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

Trends and predictors of positive surgical margins in pediatric thyroid cancer

OBJECTIVE

To understand trends in positive margin rates in pediatric thyroid cancer over time and investigate predictors of positive margins.

STUDY DESIGN AND SETTING

Retrospective analysis of deidentified National Cancer Database (NCDB) records from 2004 to 2020.

METHODS

The study cohort included pediatric patients (age 18 or younger) with thyroid cancer with available records in the NCDB. The positive margin rate was calculated by year of diagnosis. Multivariable regression was used to assess for predictors of positive margins. Survival analysis was performed stratified by margin status.

RESULTS

We identified 6240 patients who met inclusion criteria. The overall positive margin rate was 15.5 % and did not change significantly over the study period. Positive margins were independently associated with younger age, male gender, total thyroidectomy, papillary histology, and positive lymph node status on multivariable logistic regression models. Hospital volume was not a predictor of positive margin rate. Margin status did not impact overall survival.

CONCLUSION

Positive margins in pediatric thyroid cancer are more likely in younger patients, male patients, those undergoing total thyroidectomy, those with lymph node metastasis, and those with papillary thyroid carcinoma. Hospital volume is not associated with positive margin rate. Positive margins do not impact overall survival in this patient population.

Global Burden of Thyroid Cancer in Children and Adolescents, 1990-2021: Trends, Disparities, and Future Projections

BACKGROUND

Thyroid cancer is a rising concern in children and adolescents, with unique biological behaviors compared to adults. This study aimed to explore the epidemiological trends, pathological features, and regional disparities of thyroid cancer in this population using data from the Global Burden of Disease (GBD) 2021.

METHODS

Data on thyroid cancer incidence and mortality from 1990 to 2021 were extracted for individuals under 20 years old. The estimated annual percentage change (EAPC) was calculated to evaluate temporal trends. The Sociodemographic Index (SDI) was applied to assess regional variations. Future trends were projected using a Bayesian age-period-cohort model.

RESULTS

From 1990 to 2021, the global incidence of thyroid cancer in children and adolescents increased significantly, with an EAPC of 1.17%. Low-SDI regions exhibited the highest rise in incidence (EAPC: 2.19%), while high-SDI regions experienced a slight decline (EAPC: -0.69%). Mortality decreased globally (EAPC: -0.27%), with notable reductions in high- and middle-SDI regions but stable or increasing rates in low-SDI regions. Females consistently exhibited higher incidence rates across all SDI levels, while males in high-SDI regions showed higher mortality rates. Future projections suggest a steady decline in incidence and mortality rates through 2050.

CONCLUSIONS

The increasing incidence and persistent mortality disparities of thyroid cancer in children and adolescents highlight the need for targeted public health interventions. Regions with low socioeconomic development require prioritized strategies to address this growing burden. These findings provide crucial insights for early diagnosis, treatment optimization, and global health policy formulation.

Changing Clinical Presentation of Pediatric Differentiated Thyroid Cancer in Poland: A Retrospective Cohort Study Spanning 45 Years

Background: Differentiated thyroid carcinoma (DTC) in children is uncommon; clinical presentation over recent decades is incompletely characterized. Methods: This retrospective cohort study analyzed demographic and disease characteristics of consecutive juveniles with DTC treated from 1970 to 2015 at Poland's largest pediatric DTC referral center, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, who had available records. Sex, age, histopathological characteristics, and DTC stage were documented. We aimed to identify changes in these variables over time and independent risk factors for lymph node or distant metastases. Trends in these variables were assessed using the Cochran-Armitage test and Spearman correlation. Multivariable logistic regression was performed to identify risk factors associated with lymph node or distant metastases. Results: 475 of 479 patients (99.2%) were included in the analysis; roughly half were age ≥15 years, 10%, <10 years. Papillary thyroid carcinoma (PTC) represented 88% of cases and follicular thyroid carcinoma (FTC) 11%. Tumors ≤2 cm constituted 56% of cases with relevant data; those >4 cm accounted for 12%. Multifocality was observed in 37% and extrathyroidal invasion in 22%. Lymph node metastases were noted in 59% and distant metastases in 16%. Over the observation period, significant trends among new cases included: increased proportion of adolescents >15 years; increased frequency of tumors ≤2 cm, decreased multifocality rates, and increased proportion of PTC versus FTC. Extrathyroidal invasion rates remained appreciable throughout, ranging from 17 to 28% during the 5-year study subperiods after 1990. Lymph node metastases significantly increased in frequency in the central neck, remaining consistently common in lateral sites; presence of distant metastases significantly decreased. In multivariable analysis, multifocality, extrathyroidal invasion, and tumor size were independently associated with lateral lymph node metastases and multifocality, larger tumor size, and N1b metastases with distant spread. Conclusions: Our observations of a rising proportion of diagnoses in adolescence, reductions in primary tumor size, and decreased frequency of multifocality and distant metastases may reflect increased detection of patients with less aggressive DTC at earlier disease stages. Nonetheless, we found persistently substantial rates of locoregionally advanced disease features (multifocality, extrathyroidal invasion, and lymph node metastases), which multivariable analyses suggested have significant associations with lateral lymph node and/or distant metastases.

