Changes in the clinicopathological characteristics and outcomes of thyroid cancer in Korea over the past four decades

BRAF(V600E) Is Correlated with Recurrence of Papillary Thyroid Microcarcinoma: A Systematic Review, Multi-Institutional Primary Data Analysis, and Meta-Analysis

BACKGROUND

Given the increasing incidence of papillary thyroid carcinoma despite stable disease-specific mortality rates, the potential for the disease to reoccur is a key outcome to predict. The BRAF(V600E) mutation has been associated with recurrent disease in larger tumors. However, its correlation in papillary thyroid microcarcinoma (PTMC) is not clear in individual series.

METHODS

The MEDLINE, EMBASE, Web of Science, and Cochrane databases were searched for studies including patients with PTMC undergoing initial surgical treatment. Studies with at least two years of follow-up, BRAF genotyping (the comparator), and recurrence as an outcome were included, as were unpublished primary data on 485 patients from two institutions. The metameter analyzed was odds ratio (OR) for recurrence between patients with BRAF(V600E) versus BRAF wild type (BRAFwt).

RESULTS

The initial search identified 431 references. After screening of the abstracts for inclusion, 44 manuscripts were reviewed in full by two independent reviewers. Four published studies and primary data from two institutional cohorts were included in the final analysis. A meta-analysis of 2247 PTMC patients revealed that patients with a BRAF(V600E) mutation had a higher likelihood for recurrence (odds ratio 2.09 [confidence interval 1.31-3.33], p = 0.002).

CONCLUSIONS

This meta-analysis shows that BRAF mutational status correlates with recurrence of PTMCs, highlighting the potential utility of genotyping in preoperative and postoperative planning. BRAF mutation may be helpful in risk-stratifying patients with PTMC for surgical management versus observation.

Responses to Overdiagnosis in Thyroid Cancer Screening among Korean Women

Purpose

Communicating the harms and benefits of thyroid screening is necessary to help individuals decide on whether or not to undergo thyroid cancer screening. This study was conducted to assess changes in thyroid cancer screening intention in response to receiving information about overdiagnosis and to determine factors with the greatest influence thereon.

Materials and Methods

Data were acquired from subjects included in the 2013 Korean National Cancer Screening Survey (KNCSS), a nationwide, population-based, cross-sectional survey. Of the 4,100 respondents in the 2013 KNCSS, women were randomly subsampled and an additional face-to-face interview was conducted. Finally, a total of 586 female subjects were included in this study. Intention to undergo thyroid cancer screening was assessed before and after receiving information on overdiagnosis.

Results

Prior awareness of overdiagnosis in thyroid cancer screening was 27.8%. The majority of subjects intended to undergo thyroid cancer screening before and after receiving information on overdiagnosis (87% and 74%, respectively). Only a small number of subjects changed their intention to undergo thyroid cancer screening from positive to negative after receiving information on overdiagnosis. Women of higher education level and Medical Aid Program recipients reported being significantly more likely to change their intention to undergo thyroid cancer screening afterreceiving information on overdiagnosis,whilewomen with stronger beliefs on the efficacy of cancer screening were less likely to change their intention.

Conclusion

Women in Korea appeared to be less concerned about overdiagnosis when deciding whether or not to undergo thyroid cancer screening.

Changing trends in the clinicopathological features and clinical outcomes of medullary thyroid carcinoma

BACKGROUND

The early detection of papillary thyroid cancer has contributed to the increase in the incidence and improved clinical outcomes. However, recent changes of medullary thyroid carcinoma (MTC) over time remain unclear. We evaluated changes of the clinicopathological characteristics and clinical outcomes in patients with MTC in recent years.

METHODS

A total of 109 MTC patients were classified based on the year of initial surgery: 1996-2000 (n = 14), 2001-2006 (n = 39), and 2007-2011 (n = 56).

RESULTS

The primary tumor size significantly decreased and the proportion of microMTCs (size ≤1 cm) increased over time (P = 0.002 and P < 0.001, respectively). The proportion of patients with cervical lymph node (LN) metastasis significantly decreased (P = 0.037), and the ratio of metastatic LNs significantly decreased (P = 0.011). Disease-free survival (DFS) rate of patients was significantly improved over time (P = 0.007). There was no significant difference in DFS between microMTC and macroMTC patients. However, more advanced LN stage patients demonstrated more recurrences (P < 0.001). Especially, there were significantly more recurrences in patients with N1b diseases in comparison with patients without cervical LN metastases (P < 0.001).

CONCLUSIONS

The prognosis of MTC patients has significantly improved in recent years. These changes could be associated with the early diagnosis before development of lateral and extensive cervical LN metastases. J. Surg. Oncol. 2016;113:152-158. © 2015 Wiley Periodicals, Inc.

A Possible Association Between Thyroid Cancer and Breast Cancer

BACKGROUND

Several lines of evidence suggest that breast cancer (BC) and thyroid cancer (TC) occur together in the same female patients more frequently than would be expected by chance. This study investigated the prevalence and clinicopathological characteristics of second primary BC in TC patients and second primary TC in BC patients.

METHODS

A retrospective case-controlled study was performed in 4243 patients with differentiated TC and 6833 patients with BC. Age-matched control groups without second malignancies were selected.

RESULTS

Of the 4243 patients with TC, 55 patients developed subsequent BC during a five-year follow-up (range 2-40 years); the standardized incidence ratio (SIR) was 2.45 [confidence interval (CI) 1.83-2.96]. Among the 6833 patients with BC, 81 patients developed subsequent TC during a 6.2-year follow-up (range 2-40 years); the SIR was 2.18 [CI 1.43-2.82]. Subsequent second BC or TC diagnosed within five years of the initial primary malignancy showed more clinical characteristics consistent with early-stage cancer than did control BC or TC patients. Notably, the expression of both the estrogen and progesterone receptors was significantly higher in the tissues of BC patients with coexisting TC compared with those with BC alone.

