Mechanisms of Disease: molecular genetics of childhood thyroid cancers

The U-Shaped association between age and distant metastasis in patients with papillary thyroid carcinoma

PURPOSE

To investigate the association between age distribution and synchronous distant metastasis of papillary thyroid carcinoma.

METHOD

Patients with PTC who were treated from January 2013 to December 2018 at a single institute in a cancer referral center in China were retrospectively reviewed. A logistic regression model with restricted cubic splines (RCS) was used to examine the association between age at diagnosis and synchronous distant metastasis.

RESULTS

A total of 111 patients (0.7%) were diagnosed with distant metastasis. The logistic regression model with RCS revealed a "U-shape" association between age and distant metastasis. The RCS curve suggested a U-shaped pattern. The multivariable regression analysis showed that patients in the age groups ≤21 years (OR 2.33, 95% CI 1.09-4.68, P = 0.022) and >55 years (OR 3.32, 95% CI 1.99-5.46, P < 0.001) had a significantly higher incidence of distant metastasis than patients in the age group of 22 to 55 years.

CONCLUSIONS

A U-shaped association was observed between age at diagnosis and synchronous distant metastasis in papillary thyroid carcinoma patients.

DICER1 Mutations Define the Landscape of Poorly Differentiated Thyroid Carcinoma in Children and Young Adults: Case Report and Literature Review

Poorly differentiated thyroid carcinoma (PDTC) is a rare malignancy, representing ~1% of all thyroid tumors. It is characterized by high-grade histologic features without the anaplastic characteristics observed in anaplastic thyroid carcinoma. Although rare in children and young adults, there is emerging evidence of clinical and genetic differences with PDTC in adults. We present a case of a 19-year-old female with a right thyroid lobe nodule classified as an EU-TIRADS 5 lesion. Subsequent FNAC showed a cellular aspirate of solitary cells and scant microfollicles with variable nuclear irregularities, which was designated a Bethesda class IV lesion. Thyroidectomy revealed histopathological features consistent with PDTC, including solid/trabecular growth, increased mitotic activity, central necrosis, and extensive vascular invasion. Molecular analysis identified germline and somatic DICER1 mutations in the absence of other established driver mutations of PDTC. This case report describes the fourth reported patient with a PDTC and germline DICER1 mutation. Our findings contribute to a limited body of literature on pediatric/young adult PDTC cases and highlight the pivotal role of DICER1 mutations. Emerging evidence suggests that pediatric PDTC may exhibit unique clinical and genetic characteristics, prompting further research into its molecular profile.

Origins of Second Malignancies in Children and Mutational Footprint of Chemotherapy in Normal Tissues

Pediatric cancers are rare diseases, and children without known germline predisposing conditions who develop a second malignancy during developmental ages are extremely rare. We present four such clinical cases and, through whole-genome and error-correcting ultra-deep duplex sequencing of tumor and normal samples, we explored the origin of the second malignancy in four children, uncovering different routes of development. The exposure to cytotoxic therapies was linked to the emergence of a secondary acute myeloid leukemia. A common somatic mutation acquired early during embryonic development was the driver of two solid malignancies in another child. In two cases, the two tumors developed from completely independent clones diverging during embryogenesis. Importantly, we demonstrate that platinum-based therapies contributed at least one order of magnitude more mutations per day of exposure than aging to normal tissues in these children.

SIGNIFICANCE

Using whole-genome and error-correcting ultra-deep duplex sequencing, we uncover different origins for second neoplasms in four children. We also uncover the presence of platinum-related mutations across 10 normal tissues of exposed individuals, highlighting the impact that the use of cytotoxic therapies may have on cancer survivors. See related commentary by Pacyna and Nangalia, p. 900. This article is featured in Selected Articles from This Issue, p. 897.

Evolving approaches in paediatric thyroid cytopathology: A review

The guidelines for the workup of thyroid nodules have been established in adult populations and secondarily applied to paediatric populations. In particular, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is commonly applied to both adult and paediatric thyroid nodules. However, as paediatric nodules have distinct molecular drivers and behavioural trajectories, there is renewed interest in diagnostic and management strategies that are paediatric specific. Here, we review key differences between paediatric and adult thyroid cancer and recent literature evaluating the use of TBSRTC in paediatric populations.

Stress, Thyroid Dysregulation, and Thyroid Cancer in Children and Adolescents: Proposed Impending Mechanisms

Stress is a potential catalyst for thyroid dysregulation through cross-communication of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid (HPT) axes. Stress and stressors exposure motivates molecular mechanisms affecting compound feedback loops of the HPT axis. While there is evidence of connection between stress and thyroid dysregulation, the question whether this connection is implicated in the development of thyroid cancer (TC) remains unanswered. In view of the rising incidence of TC in both adults and children alongside the increasing stress in our modern society, there is a need to understand possible interrelations between stress, thyroid dysregulation, and TC. Prolonged glucocorticoid secretion due to stress interferes with immune system response by altering the cytokines, inducing low-grade chronic inflammation, and suppressing function of immune-protective cells. Chronic inflammation is a risk factor linked to TC. The role of autoimmunity has been a matter of controversy. However, there is epidemiological connection between autoimmune thyroid disease (AITD) and TC; patients with AITD show increased incidence in papillary thyroid carcinoma (PTC), and those with TC show a high prevalence of intrathyroidal lymphocyte infiltration and thyroid autoantibodies. Timing and duration-dependent exposure to specific endocrine disrupting chemicals (EDCs) has an impact on thyroid development, function, and proliferation, leading to thyroid disease and potentially cancer. Thyroid hormone imbalance, chronic inflammation, and EDCs are potential risk factors for oxidative stress. Oxygen free radicals are capable of causing DNA damage via stimulation of the mitogen-activating protein kinase or phosphatidylinositol-3-kinase and/or nuclear factor kB pathways, resulting in TC-associated gene mutations such as RET/PTC, AKAP9-BRAF, NTRK1, RAASF, PIK3CA, and PTEN. Stressful events during the critical periods of prenatal and early life can influence neuroendocrine regulation and induce epigenetic changes. Aberrant methylation of tumor suppressor genes such as P16INK4A, RASSF, and PTEN is associated with PTC; histone H3 acetylation is shown to be higher in TC, and thyroid-specific noncoding RNAs are downregulated in PTC. This review focuses on the above proposed mechanisms that potentially lead to thyroid tumorigenesis with the aim to help in the development of novel prognostic and therapeutic strategies for TC.

2022 European Thyroid Association Guidelines for the management of pediatric thyroid nodules and differentiated thyroid carcinoma

At present, no European recommendations for the management of pediatric thyroid nodules and differentiated thyroid carcinoma (DTC) exist. Differences in clinical, molecular, and pathological characteristics between pediatric and adult DTC emphasize the need for specific recommendations for the pediatric population. An expert panel was instituted by the executive committee of the European Thyroid Association including an international community of experts from a variety of disciplines including pediatric and adult endocrinology, pathology, endocrine surgery, nuclear medicine, clinical genetics, and oncology. The 2015 American Thyroid Association Pediatric Guideline was used as framework for the present guideline. Areas of discordance were identified, and clinical questions were formulated. The expert panel members discussed the evidence and formulated recommendations based on the latest evidence and expert opinion. Children with a thyroid nodule or DTC require expert care in an experienced center. The present guideline provides guidance for healthcare professionals to make well-considered decisions together with patients and parents regarding diagnosis, treatment, and follow-up of pediatric thyroid nodules and DTC.

Paediatric differentiated thyroid carcinoma: a UK National Clinical Practice Consensus Guideline

This guideline is written as a reference document for clinicians presented with the challenge of managing paediatric patients with differentiated thyroid carcinoma up to the age of 19 years. Care of paediatric patients with differentiated thyroid carcinoma differs in key aspects from that of adults, and there have been several recent developments in the care pathways for this condition; this guideline has sought to identify and attend to these areas. It addresses the presentation, clinical assessment, diagnosis, management (both surgical and medical), genetic counselling, follow-up and prognosis of affected patients. The guideline development group formed of a multi-disciplinary panel of sub-speciality experts carried out a systematic primary literature review and Delphi Consensus exercise. The guideline was developed in accordance with The Appraisal of Guidelines Research and Evaluation Instrument II criteria, with input from stakeholders including charities and patient groups. Based on scientific evidence and expert opinion, 58 recommendations have been collected to produce a clear, pragmatic set of management guidelines. It is intended as an evidence base for future optimal management and to improve the quality of clinical care of paediatric patients with differentiated thyroid carcinoma.