Outcomes of Differentiated Thyroid Cancer in Children and Adolescents at King Abdulaziz Medical City, Jeddah

Objective Differentiated thyroid cancer (DTC) is rare in the pediatric population, with most data from the Western world. We aimed to describe the clinical presentation, treatment intervention, histopathological characteristics, complications, follow-up, and response to treatment in 17 patients with DTC at or below the age of 20 years. Interventions This was a retrospective cohort study at King Abdulaziz Medical City, Jeddah, Saudi Arabia. We included patients aged younger than 20 years with DTC. Total or near-total thyroidectomy was performed in 82% of the patients, central and/or lateral neck dissection in 35% of cases, and radioactive iodine (RAI) ablation in 76% of cases. Results The study included 17 patients (14 females), with a median age of 16 years at the time of diagnosis. Thyroid nodules were the main complaint in 88% of the patients. Thyroid ultrasonography was the main method for the initial evaluation. Papillary cancer was the most common type of tumor, and lymph node spread was found in 82% of the patients. Moreover, 40% of the patients exhibited excellent responses to therapy, with 35% showing indeterminate results. Only 23.5% of the patients developed hypocalcemia postoperatively. Conclusions Classical papillary thyroid carcinoma was the predominant histopathological type, and most patients showed excellent responses to therapy, followed by indeterminate in most of the cases. The most common presentation was a neck nodule, signifying the role of thorough physical neck examinations. Finally, recurrence occurred in a minority of patients. However, none of these patients died.

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.

Automatic prediction of non-iodine-avid status in lung metastases for radioactive I131 treatment in differentiated thyroid cancer patients

Objectives

The growing incidence of differentiated thyroid cancer (DTC) have been linked to insulin resistance and metabolic syndrome. The imperative need for developing effective diagnostic imaging tools to predict the non-iodine-avid status of lung metastasis (LMs) in differentiated thyroid cancer (DTC) patients is underscored to prevent unnecessary radioactive iodine treatment (RAI).

Methods

Primary cohort consisted 1962 pretreated LMs of 496 consecutive DTC patients with pretreated initially diagnosed LMs who underwent chest CT and subsequent post-treatment radioiodine SPECT. After automatic lesion segmentation by SE V-Net, SE Net deep learning was trained to predict non-iodine-avid status of LMs. External validation cohort contained 123 pretreated LMs of 24 consecutive patients from other two hospitals. Stepwise validation was further performed according to the nodule's largest diameter.

Results

The SE-Net deep learning network yielded area under the receiver operating characteristic curve (AUC) values of 0.879 (95% confidence interval: 0.852-0.906) and 0.713 (95% confidence interval: 0.613-0.813) for internal and external validation. With the LM diameter decreasing from ≥10mm to ≤4mm, the AUCs remained relatively stable, for smallest nodules (≤4mm), the model yielded an AUC of 0.783. Decision curve analysis showed that most patients benefited using deep learning to decide radioactive I131 treatment.

Conclusion

This study presents a noninvasive, less radioactive and fully automatic approach that can facilitate suitable DTC patient selection for RAI therapy of LMs. Further prospective multicenter studies with larger study cohorts and related metabolic factors should address the possibility of comprehensive clinical transformation.

The significance and prognostic value of multifocal papillary thyroid carcinoma in children and adolescents

INTRODUCTION

The prognostic value of multifocality in paediatric papillary thyroid carcinoma (PTC) patients remains a subject of debate. This study aimed to explore the clinical significance and prognostic value of multifocality in children and adolescents with PTC.

METHODS

This study retrospectively analysed the clinicopathological characteristics and postoperative follow-up data of 338 PTC patients aged ≤ 20 years from May 2012 to July 2022. The clinical and pathological characteristics of 205 patients with unifocal lesions and 133 patients with multifocal lesions were compared. A logistic regression model evaluated the relationship between multifocal lesions and disease recurrence/persistence in children and adolescents with PTC. Based on the median follow-up time of children with multifocal PTC, 114 patients with multifocal PTC older than 20 years were added, and the clinicopathological characteristics were compared between the 133. paediatric/adolescent patients and 114 adult patients with multifocal PTC.

RESULTS

Among the paediatric and adolescent patients, over a median follow-up time of 49 months, 133 had multifocal disease and 205 had unifocal disease. Multifocal PTC patients exhibited stronger invasiveness in the form of extrathyroidal extension, tumour diameter, lymph node metastasis, and distant metastasis. Multifocality (OR 2.68; p = 0.017), lateral lymph node metastasis (OR 2.85; p = 0.036), and distant metastasis (OR 4.28; p = 0.010) were identified as independent predictive factors for the recurrence/persistence of disease. Comparing the paediatric/adolescent vs. adult multifocal patients, the former demonstrated greater tumour invasiveness. Lateral lymph node metastasis (OR 6.36; P = 0.012) and distant metastasis (OR 3.70; P = 0.027) were independent predictive factors for recurrence/persistence of disease in multifocal patients, while age was not (OR 0.95; P = 0.455).

CONCLUSION

Tumour multifocality independently predicts persistent/recurrent disease in paediatric and adolescent PTC patients.

Impact of lateral cervical lymph node metastasis on lung metastasis in pediatric thyroid cancer: A correlation study

BACKGROUND

Thyroid cancer (TC) frequently manifests with lung metastases in the pediatric population, occurring at a significant rate of 30 %. This study aims to evaluate the impact of regional patterns of cervical lymph node metastases on lung metastases in pediatric TC.