CONCLUSIONS

The overall risk of second primary TC or BC is increased in patients with prior BC or TC, respectively. The early detection of second cancer might have contributed to these findings. However, BC that coexisted with TC had a higher expression of hormone receptors, suggesting an association between the molecular pathogenesis of TC and BC.

A qualitative study of women's views on overdiagnosis and screening for thyroid cancer in Korea

Background

The incidence of thyroid cancer in Korea has increased by about 25 % every year for the past 10 years. This increase is largely due to a rising incidence in papillary thyroid cancer, which is associated with an overdiagnosis of small tumors that may never become clinically significant. This study was conducted to explore Korean women’s understanding of overdiagnosis and to investigate changes in screening intention in response to overdiagnosis information.

Methods

Focus group interviews were conducted among women of ages 30–69 years, who are commonly targeted in Korea for cancer screening. Women were divided into four groups according to thyroid cancer screening history and history of thyroid disease. Of 51 women who were contacted, 29 (57 %) participated in the interviews.

Results

Prior awareness of thyroid cancer overdiagnosis was minimal. When informed about the risks of overdiagnosis, the participants were often surprised. Overcoming initial malcontent, many women remained skeptic about overdiagnosis and trusted in the advice of their physicians. Meanwhile, some of the study participants found explanations of overdiagnosis difficult to understand. Further, hearing about the risks of overdiagnosis had limited impact on the participants’ attitudes and intentions to undergo thyroid cancer screening, as many women expressed willingness to undergoing continued screening in the future.

Conclusion

A large majority of Korean women eligible for and had undergone thyroid cancer screening were unaware of the potential for overdiagnosis. Nevertheless, overdiagnosis information generally had little impact on their beliefs about thyroid cancer screening and their intentions to undergo future screening. Further research is needed to determine whether these findings could be generalized to the wider Korean population.

Long noncoding RNA PVT1 modulates thyroid cancer cell proliferation by recruiting EZH2 and regulating thyroid-stimulating hormone receptor (TSHR)

The purposes of this study were to investigate the potential roles of long noncoding RNA (lncRNA) PVT1 in thyroid cancer cell proliferation and to explore their possible mechanisms. A total of 84 patients who were diagnosed as having thyroid cancer (papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), and anaplastic thyroid carcinoma (ATC)) in Renji Hospital were enrolled in this study. Expressions of lncRNA PVT1 in thyroid cancer tissues and cell lines (IHH-4, FTC-133, and 8505C) were analyzed using RT-polymerase chain reaction (PCR) and western blotting analysis. The effects of lncRNA PVT1 expression on thyroid cancer cell proliferation and cell cycle were analyzed using flow cytometry. Furthermore, the effects of lncRNA expression on thyroid-stimulating hormone receptor (TSHR) expression and polycomb enhancer of zeste homolog 2 (EZH2) were also analyzed using RNA immunoprecipitation (RIP) assay and chromatin immunoprecipitation (ChIP) assay, respectively. Compared to the controls, lncRNA PVT1 was significantly up-regulated in thyroid tissues, as well as in three kinds of tumor cell lines (P < 0.05). Silenced PVT1 significantly inhibited thyroid cell line IHH-4, FTC-133, and 8505C cell proliferation and arrested cell cycle at G0/G1 stage and significantly decreased cyclin D1 and TSHR expressions (P < 0.05). Moreover, lncRNA PVT1 could be enriched by EZH2, and silencing PVT1 resulted in the decreased recruitment of EZH2. This study suggested that lncRNA PVT1 may contribute to tumorigenesis of thyroid cancer through recruiting EZH2 and regulating TSHR expression.

Recent Changes in the Clinical Outcome of Papillary Thyroid Carcinoma With Cervical Lymph Node Metastasis

CONTEXT

The prognosis of papillary thyroid cancer (PTC) with cervical lymph node (LN) metastasis has changed with increased detection of subclinical metastatic LNs. The number and size of metastatic LNs were proposed as new prognostic factors in PTC with cervical LN metastasis (N1).

OBJECTIVE

The objective of the study was to evaluate changes in N1 PTC characteristics and clinical outcome over time and to confirm the prognostic value of the number and size of metastatic LNs.

DESIGN AND PATIENTS

This study included 1815 N1 PTC patients diagnosed between 1997 and 2011. Patients were classified into three risk groups according to the number and size of metastatic LNs: very low risk, five or fewer and 0.2 cm or less; low risk, five or fewer and 0.2 cm or greater; and high risk, more than five.

MAIN OUTCOME MEASURES

Response to initial therapy and disease-free survival (DFS) was measured.

RESULTS

Metastatic LNs became smaller, and the ratio of metastatic LNs, which represents the extent of LN involvement and the completeness of surgery, decreased significantly over time. The proportion of patients with excellent response significantly increased from 33% to 67% over time (P < .001). These improvements were more evident in the low- and high-risk groups than in the very low-risk group. The DFS 5 years after initial surgery was also significantly increased from 73% to 91% over time (P < .001). The new LN classification was strongly associated with outcome. Patients in the very low-risk group had longer DFS than those in the low- and high-risk groups during the study period.

CONCLUSIONS

The clinical outcome of N1 PTC has significantly changed over time with the earlier detection of thyroid cancers with less extensive LN involvement. More complete surgical neck dissection also might be responsible for these changes. The number and size of metastatic LNs are important prognostic factors of recurrence in N1 PTC.

Radioiodine Scan Index: A Simplified, Quantitative Treatment Response Parameter for Metastatic Thyroid Carcinoma

PURPOSE

We aimed to develop and validate a simplified, novel quantification method for radioiodine whole-body scans (WBSs) as a predictor for the treatment response in differentiated thyroid carcinoma (DTC) patients with distant metastasis.