Clinical Implications of Age in Differentiated Thyroid Cancer: Comparison of Clinical Outcomes between Children and Young Adults

BACKGROUND

Pediatric patients with differentiated thyroid cancer (DTC) present with unique characteristics compared to adult patients. This study aimed to evaluate clinical presentation and surgical outcomes according to age and to identify the clinical significance of age in DTC.

METHODS

In total, 98 pediatric patients, 1261 young adult patients, and 4017 adult patients with DTC who underwent thyroid surgery between January 1982 and December 2012 at Yonsei University Hospital (Seoul, Republic of Korea) were retrospectively reviewed. The mean follow-up duration was 120.4 ± 54.2 months.

RESULTS

Mean tumor size was significantly larger in the pediatric group than in the adult groups (p < 0.001). The recurrence rate was significantly higher in the pediatric group (14.3% versus 6.6% versus 3.0%, p=0.004 and p < 0.001). In multivariate analysis, the risk of disease-free survival (DFS) was lower in the adult group (HR, 0.362; p < 0.001). Reanalysis of patients with tumor size of 2-4 cm revealed that the adult group was not a significant risk factor for DFS in multivariate analysis (HR, 0.305; 95% CI, 0.158 to 0.588; p < 0.001).

CONCLUSIONS

Our findings suggest that pediatric patients present with more aggressive features and higher recurrence rates compared to adult patients and should be carefully treated from initial evaluation to surgery and postoperative care.

The Iodine Rush: Over- or Under-Iodination Risk in the Prophylactic Use of Iodine for Thyroid Blocking in the Event of a Nuclear Disaster

Iodine is an essential element for the production of thyroid hormones (THs). Both deficient and excess iodine intakes may precipitate in adverse thyroidal events. Radioactive iodine (RI) is a common byproduct of nuclear fission processes. During nuclear emergencies RI may be released in a plume, or cloud, contaminating the environment. If inhaled or ingested, it may lead to internal radiation exposure and the uptake of RI mainly by the thyroid gland that absorbs stable iodine (SI) and RI in the same way. A dose of radiation delivered to the thyroid gland is a main risk factor for the thyroid cancer development. The SI prophylaxis helps prevent childhood thyroid cancer. The thyroid gland saturation with prophylactic SI ingestion, reduces the internal exposure of the thyroid by blocking the uptake of RI and inhibiting iodide organification. However, negative impact of inadequate SI intake must be considered. We provide an overview on the recommended iodine intake and the impact of SI and RI on thyroid in children and adolescents, discussing the benefits and adverse effects of the prophylactic SI for thyroid blocking during a nuclear accident. The use of SI for protection against RI may be recommended in cases of radiological or nuclear emergencies, moreover the administration of iodine for prophylactic purposes should be cautious. Benefits and risks should also be considered according to age. Adverse effects from iodine administration cannot be excluded. Precise indications are mandatory to use the iodine for thyroid blocking. Due to this natural adaption mechanism it's possible to tolerate large doses of iodine without clinical effects, however, a prolonged assumption of the iodine when not needed can be dangerous and may precipitate in severe thyroidal and non-thyroidal negative effects.

The BRAFV600E Mutation Is Not a Risk Factor for More Aggressive Tumor Behavior in Radiogenic and Sporadic Papillary Thyroid Carcinoma at a Young Age

Simple Summary

Analysis of the groups of young Ukrainian patients (aged ≤28 years) with radiogenic and sporadic papillary thyroid carcinomas (PTCs) showed that the frequency of BRAF^V600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAF^V600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAF^V600E-negative tumors. Comparison of the BRAF^V600E-positive PTCs across the groups found a virtual absence of differences, while the BRAF^V600E-negative tumors differed markedly and displayed a higher frequency of invasive tumor features in the radiogenic PTCs. Hence, there is evidence that BRAF^V600E does not confer a more aggressive course of PTC in young patients regardless of tumor etiology.

Abstract

Histopathological changes in the fusion oncogene-driven papillary thyroid carcinomas (PTCs) from children and adolescents exposed to Chernobyl fallout have been extensively studied. However, characteristics of the radiogenic BRAF^V600E-positive PTCs, whose proportion is growing with time, are not well described yet. We analyzed the relationship between the BRAF^V600E status (determined immunohistochemically with the VE1 antibody) and the clinicopathological features of 247 radiogenic and 138 sporadic PTCs from young Ukrainian patients aged ≤28 years. The frequency of BRAF^V600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAF^V600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAF^V600E-negative tumors. Comparison of the BRAF^V600E-positive PTCs across the groups found a virtual absence of differences. In contrast, the BRAF^V600E-negative radiogenic PTCs displayed less frequent dominant papillary and more frequent solid growth patterns, lower Ki67 labeling index, and higher invasiveness than the BRAF^V600E-negative sporadic tumors. Thus, BRAF^V600E is not associated with a more aggressive course of PTC in young patients regardless of etiology. The major clinicopathological differences between the radiogenic and sporadic PTCs are observed among the BRAF^V600E-negative tumors.

Fine Needle Aspiration Cytology Implementation and Malignancy Rates in Children and Adolescents Based on Japanese Guidelines: The Fukushima Health Management Survey

Background: The thyroid ultrasound examination (TUE) program was initiated among the residents of Fukushima Prefecture aged ≤18 years at the time of the Fukushima Dai-ichi Nuclear Power Plant accident. In this program, fine needle aspiration cytology (FNAC) was performed only in cases that conformed to the Japanese guidelines for the management of thyroid nodules. To analyze the suitability of the protocol in the TUE, we analyzed the implementation rate of FNAC and the detection rate of thyroid malignancy. Methods: There were 299,939 and 269,659 voluntary participants in the Preliminarily Baseline Survey (PLBS), first-round survey, and the first Full-scale Survey (FSS), second-round survey, of the TUE, respectively. FNAC is recommended for nodules with diameters 5.1-10.0 mm showing sonographic characteristics that are strongly suspicious for thyroid carcinoma; diameters 10.1-20.0 mm with characteristics that are suspicious for carcinoma; and all nodules with diameters >20 mm. Results: In the PLBS and the first FSS, 1362 and 1382 cases with thyroid nodules sized ≥5.1 mm in diameter were found, respectively. The implementation rates of FNAC in the PLBS were 20.1%, 63.2%, and 87.7% of subjects with nodules sized 5.1-10.0, 10.1-20.0, and ≥20.1 mm in diameter, respectively. In the first FSS, the FNAC implementation rates were 7.3%, 26.0%, and 50.0% in the subjects with nodules with diameters 5.1-10.0, 10.1-20.0, and ≥20.1 mm, respectively. In the subjects who underwent FNAC, the detection rates of malignant and suspected malignant nodules were 21.4% and 34.1% in the PLBS and first FSS, respectively. In the first FSS, malignant or suspected malignant nodules were found in 0.63% and 0.40% of subjects who had nodules of diameters ≤5.0 mm and 5.1-10.0 mm in the PLBS, respectively. In contrast, in the subjects with nodules measuring ≥10.0 mm in diameter in the PLBS, no malignancies were detected. Conclusions: The use of a protocol that conformed to the Japanese guidelines led to a reduction in the FNAC implementation rate and an increase in the malignancy detection rate in smaller nodules. In addition, the use of this strategy enabled us to avoid detection failure of thyroid carcinomas >10.0 mm.

The Clinicopathological Results of Thyroid Cancer With BRAFV600E Mutation in the Young Population of Fukushima

BACKGROUND

Thyroid ultrasound screening for children aged 0 to 18 years was performed in Fukushima following the accident at the Fukushima Daiichi Nuclear Power Plant. As a result, many thyroid cancer cases were detected. To explore the carcinogenic mechanisms of these cancers, we analyzed their clinicopathological and genetic features.

METHODS

We analyzed 138 cases (52 males and 86 females) who had undergone surgery between 2013 and 2016 at Fukushima Medical University Hospital. Postoperative pathological diagnosis revealed 136 (98.6%) cases of papillary thyroid cancer (PTC).

RESULTS

The BRAFV600E mutation was detected using direct DNA sequencing in 96 (69.6%) of the thyroid cancer cases. In addition, oncogenic rearrangements were detected in 23 cases (16.7%). Regarding chromosomal rearrangements, 8 (5.8%) RET/PTC1, 6 (4.3%) ETV6(ex4)/NTRK3, 2 (1.4%) STRN/ALK, and 1 each of RET/PTC3, AFAP1L2/RET, PPFIBP/RET, KIAA1217/RET, ΔRFP/RET, SQSTM1/NTRK3 and TPR/NTRK1 were detected. Tumor size was smaller in the BRAFV600E mutation cases (12.8 ± 6.8 mm) than in wild-type BRAF cases (20.9 ± 10.5 mm). In the BRAFV600E mutation cases, 83 (86.5%) showed lymph node metastasis, whereas 26 (61.9%) of the wild-type BRAF cases showed lymph node metastasis.