METHODS

Retrospective analysis was conducted on data from pediatric TC patients spanning the years 2000 to 2018. We compared the rates of lymph node metastasis (LNR), the number of lymph node metastases, and the number of dissected lymph nodes in the central and lateral cervical regions between patients with and without lung metastases. Statistical methods were employed to adjust for confounders during hypothesis testing.

RESULTS

A total of 227 pediatric patients, with a median age of 15.12 ± 2.84 years, were included in the study. Of these, 202 (89 %) exhibited LN metastasis, with 40(17.62 %) patients presenting with lung metastasis. Patients with lung metastases were found to be younger (13.40 ± 3.11 vs. 15.50 ± 2.64, p < 0.001), had larger primary tumor diameters (3.49 ± 1.98 vs. 2.31 ± 1.45, p < 0.001), and exhibited a higher number of lymph node metastases (23.40 ± 10.75 vs. 14.65 ± 13.16, p < 0.001). Notably, in patients with LN metastases, the presence of >12 lateral cervical lymph node metastases emerged as a significant risk factor for lung metastases. Among children with metachronous lung metastases, the median time to detection of lung metastases was 43 (12-132) months, and they appeared to receive a greater proportion of radioactive iodine (RAI) treatment compared to those with synchronous lung metastases.

CONCLUSION

Lateral cervical lymph node metastasis independently predicts the likelihood of lung metastases in pediatric TC. Furthermore, our findings emphasize the importance of thorough examination of the lungs during follow-up, particularly when the number of metastatic lateral cervical lymph nodes exceeds 12.

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.

Emerging roles of circular RNAs in the invasion and metastasis of head and neck cancer: Possible functions and mechanisms

Head and neck cancer (HNC) is the seventh most prevalent malignancy worldwide in 2020. Cancer metastasis is the main cause of poor prognosis in HNC patients. Recently, circular RNAs (circRNAs), initially thought to have no biological function, are attracting increasing attention, and their crucial roles in mediating HNC metastasis are being extensively investigated. Existing studies have shown that circRNAs primarily function through miRNA sponges, transcriptional regulation, interacting with RNA-binding proteins (RBPs) and as translation templates. Among these functions, the function of miRNA sponge is the most prominent. In this review, we summarized the reported circRNAs involved in HNC metastasis, aiming to elucidate the regulatory relationship between circRNAs and HNC metastasis. Furthermore, we summarized the latest advances in the epidemiological information of HNC metastasis and the tumor metastasis theories, the biogenesis, characterization and functional mechanisms of circRNAs, and their potential clinical applications. Although the research on circRNAs is still in its infancy, circRNAs are expected to serve as prognostic markers and effective therapeutic targets to inhibit HNC metastasis and significantly improve the prognosis of HNC patients.

Differentiated Thyroid Cancers in Young Adults Versus Children: Clinical Characteristics and 10-year Follow-up Outcomes

BACKGROUND

Differentiated thyroid cancer (DTC) in young adults has been steadily rising in incidence over the decades. However, data on long-term outcomes in this specific cohort remain limited. In this study, we intended to evaluate young adults with DTC with regard to their clinical characteristics and treatment outcomes and compare the same vis-à-vis pediatric patients with DTC.

METHODS

Data of pediatric (≤18 years) and young adult (19-39 years) patients with DTC, from 1971 to 2016, were sequentially extracted and analyzed for clinical characteristics, treatment responses, rates of recurrent/persistent disease, and disease-free survival (DFS).

RESULTS

A total of 1803 patients with DTC were included (pediatric cohort: n = 176; young adult cohort: n = 1627). Pediatric patients with DTC had more frequent adverse baseline features including extrathyroidal extension (P = .040), nodal and distant metastases, and American Thyroid Association high-risk disease (P < .001 each). At 2 years posttreatment, young adult patients with DTC had significantly lower incomplete responses compared with pediatric patients with DTC (223/1627; 13.7% vs 94/176, 53.4%, respectively; P < .001). Over a median follow-up of 10.7 years, 120/1627 (7.4%) young adult patients with DTC had recurrent/persistent disease vs 23/176 (13.1%) pediatric patients with DTC (P = .012). The 10-year DFS probability was 93.6% for the young adult patients with DTC vs 88.7% for the pediatric patients with DTC (P = .007). American Thyroid Association high-risk disease and incomplete response at 2 years were independent predictors of significantly worse DFS in the young adult cohort (P < .001 each).

CONCLUSIONS

Young adult DTCs behave less aggressively compared with their pediatric counterparts with excellent long-term outcomes. Appropriate initial and dynamic risk stratification can help optimize treatment decisions and follow-up strategies.

Is Multifocality a Predictor of Poor Outcome in Childhood and Adolescent Papillary Thyroid Carcinoma?

CONTEXT

Total thyroidectomy in pediatric papillary thyroid carcinoma (PTC) is recommended in national guidelines because of the high incidence of multifocal disease (MFD).

OBJECTIVE

To determine the incidence of MFD in childhood and adolescent vs adult PTC and whether MFD is a predictor for poorer outcomes in childhood and adolescent PTC.

METHODS

We conducted an institutional review board-approved review of patients with PTC undergoing surgery (1986-2021) at Memorial Sloan Kettering Cancer Center. Clinical and pathological characteristics in patients with unifocal disease (UFD) and MFD were compared using Pearson's χ2 test. Survival outcomes were analyzed using the Kaplan-Meier method and log-rank test. Multivariate analysis assessed the impact of MFD on outcome.