METHODS

We retrospectively reviewed serial WBSs after radioiodine treatment from 2008 to 2011 in patients with metastatic DTC. For standardization of TSH simulation, only a subset of patients whose TSH level was fully enhanced (TSH > 80 mU/l) was enrolled. The radioiodine scan index (RSI) was calculated by the ratio of tumor-to-brain uptake. We compared correlations between the RSI and TSH-stimulated serum thyroglobulin (TSH_s_Tg) level and between the RSI and Tg reduction rate of consecutive radioiodine treatments.

RESULTS

A total of 30 rounds of radioiodine treatment for 15 patients were eligible. Tumor histology was 11 papillary and 4 follicular subtypes. The TSH_s_Tg level was mean 980 ng/ml (range, 0.5-11,244). The Tg reduction rate after treatment was a mean of -7 % (range, -90 %-210 %). Mean RSI was 3.02 (range, 0.40-10.97). RSI was positively correlated with the TSH_s_Tg level (R(2) = 0.3084, p = 0.001) and negatively correlated with the Tg reduction rate (R(2) = 0.2993, p = 0.037). The regression equation to predict treatment response was as follows: Tg reduction rate = -14.581 × RSI + 51.183.

CONCLUSIONS

Use of the radioiodine scan index derived from conventional WBS is feasible to reflect the serum Tg level in patients with metastatic DTC, and it may be useful for predicting the biologic treatment response after radioiodine treatment.

Analysis of pattern of occurrence of thyroid carcinoma between 2001 and 2010

INTRODUCTION

An ongoing discussion is found in medical literature about the reasons for changes in thyroid carcinoma incidence patterns over the last decades.

OBJECTIVE

To analyze the clinical and pathological characteristics of thyroid carcinoma cases over a decade.

METHODS

Cross-sectional study over an historical cohort. Medical records of 628 thyroid cancer cases in a single center were reviewed. 597 patients were included. Microcarcinoma cases were selected for a qualitative analysis phase, in which medical records were reviewed for better understanding of thyroid nodule and thyroid cancer diagnosis process.

RESULTS

An increase in the proportion of cases with thyroid cancer diagnosis was observed throughout the decade; new cases were predominantly tumors of less than 2 cm, with histopathological signs of low aggressiveness. There was an increase in proportion of cases with malignant cytological results among microcarcinomas.

CONCLUSION

There is a trend for increase in thyroidectomies due to cancer in this institution, with proportional increment of cases with histopathological characteristics indicative of early disease. Among microcarcinomas, there is an increasing group represented by cancer cases that were not incidentally diagnosed, related to an enhancement in preoperative diagnostic methods.

The Risk of Relapse in Papillary Thyroid Cancer (PTC) in the Context of BRAFV600E Mutation Status and Other Prognostic Factors

INTRODUCTION

The risk of over-treatment in low-advanced PTC stages has prompted clinicians to search for new reliable prognostic factors. The presence of BRAF mutation, the most frequent molecular event in PTC, seems to be a good candidate. However, there is still lack of randomised trials and its significance has been proved by retrospective analyses, involving a large group of patients. The question arises whether this factor is useful in smaller populations, characterised for specialised centres. Thus, the aim of the study was to evaluate the use of BRAF mutation as a potential predictive marker in PTC patients.

MATERIAL

233 PTC subjects treated between 2004-2006, were retrospectively analysed. Stage pT1 was diagnosed in 64.8% patients and lymph node metastases in 30.9%. Median follow-up was 7.5 years. BRAFV600E mutation was assessed postoperatively in all cases.

RESULTS

BRAF V600E mutation was found in 54.5%. It was more frequent in patients > 45 years (p=0.0001), and associated with larger tumour size (p=0.004). Patients with tumours <= 10 mm were over-represented among BRAF negative population (p=0.03). No association between BRAF mutation and other clinicopathological factors was observed. BRAF status was associated neither with relapse nor with disease-free survival (DFS) (p=0.76). Nodal status, extrathyroidal invasion and tumour size significantly influenced DFS.

CONCLUSION

The risk of PTC recurrence is mainly related to the presence of lymph node metastases and extrathyroidal invasion, whereas no impact of BRAF V600E mutation has been demonstrated.

The risk of second primary malignancy is increased in differentiated thyroid cancer patients with a cumulative (131)I dose over 37 GBq

BACKGROUND

The aim of this study was to investigate the risk factors for second primary malignancy (SPM) diagnosed after differentiated thyroid cancer (DTC).

METHODS

A total of 2468 DTC patients who underwent thyroidectomy were reviewed. SPM was defined as a non-thyroidal malignancy, diagnosed at least 1 year after the diagnosis of thyroid cancer. Patients were divided into five groups according to cumulative (131)I dose: very high-activity (≥ 37.0 GBq), high-activity (22.3-36.9 GBq), intermediate-activity (5.56-22.2 GBq), low-activity (1.1-5.55 GBq) and no RAI.

RESULTS

Among the 2468 patients, 61 (2.5%) had SPMs during 7.0 (1.0-33.0) years of median follow-up. Age above 40 years, male sex and very high-activity RAI were independent risk factors for the development of SPM. SPM-related mortality was highest in the very high-activity group, while DTC-related mortality was highest in the high-activity group. The overall mortality both from SPM and DTC was highest in the high-activity group.

CONCLUSION

A cumulative (131)I dose <37.0 GBq did not increase the risk of SPM. A cumulative (131) I dose ≥ 37.0 GBq increased the risk of SPM and SPM-related mortality and decreased the DTC-specific mortality, resulting in a similar all-cause mortality compared with the low-activity RAI group. Using repeated high-dose RAI for treating RAI-responsive but persistent DTC patients needs careful consideration of the individual benefits from RAI vs the risk of developing SPM.

