BRAF mutations are uncommon in papillary thyroid cancer of young patients

Clinical characteristics, risk stratifications, and long-term follow-up of childhood differentiated thyroid cancer: a single-center experience

PURPOSE

Guidelines of the Pediatric American Thyroid Association (ATA) serve as a vital reference for managing the rare thyroid cancers in childhood. This study evaluates differentiated thyroid cancer (DTC) patients using the ATA guidelines, dynamic risk stratification (DRS), and other established risk classification systems.

METHODS

Pediatric patients with DTC under observation after total thyroidectomy were included in the study. We assessed preoperative and postoperative features based on the ATA guidelines, other risk scoring systems (TNM; De Groot staging; metastasis, age, completeness of resection, invasion, and tumor size; and combined risk), and the DRS.

RESULTS

A total of 41 patients was enrolled in the study, with a median follow-up duration of 5.14±3.94 years. Of the patients who underwent total thyroidectomy, 33 were diagnosed with papillary carcinoma and 8 with follicular thyroid carcinoma. During follow-up, cervical metastases were detected in 27 patients, and one had distant metastasis. All patients underwent total thyroidectomy, and 68% received lymph node dissection. Additionally, 16 patients received radioactive iodine therapy. Of the postoperative patients, 85.3% were classified as low risk. Based on DRS, patients were classified as having no evidence of disease (n=29, 70.7%), biochemical evidence of persistent disease (n=5, 12.2%), structural evidence of persistent disease (n=6, 14.6%), and recurrent disease (n=1, 2.5%). Notably, 98% of the patients showed no evidence of disease during their latest follow-up.

CONCLUSION

Persistent disease in patients classified as low risk according to the ATA guidelines resolved following radioactive iodine therapy, emphasizing the importance of risk stratification in postoperative care.

Historical context, process, and development trends of pediatric thyroid cancer research: a bibliometric analysis

Objective

At present, the structure of knowledge in the field of childhood thyroid cancer is not clear enough, and scholars lack a sufficient understanding of the developing trends in this field, which has led to a shortage of forward-looking outputs. The purpose of this research is to help scholars construct a complete knowledge framework and identify current challenges, opportunities, and development trends.

Methods

We searched the literature in the Web of Science Core Collection database on August 7, 2023 and extracted key information from the top 100 most cited articles, such as the countries, institutions, authors, themes, and keywords. We used bibliometric tools such as bibliometrix, VOSviewer, and CiteSpace for a visualization analysis and Excel for statistical descriptions.

Results

The top 100 most cited articles fluctuated over time, and the research was concentrated in European countries, the United States, and Japan, among which scientific research institutions and scholars from the United States made outstanding contributions. Keyword analysis revealed that research has shifted from simple treatment methods for pediatric thyroid cancer (total thyroidectomy) and inducing factors (the Chernobyl power station accident) to the clinical applications of genetic mutations (such as the BRAF and RET genes) and larger-scale genetic changes (mutation studies of the DICER1 gene). The thematic strategy analysis showed an increasing trend towards the popularity of fusion oncogenes, while the popularity of research on traditional treatments and diagnostics has gradually declined.

Conclusion

Extensive research has been conducted on the basic problems of pediatric thyroid cancer, and there has been significant outputs in the follow-up and cohort analysis of conventional diagnostic and treatment methods. However, these methods still have certain limitations. Therefore, scholars should focus on exploring fusion genes, the clinical applications of molecular targets, and novel treatment methods. This study provides a strong reference for scholars in this field.

Genetic alterations landscape in paediatric thyroid tumours and/or differentiated thyroid cancer: Systematic review

Differentiated thyroid cancer (DTC) is a rare disease in the paediatric population (≤ 18 years old. at diagnosis). Increasing incidence is reflected by increases in incidence for papillary thyroid carcinoma (PTC) subtypes. Compared to those of adults, despite aggressive presentation, paediatric DTC has an excellent prognosis. As for adult DTC, European and American guidelines recommend individualised management, based on the differences in clinical presentation and genetic findings. Therefore, we conducted a systematic review to identify the epidemiological landscape of all genetic alterations so far investigated in paediatric populations at diagnosis affected by thyroid tumours and/or DTC that have improved and/or informed preventive and/or curative diagnostic and prognostic clinical conduct globally. Fusions involving the gene RET followed by NTRK, ALK and BRAF, were the most prevalent rearrangements found in paediatric PTC. BRAF V600E was found at lower prevalence in paediatric (especially ≤ 10 years old) than in adults PTC. We identified TERT and RAS mutations at very low prevalence in most countries. DICER1 SNVs, while found at higher prevalence in few countries, they were found in both benign and DTC. Although the precise role of DICER1 is not fully understood, it has been hypothesised that additional genetic alterations, similar to that observed for RAS gene, might be required for the malignant transformation of these nodules. Regarding aggressiveness, fusion oncogenes may have a higher growth impact compared with BRAF V600E. We reported the shortcomings of the systematized research and outlined three key recommendations for global authors to improve and inform precision health approaches, glocally.

Fusion Oncogenes in Patients With Locally Advanced or Distant Metastatic Differentiated Thyroid Cancer

CONTEXT

Fusion oncogenes are involved in the underlying pathology of advanced differentiated thyroid cancer (DTC), and even the cause of radioactive iodine (RAI)-refractoriness.

OBJECTIVE

We aimed to investigation between fusion oncogenes and clinicopathological characteristics involving a large-scale cohort of patients with advanced DTC.

METHODS

We collected 278 tumor samples from patients with locally advanced (N1b or T4) or distant metastatic DTC. Targeted next-generation sequencing with a 26-gene ThyroLead panel was performed on these samples.

RESULTS

Fusion oncogenes accounted for 29.86% of the samples (72 rearrangement during transfection (RET) fusions, 7 neurotrophic tropomyosin receptor kinase (NTRK) fusions, 4 anaplastic lymphoma kinase (ALK) fusions) and occurred more frequently in pediatric patients than in their adult counterparts (P = .003, OR 2.411, 95% CI 1.329-4.311) in our cohort. DTCs with fusion oncogenes appeared to have a more advanced American Joint Committee on Cancer (AJCC)_N and AJCC_M stage (P = .0002, OR 15.47, 95% CI 2.54-160.9, and P = .016, OR 2.35, 95% CI 1.18-4.81) than those without. DTCs with fusion oncogenes were associated with pediatric radioactive iodine (RAI) refractoriness compared with those without fusion oncogenes (P = .017, OR 4.85, 95% CI 1.29-15.19). However, in adult DTCs, those with fusion oncogenes were less likely to be associated with RAI refractoriness than those without (P = .029, OR 0.50, 95% CI 0.27-0.95), owing to a high occurrence of the TERT mutation, which was the most prominent genetic risk factor for RAI refractoriness in multivariate logistic regression analysis (P < .001, OR 7.36, 95% CI 3.14-17.27).

CONCLUSION

Fusion oncogenes were more prevalent in pediatric DTCs than in their adult counterparts and were associated with pediatric RAI refractoriness, while in adult DTCs, TERT mutation was the dominant genetic contributor to RAI refractoriness rather than fusion oncogenes.

More aggressive biological behavior in pediatric than in adult papillary thyroid carcinoma

OBJECTIVE

Papillary thyroid carcinoma (PTC) remains a common malignancy of the endocrine system in children and adolescents. This study aimed to investigate the differences in clinical characteristics between children and adults with PTC.

METHODS

A total of 360 patients [ 308 adults (≥20 years) and 52 children and adolescents (<20 years)] with PTC who underwent thyroid surgery in our center from 2017 to 2022 were retrospectively analyzed. Statistical analysis and comparisons of the clinicopathological data and tumor characteristics between children and adults were performed.