RESULTS

MFD was less common in childhood and adolescent patients with PTC (45%; 127/283) than in adults (54%; 3023/5564; P = .002). Childhood and adolescent patients with UFD and MFD had similar tumor stage and PTC subtype at presentation, with no significant difference in histopathologic features. Median follow-up was 68 months. There was no significant difference in 5-year recurrence-free probability and overall survival was 100% in both groups. There was no significant difference in 5-year contralateral lobe PTC-free probability between patients with UFD and MFD treated with lobectomy. Multivariate analysis showed MFD was not a predictor for recurrence.

CONCLUSION

MFD was less common in childhood and adolescent patients with PTC than adults and was not a predictor of poor outcome on multivariate analysis, with excellent long-term outcomes in all patients with PTC. MFD does not appear to warrant completion thyroidectomy in childhood and adolescent patients selected for lobectomy.

Long-term prognostic analysis of children and adolescents with differentiated thyroid carcinoma based on therapeutic response to initial radioiodine therapy

Background

The clinical features and prognosis of children and adolescents with differentiated thyroid carcinoma (caDTC) are different from that of adults. Postoperative radioiodine therapy (RIT) was recommended for some intermediate and high risk caDTC patients. The objective of this study was to evaluate the long-term prognosis of pediatric caDTC patients with different responses to initial RIT and to explore the related influencing factors.

Methods

All subjects were assigned to no clinical evidence of disease (NED) group, biochemical persistent disease (BPD) group, or structural/functional persistent disease (S/FPD) group based on the therapeutic response to initial RIT. Then, disease status was evaluated in all three groups at the last follow-up using ATA guidelines. Meanwhile, disease-free survival (DFS) for NED group and the progression-free survival (PFS) for the BPD and S/FPD groups were also assessed.

Results

117 subjects were divided into NED group (n=29), BPD group (n=48) and S/FPD group (n=34) after initial RIT. At the last follow-up, excellent response (ER), indeterminate response (IDR), biochemically incomplete response (BIR) and structurally incomplete response (SIR) rates were 93.10%, 6.90%, 0% and 0% in NED group; 29.17%, 25.00%, 43.75% and 2.08% in BPD group; and 11.77%, 2.94%, 0%, and 85.29% in S/FPD group. The 5-year DFS rate in NED group was 95.5%. The 5-year PFS rates in BPD and S/FPD groups were 79.2% and 48.6%, respectively. For children with structural or functional lesions, longer PFS were found in male children with 131I-avid lesions, and post-operative stimulated serum thyroglobulin (sti-Tg) < 149.80 ng/ml.

Conclusion

The response to initial RIT could be helpful for defining subsequent treatment and follow-up strategies for caDTC patients. Post-operative sti-Tg and 131I-avidity of lesions are correlated with PFS.

Radioactive Iodine-Refractory Pulmonary Metastases of Papillary Thyroid Cancer in Children, Adolescents, and Young Adults

CONTEXT

Few studies have explored radioactive iodine-refractory (RAIR) disease in children, adolescents, and young adults with papillary thyroid cancer (CAYA-PTC).

OBJECTIVE

This study systematically investigated the clinicopathologic characteristics and prognosis of CAYA-PTC with RAIR disease.

METHODS

Sixty-five patients with PTC aged ≤20 years were enrolled in this study, and all patients were confirmed to have pulmonary metastases. Clinicopathologic profiles were compared between the radioactive iodine-avid (RAIA) and RAIR groups. Univariate and multivariate regression analyses were performed to identify risk factors for RAIR status and progressive disease (PD). Gene alterations were detected in 17 patients.

RESULTS

Overall, 20 patients were included in the RAIR group, accounting for 30.8% (20/65) of all patients. No significant difference in pathologic characteristics was observed between patients aged <15 years and patients aged 15-20 years, but younger patients were more likely to develop RAIR disease (hazard ratio [HR] 3.500, 95% CI 1.134-10.803, P = .023). RET fusions were the most common genetic alterations in CAYA-PTC, but an association with RAIR disease was not detected (P = .210). RAIR disease (HR 10.008, 95% CI 2.427-41.268, P = .001) was identified as an independent predictor of PD. The Kaplan-Meier curve revealed a lower progression-free survival (PFS) and disease-specific survival (DSS) rate in the RAIR group than in the RAIA group (P < .001 and P = .039). Likewise, RAIR disease was a risk factor for unfavorable PFS in patients aged <15 years (P < .001).

CONCLUSION

RAIR disease occurs in one-third of CAYA-PTC with pulmonary metastases. Younger patients (aged < 15 years) are more susceptible to RAIR status, which leads to unfavorable PFS and DSS.

The impact of the initial operation of PTC in children on recurrence: 9-year experience in a single center

PURPOSE

To summarize the treatment experience of single-center children with PTC and to explore the influence of initial surgery on the recurrence/metastasis of papillary thyroid carcinoma (PTC) in children.

METHODS

A retrospective analysis of PTC case data of children (≤ 18 years old) who were admitted to and received surgical treatment in the First Affiliated Hospital of Kunming Medical University from January 2012 to December 2020.