Pediatric patients with multifocal papillary thyroid cancer have higher recurrence rates than adult patients: a retrospective analysis of a large pediatric thyroid cancer cohort over 33 years

CONTEXT

Large-sample studies with long-term follow-up data are limited for pediatric patients with thyroid cancer.

OBJECTIVE

Secular changes in clinicopathological characteristics and outcomes in pediatric patients with thyroid cancer were investigated and compared with those of adults.

DESIGN AND PATIENTS

A retrospective review of 150 pediatric patients with thyroid cancer managed between 1980 and 2013 was conducted. The long-term outcomes of 124 patients followed up for 12 months or longer were evaluated. Predictors of recurrence-free survival (RFS) in pediatric patients with papillary thyroid cancer (ped-PTC group) were compared with those of 3071 adult patients.

RESULTS

The proportion of small tumors (<1 cm) increased from 9.0% before 2010 to 36.8% after 2010 (P < .001); however, neither pathological presentations such as multifocality, extrathyroidal extension (ETE), lymph node (LN) metastasis, or lung metastasis nor the RFS rate changed over time. The 5- and 10-year recurrence rates were 14.5% and 34.4% in pediatric patients, respectively. In respective analyses of the ped-PTC group and patients of all ages with papillary thyroid cancer (all ages group), the rates of ETE, LN metastasis, and lung metastasis were higher with younger age (all P for trend <.05). RFS was lower in the pediatric than the adult patients aged 20-54 years (P < .005) and was comparable with that of older patients (≥ 55 y). Only tumor multifocality and size predicted recurrence in the ped-PTC group (P < .05), whereas LN metastasis and ETE also predicted recurrence in the all-ages group (P < .01). Among patients in the all-ages group with multifocal tumors, pediatric patients had the lowest RFS (P < .05).

CONCLUSIONS

The pathological characteristics and recurrence rates of pediatric thyroid cancer have not changed over 33 years. Although younger patients present with more advanced disease, multifocality rather than age at diagnosis predicted recurrence. Recurrence was higher in pediatric than adult patients with multifocal papillary thyroid cancer.

Role of charcoal tattooing in localization of recurred papillary thyroid carcinoma: initial experiences

Purpose

Surgical excision is the definitive treatment for localized recurrence of papillary thyroid carcinoma. Reoperation for recurrence, however, is challenging and associated with increased operative times and complication rates. For safe and effective reoperation, ultrasound-guided charcoal tattooing localization can be used. The aim of this study was to investigate the feasibility and safety of the ultrasound-guided charcoal tattooing localization.

Methods

Between November 2012 and August 2013, ten patients underwent preoperative charcoal tattooing localization for twelve recurrent lesions. Patient demographics, pathologic features, and operation results were reviewed.

Results

The technical success rate of charcoal tattooing was 100%. Eight patients had one recurrent lesion, and two patients had double lesions. Among these 12 recurrent lesions, three (25%) were found in level II, four (33%) in level IV, four (33%) in level VI, and one (8%) was found in the thyroidectomy bed site. The mean size of lesions was 0.87 ± 0.35 cm. Of these 10 patients, eight patients underwent selective lymph node dissection, one patient underwent modified radical neck dissection, and one patient underwent recurrent mass excision. Transient hypocalcemia developed in one patient, and no recurrent laryngeal nerve palsy occurred. There were no major complications related to the injection of the charcoal. The mean follow-up period after reoperation was 8.6 ± 2.7 months; in the follow-up ultrasound, there were no remnant lesions in all patients.

Conclusion

Preoperative ultrasound-guided charcoal tattooing localization for recurrent thyroid cancer appears to be a feasible and safe procedure for reoperation. Further evaluation is warranted in larger patients' cohorts.

Single nucleotide polymorphisms of ataxia telangiectasia mutated and the risk of papillary thyroid carcinoma

Genetic factors associated with susceptibility to papillary thyroid carcinoma (PTC) are not well known. We evaluated the association between single nucleotide polymorphisms (SNPs) of ataxia telangiectasia mutated (ATM) and the risk of PTC. A total of 437 histologically confirmed PTC cases and 184 cancer-free controls without thyroid nodules were recruited. Genotypes with respect to five ATM SNPs (rs189037, rs664677, rs373759, rs664143, and rs4585) were determined by the TaqMan assay, and odds ratios and 95% confidence intervals were obtained by logistic regression analysis. Linkage disequilibria and haplotypes were examined from the genotype data. When evaluated separately the genotype distributions of the five ATM SNPs were similar in the PTC cases and controls. Three ATM SNPs (rs373759, rs664143, and rs4585) were found to be in strong linkage disequilibrium (D' = 1.00, P < 0.001). When the three haplotypes (C-A-G), (T-G-T), and (C-G-T) of these three ATM SNP sites were analyzed, ATM haplotype (C-G-T) +/- was associated with a lower risk of PTC than ATM haplotype (C-G-T) -/- (P = 0.03) after adjusting for age and gender. Our results suggest that genetic polymorphisms of ATM may play an important role in the development of thyroid cancer in the Korean population.