CONCLUSIONS

The BRAFV600E mutation was mainly detected in residents of Fukushima, which was different from post-Chernobyl PTC cases with RET/PTC3 rearrangement. PTC with the BRAFV600E mutation was smaller but was shown in the high rate of central cervical lymph node metastasis than the wild-type BRAF PTC in the young population of Fukushima.

BRAF V600E and TERT promoter mutations in paediatric and young adult papillary thyroid cancer and clinicopathological correlation

Objectives The primary objective of this study was to determine the prevalence of BRAF V600E and TERTpromoter mutations in paediatric and young adult patients with papillary thyroid carcinoma (PTC) and the secondary objective, to assess their association with clinicopathological features. Methods Patients ≤20 years who underwent surgery for differentiated thyroid cancer (DTC) from 2005 to 2018 were consecutively enrolled for BRAF V600E and TERTpromoter mutations analysis and records analysed for the association of aggressive features. Univariate analysis and multivariate logistic regression were used to identify the independent predictors of BRAF V600E mutations. Results Among 100 patients with DTC, 68 patients were ≤18 years and the remaining 30 patients were >18 years of age with a median age of 17 years (IQR 14-19 years) 98 patients had PTC and 2 had FTC. BRAF V600E mutation was present in 14/98 (14.3%) PTC and TERTpromoter mutation noted in none. Multivariate analysis identified RAI refractoriness (OR:10.57, 95% CI: 2.6 to 41.6, P-0.0008) as an independent factor associated with BRAF V600E mutation. 17 patients with distant metastases were negative for both BRAF V600E or TERTpromoter mutation. No significant association was observed between age, gender, PTC variants, extra-thyroidal extension, lymphovascular invasion, multifocality, RAI administration and event rate with BRAF V600E mutation. Irrespective of BRAF V600E mutation, radioiodine refractory status (p-0.0001) had a reduced EFS probability. Conclusion In paediatric & young adult PTC, TERTpromoter mutation is absent and BRAFV600E mutation is not associated with distant metastasis. The prevalence rate of the BRAF V600E mutation is much lower compared to adult PTC patients.

Management of pediatric differentiated thyroid cancer: An overview for the pediatric oncologist

Differentiated thyroid cancer (DTC) is the most common childhood thyroid malignancy. The standard of care for pediatric DTC is total thyroidectomy followed by radioactive iodine (RAI) treatment when indicated. Molecular changes and potential therapeutic targets have been recently described in pediatric thyroid cancer. Pediatric oncologists are increasingly involved in the evaluation of thyroid nodules in childhood cancer survivors and in the management of advanced thyroid cancer. In 2015, the American Thyroid Association published management guidelines for children with DTC. We provide an overview of the current standard of care and highlight available targeted therapies for progressive or RAI refractory DTC.

Radiation-Induced Thyroid Cancers: Overview of Molecular Signatures

Enormous amounts of childhood thyroid cancers, mostly childhood papillary thyroid carcinomas (PTCs), after the Chernobyl nuclear power plant accident have revealed a mutual relationship between the radiation exposure and thyroid cancer development. While the internal exposure to radioactive ¹³¹I is involved in the childhood thyroid cancers after the Chernobyl accident, people exposed to the external radiation, such as atomic-bomb (A-bomb) survivors, and the patients who received radiation therapy, have also been epidemiologically demonstrated to develop thyroid cancers. In order to elucidate the mechanisms of radiation-induced carcinogenesis, studies have aimed at defining the molecular changes associated with the thyroid cancer development. Here, we overview the literatures towards the identification of oncogenic alterations, particularly gene rearrangements, and discuss the existence of radiation signatures associated with radiation-induced thyroid cancers.

Benign thyroid nodules in pediatric patients: determining best practices for repeat ultrasound evaluations

Background The American Thyroid Association (ATA) recommendations for the follow-up of thyroid nodules with benign fine needle aspiration (FNA) cytology in children are largely based on adult data, despite well-characterized differences between thyroid nodules in adults and children. We aimed to determine the optimal time interval for repeat evaluation of an FNA-benign thyroid nodule in a pediatric patient. Methods This is a retrospective chart review of patients <19 years of age from 2003 to 2013 with a benign thyroid nodule by FNA cytology. Results We identified 43 patients with benign thyroid nodule cytology on FNA. The average age at diagnosis was 15.6 years, with female predominance (91%). Initial ultrasound (US) findings showed an average nodule size of 2.5 cm, 10% with calcifications, 37% hyperemia, 29% hypoechogenicity and 7% lymphadenopathy. Follow-up US was done in 42%. The first follow-up US occurred on average at 15 months after the initial US. Four patients had nodules with significant growth over time. One patient with papillary thyroid carcinoma (PTC) on final pathology initially had a decreasing nodule size, and then a subsequent increase in the nodule size after 4.5 years. Thyroid nodules were surgically removed in 33% with the final pathology showing a benign cytology in four patients, follicular adenoma in eight patients and PTC in two patients. Conclusions The majority of patients with benign thyroid nodules had no significant increase in nodule size in the first year of follow-up, including one patient who was subsequently found to have PTC. We recommend follow-up US at 1 year after initial presentation in low-risk pediatric patients with benign thyroid nodule cytology.

Thyrotropin serum levels and coexistence with Hashimoto's thyroiditis as predictors of malignancy in children with thyroid nodules

Thyroid cancer (TC) in childhood is a rare disease characterized by an excellent prognosis. Thyroid nodules in children, although less common than in adults, have a greater risk of malignancies, particularly in those cases associated with anamnestic, clinical and ultrasonographic risk factors.

Among the factors, which have been found to be linked with an increased relative risk of TC in children, an important role seems to be possibly played by an underlying nodular Hashimoto’s thyroiditis (HT) and by the serum levels of TSH.

Aim of this Commentary was to specifically address this last point.

According to the available pediatric literature on the relationships between these risk factors and phenotypical expression of TC in children, it is possible to conclude that: 1) It is not completely clarified if HT per se predisposes to malignancy or if it represents an incidental histologic finding in cases with TC or if it may be the result of an immune response against tumoral cells. 2) It is unclear whether phenotypic expression of TC is more severe in the cases with associated HT but normal TSH serum levels. 3) Persistently elevated TSH levels play an independent role as predictors of the likelihood of TC, especially in children but also in adults. 4) Patients with nodular HT and subclinical hypothyroidism need to be treated with Levothyroxine in order to prevent the development of both TC and severe thyroid dysfunctions.

Clinical Analysis of Pediatric Thyroid Cancer: A Single Medical Institution Experience of 18 Years

OBJECTIVE

The incidence of pediatric thyroid cancer is relatively low compared to the disease in adults. This study aims to present the data in our institution on pediatric thyroid cancer patients, with particular emphasis on the risk factors of recurrence together with treatment outcomes.

SUBJECTS AND METHODS

Between January 2000 and July 2018, patients <20 years who were diagnosed with thyroid carcinoma and primarily treated with surgery at a major large-volume tertiary medical center specializing in thyroid cancer were enrolled. A total of 83 patients were eligible for this study.

RESULTS

The majority of the studied patients were girls and adolescents (age ≥13 years). Papillary thyroid carcinoma (PTC) was the most common pathology (n = 74). PTC tumors >1 cm showed higher rate of lymph node metastasis and extrathyroidal extension than tumors ≤1 cm. All patients survived with nine PTC patients who displayed treatment failure. Age, tumor size, multifocality, lateral lymph node metastasis, and postoperative thyroglobulin levels were significant prognosticators for disease recurrence.

CONCLUSION

Pediatric thyroid cancer is relatively rare and should be considered a specific disease entity with respect to the thyroid cancer in adults, since there are several distinctive characteristics.

The significance of gene mutations across eight major cancer types

Mutations occur spontaneously, which can be induced by either chemicals (e.g. benzene) or biological factors (e.g. virus). Not all mutations cause noticeable changes in cellular functions. However, mutation in key cellular genes leads to developmental disorders. It is one of the main ways in which proto-oncogenes can be changed into their oncogenic state. The progressive accumulation of multiple mutations throughout life leads to cancer. In the past few decades, extensive research on cancer biology has discovered many genes and pathways having role in cancer development. In this review, we tried to summarize the current knowledge of mutational effect on different cancer types and its consequences in brief for future reference and guidance of researchers in cancer biology.