RESULTS

Among all enrolled patients, the mean tumor diameter was 26.21 ± 12.72 mm in the pediatric group, while that in the adult group was 11.62 ± 10.21 mm, which was a significant difference (p < 0.001). Pediatric patients were more prone to central lymph node metastasis (90.38% vs. 49.35%, p<0.001), lateral lymph node metastasis (78.85% vs. 45.7%, p<0.001), capsular invasion (90.38% vs. 63.96%, p<0.001) and extrathyroidal extension (61.54% vs. 15.26%, p＜0.001) than adult patients. However, the pediatric group had a lower BRAFV600E mutation rate (54.76% vs. 87.7%, p < 0.001) and lower incidence of Hashimoto's thyroiditis (15.38% vs. 30.84%, p = 0.023) than the adult group. There were no significant differences in clinicopathological factors, such as sex, multifocality and hypothyroidism.

CONCLUSIONS

Pediatric patients were more likely to present with advanced disease at diagnosis, including larger tumor volume, more lymph node metastasis, more extensive local invasion, and lower rates of BRAF mutation and concomitant Hashimoto's thyroiditis. Therefore, appropriate surgical management and comprehensive treatment decisions are needed for pediatric patients with PTC.

Single BRAFV600E mutation is not associated with aggressive biological behavior in adolescent and pediatric papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma is more likely to show aggressive biological behaviors in the majority of pediatric patients than in adult patients. The aim of this study was to investigate the mutation rate of the BRAFV600E gene in adolescents and children with papillary thyroid carcinoma and to analyze the association between BRAFV600E gene mutation and tumor-aggressive pathological factors.

METHODS

A total of 42 pediatric patients with papillary thyroid carcinoma who underwent thyroid surgery from 2017 to 2022 were studied retrospectively. Whether the BRAFV600E gene mutation in papillary thyroid carcinoma was related to aggressive biological behavior was analyzed.

RESULTS

Among the 42 pediatric patients with papillary thyroid carcinoma, the median patient age was 15.71 ± 2.51 years (mean ± SD) and the median tumor diameter was 24.95 ± 12.29 mm (mean ± SD). Among all enrolled patients, the mutation rate of the BRAFV600E gene was 54.76% (23 of 42). There were 33 patients with classic papillary thyroid carcinoma, and 22 (66.67%) with classic subtypes were BRAFV600E positive. The BRAFV600E mutation was associated with lower distant metastasis (p = .013) and less Hashimoto's thyroiditis (p = .006). There was no significant difference in clinicopathological factors such as sex, age, tumor size, capsular invasion, multifocality, hypothyroidism, recurrence, lymph node metastasis, and extrathyroidal extension.

CONCLUSIONS

The BRAFV600E mutation is not uncommon in pediatric papillary thyroid carcinoma but is not significantly associated with aggressive biological behavior. It is not possible to determine whether to adopt more active diagnosis and treatment measures on the basis of the mutation of a single BRAFV600E gene.

Primary presentation and clinical course of pediatric and adolescent patients with differentiated thyroid carcinoma after radioiodine therapy

Introduction

Differentiated thyroid carcinoma (DTC) in childhood and during adolescence is extremely rare. Pediatric DTC commonly presents with advanced disease at diagnosis including a high prevalence of cervical lymph node metastases and pulmonary metastases. Studies in children with DTC are limited. Therefore, we aimed to evaluate the initial presentation, effectiveness of radioiodine therapy (RIT), and long-term outcome of prepubertal in comparison to pubertal/postpubertal patients.

Methods

Eighty-five pediatric and young patients aged 6.4 to 21.9 years with histopathologically confirmed DTC were retrospectively included. They all underwent total thyroidectomy followed by RIT. Initial presentation and outcome of prepubertal and pubertal/postpubertal patients were compared 1 year after RIT, during follow-up, and at the last visit of follow-up.

Results

Prepubertal patients presented with significantly higher T and M stages. One year after RIT, 42/81 (52%) patients still presented with evidence of disease (ED). During follow-up of a median of 7.9 years, prepubertal patients were less often in complete remission (58% vs. 82% in pubertal patients). At the last visit of follow-up, 19/80 (24%) patients still had ED without statistical differences between the two groups (42% prepubertal vs. 18% pubertal/postpubertal, p-value 0.06). None of our patients died disease-related over the observed period.

Conclusion

Prepubertal children with DTC presented with a more advanced tumor stage at the initial presentation. During follow-up, they present more often with ED. However, at the end of our study, we did not observe statistically relevant differences in patient outcomes between the prepubertal and pubertal/postpubertal groups.

Prepubertal Children with Papillary Thyroid Carcinoma Present with More Invasive Disease Than Adolescents and Young Adults

Introduction: Pediatric papillary thyroid carcinomas (PTCs) are more invasive than adult PTCs. No large, contemporary cohort study has been conducted to determine whether younger children are at higher risk for advanced disease at presentation compared to adolescents. We aimed to describe pediatric PTC and contextualize its characteristics with a young adult comparison cohort. Methods: The National Cancer Database was interrogated for pediatric and young adult PTCs diagnosed between 2004 and 2017. Clinical variables were compared between prepubertal (≤10 years old), adolescent (11-18 years old), and young adult (19-39 years old) groups. Multivariable logistic regression modeling for independent predictors of metastases was conducted. A subanalysis of microcarcinomas (size ≤10 mm) was performed. Results: A total of 4860 pediatric (prepubertal n = 274, adolescents n = 4586) and 101,159 young adult patients were included. Prepubertal patients presented with more extensive burden of disease, including significantly larger primary tumors, higher prevalence of nodal and distant metastases, and increased frequency of features such as lymphovascular invasion, and extrathyroidal extension (ETE). Prepubertal age was an independent predictor of positive regional nodes (adjusted odds ratio [AOR] = 1.36 [95% confidence interval {CI} 1.01-1.84], p = 0.04) and distant metastatic disease (AOR = 3.12 [CI 1.96-4.96], p < 0.001). However, there was no difference in survival between groups (p = 0.32). Prepubertal age independently predicted lymph node metastases for microcarcinomas (AOR = 2.19 [CI 1.10-4.36], p = 0.03). Prepubertal (n = 41) versus adolescent (n = 937) patient age was associated with gross ETE (p = 0.004), even with primary tumors ≤1 cm in size. Conclusions: Patients aged <11 years old present with more advanced disease than adolescents, with a higher likelihood of nodal and distant metastatic disease at time of diagnosis, although survival is high. Prepubertal children undergo more extensive treatment, likely reflective of more invasive disease at the outset, even in the setting of a subcentimeter primary tumor.

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.

The clinical significance of BRAFV600E mutations in pediatric papillary thyroid carcinomas

This study aimed to review the clinical significance of BRAFV600E mutations in pediatric papillary thyroid carcinoma (PTC). From 2018 to 2021, 392 pediatric thyroid operations were performed in the first affiliated Hospital of Zhengzhou University. Of these, 169 patients underwent their first operation in our hospital and were histopathologically diagnosed as papillary thyroid carcinoma. BRAFV600E gene mutation detection was performed in these 169 pediatric patients to investigate the correlation between BRAF gene mutations and clinicopathological features. Ninety-seven of our 169 patients had a BRAFV600E mutation, with a mutation rate of 57.4%. The incidence of BRAFV600E was higher in boys than in girls, and in the 13-18-year age group as compared with the 6-12-year age group (P < 0.05). The positivity rate of BRAFV600E in unilateral PTC (67.7%) was significantly higher than the ones in bilateral PTC (28.9%). The occurrence of diffuse microcalcification of the thyroid negatively correlated with the presence of BRAFV600E mutations. BRAFV600E mutations were found more frequently in patients with smaller tumor size, a lack of multifocality, lower TSH levels and central lymph node metastasis. During the follow-up time, 70 patients were treated with iodine-131. Eight patients required a second surgery (All had cervical lymph node recurrence). BRAFV600E mutations do not suggest a more aggressive course in papillary thyroid carcinoma in pediatric patients in the short term.

Mutational analysis using next generation sequencing in pediatric thyroid cancer reveals BRAF and fusion oncogenes are common

BACKGROUND

We previously described mutation rates of BRAF^V600E, RAS, RET-PTC and PAX8-PPARγ in pediatric subjects with well-differentiated thyroid cancer (WDTC). We expanded the cohort adding next-generation sequencing (NGS) and assessed genotype-phenotype correlations.