A metabolic phenotype based on mitochondrial ribosomal protein expression as a predictor of lymph node metastasis in papillary thyroid carcinoma

Metabolic reprogramming has been regarded as an essential component of malignant transformation. However, the clinical significance of metabolic heterogeneity remains poorly characterized. The aim of this study was to characterize metabolic heterogeneity in thyroid cancers via the analysis of the expression of mitochondrial ribosomal proteins (MRPs) and genes involved in oxidative phosphorylation (OxPhos), and investigate potential prognostic correlations. Gene set enrichment analysis (GSEA) verified by reverse transcription polymerase chain reaction and gene network analysis was performed using public repository data. Cross-sectional observational study was conducted to classify papillary thyroid cancer (PTC) by the expression of MRP L44 (MRPL44) messenger RNA (mRNA), and to investigate the clinicopathological features. GSEA clearly showed that the expression of OxPhos and MRP gene sets was significantly lower in primary thyroid cancer than in matched normal thyroid tissue. However, 8 of 49 primary thyroid tumors (16.3%) in the public repository did not show a reduction in OxPhos mRNA expression. Remarkably, strong positive correlations between MRPL44 expression and those of OxPhos and MRPs such as reduced nicotinamide adenine dinucleotide dehydrogenase (ubiquinone) 1 α subcomplex, 5; succinate dehydrogenase complex, subunit D; cytochrome c, somatic; adenosine triphosphate synthase, H+ transporting, mitochondrial Fo complex, subunit C1 (subunit 9); and MRP S5 (MRPS5) (P < 0.0001) were clearly denoted, suggesting that MRPL44 is a representative marker of OxPhos and MRP expressions. In laboratory experiments, metabolic heterogeneity in oxygen consumption, extracellular acidification rates (ECARs), and amounts of OxPhos complexes were consistently observed in BCPAP, TPC1, HTH-7, and XTC.UC1 cell lines. In PTCs, metabolic phenotype according to OxPhos amount defined by expression of MRPL44 mRNA was significantly related to lymph node metastasis (LNM) (P < 0.001). Furthermore, multivariate analysis clearly indicated that expression of MRPL44 is associated with an increased risk of lateral neck LNM (odds ratio 9.267, 95% confidence interval 1.852-46.371, P = 0.007). MRPL44 expression may be a representative marker of metabolic phenotype according to OxPhos amount and a useful predictor of LNM.

Standardized Thyroid Cancer Mortality in Korea between 1985 and 2010

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.

The Frequency and Clinical Implications of the BRAF(V600E) Mutation in Papillary Thyroid Cancer Patients in Korea Over the Past Two Decades

BACKGROUND

Over the past several decades, there has been a rapid worldwide increase in the prevalence of papillary thyroid cancer (PTC) as well as a number of changes in the clinicopathological characteristics of this disease. BRAF(V600E), which is a mutation of the proto-oncogene BRAF, has become the most frequent genetic mutation associated with PTC, particularly in Korea. Thus, the present study investigated whether the prevalence of the BRAF(V600E) mutation has increased over the past two decades in the Korean population and whether various PTC-related clinicopathological characteristics have changed.

METHODS

The present study included 2,624 patients who underwent a thyroidectomy for PTC during two preselected periods; 1995 to 2003 and 2009 to 2012. The BRAF(V600E) mutation status of each patient was confirmed using the polymerase chain reaction-restriction fragment length polymorphism method or by the direct sequencing of DNA.

RESULTS

The prevalence of the BRAF(V600E) mutation in Korean PTC patients increased from 62.2% to 73.7% (P=0.001) over the last two decades. Additionally, there was a greater degree of extrathyroidal extension (ETE) and lymph node metastasis in 2009 to 2012 patients with the BRAF(V600E) mutation and a higher frequency of thyroiditis and follicular variant-PTC in 2009 to 2012 patients with wild-type BRAF. However, only the frequency of ETE was significantly higher in 1995 to 2003 patients with the BRAF(V600E) mutation (P=0.047). Long-term recurrence rates during a 10-year median follow-up did not differ based on BRAF(V600E) mutation status.

CONCLUSION

The BRAF(V600E) mutation rate in Korean PTC patients has been persistently high (approximately 70%) over the past two decades and continues to increase. The present findings demonstrate that BRAF(V600E)-positive PTC was associated with more aggressive clinicopathological features, especially in patients who were recently diagnosed, suggesting that BRAF(V600E) mutation status may be a useful prognostic factor for PTC in patients recently diagnosed with this disease.

Age-Period-Cohort Analysis of Thyroid Cancer Incidence in Korea

Purpose

South Korea has the highest incidence rate of thyroid cancer in the world, and the incidence rate continues to increase. The aim of this study was to determine the age-period-cohort effects on the incidence of thyroid cancer in Korea.

Materials and Methods

Using the Korean National Cancer registry database, age-standardized incidence rates and annual percent changes (APCs) in thyroid cancer according to sex and histologic type were analyzed between 1997 and 2011. Age-period-cohort models were applied using an intrinsic estimator method according to sex.

Results

In both men and women, the incidence of thyroid cancer showed a sharp increase from 1997 through 2011. Among the histologic types, papillary carcinoma showed the greatest increase, with APCs of 25.1% (95% confidence interval [CI], 22.7% to 27.5%) in men and 23.7% (95% CI, 21.9% to 25.5%) in women, whereas anaplastic carcinoma did not show a significant increase in either sex. An increase in overall thyroid cancer incidence over time was observed in all birth cohorts. An age-period-cohort model indicated a steeply increasing period effect, which increased prominently from 1997 to 2011 in both men and women. The age effect showed an inverted U-shaped trend. The cohort effect tended to show a slight increase or remain constant from 1952 to 1977, followed by a decrease.

Conclusion

The period effect can explain the sharp increase in thyroid cancer incidence, strongly suggesting the role of thyroid screening.

Secular trends in the prognostic factors for papillary thyroid cancer

OBJECTIVE

With the recent increasing rates of screening for thyroid cancer, the cancers now tend to be smaller and less aggressive than those that are diagnosed when presented with symptoms, suggesting changes in the clinical validity of conventional prognostic factors for outcomes. We performed the retrospective study to identify the secular trends in the prognostic factors of thyroid cancer.

METHODS

We used medical records of 3147 patients diagnosed with papillary thyroid cancer (PTC) at the Seoul National University Hospital Thyroid Cancer Clinic between 1962 and 2009.