Investigation of the Relationship Between Radiation Dose and Gene Mutations and Fusions in Post-Chernobyl Thyroid Cancer

Background

Exposure to ionizing radiation during childhood is a well-established risk factor for thyroid cancer. However, the genetic mechanisms of radiation-associated carcinogenesis remain not fully understood.

Methods

In this study, we used targeted next-generation sequencing and RNA-Seq to study 65 papillary thyroid cancers (PTCs) from patients in the Ukrainian-American cohort with measurement-based iodine-131 (I-131) thyroid doses received as a result of the Chernobyl accident. We fitted linear regression models to evaluate differences in distribution of risk factors for PTC according to type of genetic alteration and logistic regression models to evaluate the I-131 dose response. All statistical tests were two-sided.

Results

Driver mutations were identified in 96.9% of these thyroid cancers, including point mutations in 26.2% and gene fusions in 70.8% of cases. Novel driver fusions such as POR-BRAF, as well as STRN-ALK fusions that have not been implicated in radiation-associated cancer before, were found. The mean I-131 dose in cases with point mutations was 0.2 Gy (range = 0.013-1.05 Gy), statistically significantly lower than 1.4 Gy (range = 0.009-6.15 Gy) for cases with fusions (P < .001). No driver point mutations were found in tumors from individuals who received more than 1.1 Gy of radiation. Relative to tumors with point mutations, the proportion of tumors with gene fusions increased with radiation dose, reaching 87.8% among individuals exposed to 0.3 Gy or higher. With a limited study sample size, the estimated odds ratio at 1 Gy was 20.01 (95% confidence interval = 2.57 to 653.02, P < .001). In addition, after controlling for I-131 dose, we found higher odds ratios for gene fusion-positive PTCs associated with several specific demographic and geographic features.

Conclusions

Our data provide support for a link between I-131 thyroid dose and generation of carcinogenic gene fusions, the predominant mechanism of thyroid cancer associated with radiation exposure from the Chernobyl accident.

Anaplastic lymphoma kinase (ALK) gene rearrangements in radiation-related human papillary thyroid carcinoma after the Chernobyl accident

Childhood radiation exposure has been associated with increased papillary thyroid carcinoma (PTC) risk. The role of anaplastic lymphoma kinase (ALK) gene rearrangements in radiation‐related PTC remains unclear, but STRN‐ALK fusions have recently been detected in PTCs from radiation exposed persons after Chernobyl using targeted next‐generation sequencing and RNA‐seq. We investigated ALK and RET gene rearrangements as well as known driver point mutations in PTC tumours from 77 radiation‐exposed patients (mean age at surgery 22.4 years) and PTC tumours from 19 non‐exposed individuals after the Chernobyl accident. ALK rearrangements were detected by fluorescence in situ hybridisation (FISH) and confirmed with immunohistochemistry (IHC); point mutations in the BRAF and RAS genes were detected by DNA pyrosequencing. Among the 77 tumours from exposed persons, we identified 7 ALK rearrangements and none in the unexposed group. When combining ALK and RET rearrangements, we found 24 in the exposed (31.2%) compared to two (10.5%) in the unexposed group. Odds ratios increased significantly in a dose‐dependent manner up to 6.2 (95%CI: 1.1, 34.7; p = 0.039) at Iodine‐131 thyroid doses >500 mGy. In total, 27 cases carried point mutations of BRAF or RAS genes, yet logistic regression analysis failed to identify significant dose association. To our knowledge we are the first to describe ALK rearrangements in post‐Chernobyl PTC samples using routine methods such as FISH and IHC. Our findings further support the hypothesis that gene rearrangements, but not oncogenic driver mutations, are associated with ionising radiation‐related tumour risk. IHC may represent an effective method for ALK‐screening in PTCs with known radiation aetiology, which is of clinical value since oncogenic ALK activation might represent a valuable target for small molecule inhibitors.

Findings of Thyroid Ultrasound Examination Within 3 Years After the Fukushima Nuclear Power Plant Accident: The Fukushima Health Management Survey

CONTEXT

Childhood thyroid cancer is of great concern after the Fukushima nuclear power plant accident. Baseline analytical data on thyroid ultrasound examination (TUE) in children are important for future studies.

OBJECTIVE

We analyzed the age and sex distribution of findings from the TUEs of children and adolescents in the Fukushima Health Management Survey (FHMS).

DESIGN, SETTING, AND PARTICIPANTS

From October 2011 through March 2014, 294,905 participants aged 18 years or younger at the time of the earthquake voluntarily had TUEs in the first round of the FHMS. A secondary confirmatory examination was performed in 2032 subjects. Age- and sex-dependent prevalence and size of thyroid cysts, nodules, and cancers were analyzed.

MAIN OUTCOME MEASURES

Age, sex, and size distribution of findings were analyzed.

RESULTS

Thyroid cysts, nodules, and cytologically suspected cancers were detected in 68,009, 1415, and 38 male subjects and in 73,014, 2455, and 74 female subjects, respectively. There was an age-dependent increase in the detection rate of thyroid nodules and cancer, but that of cysts reached a peak at 11 to 12 years. Sex affected the prevalence of thyroid nodules and cancers after the onset of puberty, but only a small difference was exhibited in that of cysts.

CONCLUSIONS

The thyroid cancer detection rate in Fukushima was clarified, and the proportion of individuals with thyroid nodules and cysts varied substantially by age. The results of this study will contribute to future epidemiological research on nodular thyroid diseases in children and adolescents.

RRS1 gene expression involved in the progression of papillary thyroid carcinoma

Background

Papillary thyroid carcinoma (PTC) is one of the most frequent malignancies of the endocrine system, whose mechanisms of pathogenesis, progression and prognosis are still far from being clearly elucidated. Despite an increasing body of evidences highlights ribosome biogenesis regulator homolog (RRS1) as a ribosome biogenesis protein in yeast and plants, little is known about human RRS1 function.

Methods

Proliferation, cell cycle and apoptosis of PTC cells were assessed following the knockdown of RRS1 expression though MTT, colony formation assay, and flow cytometry. Then, transcriptome profiling was conducted to explore pathway changes after RRS1 silencing in PTC cells. Receiver operating characteristic curve and Youden’s index were performed in twenty-four thyroid carcinoma samples to assess their potential clinical diagnostic value.

Results

Firstly, we found that silencing RRS1 significantly reduced cell proliferation, inhibited cell cycle, and promoted apoptosis in PTC cell line. The result also showed that knock-down of RRS1 could up-regulate genes involving apoptosis and metabolism, while, down-regulate genes relative to cell proliferation and blood vessel development. Notably, the present study confirmed the diagnostic value of RRS1 for thyroid carcinoma in both children and adults.

Conclusions

In conclusion, these data afford a comprehensive view of a novel function of human RRS1 by promoting cell proliferation and could be a potential indicator for papillary thyroid carcinoma.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0519-x) contains supplementary material, which is available to authorized users.

Hashimoto's Disease and Thyroid Cancer in Children: Are They Associated?

Hashimoto's thyroiditis (HT) is the most common cause of thyroid disease in children and adolescents. Along with significant modifications of thyroid function, HT in pediatric age can be accompanied by relevant thyroid structural alterations. Over time, benign thyroid nodules, carcinoma and, rarely, primary non-Hodgkin lymphoma can develop. However, the relationships between HT and neoplasms are poorly defined. The main aim of this paper is to discuss what is presently known regarding the coexistence of HT and thyroid tumors. Moreover, we attempt to define the pathogenesis of cancer development in children with HT. Literature analysis showed that despite its rarity and relatively promising prognosis, thyroid cancer is associated with HT. Although not all reasons for the coexistence of these diseases are clearly defined, children with HT should be considered at higher risk for thyroid cancer development. Strict correlations between high levels of serum TSH and anti-thyroid antibodies with cancer must be remembered. The same is true for the presence of nodules, especially if multiple nodules are present and ultrasonography and thyroid fine needle aspiration cytology should be promptly used in uncertain cases.

