II, III, and IV by TNM-8 were 99.8%, 95.9%, 81.0%, and 41.6%, respectively. The DSS rates of patients classified as stages I, IIA, IIB, III, and IV according to the modified-TNM were 99.8%, 96.4%, 93.3%, 81.0%, and 41.6%, respectively. DSS curves between stages on TNM-8 (P<0.001) and modified-TNM (P<0.001) differed significantly, but the modified-TNM discriminated better than TNM-8. The proportions of variation explained values of TNM-8 and modified-TNM were 6.3% and 6.5%, respectively. Conclusion: Modification of the TNM staging system focusing on ETE and N1b could improve the prediction of DSS in patients with DTC. Further researches are needed to validate the prognostic accuracy of this modified-TNM staging system. [ABSTRACT FROM AUTHOR]

Background: Recently, there has been some controversy regarding the role of radioactive iodine (RAI) ablation in the treatment of low-risk differentiated thyroid carcinoma (DTC), especially papillary thyroid microcarcinoma (PTMC). This study aimed to compare quality of life (QoL) parameters between patients with PTMC who underwent total thyroidectomy (TT) alone and those who underwent TT with RAI ablation. Methods: In this cross-sectional study, patients with PTMC who underwent TT with/without RAI remnant ablation were prospectively enrolled between June 2016 and October 2017. All patients completed three questionnaires: the 12-item short-form health survey (SF-12), thyroid cancer-specific quality of life (THYCA-QoL) questionnaire, and fear of progression (FoP) questionnaire. Results: The TT and TT with RAI groups comprised 107 and 182 patients, respectively. The TT with RAI group had significantly lower serum thyrotropin (TSH) levels than the TT group. However, after matching for TSH levels between the groups (n=100 in both groups), there were no significant differences in baseline characteristics. According to the SF-12, the score for general health was significantly lower in the TT with RAI group than in the TT group (P=0.047). The THYCA-QoL also showed a significant difference in the "felt chilly" score between groups (P=0.023). No significant differences in FoP scores were observed between the groups. Conclusion: Patients with PTMC who underwent TT with RAI ablation experienced more health-related problems than those managed with TT alone. These findings support the idea that RAI ablation should be carefully considered in patients with low-risk DTCs. [ABSTRACT FROM AUTHOR]

The increased incidence of thyroid cancer is a worldwide phenomenon; however, the issue of overdiagnosis has been most prominent in South Korea. The age-standardized mortality rate of thyroid cancer in Korea steeply increased from 1985 to 2004 (from 0.17 per 100,000 to 0.85 per 100,000), and then decreased until 2015 to 0.42 per 100,000, suggesting that early detection reduced mortality. However, early detection of thyroid cancer may be cost-ineffective, considering its very high prevalence and indolent course. Therefore, risk stratification and tailored management are vitally important, but many prognostic markers can only be evaluated postoperatively. Discovery of preoperative marker(s), especially for small cancers, is the most important unmet clinical need for thyroid cancer. Herein, we discuss some such factors that we recently discovered. Another unmet clinical need is better treatment of radioiodine- refractory (RAIR) differentiated thyroid cancer (DTC) and undifferentiated cancers. Although sorafenib and lenvatinib are available, better drugs are needed. We found that phosphoglycerate dehydrogenase, a critical enzyme for serine biosynthesis, could be a novel therapeutic target, and that the lymphocyte-to-monocyte ratio is a prognostic marker of survival in patients with anaplastic thyroid carcinoma or RAIR DTC. Deeper insights are needed into tumor-host interactions in thyroid cancer to improve treatment. [ABSTRACT FROM AUTHOR]