RESULTS

During the median 5.1-year follow-up, the overall recurrence rate was 13.3%, and male sex, tumor size, lymph node (LN) involvement, and extrathyroidal extension (ETE) were the significant prognostic factors for recurrence. Thyroid cancer-specific mortality was 1.4%, and the associated prognostic factors were older age, male sex, and LN involvement. For tumor recurrence, the hazard ratio (HR) for male sex decreased from 2.809 (95% CI, 1.497-5.269) in the pre-1989 period to 1.142 (95% CI, 0.736-1.772) in the post-1999 period. The pathologic characteristics, such as tumor size, LN involvement, and ETE, showed similar or increasing HRs over the time periods. For cancer-specific mortality, the HR for male sex decreased from 6.460 (95% CI, 1.714-24.348) in the pre-1990 period to 0.781 (95% CI, 0.083-7.379) in the post-1999 period.

CONCLUSION

The risk for poor outcomes in PTC associated with male sex decreased over time; in contrast, the risk associated with pathologic characteristics remained the same or increased over time. These trends might be associated with recent changes in the characteristics of patients with thyroid cancer.

Clinicopathologic correlations of the BRAFV600E mutation, BRAF V600E immunohistochemistry, and BRAF RNA in situ hybridization in papillary thyroid carcinoma

BACKGROUND

The BRAF(V600E) mutation is the most common genetic alteration in papillary thyroid carcinoma (PTC). The aim of this study is to analyze the clinicopathologic correlations of the BRAF(V600E) mutation, BRAF V600E immunohistochemistry (IHC) and BRAF RNA in situ hybridization (ISH) in PTC.

METHODS

This study included 467 patients with PTC who underwent surgical resection. We studied the BRAF(V600E) mutation using real-time PCR and BRAF V600E and BRAF RNA ISH using tissue microarray (TMA).

RESULTS

The frequencies of a positive BRAF(V600E) mutation by real-time PCR, positive BRAF V600E IHC, and high BRAF RNA ISH were 84%, 86%, and 70%, respectively, in PTC. Conventional PTC had higher positive rates in all three tests than other histologic types. The BRAF(V600E) mutation, BRAF V600E IHC, low ΔCt, and high BRAF RNA ISH were significantly associated with lymph node metastasis. The BRAF(V600E) mutation was significantly associated with positive immunostaining for BRAF V600E mutant protein (P<0.001) overall, with high BRAF RNA ISH only in the follicular variant (P=0.035). No significant correlation was noted between BRAF V600E IHC and BRAF RNA ISH. The sensitivity of BRAF V600E IHC for the BRAF(V600E) mutation was 95%, and the specificity was 61% overall, 96% and 54% in the conventional type, and 85% and 70% in the follicular variant.

CONCLUSIONS

Our results showed that positive BRAF V600E IHC significantly correlated with the BRAF(V600E) mutation. This suggests its clinical utility as a screening tool for the BRAF(V600E) mutation. In addition, a high BRAF RNA ISH score could be a candidate marker of aggressive behavior in BRAF(V600E) mutation-positive cases of PTC.

A review of the Fukushima nuclear reactor accident: radiation effects on the thyroid and strategies for prevention

PURPOSE OF REVIEW

This is a summary of the nuclear accident at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Stations (FDNPS) on 11 March 2011 to be used as a review of the radiation effects to the thyroid and strategies of prevention.

RECENT FINDINGS

The amount of radioiodine released to the environment following the Fukushima accident was 120 Peta Becquerel, which is approximately one-tenth of that in the Chernobyl accident. Residents near the FDNPS were evacuated within a few days and foodstuffs were controlled within 1 or 2 weeks. Therefore, thyroid radiation doses were less than 100 mSv (intervention levels for stable iodine administration) in the majority of children, including less than 1 year olds, living in the evacuation areas. Because the incidence of childhood thyroid cancer increased in those residing near the site following the Chernobyl accident, thyroid screening of all children (0-18 years old) in the Fukushima Prefecture was started. To date, screening of more than 280 000 children has resulted in the diagnosis of thyroid cancer in 90 children (approximate incidence, 313 per million). Thus, although the dose of radiation was much lower, the incidence of thyroid cancer appears to be much higher than that following the Chernobyl accident.

SUMMARY

A comparison of the thyroidal consequences following the Fukushima and Chernobyl nuclear reactor accidents is discussed. We also summarize the recent increased incidence in thyroid cancer in the Fukushima area following the accident in relation to increased thyroid ultrasound screening and the use of advanced ultrasound techniques.

VIDEO ABSTRACT

http://links.lww.com/COE/A8.

Differentiating the location of cervical lymph node metastasis is very useful for estimating the risk of distant metastases in papillary thyroid carcinoma

OBJECTIVE

A larger primary tumour size, greater numbers of cervical lymph node (LN) metastasis are associated with a higher risk of distant metastases in papillary thyroid carcinoma (PTC). However, the impact of the location of cervical LN metastasis on distant metastasis is controversial. The aim of this study was to evaluate the risk of distant metastases according to the tumour size and LN status in PTC patients, with special consideration of the LN metastasis pattern.

PATIENTS

This retrospective cohort study reviewed 1700 classical PTC patients who underwent initial thyroid surgery at Asan Medical Center between 2000 and 2004.

RESULTS

The cumulative risk of distant metastases was increased with the increase in tumour size and was significantly different according to the location of involved LNs by the tumour node metastasis (TNM) staging. The cumulative risk in pN1b group showed the steepest increasing pattern with the increase in tumour size compared with pN1a and pN0/Nx group. When we analysed the cumulative risk of distant metastases according to the number of involved LNs, patients with more than 20 involved LNs also had the steepest increase in the risk of distant metastases with the increase in tumour size. However, only the location of involved LNs, not the number of involved LNs, was associated with distant metastases in multivariate analysis.