N-Acetyl-L-cysteine protects thyroid cells against DNA damage induced by external and internal irradiation

We evaluated the effect of the antioxidant N-acetyl-L-cysteine (NAC) on the levels of reactive oxygen species (ROS), DNA double strand breaks (DSB) and micronuclei (MN) induced by internal and external irradiation using a rat thyroid cell line PCCL3. In internal irradiation experiments, ROS and DSB levels increased immediately after ¹³¹I addition and then gradually declined, resulting in very high levels of MN at 24 and 48 h. NAC administration both pre- and also post-¹³¹I addition suppressed ROS, DSB and MN. In external irradiation experiments with a low dose (0.5 Gy), ROS and DSB increased shortly and could be prevented by NAC administration pre-, but not post-irradiation. In contrast, external irradiation with a high dose (5 Gy) increased ROS and DSB in a bimodal way: ROS and DSB levels increased immediately after irradiation, quickly returned to the basal levels and gradually rose again after >24 h. The second phase was in parallel with an increase in 4-hydroxy-2-nonenal. The number of MN induced by the second wave of ROS/DSB elevations was much higher than that by the first peak. In this situation, NAC administered pre- and post-irradiation comparably suppressed MN induced by a delayed ROS elevation. In conclusion, a prolonged ROS increase during internal irradiation and a delayed ROS increase after external irradiation with a high dose caused serious DNA damage, which were efficiently prevented by NAC. Thus, NAC administration even both after internal or external irradiation prevents ROS increase and eventual DNA damage.

Clinicopathological Characteristics of Papillary Thyroid Cancer in Children with Emphasis on Pubertal Status and Association with BRAFV600E Mutation

OBJECTIVE

Papillary thyroid cancer (PTC) may behave differently in prepubertal children as compared to pubertal children and adults. BRAF gene activating mutations may associate with PTC by creating aberrant activation. We aimed to evaluate the clinicopathological characteristics of PTC patients with emphasis on the pubertal status and also to investigate the association of BRAF^V600E mutation with disease characteristics.

METHODS

The medical records of 75 patients with PTC were reviewed retrospectively. BRAF^V600E mutation status was available only in the medical records of 56 patients.

RESULTS

Mean age at diagnosis was 12.4±3.8 years. There was no difference in sex, initial signs, tumor histopathology, and pathological evidence of tumor aggressiveness between prepubertal and pubertal children. Although not statistically significant, lateral neck nodal metastasis and lung metastasis at diagnosis were more prevalent in prepubertal children. After excluding patients with microcarcinoma, prepubertal children were found to require lateral neck dissection and further doses of radioactive iodine more frequently than pubertal patients. Recurrence was also more frequent in prepubertal children (p=0.016). Frequency of BRAF^V600E mutation was similar in prepubertal and pubertal patients. BRAF^V600E mutation was found in 14/56 (25%) patients and was high in the classic variant PTC (p=0.004). Multicentricity was high in BRAF^V600E mutation (p=0.01). There was no relation between BRAF^V600E mutation and lymph node and pulmonary metastasis at diagnosis, or between BRAF^V600E mutation and pathological evidence of tumor aggressiveness.

CONCLUSION

PTC is more disseminated in prepubertal children. BRAF^V600E mutation does not correlate with a more extensive or aggressive disease. BRAF^V600E mutation is not the cause of the differences in the biological behavior of PTC in prepubertal and pubertal children.

Management of Differentiated Thyroid Cancer in Children: Focus on the American Thyroid Association Pediatric Guidelines

First introduced in 1946, radioactive iodine (I-131) produces short-range beta radiation with a half-life of 8 days. The physical properties of I-131 combined with the high degree of uptake in the differentiated thyroid cancers (DTCs) led to the use of I-131 as a therapeutic agent for DTC in adults. There are two indications for the potential use of I-131 therapy in pediatric thyroid disorders: nonsurgical treatment of hyperthyroidism owing to Graves' disease and the treatment of children with intermediate- and high-risk DTC. However, children are not just miniature adults. Not only are children and the pediatric thyroid gland more sensitive to radiation than adults but also the biologic behavior of DTC differs between children and adults as well. As opposed to adults, children with DTC typically present with advanced disease at diagnosis; yet, they respond rapidly to therapy and have an excellent prognosis that is significantly better than that in adult counterparts with advanced disease. Unfortunately, there are also higher rates of local and distant disease recurrence in children with DTC compared with adults, mandating lifelong surveillance. Further, children have a longer life expectancy during which the adverse effects of I-131 therapy may become manifest. Recognizing the differences between adults and children with DTC, the American Thyroid Association commissioned a task force of experts who developed and recently published a guideline to address the unique issues related to the management of thyroid nodules and DTC in children. This article reviews the epidemiology, diagnosis, staging, treatment, therapy-related effects, and suggestions for surveillance in children with DTC, focusing not only on the differences between adults and children with this disease but also on the latest recommendations from the inaugural pediatric management guidelines of the American Thyroid Association.

ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection

This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells; (c) retention of the DNA parental template strand during divisions in some tissue systems, so that mutations are passed to the daughter differentiating cells and not retained in the parental cell; and (d) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the niche. DNA repair mainly occurs within a few days of irradiation, while stem cell competition requires weeks or many months depending on the tissue type. The aforementioned processes may contribute to the differences in carcinogenic radiation risk values between tissues, and may help to explain why a rapidly replicating tissue such as small intestine is less prone to such risk. The processes also provide a mechanistic insight relevant to the LNT model, and the relative and absolute risk models. The radiobiological knowledge also provides a scientific insight into discussions of the dose and dose-rate effectiveness factor currently used in radiological protection guidelines. In addition, the biological information contributes potential reasons for the age-dependent sensitivity to radiation carcinogenesis, including the effects of in-utero exposure.

Comparison of childhood thyroid cancer prevalence among 3 areas based on external radiation dose after the Fukushima Daiichi nuclear power plant accident: The Fukushima health management survey

The 2011 Great East Japan Earthquake led to a subsequent nuclear accident at the Fukushima Daiichi Nuclear Power Plant. In its wake, we sought to examine the association between external radiation dose and thyroid cancer in Fukushima Prefecture. We applied a cross-sectional study design with 300,476 participants aged 18 years and younger who underwent thyroid examinations between October 2011 and June 2015. Areas within Fukushima Prefecture were divided into three groups based on individual external doses (≥1% of 5 mSv, <99% of 1 mSv/y, and the other). The odds ratios (ORs) and 95% confidence intervals of thyroid cancer for all areas, with the lowest dose area as reference, were calculated using logistic regression models adjusted for age and sex. Furthermore, the ORs of thyroid cancer for individual external doses of 1 mSv or more and 2 mSv or more, with the external dose less than 1 mSv as reference, were calculated. Prevalence of thyroid cancer for the location groups were 48/100,000 for the highest dose area, 36/100,000 for the middle dose area, and 41/100,000 for the lowest dose area. Compared with the lowest dose area, age-, and sex-adjusted ORs (95% confidence intervals) for the highest-dose and middle-dose areas were 1.49 (0.36-6.23) and 1.00 (0.67-1.50), respectively. The duration between accident and thyroid examination was not associated with thyroid cancer prevalence. There were no significant associations between individual external doses and prevalence of thyroid cancer. External radiation dose was not associated with thyroid cancer prevalence among Fukushima children within the first 4 years after the nuclear accident.

Classic Architecture with Multicentricity and Local Recurrence, and Absence of TERT Promoter Mutations are Correlates of BRAF (V600E) Harboring Pediatric Papillary Thyroid Carcinomas

This study is aimed to investigate the BRAF (V600E) and TERT promoter mutation profile of 50 pediatric papillary thyroid carcinomas (PTCs) to refine their clinicopathological correlates. The median age at the time of surgery was 16 years (range, 6-18). No TERT promoter mutations were identified in this series. The BRAF (V600E) mutation was present in 15 (30 %) tumors. From genotype-histologic variant correlation perspective, 13 of 24 classic variant PTCs and 2 of 7 diffuse sclerosing variant PTCs were found to harbor BRAF (V600E) mutation. One cribriform-morular variant, 3 solid variant, and 15 follicular variant PTCs were BRAF wild type. While tumors with distant metastasis were BRAF wild type, two of five tumors with extrathyroidal extension (ETE) harbored BRAF (V600E) mutation. Nine of 15 BRAF (V600E) harboring tumors had central lymph node metastases. There was no significant correlation with BRAF (V600E) mutation and age, gender, tumor size, ETE, central lymph node metastasis, the status of pT, pN1a-b, and distant metastasis. An adverse correlation between BRAF (V600E) mutation and disease-free survival (DFS) was noted in the entire cohort; however, the predictive value of BRAF (V600E) mutation disappeared within the group of tumors displaying classic architecture as well as classic variant PTCs. The present cohort identifies that the classic architecture with multicentricity and local recurrence are correlates of BRAF (V600E) harboring pediatric PTCs. While the small size of this cohort is one of the limitations, neither the BRAF mutation status nor the classic tumor architecture does seem to be an independent prognosticator of DFS in this series. Evidence also suggests that TERT promoter mutations do not seem to play a major role in the pathogenesis of pediatric PTCs.