RESULTS

A total of 64 children with PTC were included, including 45 cases (70.31%) with a single lesion, and 19 cases (29.69%) with multiple lesions (≥ 2 lesions). Fifteen patients relapsed. Univariate analysis found that gender, thyroidectomy scope, central lymph node dissection, and lateral lymph node dissection were risk factors affecting reoperation; multi-factor analysis showed that central lymph node dissection was an independent risk factor affecting reoperation. According to Kaplan-Meier analysis, central lymph node dissection, total thyroidectomy (TT), lobectomy (LT), and disease-free survival (DFS) were statistically significant (p = 0.000, p = 0.000).

CONCLUSION

At the time of diagnosis of PTC in children, the rate of lymph node metastasis in the central and lateral cervical regions is high. The vast majority of children with PTC should be treated with TT, and LT is chosen for a small number of patients. CND should be routinely lined.

Surgical treatment of pediatric and adolescent papillary thyroid cancer: a retrospective study of 54 patients in a single center

OBJECTIVE

In 2015, American Thyroid Association (ATA) issued the first version of Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer. The purpose of this study is to evaluate whether the ATA pediatric guidelines recommended surgical approach for the patient can be applied to surgical treatment of pediatric PTC in China.

METHOD

From April 2012 to December 2020, clinical data of children (≤18 years) with PTC consecutively admitted and treated with initial surgery in the study's department were retrospectively reviewed.

RESULTS

The authors found that the central lymph node metastasis (CLNM) rate was significantly higher than that in the lateral neck (83.33 % vs 62.96%, χ² = 5.704, p = 0.017) .The lymph node metastasis rate was significantly lower in cN1b (-) patients than in cN1b (+) patient (55.00% vs 100.00%, χ² = 15.263, p = 0.000); Meanwhile, the CLNM and LLNM rates of ipsilateral were significantly higher than those of contralateral central compartment (83.33༅vs 57.41༅%, χ² = 8.704, p = 0.003). Lymph nodes of 51 lateral lymph node dissection (LND) were analyzed, which revealed the LNM rate of cN1b (-) patients was significantly lower than that of cN1b (+) patients (55.00% vs. 100.00%, χ² = 15.263, p = 0.000).

CONCLUSION

Children and adolescents have a higher rate of lymph node metastasis at the time of diagnosis. TT should be conducted in the majority of children with PTC. CND should be routinely performed; therapeutic LND is recommended for children with cN1b (+).

Aggressiveness of Differentiated Thyroid Carcinoma in Pediatric Patients Younger Than 16 years: A Propensity Score-Matched Analysis

Background

The biological behavior of thyroid cancer in children has been known to be different from that in adults. We sought to understand the differences between DTC presentation in pediatric (<16 years) and adult patients, to guide better prognosis and clinical treatments.

Methods

This retrospective study included 48 pediatric patients younger than 16 years who underwent initial thyroid surgery and were diagnosed with DTC between January 1992 and December 2014 at Yonsei University in Seoul, South Korea. For a 1:4 propensity score-matched analysis, adult patients with matched sex and cancer size were included.

Results

The mean age was 12.54 ± 3.01 years. Total thyroidectomy (70.8%) without lateral lymph node dissection (47.9%) was the most commonly performed surgery. Central (73.9%) and lateral neck node metastases (62.5%) were common; distant metastasis was observed in 2 (4.2%) patients and recurrence occurred in 11 (22.9%). In propensity score-matched analysis, central lymph node metastasis and lateral neck node metastasis were significantly more frequent in pediatric patients. Symptoms were more common in the pediatric group than in the adult group (p < 0.001). In stratified cox regression, pediatric patients were more likely to experience recurrence [HR 5.339 (1.239–23.007)]. In stratified log-rank analysis, recurrence-free survival was significantly different between the adult and pediatric groups (p = 0.0209).

Conclusion

DTC in the pediatric group revealed more aggressive patterns than in the adult group with the same cancer size. Central lymph node metastasis and lateral neck node metastasis were more frequent. Stratified log-rank analysis revealed that recurrence was significantly higher in pediatric patients than in matched adult patients.

Age, American Thyroid Association Risk Group, and Response to Therapy Are Prognostic Factors in Children With Differentiated Thyroid Cancer

CONTEXT

Against the background of increasing incidence, pediatric differentiated thyroid carcinoma (DTC) frequently presents with advanced disease and high recurrence rates while prognosis remains excellent.

BACKGROUND

We investigated the use of a pediatric classification and an adult response to therapy risk stratification for pediatric DTC patients and their implications for adaptation of treatment and follow-up.

METHODS

Data from patients aged <18 years with a diagnosis of primary DTC, registered with the German Pediatric Oncology Hematology-Malignant Endocrine Tumor registry since 1995, were analyzed. For risk prediction, patients were retrospectively assigned to the American Thyroid Association (ATA) risk groups and evaluated for response to therapy.

RESULTS

By October 2019, 354 patients with DTC had been reported (median age at diagnosis 13.7 years, range 3.6-17.9) with lymph node and distant metastases in 74.3% and 24.5%. Mean follow-up was 4.1 years (range 0-20.6). Ten-year overall and event-free survival (EFS) rates were 98.9% and 78.1%. EFS was impaired for patients with lymph node and distant metastases (P < .001), positive postoperative thyroglobulin (P = .006), incomplete resection (P = .002), sequential surgeries to achieve total thyroidectomy (P = .042), invasion of capsule (P < .001) and lymph vessels (P = .005), infiltration of surrounding soft tissues (P < .001), tumor multifocality (P < .001), ATA intermediate- and high-risk group (P < .001), and age <10 years (P < .001). Multivariate analysis revealed age <10 years at diagnosis, ATA high-risk level, and poor response to therapy as significant negative prognostic factors for EFS.