CONCLUSIONS

We confirm that the location of involved LNs categories based on the TNM staging system is more useful than the number of involved LNs categories for estimating the risk of distant metastasis in PTC. Differentiating N1a disease from N1b disease is important for the follow-up and management of patients with PTC.

Risk factors for developing hyponatremia in thyroid cancer patients undergoing radioactive iodine therapy

Background

Due to the alarming increase in the incidence of thyroid cancer worldwide, more patients are receiving postoperative radioactive iodine (RAI) therapy and these patients are given a low-iodine diet along with levothyroxine withdrawal to induce a hypothyroid state to maximize the uptake of RAI by thyroid tissues. Recently, the reported cases of patients suffering from life-threatening severe hyponatremia following postoperative RAI therapy have increased. This study aimed to systematically assess risk factors for developing hyponatremia following RAI therapy in post-thyroidectomy patients.

Methods

We reviewed the medical records of all thyroid cancer patients who underwent thyroidectomy and postoperative RAI therapy from July 2009 to February 2012. Demographic and biochemical parameters including serum sodium and thyroid function tests were assessed along with medication history.

Results

A total of 2229 patients (47.0±11.0 years, female 76.3%) were enrolled in the analysis. Three hundred seven patients (13.8%) of all patients developed hyponatremia; 44 patients (2.0%) developed moderate to severe hyponatremia (serum Na⁺≤130 mEq/L) and another 263 (11.8%) patients showed mild hyponatremia (130 mEq/L<serum Na⁺≤135 mEq/L). In univariate analysis, old age, female sex, presence of hypertension, presence of diabetes, use of thiazide diuretics, use of angiotensin receptor blocker or angiotensin-converting enzyme inhibitors, lung metastasis, and hyponatremia and lower estimated glomerular filtration rate at the start of RAI therapy were significantly associated with hyponatremia in patients undergoing RAI therapy after total thyroidectomy. Multivariate analysis showed that old age, female sex, use of thiazide diuretics, and hyponatremia at the initiation of RAI therapy were independent risk factors for the development of hyponatremia.

Conclusion

Our data suggest that age greater than 60 years, female sex, use of thiazide, and hyponatremia at the initiation of RAI therapy are important risk factors for developing hyponatremia following RAI therapy in post-thyroidectomy patients.

Therapeutic potential of metformin in papillary thyroid cancer in vitro and in vivo

Metformin, an anti-diabetic drug used in type 2 diabetes treatment, is reported to have oncopreventive or therapeutic roles in several human cancers. The present study investigated the therapeutic potential of physiologic dose of metformin in PTC. Metformin inhibited PTC cell viability and increased cell apoptosis in various doses (0.5-20mM) in BCPAP and BHP10-3SC cells. Western blot analysis demonstrated that the p-AMPK/AMPK ratio increased with increased metformin treatment. The ectopic tumor experiment was performed using BHP10-3SC cells and athymic nude mice. Oral metformin treatment via drinking water significantly delayed tumor growth in both tumor development model and established tumor models. Necrotic area in tumors significantly increased with metformin treatment. Western blot analysis revealed an increase in p-AMPK/AMPK ratio and suppressions of mTOR and Akt expressions in metformin-treated mice compared to the results in mock-treated control mice. Our results indicate that a physiologic dose of metformin has anti-tumorigenic effects that result from activation of AMPK signaling and inhibition of Akt signaling.

Increased prevalence of chronic lymphocytic thyroiditis in Korean patients with papillary thyroid cancer

Background

In recent years, some reports have suggested that papillary thyroid cancers are more frequently associated with lymphocytic thyroiditis or Hashimoto's thyroiditis. This study investigated a potential increase in the prevalence of chronic lymphocytic thyroiditis among papillary thyroid cancer patients.

Materials and Methods

We used national epidemiological survey data on thyroid cancer patients diagnosed in 1999, 2005, and 2008. A retrospective medical record survey was conducted by representative sampling of a national cancer incidence database. The analysis included 5,378 papillary thyroid cancer patients aged 20–79 years. We calculated the age-standardized prevalence and age-adjusted prevalence ratios using a binomial regression model with a log link for the prevalence of chronic lymphocytic thyroiditis among papillary thyroid cancer patients by sex for each year.

Results

The prevalence of chronic lymphocytic thyroiditis among papillary thyroid cancer patients was 4.0% and 12.8% for men and women in 1999, 6.5% and 24.6% in 2005, and 10.7% and 27.6% in 2008, respectively. Between 1999 and 2008, the age-standardized prevalence of chronic lymphocytic thyroiditis increased 4.1-fold in male patients and 2.0-fold in female patients with papillary thyroid cancer. The prevalence of other thyroid diseases, however, did not increase in either gender.

Conclusions

Among Korean papillary thyroid cancer patients, the prevalence of chronic lymphocytic thyroiditis increased between 1999 and 2008, whereas the prevalence of other thyroid disorders did not change.

Heterogeneous echogenicity of the thyroid parenchyma does not influence the detection of multi-focality in papillary thyroid carcinoma on preoperative ultrasound staging

Heterogeneous echogenicity and micro-nodulations of diffuse thyroid disease on ultrasonography (US) might influence the diagnostic performance of pre-operative US staging, especially the detection of multi-focality. This study was designed to determine whether heterogeneous echogenicity of the thyroid parenchyma influences the diagnostic performance of US in the detection of multi-focality in papillary thyroid carcinoma. Between December 2010 and April 2011, 811 patients underwent pre-operative staging US for papillary thyroid carcinoma and surgery. Twelve radiologists performed the pre-operative US for T and N staging. Underlying parenchymal echogenicity and unilateral and bilateral multi-focality of the thyroid nodules were also evaluated. Patients were divided into two groups on the basis of the underlying echogenicity of the thyroid gland. To evaluate the diagnostic accuracy of US with respect to underlying echogenicity, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated and compared between the two groups. Among the 811 patients included, US revealed underlying heterogeneous echogenicity of the thyroid parenchyma in 204 (25.2%) and underlying homogeneous echogenicity of the thyroid parenchyma in 607 (74.8%). There were no significant differences between the two groups in the diagnostic performance of pre-operative staging US in predicting unilateral multi-focality and bilaterality. Underlying heterogeneous echogenicity in a thyroid gland with Hashimoto's thyroiditis does not significantly influence the detection of multi-focality in papillary thyroid cancer on pre-operative US staging.