Comparison of differentiated thyroid cancer in children and adolescents (≤20 years) with young adults

CONTEXT

Age is a major prognostic factor in differentiated thyroid cancer (DTC). It is not clear if paediatric DTC has a different histopathological profile and outcome than DTC in adult patients <45 years of age.

OBJECTIVE

To assess whether DTC in children and adolescents differs from young age group by comparing paediatric DTC (age ≤ 20) with DTC in patients >20 to <45 years of age.

PATIENTS AND METHODS

We studied all cases of paediatric DTC seen during the period 1998-2011. We compared this group with a large sample of 213 consecutive adult patients in the age group >20 to <45 years seen during the period 1998-1999 in terms of their pathological features, extent of the disease and long-term outcome. Both groups were managed by the same team at a single institution.

RESULTS

A total of 310 DTC were studied including 97 paediatric patients [median age 17 years (range, 8-20)] and 213 young adult patients [median age 33 years (range, 20·5-44·9)]. There was no difference in gender distribution, tumour subtypes, size and tumour multifocality, but there was a significantly higher rate of extrathyroidal extension [40/75 (53·3%) vs 81/213 (38·0%), P = 0·03], lymph node [57/73 (78%) vs 102/183 (55·7%), P < 0·0001] and distant metastases [16/97 (16·5%) vs 8/213 (3·8%), P < 0·0001] in the paediatric than the adult groups. Kaplan-Meier analysis showed a higher risk of persistent/recurrent disease in the paediatric group than adults (log-rank test 0·03). However, there was no mortality secondary to DTC in both groups.

CONCLUSION

Paediatric DTC is distinct from DTC in the young adults (age >20 to <45 years). It is characterized by a higher rate of extrathyroidal extension, lymph node and distant metastases and a higher risk of persistent/recurrent DTC.

Uncommon TERT Promoter Mutations in Pediatric Thyroid Cancer

PURPOSE

The aim of this study was to determine the rate and significance of TERT promoter mutations that have been recently described in adult thyroid cancer (TC) but not yet in the uncommonly occurring pediatric TC. Furthermore, the role of the BRAF(V600E) mutation in the clinical outcome of pediatric TC is unknown.

METHOD

The study included 55 pediatric (median age 16 years, range 9-18 years; 46 females) and 210 adult TC patients (median age 40 years, range 20-75 years; 155 females) seen during the same time period. DNA was isolated from TC tissues and subjected to direct sequencing. Genetic-clinicopathological correlations were analyzed.

RESULTS

Only one case of pediatric TC was found to harbor the C228T TERT promoter mutation (1.8%). The C250T mutation was not detected in any of the 55 pediatric TC. In contrast, there was a significantly higher rate of TERT promoter mutations in the adult patients (15.7%, 33/210) compared with the pediatric patients (p = 0.003). In addition, persistent/recurrent TC was seen in 8/12 (66.7%) pediatric patients harboring the BRAF(V600E) mutation versus 14/41 (34.1%) patients harboring the wild type BRAF (p = 0.05), and when only conventional papillary TC was examined, in 7/9 (77.8%) cases harboring BRAF(V600E) mutation versus 11/33 (33.3%) cases harboring wild type BRAF (p = 0.025).

CONCLUSIONS

This is the first study on TERT promoter mutations in pediatric TC, which revealed an exceedingly low prevalence, suggesting a limited role of these mutations in pediatric TC. This study also for the first time demonstrates an association of the BRAF(V600E) mutation with TC recurrence in pediatric patients.

Mutational Analysis in Pediatric Thyroid Cancer and Correlations with Age, Ethnicity, and Clinical Presentation

BACKGROUND

Well-differentiated thyroid cancer (WDTC) incidence in pediatrics is rising, most being papillary thyroid carcinoma (PTC). The objective of the study was to assess the prevalence of different mutations in pediatric WDTC and correlate the genotype with the clinical phenotype.

METHODS

This is a single-center retrospective study. Thyroid tissue blocks from 42 consecutive pediatric WDTC patients who underwent thyroidectomy between 2001 and 2013 were analyzed at Quest Diagnostics for BRAF(V600E), RAS mutations (N,K,H), and RET/PTC and PAX8/PPARγ rearrangements, using validated molecular methods. Thyroid carcinomas included PTC, follicular thyroid carcinoma (FTC), and follicular variant of PTC (FVPTC).

RESULTS

Thirty-nine samples (29 females) were genotyped. The mean age at diagnosis was 14.7 years (range 7.9-18.4 years), and most were Hispanic (56.4%) or Caucasian (35.9%). The mean follow-up period was 2.9 years. Mutations were noted in 21/39 (53.8%), with both BRAF(V600E) (n = 9), and RET/PTC (n = 6) detected only in PTC. Mutations were detected in 2/5 FTC (PAX8/PPARγ and NRAS) and 3/6 FVPTC cases (PAX8/PPARγ). Of 28 PTC patients, 57.1% had mutations: 32.1% with BRAF(V600E), 21.4% with RET/PTC, and 3.6% with NRAS. Of patients with BRAF(V600E), 77.8% were Hispanic and 88.9% were >15 years, while all RET/PTC-positive patients were ≤15 years (p = 0.003). Tumor size, lymph node involvement, and distant metastasis at diagnosis (or soon after (131)I ablation) did not vary significantly based on the mutation.

CONCLUSIONS

BRAF(V600E) was the most common mutation, especially in older and Hispanic adolescents. A larger, ethnically diverse pediatric cohort followed long term will enable the genotypic variability, clinical presentation, and response to therapy to be better assessed.

BRAF(V600E) mutation is highly prevalent in thyroid carcinomas in the young population in Fukushima: a different oncogenic profile from Chernobyl

After the accident at the Fukushima Daiichi Nuclear Power Plant, the thyroid ultrasound screening program for children aged 0–18 at the time of the accident was started from October 2011. The prevalence of thyroid carcinomas in that population has appeared to be very high (84 cases per 296,253). To clarify the pathogenesis, we investigated the presence of driver mutations in these tumours. 61 classic papillary thyroid carcinomas (PTCs), two follicular variant PTCs, four cribriform-morular variant PTCs and one poorly-differentiated thyroid carcinoma were analysed. We detected BRAF^V600E in 43 cases (63.2%), RET/PTC1 in six (8.8%), RET/PTC3 in one (1.5%) and ETV6/NTRK3 in four (5.9%). Among classic and follicular variant PTCs, BRAF^V600E was significantly associated with the smaller size. The genetic pattern was completely different from post-Chernobyl PTCs, suggesting non-radiogenic etiology of these cancers. This is the first study demonstrating the oncogene profile in the thyroid cancers discovered by large mass screening, which probably reflects genetic status of all sporadic and latent tumours in the young Japanese population. It is assumed that BRAF^V600E may not confer growth advantage on paediatric PTCs, and many of these cases grow slowly, suggesting that additional factors may be important for tumour progression in paediatric PTCs.

Predictors of Malignancy in Children with Thyroid Nodules

OBJECTIVE

To evaluate the diagnostic accuracy of clinical, laboratory, and ultrasound (US) imaging characteristics of thyroid nodules in assessing the likelihood of malignancy.

STUDY DESIGN

Data from 184 children and adolescents with thyroid nodules were evaluated and compared with respective cytologic/histologic outcomes. A regression model was designed to assess the predictors associated with malignancy and to calculate ORs.

RESULTS

Twenty-nine malignant neoplasms (25 papillary, 1 medullary, 3 Hurtle-cell carcinomas), 8 follicular adenomas, and 147 goitrous nodules (92 based on cytology, 55 on follow-up) were diagnosed. Fine-needle aspiration biopsy diagnostic accuracy, sensitivity, and specificity were 91%, 100%, and 88%, respectively. Male sex, compression symptoms, palpable lymphopathy, thyroid stimulating hormone concentration, microcalcifications, indistinct margins, hypoechoic US pattern, pathologic lymph node alterations, and increased intranodular vascularization were associated with malignancy. Regular margins, mixed echoic pattern, and peripheral-only vascularization were associated with benignity. During follow-up, nodule growth was associated with malignant disease, especially with levothyroxine therapy. A multivariate analysis confirmed that microcalcifications, hypoechoic pattern, intranodular vascularization, lymph node alterations, and thyroid stimulating hormone concentration were independent predictors of malignant outcome. For each predictor, we provide sensitivity, specificity, and positive/negative predictive values.