METHODS

Single-center retrospective cohort examining thyroidectomy tissue blocks from consecutive pediatric WDTC patients between 2001 and 2015. Tissues were analyzed at Quest Diagnostics for BRAF, RAS mutations, RET-PTC and PAX8-PPARγ, and additional fusions, using standalone and NGS tests. WDTC included papillary (PTC), follicular (FTC) and follicular-variant PTC (FVPTC).

RESULTS

We genotyped 46 samples (36 females). Mean age at diagnosis was 14.7 years and the cohort comprised of mostly Hispanic (60.9%) and Caucasian (26.1%) patients. Mean follow-up was 3.5 years. Genetic alterations (GA) were noted in 69.6%, with BRAF^V600E (n = 11), and RET-PTC (n = 8) detected only in PTC. GA were detected in 2/7 FTC (1 PAX8-PPARγ, 1 NRAS) and 6/10 FVPTC (3 PAX8-PPARγ, 1 STRN-ALK, 1 BRAF^K601E, 1 NRAS). Patients with BRAF^V600E were predominantly Hispanic (81.8%) and >15 years (81.8%), whereas 87.5% RET-PTC and 50% other-fusions occurred in patients ≤15 years (p = 0.044). Of the 29 PTC patients, 82.8% had GA: BRAF^V600E (37.9%), RET-PTC (27.6%), 17.2% other fusion-oncogenes (2 -ALK, 3 -NTRK). Non-RET fusions had the highest vascular invasion (100%, p = 0.042 vs RET-PTC) and frequent lymphatic invasion (80%). GA were most common in PTC with cervical metastasis.

CONCLUSIONS

BRAF^V600E was the most common single mutation, especially in older and Hispanic adolescents. All fusions combined are more common than BRAF^V600E. NGS reveals a genetic basis in most pediatric WDTC, which may have implications for the role of molecular testing and systemic therapy.

Epidemiology and treatment of head and neck malignancies in the AYA generation

The Adolescent and Young Adult (AYA) population refers to the population of young adults and adolescents in the 15-39 years age group. This population subgroup experiences various important life events. Head and neck malignancies are rare tumors, in general, but they are extremely rare in the AYA population. When analyzed by the primary site of the tumors, thyroid gland, soft tissue, and nasopharyngeal malignancies are the most commonly encountered head and neck malignancies in the AYA generation. The most common histopathologic subtypes are carcinomas (thyroid carcinoma, nasopharyngeal carcinoma) and rhabdomyosarcoma. Therefore, in this review, the author discusses these three diseases in the AYA population in detail. Especially, patients with parameningeal rhabdomyosarcoma are at a high risk of dysfunction and facial deformity. Infertility problems may also occur as long-term sequelae of chemotherapy in this population. Radiation therapy might be associated with considerable morbidity. Complications such as cataract, xerostomia, hearing loss, neck fibrosis, and trismus are also common. Head and neck surgeons and medical oncologists should choose the optimal treatment taking into account the curability of the tumors relative to the long-term adverse events of treatment use. Finally, little evidence has been accumulated on head and neck malignancies in the AYA population, and it is urgently necessary to build a high level of evidence for the future.

Major Oncogenic Drivers and Their Clinicopathological Correlations in Sporadic Childhood Papillary Thyroid Carcinoma in Belarus

Childhood papillary thyroid carcinoma (PTC) diagnosed after the Chernobyl accident in Belarus displayed a high frequency of gene rearrangements and low frequency of point mutations. Since 2001, only sporadic thyroid cancer occurs in children aged up to 14 years but its molecular characteristics have not been reported. Here, we determine the major oncogenic events in PTC from non-exposed Belarusian children and assess their clinicopathological correlations. Among the 34 tumors, 23 (67.6%) harbored one of the mutually exclusive oncogenes: 5 (14.7%) BRAFV600E, 4 (11.8%) RET/PTC1, 6 (17.6%) RET/PTC3, 2 (5.9%) rare fusion genes, and 6 (17.6%) ETV6ex4/NTRK3. No mutations in codons 12, 13, and 61 of K-, N- and H-RAS, BRAFK601E, or ETV6ex5/NTRK3 or AKAP9/BRAF were detected. Fusion genes were significantly more frequent than BRAFV600E (p = 0.002). Clinicopathologically, RET/PTC3 was associated with solid growth pattern and higher tumor aggressiveness, BRAFV600E and RET/PTC1 with classic papillary morphology and mild clinical phenotype, and ETV6ex4/NTRK3 with follicular-patterned PTC and reduced aggressiveness. The spectrum of driver mutations in sporadic childhood PTC in Belarus largely parallels that in Chernobyl PTC, yet the frequencies of some oncogenes may likely differ from those in the early-onset Chernobyl PTC; clinicopathological features correlate with the oncogene type.

Management of Differentiated Thyroid Carcinoma in Pediatric Patients

Differentiated thyroid carcinomas are rare in young children but represent almost 10% of all malignancies diagnosed in older adolescents. Differentiated thyroid carcinoma in children is more likely to demonstrate nodal involvement and is associated with higher recurrence rates than seen in adults. Decisions regarding extent of surgical resection are based on clinical and radiologic features, cytology, and risk assessment. Total thyroidectomy and compartment-based resection of involved lymph node basins form the cornerstone of treatment. The use of molecular genetics to inform treatment strategies and the use of targeted therapies to unresectable progressive disease is evolving.

Integrated DNA and RNA sequencing reveals targetable alterations in metastatic pediatric papillary thyroid carcinoma

BACKGROUND

Pediatric papillary thyroid carcinoma (PTC) is clinically and biologically distinct from adult PTC. We sequenced a cohort of clinically annotated pediatric PTC cases enriched for high-risk tumors to identify genetic alterations of relevance for diagnosis and therapy.

METHODS

Tumor DNA and RNA were extracted from FFPE tissue and subjected to next-generation sequencing (NGS) library preparation using a custom 124-gene hybridization capture panel and the 75-gene Archer Oncology Research Panel, respectively. NGS libraries were sequenced on an Illumina MiSeq.

RESULTS

Thirty-six pediatric PTC cases were analyzed. Metastases were frequently observed to cervical lymph nodes (29/36, 81%), with pulmonary metastases less commonly found (10/36, 28%). Relapsed or refractory disease occurred in 18 patients (18/36, 50%). DNA sequencing revealed targetable mutations in 8 of 31 tumors tested (26%), most commonly BRAF p.V600E (n = 6). RNA sequencing identified targetable fusions in 13 of 25 tumors tested (52%): RET (n = 8), NTRK3 (n = 4), and BRAF. Mutually exclusive targetable alterations were discovered in 15 of the 20 tumors (75%) with both DNA and RNA analyzed. Fusion-positive PTC was associated with multifocal disease, higher tumor staging, and higher American Thyroid Association risk levels. Both BRAF V600E mutations and gene fusions were correlated with the presence of cervical metastases.

CONCLUSIONS

Targetable alterations were identified in 75% of pediatric PTC cases with both DNA and RNA evaluated. Inclusion of RNA sequencing for detection of fusion genes is critical for evaluation of these tumors. Patients with fusion-positive tumors were more likely to have features of high-risk disease.

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.

Pediatric differentiated thyroid carcinoma: An update from the APSA Cancer Committee

BACKGROUND

Differentiated thyroid carcinomas (DTCs) are rare in young children but represent almost 10% of all malignancies diagnosed in older adolescents.

METHODS

This article reviews the recent literature describing surgical therapeutic approaches to pediatric DTC, associated complications, and long-term recurrence and survival outcomes.

RESULTS

Similar to adult thyroid cancers, pediatric DTCs are more common in females and are associated with thyroid nodules, family history of thyroid cancer, radiation exposure, iodine deficiency, autoimmune thyroid disease, and genetic syndromes. Management of thyroid cancers in children involves ultrasound imaging, fine needle aspiration, and surgical resection with treatment decisions based on clinical and radiological features, cytology and risk assessment.

CONCLUSIONS

Total thyroidectomy and compartment based resection of clinically involved lymph node basins form the cornerstone of treatment of DTC. There is an evolving literature regarding the use of molecular genetics to inform treatment strategies and the use of targeted therapies to treat iodine refractory and surgically unresectable progressive disease.