Background: We previously reported the frequent neurofibromatosis 2 (NF2) gene mutations in anaplastic thyroid cancers in association with the BRAFV600E mutation. We aimed to investigate the role of NF2 in thyroid cancer with BRAF mutation. Background: We previously reported the frequent neurofibromatosis 2 (NF2) gene mutations in anaplastic thyroid cancers in association with the BRAFV600E mutation. We aimed to investigate the role of NF2 in thyroid cancer with BRAF mutation. Results: First, NF2 was overexpressed in 8505C and KTC-1 cells. Compared to control, NF2 overexpressed group of both thyroid cancer cells showed significant inhibition in cell proliferation and colony formation. These results were also confirmed by cell migration and invasion assay. After knock-down of NF2 in 8505C cells, there were no significant changes in cell proliferation and colony formation, compared with the control group. However, after mutagenized S288* and Q470* sites of NF2 gene, the cell proliferation increased compared to NF2 overexpression group. In the analysis of TCGA data, the mRNA expression of NF2 was significantly decreased in PTCs with lateral cervical lymph node (LN) metastasis compared with PTCs without LN metastasis. Conclusion: Our study suggests that NF2 might play a role as a tumor suppressor in thyroid cancer with BRAF mutation. More studies are needed to elucidate the mechanism how NF2 acts in thyroid cancer with BRAF mutation. [ABSTRACT FROM AUTHOR]

Background: Differentiated thyroid carcinoma (DTC) shows a very good prognosis, but older patients have a higher recurrence rate and those show poor prognosis than younger patients. The aim of this study was to determine the clinical outcomes of thyroid cancer patients who experienced recurrence in old age according to the treatment strategy used. Methods: This retrospective observational cohort study was conducted at Asan Medical Center, Seoul, Korea. Among DTC patients with no evidence of disease after initial treatment, we enrolled 86 patients who experienced recurrence at an age >65 years from 1994 to 2012. Sixty-nine patients had local recurrence and 17 patients showed distant metastasis. Results: The mean age of patients at recurrence was 72 years. Patients were followed up for a median of 4.1 years after recurrence. Sixty-three of the 69 patients with local recurrence received additional treatment, while the other six received conservative care. The cancer-specific mortality rate was 15.5% in the local recurrence group. Airway problems were the main cause of death in patients who did not receive further treatment for local recurrence. Among the 17 patients with distant metastasis, 10 underwent specific treatment for metastasis and seven received only supportive management. Seven of those 17 patients died, and the cancer-specific mortality rate was 35% in the distant metastasis group. Conclusion: The overall cancer-specific mortality rate was 20% in DTC patients in whom recurrence was first detected at an age >65 years. Mortality due to uncontrolled local disease occurred frequently in patients who did not receive definitive management for recurrence. [ABSTRACT FROM AUTHOR]

Background: Most patients with differentiated thyroid cancer (DTC) have a favorable prognosis. However, patients with DTC and initial distant metastasis have not been commonly found, and their clinical characteristics have seldom been reported. In this study, we analyzed the clinical features and prognosis of patients with DTC and initial distant metastasis in Korea. Methods: We retrospectively reviewed the clinical data of 242 patients with DTC and initial distant metastasis treated from 1994 to 2013, collected from five tertiary hospitals in Korea. Results: The patients' median age was 51 years, and 65% were women. They were followed for a median of 7 years. Lung was the most common site of distant metastasis: only lung 149 patients (62%), only bone 49 (20%), other single site one (pleura), and combined sites 43 (40 were lung and bone, two were bone and other site, and one was lung and other site). At the time of diagnosis, 50 patients (21%) had non-radioactive iodine (RAI) avidity. Five-year disease-specific survival (DSS) was 85% and 10-year DSS was 68%, which were better than those in previous studies. After multivariate analysis, old age, male sex, metastatic site, and histologic type (follicular type) were significant factors for poor prognosis. However, negative RAI avidity status was not a significant prognostic factor after adjusting for other variables. Conclusion: The prognosis of Korean patients with DTC and initial distant metastasis was better than in previous studies. Old age, male sex, metastasis site, and histologic type were significant prognostic factors. [ABSTRACT FROM AUTHOR]