CONCLUSIONS

Clinical, laboratory, and US features of nodules can be used as predictors of malignancy in children. Although none has diagnostic accuracy as high as that of fine-needle aspiration biopsy, these predictors should be considered in deciding the diagnostic approach of children with thyroid nodules.

Review of clinical and pathological features of 93 cases of well-differentiated thyroid carcinoma in pediatric age at the Lisbon Centre of the Portuguese Institute of Oncology between 1964 and 2006

INTRODUCTION

Thyroid carcinoma is the most common endocrine malignancy. In childhood, thyroid carcinoma usually behaves aggressively and relapses frequently. Nevertheless, it has a favorable prognosis. Our aim is to present our experience with pediatric well-differentiated thyroid carcinoma (WDTC) treated at the Portuguese Institute of Oncology in Lisbon (L-PIO), between 1964 and 2006.

METHODS

Review of clinical files of WDTC in≤18-year-old patients selected from the databases of the Endocrinology Service of L-PIO and the South Portugal Regional Cancer Registry (SPCR).

RESULTS

93 cases of WDTC were found. Of these, 70 (75.3%) were girls. The median age was 15 years old (range 5-18) with a median follow-up time of 15.1 years (range 0.2-47.8). The most common histological diagnosis was papillary carcinoma of the classical variant (n=60, 64.5%). Initial staging showed locoregional dissemination in 27 (29.0%) patients and distant metastasis in 16 (17.2%) patients. Median age was lower in patients with distant disease than in patients with locoregional disease or with disease confined to the thyroid (P=0.007). After the initial treatment, 44 (47.3%) patients were in remission and 46 (49.5%) had persistent disease (lost follow-up in 3). Of the disease-free patients after initial treatment, 11 (25.0%) relapsed later. At the last observation, most patients (n=63, 67.7%) showed no evidence of disease.

CONCLUSION

Our study demonstrates that children with distant metastatic disease are younger than children with a less aggressive disease. However, in both groups the response to treatment is favorable and the prognosis is usually excellent.

Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Previous guidelines for the management of thyroid nodules and cancers were geared toward adults. Compared with thyroid neoplasms in adults, however, those in the pediatric population exhibit differences in pathophysiology, clinical presentation, and long-term outcomes. Furthermore, therapy that may be recommended for an adult may not be appropriate for a child who is at low risk for death but at higher risk for long-term harm from overly aggressive treatment. For these reasons, unique guidelines for children and adolescents with thyroid tumors are needed.

METHODS

A task force commissioned by the American Thyroid Association (ATA) developed a series of clinically relevant questions pertaining to the management of children with thyroid nodules and differentiated thyroid cancer (DTC). Using an extensive literature search, primarily focused on studies that included subjects ≤18 years of age, the task force identified and reviewed relevant articles through April 2014. Recommendations were made based upon scientific evidence and expert opinion and were graded using a modified schema from the United States Preventive Services Task Force.

RESULTS

These inaugural guidelines provide recommendations for the evaluation and management of thyroid nodules in children and adolescents, including the role and interpretation of ultrasound, fine-needle aspiration cytology, and the management of benign nodules. Recommendations for the evaluation, treatment, and follow-up of children and adolescents with DTC are outlined and include preoperative staging, surgical management, postoperative staging, the role of radioactive iodine therapy, and goals for thyrotropin suppression. Management algorithms are proposed and separate recommendations for papillary and follicular thyroid cancers are provided.

CONCLUSIONS

In response to our charge as an independent task force appointed by the ATA, we developed recommendations based on scientific evidence and expert opinion for the management of thyroid nodules and DTC in children and adolescents. In our opinion, these represent the current optimal care for children and adolescents with these conditions.

Radiation signatures in childhood thyroid cancers after the Chernobyl accident: possible roles of radiation in carcinogenesis

After the Tokyo Electric Power Company Fukushima Daiichi nuclear power plant accident, cancer risk from low-dose radiation exposure has been deeply concerning. The linear no-threshold model is applied for the purpose of radiation protection, but it is a model based on the concept that ionizing radiation induces stochastic oncogenic alterations in the target cells. As the elucidation of the mechanism of radiation-induced carcinogenesis is indispensable to justify the concept, studies aimed at the determination of molecular changes associated with thyroid cancers among children who suffered effects from the Chernobyl nuclear accident will be overviewed. We intend to discuss whether any radiation signatures are associated with radiation-induced childhood thyroid cancers.

Evaluation and management of the pediatric thyroid nodule

Thyroid nodules are commonly diagnosed in adults. Although rare in children, the risk for thyroid cancer is much higher in the pediatric population compared with adults. Presenting as either a solitary nodule or a multinodular goiter, thyroid nodular disease in children requires a thorough workup that includes a detailed clinical examination comprised of prior history of thyroid disease in the patient or in their family, history of radiation exposure, careful palpation of the thyroid and lymph nodes, blood tests, ultrasonography, and cytological assessment. Thyroid surgery is the gold-standard treatment for pediatric thyroid nodules; nonetheless, the extent of surgery remains controversial. Because surgery is not without risk, the decision matrix necessitates focus on the benefits of surgery for the child contingent upon all the preoperative exams. New diagnostic technology such as molecular testing with fine needle aspiration biopsy may help distinguish between benign and malignant lesions while potentially decreasing surgery for benign disease. The objective of this review is to summarize new concepts in clinical disease management of nodular thyroid disease in the pediatric population, including patient history, medical examination, and diagnosis workup.

The evaluation of thyroid carcinoma in childhood and concomitance of autoimmune thyroid disorders

Autoimmune thyroiditis has been suggested as a precancerous condition in some adult studies, but there is still controversy. The importance of autoimmune thyroiditis in childhood thyroid cancer is not yet completely clear. We aimed to evaluate in this study the characteristics of childhood thyroid cancer in patients particularly in terms of coexisting factors including autoimmune thyroid disorders (ATD). Twenty patients diagnosed with primary thyroid cancer were evaluated retrospectively in a Pediatric Endocrinology clinic for 10 years. Patients were followed up for 57.22±11 months. Concomitant conditions (thyroidal and/or extra thyroidal) were determined. Most of the patients (80%) had a coexisting factor. ATDs are the most frequently encountered among them (40%). The ages at the time of diagnosis were older; and the tumor sizes were smaller in patients with concomitant ATDs than without autoimmune thyroid disorders. The follow-up characteristics were similar in both groups. In conclusion, ATDs are frequently encountered in association with thyroid cancer during childhood and adolescence. A thyroid autoimmunity may facilitate the development of a malignant thyroid tumor; on the other hand, increased attention to the thyroid gland may facilitate frequent diagnosis of thyroid cancer. A close follow-up of ATD patients should also include the evaluation of the development of thyroid malignancy.

BRAF V600E mutational status in pediatric thyroid cancer

BACKGROUND

Clinical outcome of papillary thyroid carcinoma (PTC) in children differs significantly from that of adults. There is no clear explanation of this difference although previous studies have demonstrated a lower prevalence of the BRAF(V600E) mutation in PTC of children. However, data are limited due to the rarity of this diagnosis. BRAF(V600E) mutation prevalence and its relationship with outcome in pediatric PTC remain unclear.

PROCEDURE

BRAF(V600E) mutational status was determined in 27 PTC patients less than 22 years of age using restriction fragment length polymorphism (RFLP) analysis. The relationship between BRAF(V600E) mutation status, patient and tumor characteristics as well as progression-free survival (PFS) were analyzed.

RESULTS

BRAF(V600E) was present in 63% of patients and occurred more often in male patients versus females (P = 0.033). Presence of the mutation did not correlate with any difference in extent of disease at diagnosis, tumor size, capsular invasion, vascular invasion, soft tissue invasion, or margin status. At 10 years, PFS for BRAF(V600E) positive versus negative patients was 55.5% versus 70.0%, respectively (P = 0.48). Overall survival was 100% and median follow-up was 13.9 years.

CONCLUSIONS

This study of pediatric PTC demonstrates that BRAF(V600E) mutations occur in children at a rate comparable to adults. We found a correlation of BRAF(V600E) with the male gender, but no evidence that the mutation correlates with more extensive or aggressive disease. This analysis suggests that differences in disease course of PTC in children versus adults are not strongly dependent upon the presence of the BRAF(V600E) mutation.