TYPE OF STUDY

Summary review.

LEVEL OF EVIDENCE

This is a review article of previously published Level 1-5 articles that includes expert opinion (Level 5).

Thyroid carcinoma in children, adolescents, and young adults in Brazil: A report from 11 population-based cancer registries

Background

The increasing incidence of thyroid cancer has been described worldwide. Overdiagnosis, improved imaging, and increased environmental risk factors have contributed to the rising incidence. The objective of this study was to analyze the population incidence rate and trends during the period of 2000–2013 in children, adolescents and young adults (AYAs) in Brazil.

Methods

Data were extracted from 11 population-based cancer registries (PBCRs) encompassing the five geographic regions of Brazil. Incidence rates per million in children (0–14) and AYAs (15–39) according to world population were analyzed according to sex, age, and type of carcinoma. Incidence trends were evaluated using joinpoint regression.

Results

During 2000 to 2013, we identified 11,081 children and AYAs (0–39 years) with thyroid carcinoma in 11 PBCRs, with an age-adjusted incidence rate (AAIR) of 42 cases per million. Females had a higher AAIR of 66 cases per million versus 14 cases per million in males. Age-specific incidence rate (ASR) increased with age. Geographic variation was also observed; the Midwest and Southeast regions had the highest ASR in all age groups. The lowest ASR in all age groups was seen in the North region. Papillary subtype was the most common. Overall, the incidence rates in children and AYAs significantly increased from 0.2 in 2000 to 2.8 in 2013 and from 47.1 to 115.3, respectively, with an annual average percent change of 18.8 [8.1; 30.6] for children and 7.9 [CI 5.6; 10.3] for AYAs.

Conclusions

Rates of thyroid cancer, particularly the papillary subtype, are steadily increasing in children and AYAs, especially among females. There are variations among geographic areas. This increased incidence is unlikely to be explained by screening, as children less than 14 years of age do not typically undergo medical surveillance. Environmental risk factors must be investigated.

Incidence of BRAF V600E mutation in patients with papillary thyroid carcinoma: a single-institution experience

Objective

Papillary thyroid carcinoma (PTC) accounts for 95% of all thyroid carcinomas. PTC is an epithelial tumor characterized by the proliferation of follicular cells with distinctive nuclear features, and is heterogeneous in terms of its carcinogenesis and behavior. PTC has been associated with several genetic abnormalities, of which the BRAF V600E mutation is the most common. However, reported incidences of this mutation have varied depending on the patient background, population size, or methods. In this study, we investigated the incidence of BRAF V600E mutation and its relationships with clinicopathological characteristics in patients with PTC.

Methods

Surgical specimens were obtained from 40 patients with PTC who underwent surgery at Nippon Medical School Hospital between 2009 and 2017. DNA from exon 15 of the BRAF gene was extracted and amplified by polymerase chain reaction, followed by direct sequencing.

Results

The frequency of BRAF V600E mutation increased with age. However, there were no correlations between BRAF V600E mutation and other clinicopathological features including sex, Hashimoto disease, family history of thyroid disease, tumor size, pathological T stage, pathological N stage, lymphovascular invasion, extrathyroidal extension, and metastasis.

Conclusions

This study demonstrated that PTCs harboring the BRAF V600E mutation increased in an age-dependent manner.

Differentiated Thyroid Cancer in the Pediatric/Adolescent Population: Evolution of Treatment

Differentiated thyroid cancer (DTC) is the most common cancer in adolescents and young adults. In 2015, the American Thyroid Association published guidelines for management of pediatric DTC. We report our institutional experience and highlight changing practices and new opportunities. A retrospective analysis of all patients diagnosed with DTC from 2001 to 2016 was performed. Among 59 eligible patients, 31 (53%), 15 (25%), and 13 (22%) had low-risk, intermediate-risk, and high-risk disease, respectively. Half (15/31) of low-risk and all intermediate-risk/high-risk patients received radioactive iodine (I-131) ablation. For low-risk patients, average I-131 dose decreased from 80 to 42.05 mCi, and the percentage of patients who received I-131 decreased over time. Eleven of 16 patients with tumor genomic data were found to have somatic targetable (n=6) or germline (n=5) mutations. Persistent/recurrent disease was only present in high-risk (n=8) and intermediate-risk (n=1) patients. Two patients with iodine-refractory disease received trametinib to enhance radioiodine uptake. All patients were alive at follow-up (median, 5 y; range, 1 to 15 y). Coincident with the recent American Thyroid Association guidelines, the use of I-131 in low-risk patients has decreased over time in our practice. Tumor sequencing and cancer genetic evaluation may help redefine opportunities for treatment of high-risk patients and family counseling.

Thyroid Cancer in the Pediatric Population

Thyroid cancer is rare in the pediatric population, but thyroid carcinomas occurring in children carry a unique set of clinical, pathologic, and molecular characteristics. In comparison to adults, children more often present with aggressive, advanced stage disease. This is at least in part due to the underlying biologic and molecular differences between pediatric and adult thyroid cancer. Specifically, papillary thyroid carcinoma (which accounts for approximately 90% of pediatric thyroid cancer) has a high rate of gene fusions which influence the histologic subtypes encountered in pediatric thyroid tumors, are associated with more extensive extrathyroidal disease, and offer unique options for targeted medical therapies. Differences are also seen in pediatric follicular thyroid cancer, although there are few studies of non-papillary pediatric thyroid tumors published in the literature due to their rarity, and in medullary carcinoma, which is most frequently diagnosed in the pediatric population in the setting of prophylactic thyroidectomies for known multiple endocrine neoplasia syndromes. The overall shift in the spectrum of histotypes and underlying molecular alterations common in pediatric thyroid cancer is important to recognize as it may directly influence diagnostic test selection and therapeutic recommendations.

AGK-BRAF is associated with distant metastasis and younger age in pediatric papillary thyroid carcinoma

BACKGROUND

The incidence of thyroid carcinoma has increased in most populations, including pediatric patients. The increase is almost exclusively due to an increase in the incidence of papillary thyroid carcinoma (PTC). Genetic alterations leading to mitogen-activated protein kinase (MAPK) pathway activation are highly prevalent in PTC, with BRAF V600E mutation being the most common event in adult PTC. Although a lower prevalence of BRAF V600E had been reported among pediatric patients, a higher prevalence of BRAF fusion has been identified in both radiation-exposed and sporadic pediatric PTC. However, little is known about the prognostic implications of BRAF fusions in pediatric PTC.

PROCEDURE

In this study, we investigated the prevalence of BRAF alterations (AGK-BRAF fusion and BRAF V600E mutation) in a large set of predominantly sporadic pediatric PTC cases and correlate with clinicopathological features. Somatic AGK-BRAF fusion was investigated by RT-PCR and confirmed by FISH break-apart. The BRAF V600E mutation was screened using Sanger sequencing.

RESULTS

AGK-BRAF fusion, found in 19% of pediatric PTC patients, was associated with distant metastasis and younger age. Conversely, the BRAF V600E, found in 15% of pediatric PTC patients, was correlated with older age and larger tumor size.

CONCLUSION

Collectively, our results advance knowledge concerning genetic bases of pediatric thyroid carcinoma, with potential implications for diagnosis, prognosis, and therapeutic approaches.

Somatic genetic alterations in a large cohort of pediatric thyroid nodules

There is a rise in the incidence of thyroid nodules in pediatric patients. Most of them are benign tissues, but part of them can cause papillary thyroid cancer (PTC). The aim of this study was to detect the mutations in commonly investigated genes as well as in novel PTC-causing genes in thyroid nodules and to correlate the found mutations with clinical and pathological data. The cohort of 113 pediatric samples consisted of 30 benign lesions and 83 PTCs. DNA from samples was used for next-generation sequencing to identify mutations in the following genes: HRAS, KRAS, NRAS, BRAF, IDH1, CHEK2, PPM1D, EIF1AX, EZH1 and for capillary sequencing in case of the TERT promoter. RNA was used for real-time PCR to detect RET/PTC1 and RET/PTC3 rearrangements. Total detection rate of mutations was 5/30 in benign tissues and 35/83 in PTCs. Mutations in RAS genes (HRAS G13R, KRAS G12D, KRAS Q61R, NRAS Q61R) were detected in benign lesions and HRAS Q61R and NRAS Q61K mutations in PTCs. The RET/PTC rearrangement was identified in 18/83 of PTCs and was significantly associated with higher frequency of local and distant metastases. The BRAF V600E mutation was identified in 15/83 of PTCs and significantly correlated with higher age of patients and classical variant of PTC. Germline variants in the genes IDH1, CHEK2 and PPM1D were found. In conclusion, RET/PTC rearrangements and BRAF mutations were associated with different clinical and histopathological features of pediatric PTC. RAS mutations were detected with high frequency in patients with benign nodules; thus, our results suggest that these patients should be followed up intensively.