CONCLUSION

Age, ATA risk group, and response to therapy emerged as significant prognostic factors for EFS in pediatric patients with DTC, requiring risk-adapted individualized therapy and follow-up.

Retrospective analysis of clinical characteristics and risk factors of differentiated thyroid cancer in children

BACKGROUND

The incidence rate of children with thyroid cancer has an increasing trend. This study aimed to investigate the clinical characteristics and therapeutic approaches of differentiated thyroid cancer (DTC) in Chinese children.

MATERIALS AND METHODS

From January 1998 to March 2022, 52 cases undergoing surgical resection in Xinhua Hospital affiliated to Shanghai Jiao Tong University were divided by age (≤ 7 years old: n = 14 and 8-13 years old, n = 38). Treatment methods and clinical features were analyzed to evaluate prognostic factors for oncological outcomes.

RESULTS

Among the 52 cases, the proportion of local invasion in the pre-school group was found to be higher than that in the school-age group (p = 0.01). T stage was significantly different between the two groups (p ≤ 0.05); the proportion of T_1-2 was higher in the school-age group (32 cases, 84.2%), while the proportion of T₄ was higher in the pre-school group (6 cases, 42.8%) relatively. The postoperative complication rate was dramatically higher in pre-school children (p ≤ 0.05). Additionally, the total thyroidectomy rate in the non-recurrent group was slightly higher than that in the recurrent group (p ≤ 0.05). Over half of the recurrent cases had low T stage and low ATA (American Thyroid Association) risk levels at initial diagnosis (78.3 and 51.4%).

CONCLUSION

The local invasion, tumor stage, and recurrent laryngeal nerve (RLN) injury rates of the pre-school group were higher than that of the school-age group, where young age served as a potential hazard in DTC children. Hence, surgeons should emphasize high-risk features and optimize individualized surgical procedures for DTC children.

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.

Considerations for Balance Between Fundamental Treatment and Improvement of Quality of Life of Pediatric Thyroid Cancer Patient: Comparative Analysis With Adult Using Propensity Score Matching

BACKGROUND

Thyroid cancer is very rarely observed in children and adolescents, some reports have shown that the long-term outcome of treatment is better than that of adult patients, despite many treatment failures or a high risk of recurrence. This study considers whether it is appropriate to treat pediatric thyroid cancer patients aggressively, as per the ATA guidelines, based on the balance between the fundamental treatment of thyroid cancer and the improvement of the long-term quality of life of pediatric patients.

METHODS

A total of 1,950 patients were recruited, including 83 pediatric and 1,867 adult patients, who were diagnosed with thyroid cancer and underwent surgical treatment at one of our medical center hospitals from March 2000 to January 2020.

RESULTS

Sixty-nine pairs of pediatric and adult patients were matched in a ratio of 1:2 through propensity score matching. When compared through propensity score matching, there was no significant difference in prognosis such as recurrence rate in children and adults at the same stage.

CONCLUSION

This study showed that the prognosis of both pediatric and adult patients who underwent a total thyroidectomy and lobectomy was not significantly different. If more pediatric patients can be considered for the less-aggressive lobectomy than a total thyroidectomy through various preoperative examinations and meticulous pre-diagnosis, it may be possible to properly determine the balance between improving long-term quality of life while providing fundamental cancer treatment.

Prevalence and Risk Factors for Multifocality in Pediatric Thyroid Cancer

Importance

Current guidelines recommend total thyroidectomy for the majority of pediatric thyroid cancer owing to an increased prevalence of multifocality. However, there is a paucity of information on the exact prevalence and risk factors for multifocal disease-knowledge that is critical to improving pediatric thyroid cancer management and outcomes.

Objective

To determine the prevalence and risk factors for multifocal disease in pediatric patients with papillary thyroid carcinoma (PTC).

Design, Setting, and Participants

This multicenter retrospective cohort study included patients 18 years or younger who underwent thyroidectomy for PTC from 2010 to 2020 at 3 tertiary pediatric hospitals and 2 tertiary adult and pediatric hospitals in the US.

Main Outcomes and Measures

Demographic and clinical variables, including age, family history of thyroid cancer, autoimmune thyroiditis, prior radiation exposure, cancer predisposition syndrome, tumor size, tumor and nodal stage, PTC pathologic variant, and preoperative imaging, were assessed for association with presence of any multifocal, unilateral multifocal, and bilateral multifocal disease using multiple logistic regression analyses. Least absolute shrinkage and selection operator analysis was performed to develop a model of variables that may predict multifocal disease.

Results

Of 212 patients, the mean age was 14.1 years, with 23 patients 10 years or younger; 173 (82%) patients were female. Any multifocal disease was present in 98 (46%) patients, with bilateral multifocal disease in 73 (34%). Bilateral multifocal disease was more accurately predicted on preoperative imaging than unilateral multifocal disease (48 of 73 [66%] patients vs 9 of 25 [36%] patients). Being 10 years or younger, T3 tumor stage, and N1b nodal stage were identified as predictors for multifocal and bilateral multifocal disease.