Background: The BRAFV600E mutation is the most common genetic alteration identified in papillary thyroid carcinoma (PTC). Because of its costs effectiveness and sensitivity, direct Sanger sequencing has several limitations. The aim of this study was to evaluate the efficiency of immunohistochemistry (IHC) as an alternative method to detect the BRAFV600E mutation in preoperative and postoperative tissue samples. Methods: We evaluated 71 patients who underwent thyroid surgery with the result of direct sequencing of the BRAFV600E mutation. IHC staining of the BRAFV600E mutation was performed in 49 preoperative and 23 postoperative thyroid specimens. Results: Sixty-two patients (87.3%) had PTC, and of these, BRAFV600E was confirmed by direct sequencing in 57 patients (91.9%). In 23 postoperative tissue samples, the BRAFV600E mutation was detected in 16 samples (70%) by direct sequencing and 18 samples (78%) by IHC. In 24 fine needle aspiration (FNA) samples, BRAFV600E was detected in 18 samples (75%) by direct sequencing and 16 samples (67%) by IHC. In 25 core needle biopsy (CNB) samples, the BRAFV600E mutation was detected in 15 samples (60%) by direct sequencing and 16 samples (64%) by IHC. The sensitivity and specificity of IHC for detecting the BRAFV600E mutation were 77.8% and 66.7% in FNA samples and 99.3% and 80.0% in CNB samples. Conclusion: IHC could be an alternative method to direct Sanger sequencing for BRAFV600E mutation detection both in postoperative and preoperative samples. However, application of IHC to detect the BRAFV600E mutation in FNA samples is of limited value compared with direct sequencing. [ABSTRACT FROM AUTHOR]

In Korea, the incidence of thyroid cancer increased explosively in the early 2000s, and reached a plateau in the early 2010s. Most cases of newly diagnosed thyroid cancer are small indolent microcarcinoma and could be good candidates for active surveillance (AS) instead of immediate surgery. Many considerations must be taken into account for establishing selection criteria for candidates for AS of papillary thyroid microcarcinoma (PTMC), including the characteristics of the tumor, the patient, and the medical team. If possible, AS of PTMC should be a part of a prospective clinical trial to ensure long-term safety and to identify clinical and/or molecular markers of the progression of PTMC. In this review, we discuss lessons regarding surgical interventions for PTMC, and then describe the concept, application, caveats, unanswered questions, and future perspectives of AS of PTMC. For appropriately selected patients with PTMC, AS can be a good alternative to immediate surgery. [ABSTRACT FROM AUTHOR]

Background: Little is known regarding disease-specific mortality of differentiated thyroid cancer (DTC) patients and its risk factors in Korea. Methods: We retrospectively reviewed a large multi-center cohort of thyroid cancer from six Korean hospitals and included 8,058 DTC patients who underwent initial surgery between 1996 and 2005. Results: Mean age of patients at diagnosis was 46.2±12.3 years; 87% were females. Most patients had papillary thyroid cancer (PTC; 97%) and underwent total thyroidectomy (85%). Mean size of the primary tumor was 1.6±1.0 cm. Approximately 40% of patients had cervical lymph node (LN) metastases and 1.3% had synchronous distant metastases. During 11.3 years of follow-up, 150 disease-specific mortalities (1.9%) occurred; the 10-year disease-specific survival (DSS) rate was 98%. According to the year of diagnosis, the number of disease-specific mortality was not different. However, the rate of disease-specific mortality decreased during the study period (from 7.7% to 0.7%). Older age (≥45 years) at diagnosis, male, follicular thyroid cancer (FTC) versus PTC, larger tumor size (>2 cm), presence of extrathyroidal extension (ETE), lateral cervical LN metastasis, distant metastasis and tumor node metastasis (TNM) stage were independent risk factors of disease-specific mortality of DTC patients. Conclusion: The rate of disease-specific mortality of Korean DTC patients was 1.9%; the 10-year DSS rate was 98% during 1996 to 2005. Older age at diagnosis, male, FTC, larger tumor size, presence of ETE, lateral cervical LN metastasis, distant metastasis, and TNM stages were significant risk factors of disease-specific mortality of Korean DTC patients. [ABSTRACT FROM AUTHOR]