Response to Lenvatinib in Children with Papillary Thyroid Carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy in children and adolescents. Infrequently, children with PTC may present with or develop disease not amenable to surgery or radioactive iodine (RAI), and systemic therapy may be an option. Lenvatinib is an oral tyrosine kinase inhibitor that is approved by the Food and Drug Administration for the treatment of adults with locally recurrent or metastatic, progressive, RAI-refractory well-differentiated thyroid carcinoma. The effect of lenvatinib in children with PTC has not been reported.

PATIENT FINDINGS

Three children with metastatic PTC not amenable or refractory to RAI who responded to lenvatinib are reported. All of them developed respiratory distress requiring oxygen caused by extensive bilateral metastatic pulmonary disease. The first patient is a 14-year-old female who was initially treated with sorafenib for extensive PTC not amenable to upfront surgery or RAI. She had progressive pulmonary disease after five months, and was subsequently treated with oral lenvatinib (14 mg/m²/day). She was weaned to room air after eight weeks. The second patient is a 15-year-old male who was treated with lenvatinib (14 mg/m²/day) for iodine non-avid diffuse pulmonary disease after initial total thyroidectomy and cervical lymph node dissection. He was weaned off oxygen in six weeks. The third patient is a five-year-old male who was treated with lenvatinib (14 mg/m²/day) for pulmonary disease progression 24 months after treatment with total thyroidectomy, cervical lymph node dissection, and RAI treatment. He was weaned off oxygen one day after starting lenvatinib. Two of the patients required dose adjustments secondary to proteinuria. Otherwise, all patients tolerated lenvatinib well. The first two patients remained clinically stable on lenvatinib 23 months and 11 months after initiation of therapy, respectively, and the third patient transitioned to a tumor-specific targeted therapy after one month.

SUMMARY

Three pediatric patients are reported with metastatic PTC not amenable or refractory to RAI who achieved a response on lenvatinib.

CONCLUSION

Lenvatinib therapy is well tolerated and demonstrated clinical activity in children with advanced PTC. Lenvatinib should be considered in children with PTC that is refractory or not amenable to conventional management.

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.

Sporadic pediatric papillary thyroid carcinoma harboring the ETV6/NTRK3 fusion oncogene in a 7-year-old Japanese girl: a case report and review of literature

BACKGROUND

There have been great concerns about pediatric thyroid cancers after the accident at the Fukushima Daiichi Nuclear Power Plant in 2011.

CASE PRESENTATION

We report a case of a 7-year-old Japanese girl with sporadic papillary thyroid carcinoma (PTC) harboring an ETV6/NTRK3 rearrangement. The patient presented with tumors in both lobes and underwent thyroidectomy followed by radioactive iodine (RAI) ablation. Histopathology showed a classic type of PTC with cervical lymph node metastasis.

CONCLUSIONS

Genetic evaluation showed ETV6/NTRK3 fusion but no BRAF mutations or RET/PTC rearrangements. RET/PTC rearrangement and BRAF mutations often contribute to the pathogenesis of PTC; however, rearrangements of NTRK genes are relatively rare in pediatric PTC. Although NTRK rearrangement has been shown to often present unique pathological types and infiltrative architectures in the western population, such findings were not observed in this patient. Thus, the present case of classic PTC with ETV6/NTRK3 rearrangement highlights the disparate collection of clinic-pathological features compared to the trend in the western population. We therefore emphasize the need to further accumulate clinical as well as genetic data in pediatric PTCs.

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.

Molecular Testing for Oncogenic Gene Alterations in Pediatric Thyroid Lesions

BACKGROUND

Thyroid nodules are less common in pediatric patients (i.e., those ≤18 years) than they are in adults. The Bethesda System for Reporting Thyroid Cytopathology allows for individual risk stratification, but a significant number of nodules are indeterminate. Incorporating gene mutation panels and gene expression classifiers may aid in preoperative diagnosis. The overall aim of this study was to assess the prevalence of oncogene alterations in a representative pediatric population and across a broad-spectrum of thyroid tumor diagnoses.

METHODS

This was a retrospective cross-sectional evaluation of 115 archived samples, including: 47 benign (29 follicular adenoma, 11 diffuse hyperplasia, four thyroiditis, and three multinodular goiter), six follicular thyroid carcinomas (FTC), 24 follicular variant of papillary thyroid carcinomas (fvPTC), 27 classic variant of PTC (cPTC), eight diffuse sclerosing variant of PTC (dsvPTC), and three other PTC. Molecular testing was performed by multiplex qualitative polymerase chain reaction followed by bead array cytometry. Oncogene results were analyzed for association with age, sex, histology, lymph node metastasis, and intrathyroidal spread.

RESULTS

A mutation in one of the 17 molecular markers evaluated was found in: 2/6 (33%) FTC, 8/24 (33%) fvPTC, 17/27 (63%) cPTC, and 4/8 (50%) dsvPTC. Mutations in RAS or PAX8/PPARG were exclusive to FTC and fvPTC. BRAF was the most common mutation in cPTC (12/17; 71%), and RET/PTC was the only mutation associated with dsvPTC. Overall, a mutation was found in 32/68 (47%) malignant specimens, with a single follicular adenoma positive for PAX8/PPARG. The relative distribution of gene alterations in pediatric lesions was similar to adults. The presence of a BRAF mutation in pediatric cPTC did not predict a more invasive phenotype.

CONCLUSIONS

Of 33 nodules with genetic alterations, 32 were malignant. Mutations in RAS were most frequently associated with FTC, RET/PTC rearrangements with dsvPTC, and invasive fvPTC, and BRAF with cPTC. These results suggest a clinical role for mutational analysis of pediatric nodules to guide the surgical approach.

Radiation exposure, young age, and female gender are associated with high prevalence of RET/PTC1 and RET/PTC3 in papillary thyroid cancer: a meta-analysis

Background

RET/PTC rearrangements have been identified as a specific genetic event in papillary thyroid cancer (PTC). We conducted this meta-analysis to identify an enriched population who were more likely to occur RET/PTC fusion genes.

Methods

All relevant studies in the PubMed, Web of Science, and Embase databases were searched up to June 2015. The studies found were screened according to our inclusion and exclusion criteria. All analyses were performed using STATA software.

Results

Eventually, 38 eligible studies comprising 2395 participants were included. Overall analysis indicated that radiation exposure contributed to increased RET/PTC risk (OR = 2.82; 95%CI: 1.38–5.78, P = 0.005). Stratified analysis according to RET/PTC subtype and geographical area showed that this association was restricted to the RET/PTC3 subtype (OR = 8.30, 95%CI: 4.32–15.96, P < 0.001) in the Western population. In addition, age < 18 years, i.e., young age, was associated with higher prevalence of RET/PTC3 (OR = 2.03, 95%CI: 1.14–3.62, P = 0.017), especially in the radiation-exposure subpopulation (OR = 2.35, 95%CI: 1.01–5.49, P = 0.048). The association between female gender and RET/PTC1 risk was more significant in the PTC patients without radiation exposure (OR = 1.69, 95%CI: 1.04–2.74, P = 0.034).

Conclusion

Both radiation exposure and young age are associated with increased risk of RET/PTC3 and that female gender is associated with higher prevalence of RET/PTC1 in the subpopulation without radiation exposure. The RET/PTC status in combination with radiation exposure, age, and sex should be considered in the differential diagnosis of suspicious PTC.