Conclusions and Relevance

This large, multicenter cohort study demonstrated a high prevalence of multifocal disease in pediatric patients with PTC. Additionally, several potential predictors of multifocal disease, including age and advanced T and N stages, were identified. These risk factors and the high prevalence of multifocal disease should be considered when weighing the risks and benefits of surgical management options in pediatric patients with PTC.

Clinical Assessment of Pediatric Patients with Differentiated Thyroid Carcinoma: A 30-Year Experience at a Single Institution

Background

Thyroidectomy is the typical treatment for pediatric thyroid carcinoma; total thyroidectomy is commonly performed. We aimed to report our experience at a single tertiary institution and to evaluate the risk factors for recurrence, especially based on surgical extent, in pediatric patients with differentiated thyroid carcinoma (DTC).

Methods

A data of 94 pediatric patients who underwent thyroid surgery for DTC from January 1982 to December 2012 at Yonsei University Hospital (Seoul, Korea) were reviewed. The clinicopathologic features and surgical outcomes were retrospectively analyzed through complete chart reviews.

Results

The mean age was 16.6 ± 3.0 (range, 5–19) years. Fourteen patients had recurrence. Tumor size >2 cm (hazard ratio [HR], 14.241; p = 0.011) and positive lymph nodes (HR, 1.056; p = 0.039) were significant risk factors for disease-free survival (DFS) in multivariate analysis. In Kaplan–Meier analysis, a statistically significant difference was noted in the DFS according to tumor size 2 cm (p < 0.001). However, the DFS was not significantly different between the bilateral total thyroidectomy (BTT) and less than BTT groups (p = 0.215).

Conclusions

BTT remains the treatment of choice in pediatric patients with DTC. Lobectomy may be considered for patients with limited disease, including those with tumor size <2 cm, no suspicious lymph nodes, intrathyroidal lesion, and no multifocal disease.

Lung Metastasis in Children with Differentiated Thyroid Cancer: Factors Associated with Diagnosis and Outcomes of Therapy

Background: Lung metastasis from differentiated thyroid cancer (DTC) in children and young adults (CAYA) is estimated at 25%, which is 3-4 times higher than in adults. Lung metastases may respond to radioactive iodine (RAI) therapy and overall survival is excellent. Associations with lung metastasis include lateral lymph node (LN) disease although CAYA data are limited. We investigated factors associated with lung metastasis in children and adolescents and described their presentation and outcome. Methods: A retrospective review of medical records from 1998 to 2017 in patients aged <18 years treated at a tertiary pediatric center was carried out. Data on age, clinical features at diagnosis, histology, biochemistry, imaging, RAI therapy, and outcome were collected. Results: Patients treated for DTC totaled 98 and 19 of 98 (19%) patients had lung metastasis; 17 of 19 (89%) patients were identified within 6 months from thyroidectomy. Patients with lung metastasis were younger (p < 0.001)-40% <13 years old had lung metastasis-and had a larger primary tumor diameter (p = 0.01). Absence of LN disease had negative predictive values ≥90% (p < 0.02). Patients with lung metastasis had a higher postoperative thyrotropin-stimulated thyroglobulin (Tg) (p < 0.001), ≥2 ng/mL in 10 of 11 (91%) patients, and 100% had an elevated preoperative Tg (>60 ng/mL). Post-therapy whole body scan (WBS) identified most metastasis (13 of 17 patients), which were mostly diffuse (11 of 19 patients). Discordant findings were found between WBS and computed tomography (CT) at diagnosis (2 patients), WBS and CT during surveillance (3 patients), and diagnostic and post-therapy WBS (2 patients). Final outcome was "excellent" in 3 of 19 (16%) patients, "biochemically persistent" in 1 of 19 (5%) patients, "structurally persistent" in 13 of 19 (68%) patients-including 1 death-and indeterminate in 2 of 19 (11%) patients. Postoperative Tg correlated with response to therapy. Lung metastasis pattern and RAI cumulative activity were not predictive of response to therapy. Conclusions: Lung metastases are mostly observed at diagnosis of DTC and higher suspicion should be maintained in CAYA who are younger, have LN disease, and have elevated postoperative Tg. Preoperative Tg shows promise as another predictive marker, but limited sample size precludes generalization. "Excellent" response to therapy is uncommon-multiple RAI courses do not necessarily improve outcome-response appears unrelated to RAI activity or metastasis pattern.

Distant Metastasis in Pediatric and Adolescent Differentiated Thyroid Cancer: Clinical Outcomes and Risk Factor Analyses

CONTEXT

The specific characteristics of pediatric and adolescent differentiated thyroid cancer (DTC) is the more frequent occurrence of distant metastasis (DM) compared with adult DTC.

OBJECTIVE

To investigate the clinical outcomes of DM in this population and analyze risk factors related to DM.

DESIGN, SETTING, AND PARTICIPANTS

Medical records of 171 patients with DTC < 19 years old, who underwent initial surgery between 1979 and 2014 were retrospectively reviewed.

MAIN OUTCOME MEASURE

Clinical responses to radioiodine (RAI) therapy evaluated by the American Thyroid Association (ATA) guidelines for adult DTC and Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Risk factors related to distant-metastasis-free survival (DMFS).