Background: No nationwide epidemiological study evaluating the prevalence of subclinical and overt forms of hypothyroidism and hyperthyroidism has yet been conducted in Korea. This study aimed to evaluate the reference range of serum thyroid stimulating hormone (TSH) and the national prevalence of thyroid dysfunctions in Korea. Methods: Nation-wide cross-sectional data were analyzed from a representative sample of the civilian, non-institutionalized Korean population (n=6,564) who underwent blood testing for thyroid function and anti-thyroid peroxidase antibody (TPOAb) as part of the Korea National Health and Nutrition Examination Survey VI (2013 to 2015). Results: The reference interval of serum TSH in the Korean reference population was 0.62 to 6.68 mIU/L. Based on this reference interval, the prevalence of overt and subclinical hypothyroidism was 0.73% (males 0.40%, females 1.10%) and 3.10% (males 2.26%, females 4.04%), respectively. The prevalence of hypothyroidism increased with age until the age group between 50 to 59 years. Positive TPOAb were found in 7.30% of subjects (males 4.33%, females 10.62%). The prevalence of overt and subclinical hypothyroidism TPOAb-positive subjects was 5.16% and 10.88%, respectively. The prevalence of overt and subclinical hyperthyroidism was 0.54% (males 0.30%, females 0.81%) and 2.98% (males 2.43%, females, 3.59%), respectively. Conclusion: The Serum TSH reference levels in the Korean population were higher than the corresponding levels in Western countries. Differences were found in the prevalence of hypothyroidism and hyperthyroidism according to age, sex, and TPOAb positivity. This study provides important baseline information for understanding patterns of thyroid dysfunction and diseases in Korea. [ABSTRACT FROM AUTHOR]

Background: Molecular analysis for common somatic mutations in thyroid cancer can improve diagnostic accuracy of fine-needle aspiration cytology (FNAC) in the nondiagnostic or indeterminate category of thyroid nodules. In this study, we evaluated the feasibility of molecular diagnosis from residual liquid-based cytology (LBC) material after cytological diagnosis. Methods: This prospective study enrolled 53 patients with thyroid nodules diagnosed as nondiagnostic, atypia of undetermined significance (AUS), or follicular lesion of undetermined significance (FLUS) after FNAC. DNAs and RNAs were isolated from residual LBC materials. BRAFV600E and RAS point mutations, PAX8/peroxisome proliferator-activated receptor γ (PPARγ), RET/PTC1, and RET/PTC3 rearrangements were evaluated by real-time polymerase chain reaction and pyrosequencing. Results: All DNAs from 53 residual LBC samples could be analysed and point mutations were detected in 10 samples (19%). In 17 AUS nodules, seven samples (41%) had point mutations including BRAF (n=4), NRAS (n=2), and KRAS (n=1). In 20 FLUS nodules, three samples (15%) had NRAS point mutations. RNA from only one FLUS nodule could be analysed for rearrangements and there was no abnormality. Conclusion: Molecular analysis for BRAF and RAS mutations was feasible in residual LBC materials and might be useful for diagnosis of indeterminate thyroid nodules. [ABSTRACT FROM AUTHOR]