Genomic Hallmarks of Thyroid Neoplasia

The genomic landscape of thyroid cancers that are derived from follicular cells has been substantially elucidated through the coordinated application of high-throughput genomic technologies. Here, I review the common genetic alterations across the spectrum of thyroid neoplasia and present the resulting model of thyroid cancer initiation and progression. This model illustrates the striking correlation between tumor differentiation and overall somatic mutational burden, which also likely explains the highly variable clinical behavior and outcome of patients with thyroid cancers. These advances are yielding critical insights into thyroid cancer pathogenesis, which are being leveraged for the development of new diagnostic tools, prognostic and predictive biomarkers, and novel therapeutic approaches.

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.

Paediatric follicular thyroid carcinoma - indolent cancer with low prevalence of RAS mutations and absence of PAX8-PPARG fusion in a Japanese population

AIMS

Paediatric follicular thyroid carcinomas are uncommon, and their clinicopathological features and molecular profiles are still unknown. In the present study, we aimed to investigate the clinicopathological aspects of a large series of follicular thyroid carcinomas (FTCs) in paediatric patients and to analyse the point mutations in codons 12, 13 and 61 of NRAS, HRAS and KRAS genes and the rearrangements of PAX8-PPARG.

METHODS AND RESULTS

A total of 41 paediatric FTCs less than 21 years of age were enrolled into the present study. We used direct sequencing and reverse transcription-polymerase chain reaction (RT-PCR) to detect RAS mutations and PAX8-PPARG fusions, respectively. The paediatric FTCs were 6:1 in a female to male ratio, with a mean tumour size of 52.7 mm. Distant metastasis was found in one case at the time of presentation. During a median follow-up time of 69 months, two cases had lung metastasis and all patients were alive. Histologically, all cases were minimally invasive FTCs and varied in growth patterns: microfollicular (39%), follicular (14.6%), solid/trabecular (6%), oncocytic (4.9%) and mixed patterns (26.8%). The mean Ki67 index was 5.7% and it was not statistically different among the growth patterns. NRAS mutations were found in five cases (12.2%) and associated significantly with small tumour size (P = 0.014). PAX8-PPARG fusion was not detected in our series.

CONCLUSION

Paediatric FTCs are indolent in clinical course in spite of their large tumour size and have a distinct genetic background. RAS mutations and PAX8-PPARG fusions may not play major roles in the tumorigenesis of paediatric FTCs.

Correlation between BRAF V600E mutation and clinicopathological features in pediatric papillary thyroid carcinoma

In adults, the presence of the BRAF ^V600E mutation in papillary thyroid cancer (PTC) has been demonstrated to be strongly associated with aggressive cancer-cell characteristics and poor patient prognosis. In contrast, the frequency of this mutation in pediatric PTC has undergone limited study, and the few available estimates range from 0 to 63%. Furthermore, the role of the BRAF ^V600E mutation in pediatric PTC is controversial; thus, the present study aimed to investigate the prevalence and role of the BRAF ^V600E mutation in 48 pediatric patients with PTC, aged 3-13 years. Of these patients, 41 were diagnosed with classic PTC, five were found to have a follicular variant of PTC, and two to exhibit a diffuse sclerosing PTC variant. The BRAF ^V600E mutation was identified to be present in 35.4% of the 48 analyzed patients, and in 41.5% of the patients diagnosed with classical PTC. Furthermore, the presence of the BRAF ^V600E mutation was found to be associated with a patient age at diagnosis of less than ten years (P=0.011), the performance of a thyroidectomy (P=0.03), exhibited tumor multifocality (P=0.02) and/or extra-thyroidal invasion (P=0.003), and both a low MACIS (Metastases, Age, Completeness of resection, Invasion, Size)(P=0.036) and AMES (Age, Metastasis, Extent of tumor, Size)(P=0.001) score. Together, these data suggest that the presence of the BRAF ^V600E mutation may be negatively correlated with partial aggressive clinicopathological features of pediatric PTC.

Identification of Three Novel Fusion Oncogenes, SQSTM1/NTRK3, AFAP1L2/RET, and PPFIBP2/RET, in Thyroid Cancers of Young Patients in Fukushima

BACKGROUND

The BRAF^V600E mutation is the most frequent genetic abnormality in adult papillary thyroid carcinomas (PTCs). On the other hand, various chromosomal rearrangements are more prevalent in childhood and adolescent PTCs. The aim of the present study was to identify novel rearrangements in PTCs from young patients.

METHODS

Among 63 postoperative specimens of childhood and adolescent PTCs, which had been discovered by the thyroid ultrasound screening program in Fukushima, nine samples without prevalent known oncogenes, BRAF^V600E, RAS, RET/PTC1, RET/PTC3, and ETV6/NTRK3, were analyzed in the current study by quantitative real-time reverse transcription polymerase chain reaction to screen for novel fusion genes by comparing transcript expression between extracellular and kinase domains of ALK, NTRK1, NTRK3, and RET.

RESULTS

Of the above nine samples, five samples were suspected to harbor a fusion, and using subsequent 5' rapid amplification of cDNA end (RACE), two already reported fusion oncogenes, STRN/ALK and TPR/NTRK1, and three novel fusions, SQSTM1/NTRK3, AFAP1L2/RET, and PPFIBP2/RET, were identified. Functional analyses of these three chimeric genes were performed, and their transforming abilities were confirmed through the activation of mitogen-activated protein kinase (MAPK).

CONCLUSIONS

Three novel fusion oncogenes have been identified in young PTC patients in Fukushima, suggesting that rare fusions may be present among the cases negative for known oncogenes in this age group and that such rearrangements can play a significant role in thyroid carcinogenesis.

Molecular Genetics of Thyroid Cancer in Children and Adolescents

There has been a steady incorporation of powerful new molecular tools into the evaluation and management of thyroid nodules and thyroid cancer. With an increasing incidence of nodules and differentiated thyroid cancer (DTC) being diagnosed in children and adolescents, oncogene data are providing insight into the clinical differences between pediatric and adult patients with histologically similar DTC. However, additional investment and efforts are needed to define the genomic landscape for pediatric DTC with the goal of improving preoperative diagnostic accuracy as well as stratifying treatment in an effort to reduce complications of therapy.

Pathologic Characteristics, Natural History, and Prognostic Implications of BRAFV600E Mutation in Pediatric Papillary Thyroid Carcinoma

The BRAF^V600E mutation is the most common genetic aberration in papillary thyroid cancer (PTC), found in up to 68% of PTC in adults where it is associated with aggressive features. The incidence of this mutation in pediatric PTC is less frequent, reported as 0%-20% in the past and up to 63% in one recent series. Data suggest the mutation is not associated with an aggressive course in children; however, there are limited numbers of reported case series, so the prognostic implications remain poorly understood. The aim of this retrospective study was to examine the histologic characteristics and clinical outcomes of BRAF positive pediatric PTC at a single institution. A 12-year retrospective review of all thyroidectomies performed at a tertiary medical center identified 59 pediatric cases with a surgical pathology diagnosis of PTC. Fifty patients had BRAF^V600E mutation analysis data and were selected for further study. BRAF^V600E mutations were present in 48% of cases (n = 24) and absent in 52% (n = 26). The molecular characteristics of the BRAF negative cases will further be evaluated in future studies. BRAF positive cases occurred in patients who were on average older than the BRAF negative patients. Classic histology PTC was present in both BRAF positive and negative cases; however, only cases with classic PTC histology were positive for the mutation. No patients died and BRAF mutation was not associated with an increased recurrence rate. Our study supports BRAF^V600E is more common in children than previously thought and does not portend a more aggressive clinical course.