The prediction of malignant risk in the category "atypia of undetermined significance/follicular lesion of undetermined significance" of the Bethesda System for Reporting Thyroid Cytopathology using subcategorization and BRAF mutation results

BACKGROUND

The "atypia of undetermined significance/follicular lesion of undetermined significance" (AUS/FLUS) category in the Bethesda System for Reporting Thyroid Cytopathology is a heterogeneous category of cases that are not clearly benign or malignant.

METHODS

We conducted an analysis of cytologic and histologic evaluations of thyroid nodules that had been interpreted as AUS/FLUS on fine-needle aspiration (FNA) at a single institution from April 2011 to April 2012. Those cases were classified into 2 subgroups according to the predominance of nuclear atypia (AUS) or microfollicular architecture (FLUS). In addition, for a number of these cases, BRAF gene mutation analyses were performed.

RESULTS

Of 6402 thyroid FNAs performed, 431 cases were diagnosed as AUS and 120 as FLUS. Follow-up cytologic or histologic outcome data were available for 315 AUS cases and 73 FLUS cases. Among AUS cases, 52.7% were malignant on repeat FNA or histologic diagnosis. In contrast, for FLUS, 6.8% were malignant on repeat FNA or histologic diagnosis. Among AUS/FLUS cases, 147 had adequate BRAF mutation analysis, which accompanied the histologic diagnosis. BRAF mutations were found in 87 AUS cases, 86 of which were papillary carcinoma. In contrast, there was only 1 case of BRAF mutation in FLUS. Correlating molecular results with histologic outcome revealed a 98.9% cancer probability for AUS cases with BRAF mutation.

CONCLUSIONS

The AUS subcategory indicates a higher risk of malignancy than the FLUS subcategory. Furthermore, BRAF molecular testing is helpful in stratifying the malignant risk of AUS cases into high-risk and low-risk groups.

Long-term prognosis of differentiated thyroid cancer with lung metastasis in Korea and its prognostic factors

BACKGROUND

Distant metastasis, generally to lung and bone, is rare in differentiated thyroid carcinoma (DTC) and the prognosis is still elusive. We investigated long-term outcomes of lung metastasis in DTC patients and its prognostic factors.

METHODS

A retrospective review was performed of 4572 patients who underwent surgery for DTC from 1962 to 2009 at Seoul National University Hospital. Among them, 164 patients were identified with lung metastasis and 152 patients were enrolled in the final analysis. Poor prognosis was defined as progressive disease or death.

RESULTS

Of these 152 patients, 10- and 20-year survival rates were 85.0% and 71.0%, respectively. No evidence of disease, stable disease, progressive disease, and death was identified in 22.4%, 28.3%, 35.5%, and 13.8%, respectively, after 11 years of median follow-up (range 2-41 years). Older age at diagnosis (≥45 years), primary tumor size ≥2 cm, follicular thyroid cancer, metastasis diagnosed after initial evaluation or (131)I remnant ablation (late metastasis), multiple metastases other than lung, (131)I nonavidity, and the presence of macronodules (≥1 cm) were more frequent in poor prognoses. Cox proportional hazard ratio for progression-free survival showed that (131)I nonavidity was the only independent predictive factor for poor prognosis.

CONCLUSIONS

The prognosis of lung metastasis from DTC in Korea within this study was favorable. (131)I nonavidity, observed more frequently in late metastasis, was the only independent factor predicting poor prognosis.

Modified dynamic risk stratification for predicting recurrence using the response to initial therapy in patients with differentiated thyroid carcinoma

OBJECTIVE

A new risk stratification system was proposed to estimate the risk of recurrence in patients with differentiated thyroid carcinoma (DTC) using the response to initial therapy. Here, we describe the modified dynamic risk stratification system, which takes into consideration the status of serum anti-Tg antibody (TgAb), and validate this system for assessing the risk of recurrence in patients with DTC.

PATIENTS AND METHODS

Patients who underwent total thyroidectomy with radioiodine remnant ablation due to DTC between 2000 and 2005 were included. We classified patients into four groups based on the response to the initial therapy ('excellent', 'acceptable', 'biochemical incomplete', and 'structural incomplete' response).

RESULTS

The median follow-up period of 715 patients with DTC was 8 years. The response to initial therapy was an important risk predictor for recurrent/persistent DTC. The relative risks (95% CI) of recurrence were 16.5 (6.3-43.0) in the 'acceptable response' group, 41.3 (15.4-110.8) in the 'biochemical incomplete response' group, and 281.2 (112.9-700.5) in the 'structural incomplete response' group compared with the 'excellent response' group (P<0.001, P<0.001, and P<0.001 respectively). The disease-free survival rate of the 'excellent response' group to initial therapy was 98.3% whereas that of the 'structural incomplete response' group was only 6.8%.

CONCLUSIONS

Our study validates the usefulness of the modified dynamic risk stratification system including the status of serum TgAb for predicting recurrent/persistent disease in patients with DTC. Personalized risk assessment using the response to initial therapy could be useful for the follow-up and management of patients with DTC.