Background: Hyperthyroidism relapse in Graves disease after antithyroid drug (ATD) withdrawal is common; however, measuring the thyrotropin receptor antibody (TRAb) at ATD withdrawal in order to predict outcomes is controversial. This study compared measurement of thyroid stimulatory antibody (TSAb) and thyrotropin-binding inhibitory immunoglobulin (TBII) at ATD withdrawal to predict relapse. Methods: This retrospective study enrolled patients with Graves disease who were treated with ATDs and whose serum thyroidstimulating hormone levels were normal after receiving low-dose ATDs. ATD therapy was stopped irrespective of TRAb positivity after an additional 6 months of receiving the minimum dose of ATD therapy. Patients were followed using thyroid function tests and TSAb (TSAb group; n=35) or TBII (TBII group; n=39) every 3 to 6 months for 2 years after ATD withdrawal. Results: Twenty-eight patients (38%) relapsed for a median follow-up of 21 months, and there were no differences in baseline clinical characteristics between groups. In the TSAb group, relapse was more common in patients with positive TSAb at ATD withdrawal (67%) than patients with negative TSAb (17%; P=0.007). Relapse-free survival was shorter in TSAb-positive patients. In the TBII group, there were no differences in the relapse rate and relapse-free survivals according to TBII positivity. For predicting Graves disease relapse, the sensitivity and specificity of TSAb were 63% and 83%, respectively, whereas those of TBII were 28% and 65%. Conclusion: TSAb at ATD withdrawal can predict the relapse of Graves hyperthyroidism, but TBII cannot. Measuring TSAb at ATD withdrawal can assist with clinical decisions making for patients with Graves disease. [ABSTRACT FROM AUTHOR]

Background: Thyrotoxic periodic paralysis (TPP) is a rare complication of thyrotoxicosis characterized by acute attacks of muscle weakness and hypokalemia. Recently, variation in several genes was suggested to be associated with TPP. This study evaluated the genetic predisposition to TPP in terms of the β2-adrenergic receptor (ADRB2), androgen receptor (AR), and γ-aminobutyric acid receptor α3 subunit (GABRA3) genes. Methods: This study enrolled 48 men with Graves disease (GD) and TPP, and 48 GD patients without TPP. We compared the frequencies of candidate polymorphisms between the two groups. Results: The frequency of the Gly16/Gly16 genotype in ADRB2 was not significantly associated with TPP (P=0.32). More CAG repeats (≥26) in the AR gene were not correlated with TPP (odds ratio [OR], 2.46; 95% confidence interval [CI], 0.81 to 8.09; P=0.08). The allele frequency of the TT genotype in the GABRA3 gene was not associated with TPP (OR, 1.83; 95% CI, 0.54 to 6.74; P=0.41). Conclusion: The polymorphisms in the ADRB2, AR, and GABRA3 genes could not explain the genetic susceptibility to TPP in Korean men with GD. [ABSTRACT FROM AUTHOR]

Background: Transcriptional activating mutations of telomerase reverse transcriptase (TERT) are associated with more aggressive thyroid cancer. We evaluated the significance of TERT promoter mutations in Korean patients with classic papillary thyroid cancer (PTC). Methods: Genomic DNA was isolated from four thyroid cancer cell lines and 35 fresh-frozen PTC tissues. TERT promoter mutations (C228T and C250T) and the BRAF V600E mutation were evaluated by polymerase chain reaction amplification and direct sequencing. Results: The CC228229TT mutation in the TERT promoter was detected in BCPAP cells and the C250T mutation was found in 8505C cells. No TERT promoter mutation was observed in Cal-62 or ML-1 cells. The C228T mutation was found in only 1 of 35 (2.8%) PTCs and no C250T mutations were detected in any of the study subjects. The BRAF V600E mutation was found in 20 of 35 (57.1%) PTCs. One patient with the C228T TERT mutation also harbored the BRAF V600E mutation and developed a recurrence. Conclusion: The prevalence of somatic TERT promoter mutations was low in Korean patients with classic PTC. Therefore, the prognostic role of TERT promoter mutations might be limited in this patient cohort. [ABSTRACT FROM AUTHOR]