Frequent BRAF V600E and Absence of TERT Promoter Mutations Characterize Sporadic Pediatric Papillary Thyroid Carcinomas in Japan

Pediatric papillary thyroid carcinoma (PTC) has unique features but requires further genetic investigation. Moreover, there has been increasing concern about the risk for pediatric PTC in Japan after the Fukushima accident. This study aims to evaluate the frequencies of BRAF and TERT promoter mutations and to examine their significance in non-radiation-associated pediatric PTCs in Japan. We enrolled 81 pediatric PTC patients aged ≤20 years. The control group included 91 adult PTCs from patients >20 years old. BRAF and TERT mutations were analyzed by allele-specific-PCR and/or Sanger sequencing. Compared with adult PTCs, pediatric PTCs exhibited larger tumor size, more frequent lymph node metastasis, and less classical histology. The prevalence of BRAF ^V600E in pediatric PTCs was 54% and significantly lower than that in adults of 85%. In the pediatric PTCs, BRAF ^V600E was positively associated with older age, classical histology, and the lymph node metastasis but independent from other clinicopathological factors. TERT mutations were identified in 13% of adults and in none of the pediatric PTCs. In conclusion, pediatric PTCs are characterized by more advanced clinicopathological features, lower BRAF ^V600E frequency, and absence of TERT mutation. The BRAF ^V600E frequency in this study is similar to the reported BRAF ^V600E frequency in the ultrasonographically screened pediatric PTCs in Fukushima.

Pediatric, Adolescent, and Young Adult Thyroid Carcinoma Harbors Frequent and Diverse Targetable Genomic Alterations, Including Kinase Fusions

BACKGROUND

Thyroid carcinoma, which is rare in pediatric patients (age 0-18 years) but more common in adolescent and young adult (AYA) patients (age 15-39 years), carries the potential for morbidity and mortality.

METHODS

Hybrid-capture-based comprehensive genomic profiling (CGP) was performed prospectively on 512 consecutively submitted thyroid carcinomas, including 58 from pediatric and AYA (PAYA) patients, to identify genomic alterations (GAs), including base substitutions, insertions/deletions, copy number alterations, and rearrangements. This PAYA data series includes 41 patients with papillary thyroid carcinoma (PTC), 3 with anaplastic thyroid carcinoma (ATC), and 14 with medullary thyroid carcinoma (MTC).

RESULTS

GAs were detected in 93% (54/58) of PAYA cases, with a mean of 1.4 GAs per case. In addition to BRAF V600E mutations, detected in 46% (19/41) of PAYA PTC cases and in 1 of 3 AYA ATC cases, oncogenic fusions involving RET, NTRK1, NTRK3, and ALK were detected in 37% (15/41) of PAYA PTC and 33% (1/3) of AYA ATC cases. Ninety-three percent (13/14) of MTC patients harbored RET alterations, including 3 novel insertions/deletions in exons 6 and 11. Two of these MTC patients with novel alterations in RET experienced clinical benefit from vandetanib treatment.

CONCLUSION

CGP identified diverse clinically relevant GAs in PAYA patients with thyroid carcinoma, including 83% (34/41) of PTC cases harboring activating kinase mutations or activating kinase rearrangements. These genomic observations and index cases exhibiting clinical benefit from targeted therapy suggest that young patients with advanced thyroid carcinoma can benefit from CGP and rationally matched targeted therapy. The Oncologist 2017;22:255-263 IMPLICATIONS FOR PRACTICE: The detection of diverse clinically relevant genomic alterations in the majority of pediatric, adolescent, and young adult patients with thyroid carcinoma in this study suggests that comprehensive genomic profiling may be beneficial for young patients with papillary, anaplastic, or medullary thyroid carcinoma, particularly for advanced or refractory cases for which clinical trials involving molecularly targeted therapies may be appropriate.

Single Point Mutations in Pediatric Differentiated Thyroid Cancer

PURPOSE

Differentiated thyroid cancer (DTC) is rare in children. Previous studies have suggested that it has different clinicopathologic features and mutation profiles compared with adult DTC. However, those studies focused on a single or limited number of gene mutations. This study comprehensively investigated a large series of pediatric DTC for single point mutations in BRAF, HRAS, KRAS, NRAS, PIK3CA, PTEN, and TERT. It also analyzed associations between clinicopathologic features and the BRAF^V600E mutation.

PATIENTS AND METHODS

Eighty-nine consecutive cases seen in children and adolescents (≤18 years) during 1998-2015 were identified. Rare variants of DTC were excluded, and the study focused on 72 (91.1%) classical papillary thyroid carcinoma (PTC) and seven (8.9%) follicular variant PTC. These included 68 (86.1%) females and 11 (13.9%) males, with a median age of 15.5 years (range 8-18 years). The clinical and histopathological data were obtained from medical records. DNA was extracted from paraffin-embedded tumor tissue, and was PCR-amplified and directly sequenced.

RESULTS

Mutations detected included BRAF^V600E in 19/72 (26.4%) classical PTC samples, and in none of seven follicular variant PTC. Other mutations included: 1/78 (1.3%) successfully amplified tumor samples with TERT^C228T; 2/79 (2.5%) NRAS 61 (c.181C>A and c.182A>G); 1/73 (1.4%) PIK3CA exon 9 (c.1589A>G and c.1598C>T in one tumor); 1/79 (1.3%) PIK3CA exon 20 (c.2951G>A); and 1/74 (1.4%) PTEN exon 5 (c.295G>A). No mutation was found in HRAS, KRAS, NRAS12, PTEN exons 6, 7, and 8, and TERT^C250T. No significant association was found between BRAF^V600E mutation and sex, extrathyroidal invasion, tumor multifocality, vascular invasion, lymph node or distant metastases, and persistent/recurrent disease.

CONCLUSIONS

In pediatric DTC, the prevalence of the BRAF^V600E mutation is significantly less common compared with adult DTC, and there is no association between this mutation and the histopathological features and outcome of PTC. PIK3CA, PTEN, NRAS 61, and TERT^C228T mutations are rare.

Fusion Oncogenes Are the Main Genetic Events Found in Sporadic Papillary Thyroid Carcinomas from Children

BACKGROUND

Previous studies reported significant differences in the clinical presentation and outcomes of papillary thyroid carcinoma (PTC) in pediatric patients compared with adults. Previous studies have suggested that the clinicopathological differences observed between pediatric and adult PTCs may be due the existence of distinct genetic alterations. However, the knowledge of genetic events in pediatric PTCs is based primarily on studies in radiation-exposed PTCs or in the few studies that enrolled predominantly adolescent patients. The aim of this study was to characterize the known oncogenic alterations of the MAPK pathway found in adult and radiation-exposed PTCs in a cohort of predominantly sporadic pediatric PTC patients.

METHODS

Thirty-five pediatric PTCs were screened for the most prevalent fusions (RET/PTC1, RET/PTC2, RET/PTC3, ETV6-NTRK3, and AGK-BRAF) and point mutations (BRAFV600E and NRASQ61) described in sporadic pediatric PTCs. The mutational status was correlated with clinicopathological data.

RESULTS

Mutations were found in 20 out of 35 (57%) PTC cases. Fusion oncogenes were the main genetic alterations found. RET/PTC1-3 rearrangements were found in 13 (37%), ETV6-NTRK3 in 3 (9%), AGK-BRAF in 4 (11%), and BRAFV600E in 3 (9%). No mutation was found in NRASQ61. BRAFV600E was associated with older age and larger tumor size (p < 0.05), and RET/PTC3 was associated with a larger tumor size and multifocality (p < 0.05).

CONCLUSIONS

The genetic signature in this cohort was remarkably different than that observed in adults. Although observed at a lower prevalence, the spectrum of mutations was quite similar to that described in radiation-exposed pediatric PTCs. As mutations were unidentifiable in over 40% of the PTC cases, more comprehensive studies conducted in these patients will help to decipher the genetic landscape of sporadic pediatric PTCs.

Mutational analysis of metastatic lymph nodes from papillary thyroid carcinoma in adult and pediatric patients

BACKGROUND

Limited data are available on the analysis of somatic mutations in metastatic lymph nodes in adult and pediatric patients with papillary thyroid carcinomas.

METHODS

A total of 92, microdissected, formalin-fixed, paraffin-embedded tissue specimens from 39 patients were analyzed for the presence of somatic mutations utilizing the ThyGenX next-generation sequencing test.