Best practice for the management of pediatric thyroid cancer

The presentation of differentiated thyroid cancer in children often includes dissemination to lymph nodes. Despite this, the long-term prognosis is excellent with appropriate treatment. A few known hereditary syndromes are associated with paediatric thyroid cancer, although most tumours are sporadic. Ultrasound and cytology is used to evaluate suspect thyroid nodules, and treatment consists of surgery, radioactive iodine and thyroxine suppression therapy. Follow-up includes serum thyroglobulin measurements, serial ultrasounds of the neck, radioiodine whole body scans and occasionally other cross-sectional imaging or positron emission tomography. This review focuses on paediatric well differentiated follicular and papillary thyroid cancer, diagnosis and preoperative evaluation, underlying genetic mechanisms, surgery, other treatment options and follow-up.

The rising trend of papillary carcinoma in thyroidectomies: 14-years of experience in a referral center of Turkey

Background

During the past 25 years, the incidence of thyroid papillary carcinoma (TPC), especially the micropapillary subtype, has been increasing in different countries worldwide. The rise in the rate of thyroid malignancies were also determined in Turkey in the last two decades. This fact was attributed to the Chernobyl accident because Turkey is one of the affected countries by the radioactive fallout. The aim of this study was to assess the changes in the parameters of the thyroid and put forth the reasons in a 14-year period.

Methods

The patient records, demographic and malignancy characteristics, and operations of 1,585 patients who had a thyroidectomy from 1996 to 2009 were reviewed retrospectively. The study was divided in two equal time periods for comparison of data.

Results

A total of 216 thyroid carcinomas (13.6%) were diagnosed in the study period. There was a significant increase in the frequency of papillary (P <0.023) and micropapillary (P <0.001) carcinomas when the two different time periods were compared. The rate of follicular, medullary and other types of malignancies did not change. In the second period (2003 to 2009) of analysis, the rate of micropapillary carcinoma (P = 0.001) and within male (P = 0.031) and female (P <0.001) genders, application of total thyroidectomy (p = 0.029), and multicentric disease (P = 0.015) increased significantly. A slight decrease in the mean age of the whole number of patients and patients with papillary and micropapillary carcinomas (P >0.05) was observed. The increased number of TPC >10 mm was insignificant. Geographic region and age specific malignancy increase was not determined.

Conclusions

Micropapillary carcinoma has become a dominant type of thyroid malignancy in Turkey. The main reasons of this transition were mandatory iodization and much higher application of total thyroidectomy in surgery. Improvement in healthcare and diagnostic techniques are the complementary factors. Due to its lack of molecular and genetic basis from the perspective of thyroid cancer, the Chernobyl disaster has lost its importance in Turkey.

Tenth Warren K. Sinclair keynote address-the Fukushima nuclear power plant accident and comprehensive health risk management

Just two years have passed since the Tokyo Electric Power Company-Fukushima Daiichi Nuclear Power Plant (NPP) accident, a multidimensional disaster that combined to destroy the local infrastructure on which the safety system depended and gave a serious impact to the world. Countermeasures including evacuation, sheltering, and control of the food chain were implemented in a timely manner by the Japanese government. However, there is a clear need for improvement, especially in the areas of nuclear safety and protection and also in the management of the radiation health risk during and even after the accident. To date there have been no acute radiation injuries. The radiation-related physical health consequences to the general public, including evacuees, are likely to be much lower than those arising from the Chernobyl nuclear reactor accident, because the radiation fallout and the subsequent environmental contamination were much more limited. However, the social, psychological, and economic impacts of the Fukushima NPP accident are expected to be considerable. Currently, continued monitoring and characterization of the levels of radioactivity in the environment and foods in Fukushima are vital for obtaining informed consent to the decisions on living in the areas already radiocontaminated and returning back to the evacuated areas once re-entry is permitted; it is also important to perform a realistic assessment of the radiation doses on the basis of measurements. We are currently implementing the official plans of the Fukushima Health Management Survey, which includes a basic survey for the estimation of the external doses that were received during the first 4 mo after the accident and four more detailed surveys (thyroid ultrasound examination, comprehensive health check-up, mental health and life-style survey, and survey of pregnant women and nursing mothers), with the aim to take care of the health of all of the residents of the Fukushima Prefecture for a long time. Introduction of the Sinclair Lecture (Video 2:01, http://links.lww.com/HP/A24).

Needle core biopsy in the diagnosis of pediatric thyroid neoplasms: a single institution retrospective review

PURPOSE

Our institution routinely utilizes needle core biopsy (NCB), instead of fine needle aspiration, in the evaluation of pediatric thyroid nodules. This practice initially arose from limited cytopathology services in our hospital. Given the lack of information regarding the utility of NCB in diagnosing pediatric thyroid neoplasms, we set out to review our institution's experience with this technique.

METHODS

We performed a single institution retrospective chart review of all children who underwent thyroidectomy for primary thyroid pathology.

RESULTS

Seventy-four patients, with a mean age of 12.9 ± 4.5 (SD) years, underwent partial or total thyroidectomy between 2002 and 2010. Seven of these patients had medically refractive hyperthyroidism. The remaining 67 patients had one or more thyroid nodules as identified by ultrasound. 24 (36 %) of these cases were malignant on final pathology. 14 (58 %) of the malignant cases were papillary thyroid carcinoma. 46 of the thyroid nodule cases underwent pre-operative NCB. Biopsy results for these patients were non-diagnostic in 6 (13 %), benign in 11 (24 %), atypical in 17 (37 %), and malignant in 12 (26 %). There were no complications arising from NCB. Sensitivity of NCB for diagnosing papillary carcinoma (PC) and follicular neoplasm was calculated at 0.88 (0.47-1.0, 95 % CI) and 0.84 (0.60-0.97, 95 % CI), respectively. Of the 28 patients not undergoing preoperative NCB, 12 underwent hemithyroidectomy, with one patient (8 %) requiring completion thyroidectomy for PC. Overall, the sensitivity of NCB in diagnosing PC and follicular thyroid neoplasms was 0.85 (0.55-0.99, 95 % CI), while the specificity was 0.63 (0.42-0.82, 95 % CI).

CONCLUSIONS

Needle core biopsy appears to have a low rate of associated complications, and its sensitivity for diagnosing PC and follicular neoplasm is comparable to what has been reported for fine needle aspiration biopsy in a similar patient population.

Thyroid nodules in pediatrics: which ones can be left alone, which ones must be investigated, when and how

Thyroid nodules are less frequent in childhood than in adulthood, but are more often malignant. Recent estimates suggest that up to 25% of thyroid nodules in children are malignant, therefore, a more aggressive approach is recommended. In this review, we suggest an approach based on a first-step clinical, laboratory, and sonographic evaluation. A history of irradiation of the neck, cranium or upper thorax, previous thyroid diseases or thyroid neoplasms in the family should alert clinicians as being associated with a greater likelihood of malignant nodules. Signs or symptoms of hyperthyroidism and dysmorphic features should be carefully considered during the physical examination. Palpable firm lymph nodes, found in some 70% of cases, are the most significant clinical finding in children with malignant nodules. Although the routine determination of calcitonin levels is not uniformly practiced, it can help recognize sporadic or familial medullary thyroid neoplasms. Blood thyroid stimulating hormone, free thyroxine, and free triiodothyronine determinations (the latter in case of symptoms of hyperthyroidism) are aimed at identifying the few hyperthyroid patients, for whom the next step should be scintiscan. Hyperthyroid patients usually disclose an increased uptake, and a diagnosis of toxic adenoma is commonly made. Cases with normal thyroid function or hypothyroidism (which is usually subclinical) should be evaluated by fine-needle aspiration biopsy (FNAB). In eu/hypo-thyroid patients, scintiscan provides poor diagnostic information and should not be routinely employed. Thyroid ultrasonography is used to select cases for FNAB. Although ultrasound cannot reliably discriminate between benign and malignant lesions, it does provide an index of suspicion. Sonographic features that increase the likelihood of malignancy are microcalcifications, lymph node alterations, nodule growth under levothyroxine treatment, and increased intranodular vascularization demonstrated by color Doppler. There is growing evidence that elastography may provide further information on nodule characteristics. FNAB is indicated in all cases with a likelihood of malignancy. FNAB has a diagnostic accuracy of approximately 90% and is used in selection of patients which require surgery. Recently, histological markers and elastography have been introduced to increase the specificity of FNAB and ultrasound, respectively. The pitfall in FNAB cytology is the follicular cytology, in which it is not possible to distinguish between adenoma and carcinoma and therefore thyroidectomy is advised.