Background : Antithyroid drugs (ATDs) can lead to the development of agranulocytosis, which is the most serious adverse effect. Characteristics of ATD-induced agranulocytosis (AIA) have seldom been reported due to the rarity. In this study, we characterized the clinical features for AIA in Korean patients. Methods: We retrospectively reviewed data from patients with AIA diagnosed between 1997 and 2014 at four tertiary hospitals. Agranulocytosis was defined as an absolute neutrophil count (ANC) below 500/mm³. Results: The mean age of the patients (11 males, 43 females) was 38.2±14.9 years. Forty-eight patients (88.9%) with AIA had fever and sore throat on initial presentation, 20.4% of patients developed AIA during the second course of treatment, and 75.9% of patients suffered AIA within 3 months after initiation of ATD. The patients taking methimazole (n=39) showed lower levels of ANC and more frequent use of granulocyte-macrophage colony-stimulating factor than propylthiouracil (n= 15) users. The median duration of agranulocytosis was 5.5 days (range, 1 to 20). No differences were observed between the long (≥6 days) and short recovery time (≥ 5 days) groups in terms of age, gender, ATDs, duration of ATDs, or initial ANC levels. Four patients (7.4%) who were taking ATDs for less than 2 months died of sepsis on the first or second day of hospitalization. Conclusion: The majority of AIA incidents occur in the early treatment period. Considering the high fatality rate of AIA, an early aggressive therapeutic approach is critical and patients should be well informed regarding the warning symptoms of the disease. [ABSTRACT FROM AUTHOR]

Background: Obesity is associated with aggressive pathological features and poor clinical outcomes in breast and prostate cancers. In papillary thyroid carcinoma (PTC), these relationships remain still controversial. This study aimed to evaluate the associations between body mass index (BMI) and the clinical outcomes of patients with PTC. Methods: This retrospective study included 1,189 patients who underwent total thyroidectomy for PTCs equal to or larger than 1 cm in size. Clinical outcomes were evaluated and compared based on the BMI quartiles. Results: There were no significant associations between BMI quartiles and primary tumor size, extrathyroidal invasion, cervical lymph node metastasis, or distant metastasis. However, an increase in mean age was associated with an increased BMI (P for trend <0.001). Multifocality and advanced tumor-node-metastasis (TNM) stage (stage III or IV) were significantly associated with increases of BMI (P for trend 0.02 and <0.001, respectively). However, these associations of multifocality and advanced TNM stage with BMI were not significant in multivariate analyses adjusted for age and gender. Moreover, there were no differences in recurrence-free survivals according to BMI quartiles (P=0.26). Conclusion: In the present study, BMI was not associated with the aggressive clinicopathological features or recurrence-free survivals in patients with PTC. [ABSTRACT FROM AUTHOR]

Background: The prevalence of thyroid cancer has increased very rapidly in Korea. However, there is no published report focusing on thyroid cancer mortality in Korea. In this study, we aimed to evaluate standardized thyroid cancer mortality using data from Statistics Korea (the Statistical Office of Korea). Methods: Population and mortality data from 1985 to 2010 were obtained from Statistics Korea. Age-standardized rates of thyroid cancer mortality were calculated according to the standard population of Korea, as well as World Health Organization (WHO) standard population and International Cancer Survival Standard (ICSS) population weights. Results: The crude thyroid cancer mortality rate increased from 0.1 to 0.7 per 100,000 between 1985 and 2010. The pattern was the same for both sexes. The age-standardized mortality rate (ASMR) for thyroid cancer for Korean resident registration population increased from 0.19 to 0.67 between 1985 and 2000. However, it decreased slightly, from 0.67 to 0.55, between 2000 and 2010. When mortality was adjusted using the WHO standard population and ICSS population weights, the ASMR similarly increased until 2000, and then decreased between 2000 and 2010. Conclusion: Thyroid cancer mortality increased until 2000 in Korea. It started to decrease from 2000. [ABSTRACT FROM AUTHOR]