RESULTS

Somatic mutations were detected in 67% of papillary thyroid carcinoma specimens. The majority of patients with synchronous and all 6 patients with radioactive iodine-resistant (metachronous) metastatic lymph nodes contained BRAF mutations. Four patients had mutations detected in their metastatic lymph nodes that were not detected in their primary tumors. For the most part, BRAF mutations were seen in adults, and RAS mutations were seen in children.

CONCLUSION

Findings of different mutations in metastatic lymph nodes compared with the primary papillary thyroid carcinomas are probably the result of tumor heterogeneity. The presence of the BRAF mutation in metastatic lymph nodes might be responsible for the recurrence of papillary thyroid carcinomas and resistance to radioactive iodine therapy. The good prognosis observed in papillary thyroid carcinomas found in pediatric and young adult patients might be explained by the predominance of RAS rather than BRAF mutations.

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.

BRAF analysis before surgery for papillary thyroid carcinoma: correlation with clinicopathological features and prognosis in a single-institution prospective experience

Background:

Risk stratification in patients with papillary thyroid carcinoma (PTC) currently relies on postoperative parameters. Testing forBRAFmutations preoperatively may serve as a novel tool for identifying PTC patients at risk of persistence/recurrence after surgery.

Methods:

The study involved 185 consecutive patients with a histological diagnosis of PTC andBRAFanalysis performed on thyroid fine-needle aspiration biopsy (FNAB). We assessedBRAFstatus in FNAB specimens obtained before thyroidectomy for PTC, and examined its association with the clinicopathological characteristics identified postoperatively, and with outcome after a mean 55±15 months of follow-up.

Results:

One hundred and fifteen of 185 (62%) PTCs carried aBRAFmutation. Univariate analysis showed thatBRAFstatus correlated with the histological variant of PTC, cancer size, and stage at diagnosis, but not with gender, age, multifocality, or lymph node involvement.BRAF-mutated cases had a higher prevalence of persistent/recurrent disease by the end of the follow-up (11% vs. 8%), but this difference was not statistically significant. The Kaplan-Meier curve shows that among the patients with persistent/recurrent disease,BRAF-mutated patients needed a second treatment earlier than patients withBRAFwild-type, although the difference did not completely reach the statistical significance.

Conclusions:

Our study confirmed that preoperatively-identifiedBRAFmutation are associated with certain pathological features of PTC that correlate with prognosis. We speculate that it has a role in identifying PTCs that would generally be considered low-risk but that may reveal an aggressive behavior during their follow-up.

Mutation in BRAF and Other Members of the MAPK Pathway in Papillary Thyroid Carcinoma in the Pediatric Population

CONTEXT

Papillary thyroid carcinoma (PTC) is an uncommon tumor in the pediatric population. A limited number of studies have examined genetic mutations affecting the mitogen-activated protein kinase (MAPK) pathway in the pediatric population.

OBJECTIVE

To examine mutations affecting this pathway in PTC in our pediatric population and compare the BRAF V600E mutation rates in pediatric and adult tumors.

DESIGN

Eighty-four patients, including 14 pediatric and 70 adult, with PTC were tested for the BRAF V600E mutation by using real-time polymerase chain reaction and sequencing. Additionally, we examined the rate of RAS point mutations with real-time polymerase chain reaction and rearrangements of RET/PTC1 and RET/PTC3 in the pediatric group with fluorescence in situ hybridization. Clinical and histologic data were compared as well.

RESULTS

Of 77 tumors that had an interpretable result, the BRAF V600E mutant was identified in 4 of 13 pediatric patients (31%) and 43 of 64 adult patients (67%), which was a significant difference (using Fisher exact test, P = .03). One pediatric and 6 adult cases did not reveal an interpretable result with melting curve analysis. One of these cases harbored a rare 3-base pair deletion mutation (c.1799_1801delTGA). Mutations in RAS genes were not seen in any pediatric tumors. One tumor with a RET/PTC1 rearrangement and another with RET/PTC3 were identified in the pediatric population (15%).

CONCLUSIONS

The rate of the BRAF V600E mutation in the pediatric population is significantly lower than that seen in the adult population. Mutations in RAS do not contribute significantly to pediatric PTC. This experience from our institution adds to the growing body of knowledge regarding tumor genetics in pediatric PTC.

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.

NTRK fusion oncogenes in pediatric papillary thyroid carcinoma in northeast United States

BACKGROUND

An increase in thyroid cancers, predominantly papillary thyroid carcinoma (PTC), has been recently reported in children.

METHODS

The histopathology of 28 consecutive PTCs from the northeast United States was reviewed. None of the patients (ages 6-18 years; 20 females, 8 males) had significant exposure to radiation. Nucleic acid from tumors was tested for genetic abnormalities (n = 27). Negative results were reevaluated by targeted next-generation sequencing.

RESULTS

Seven of 27 PTCs (26%) had neurotrophic tyrosine kinase receptor (NTRK) fusion oncogenes (NTRK type 3/ets variant 6 [NTRK3/ETV6], n =5; NTRK3/unknown, n = 1; and NTRK type 1/translocated promoter region, nuclear basket protein [NTRK1/TPR], n = 1), including 5 tumors that measured >2 cm and 3 that diffusely involved the entire thyroid or lobe. All 7 tumors had lymphatic invasion, and 5 had vascular invasion. Six of 27 PTCs (22%) had ret proto-oncogene (RET) fusions (RET/PTC1, n = 5; RET/PTC3, n = 1); 2 tumors measured >2 cm and diffusely involved the thyroid, and 5 had lymphatic invasion, with vascular invasion in 2. Thirteen PTCs had the B-Raf proto-oncogene, serine/threonine kinase (BRAF) valine-to-glutamic acid mutation at position 600 (BRAF(V) (600E)) (13 of 27 tumors; 48%), 11 measured <2 cm, and 6 had lymphatic invasion (46%), with vascular invasion in 3. Fusion oncogene tumors, compared with BRAF(V) (600E) PTCs, were associated with large size (mean, 2.2 cm vs 1.5 cm, respectively; P = .05), solid and diffuse variants (11 of 13 vs 0 of 13 tumors, respectively; P < .001), and lymphovascular invasion (12 of 13 vs 6 of 13 tumors, respectively; P = .02); BRAF(V) (600E) PTCs were predominantly the classic variant (12 of 13 vs 1 of 13 tumors). Two tumors metastasized to the lung, and both had fusion oncogenes (NTRK1/TPR, n = 1; RET/PTC1, n = 1).

CONCLUSIONS

Fusion oncogene PTC presents with more extensive disease and aggressive pathology than BRAF(V) (600E) PTC in the pediatric population. The high prevalence of the NTRK1/NTRK3 fusion oncogene PTCs in the United States is unusual and needs further investigation.

AGK-BRAF gene fusion is a recurrent event in sporadic pediatric thyroid carcinoma

Thyroid cancer is the fastest increasing cancer worldwide in all age groups. Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer in both adults and children. PTC genomic landscape has been extensively studied in adults, but information regarding sporadic pediatric patients is lacking. Although BRAF V600E mutation is highly prevalent in adults, this mutation is uncommon in pediatric cases. As adult and pediatric PTC is a mitogen‐activated protein kinase‐driven cancer, this altered pathway might be activated by different genetic events. The aim of this study was to investigate the occurrence of AGK‐BRAF fusion gene, recently described in radiation‐exposed pediatric PTC, in a cohort of exclusively sporadic pediatric PTC. The series consisted of 30 pediatric PTC younger than 18 years of age at the time of diagnosis and 15 matched lymph node metastases (LNM). Primary tumors and matched LNM were screened for the presence of the AGK‐BRAF fusion transcript by RT‐PCR. To confirm the identity of the amplified products, randomly selected samples positive for the presence of the fusion transcripts were sequenced. Moreover, BRAF dual‐color, break‐apart probes confirmed BRAF rearrangement. Overall, the AGK‐BRAF fusion gene was detected in 10% (3/30) of primary tumors. For one of these cases, paired LNM was also available, which also shows the presence of AGK‐BRAF fusion gene. This study described, for the first time, the presence of AGK‐BRAF in sporadic pediatric PTC. Understanding the molecular events underlying pediatric PTC may improve preoperative diagnosis, allow molecular prognostication and define a therapeutic approach toward sporadic PTC patients.