A solitary skin metastasis is a rare manifestation of papillary thyroid carcinoma (PTC). A 55-year-old woman presented with a movable subcutaneous nodule in her anterior neck for several months. Three years ago, she underwent total thyroidectomy and remnant ablation for classical PTC (pT3N0M0) and was under thyroxine suppression therapy without any evidence of recurrent disease. The subcutaneous nodule was 0.4 cm in size, firm, and movable without any change in the overlying skin. Recurrent PTC was confirmed after excision biopsy. Eight months after, she got a new nodule along the previous excision site. After punch biopsy, metastatic PTC was confirmed in the deep dermis and was re-excised with a clear resection margin. This is the first report of a case of solitary skin metastasis of PTC in Korea. Although solitary skin metastasis of PTC is rare, it should be considered in patients with a skin nodule. [ABSTRACT FROM AUTHOR]

Thyroid cancer is increasing all over the world. The exact cause of this increase is still debated and there are conflicting reports. Sophisticated molecular studies suggest that environmental chemicals may have effects of thyroid carcinogenesis. The development of powerful molecular biology techniques has enabled targeted next-generation sequencing for detection of mutations in thyroid cancer, and this technique can make a specific diagnosis of thyroid cancer in cytologically indeterminate cases. The initial treatment of well-differentiated thyroid cancer (DTC) is surgery followed by radioiodine remnant ablation. However, further studies are needed to determine the optimal dosage of radioactive iodine for DTC patients with lateral neck metastasis. DTC is an indolent tumor and may cause death even decades later. Thus, long-term follow-up is mandatory. Recently, dynamic risk stratification (DRS) has begun to use stimulated thyroglobulin level at 1 year after the initial treatment and restratified the risk in accordance with the response to the initial treatment. This DRS strategy accurately predicts disease free survival and can be widely used in daily clinical settings. For the iodine refractory metastatic disease, redifferentiation therapy and targeted therapy are two promising alternative treatments. Sorafenib is the first approved agent for the treatment of progressive iodine refractory advanced thyroid cancer in Korea and may be very helpful for radioactive-refractory locally advanced or metastatic DTC. Selumetinib may be an effective redifferentiating agent and could be used within several years. [ABSTRACT FROM AUTHOR]

Www.e-enm.org 201 Endocrinol Metab 2021;36:201-202 https://doi.org/10.3803/EnM.2020.884 pISSN 2093-596X - eISSN 2093-5978 Image of Interest Anaplastic Thyroid Carcinoma with Initial Ultrasonography Features Mimicking Subacute Thyroiditis Meihua Jin, Tae Yong Kim Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea A 61-year-old man came to the Asan Medical Center for febrile sensation and neck pain. Initial thyroid scan and neck computed tomography (CT) taken after the diagnosis of anaplastic thyroid carcinoma. [Extracted from the article]

Cancer metastases to the thyroid or adrenal gland are uncommon. Furthermore, cases showing long-term survival after surgical resection of those metastatic tumors are rare. We report a case of pulmonary artery intimal sarcoma with metastases to the thyroid and adrenal glands sequentially that was successfully treated with sequential metastasectomies. A 62-year-old woman presented with a 4-week history of dyspnea on exertion and facial edema in November 1999. Echocardiography and chest computed tomography (CT) revealed an embolism-like mass in the pulmonary trunk. Pulmonary artery endarterectomy with pulmonary valve replacement was performed, and histopathology revealed pulmonary artery intimal sarcoma. A thyroid nodule was found by chest CT in November 2001 (2 years after initial surgery). During follow-up, this lesion showed no change, but we decided to obtain fine needle aspiration cytology (FNAC) in August 2004 (4.7 years after initial surgery). FNAC revealed atypical spindle cells suggestive of metastatic intimal sarcoma. She underwent total thyroidectomy. During follow-up, a right adrenal gland mass was detected by chest CT in March 2006 (6.3 years after initial surgery), and adrenalectomy was done, which also revealed metastatic sarcoma. She has been followed up without any evidence of recurrent disease until May 2012 (12.5 years after initial surgery). [ABSTRACT FROM AUTHOR]