RESULTS

DM was observed in 29 patients, and all were lung metastases. The pattern of lung metastasis was classified into 3 categories: macronodular, micronodular, and no apparent nodule (detected only by RAI scintigraphy). Patients with excellent responses according to the ATA guideline criteria or complete remission of the RECIST criteria were most frequently observed in those with no apparent nodule. Significant factors related to DMFS were sex, clinical lymph node metastasis (LNM), extrathyroidal extension, and number of LNM. Subjects were divided into 3 groups according to the number of risk factors: low risk (no risk factors); intermediate risk (1 risk factor); and high risk (≥2 risk factors). Twenty-year DMFS rates in the low-, intermediate-, and high-risk groups were 99.0%, 71.7%, and 28.6%, respectively.

CONCLUSION

To achieve the full efficacy of RAI therapy, early diagnosis of DM before apparent metastases appear is desirable. The selective approach would be preferable for pediatric and adolescent DTC.

Genetic Landscape of Papillary Thyroid Carcinoma and Nuclear Architecture: An Overview Comparing Pediatric and Adult Populations

Thyroid cancer is a rare malignancy in the pediatric population that is highly associated with disease aggressiveness and advanced disease stages when compared to adult population. The biological and molecular features underlying pediatric and adult thyroid cancer pathogenesis could be responsible for differences in the clinical presentation and prognosis. Despite this, the clinical assessment and treatments used in pediatric thyroid cancer are the same as those implemented for adults and specific personalized target treatments are not used in clinical practice. In this review, we focus on papillary thyroid carcinoma (PTC), which represents 80-90% of all differentiated thyroid carcinomas. PTC has a high rate of gene fusions and mutations, which can influence the histologic subtypes in both children and adults. This review also highlights telomere-related genomic instability and changes in nuclear organization as novel biomarkers for thyroid cancers.

Genetic Alterations in Pediatric Thyroid Cancer Using a Comprehensive Childhood Cancer Gene Panel

CONTEXT

Pediatric differentiated thyroid cancer (DTC) differs from adult DTC in its underlying genetics and clinicopathological features. In this report, we studied these aspects in 48 cases of pediatric DTC.

PATIENTS AND METHODS

We used the comprehensive Oncomine Childhood Cancer Gene panel on Ion Torrent next-generation sequencing platform. We included 48 patients (37 girls and 11 boys) with pediatric DTC (median age 17 years; range, 5-18 years) and studied the association between these genetic alterations and the clinicopathological features and outcome.

RESULTS

Of 48 tumors, 33 (69%) had somatic genetic alterations that were mutually exclusive except in one tumor. BRAFV600E and RET-PTC1 were the most common, occurring in 9 different tumors (19%) each. RET-PTC3 and ETV6-NTRK3 were the next most common, with each occurring in 4 different tumors (8%). Other genetic alterations including EML4-NTRK1, EML4-ALK, NRAS, KRAS, PTEN, and CREBBP occurred once each. There were no differences between those who had mutations and those without mutations with respect to age, sex, tumor multifocality, extrathyroidal extension, vascular invasion, lymph node or distant metastasis, and American Thyroid Association response to therapy status at the last follow-up visits. Similarly, none of these factors was different between those with fusion genes vs single-point mutations vs no mutations.

CONCLUSIONS

In pediatric DTC, fusion genes are more common than single-point mutations. The most common genetic alterations are RET-PTC1, BRAFV600E, RET-PTC3, and ETV6-NTRK3. Other alterations occur rarely. Genetic alterations do not correlate with the clinicopathological features or the outcome.

Hsa_circRNA_102002 facilitates metastasis of papillary thyroid cancer through regulating miR-488-3p/HAS2 axis

As important modulators in various physiological processes, circular RNAs (circRNAs) have been increasingly demonstrated in tumors, including papillary thyroid cancer (PTC). Hsa_circRNA_102002 (circ_102002) is a circRNA derived from alternative splicing of ubiquitin-specific peptidase 22 (USP22) transcript, the role of which needs further investigation. Our results suggested the upregulation of circ_102002 in PTC tissues and cells, and its promoting effects on epithelial–mesenchymal transition (EMT) and cell migration. Mechanism studies showed that circ_102002 could sponge microRNA-488-3p (miR-488-3p) and downregulate its expression. The target relationship between miR-488-3p and hyaluronic acid synthetase 2 (HAS2) in PTC was systematically studied. In addition, our results showed that HAS2 overexpression could restore the inhibited cell EMT and migration. Moreover, the inhibitory effect of downregulation of circ_102002 on PTC growth was evaluated in a mouse xenograft model, which involved miR-488-3p and HAS2 regulation. These findings about the signal axis of circ_102002/miR-488-3p/HAS2 may further elucidate the PTC pathogenesis and improve clinical treatment.

Performance of the American Thyroid Association Risk Classification in a Single Center Cohort of Pediatric Patients with Differentiated Thyroid Cancer: A Retrospective Study

Introduction

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy in children. Retrospective studies show conflicting results regarding predictors of persistent and recurrent disease after initial therapy. In 2015, the American Thyroid Association (ATA) proposed a clinical classification system to identify pediatric thyroid cancer patients at risk for persistent/recurrent disease.

Material and Methods

We retrospectively included all patients in our registry diagnosed with papillary DTC at ≤ 18 years of age. We analyzed the prognostic performance of the ATA classification and other risk factors for predicting response to initial treatment and final outcome in pediatric DTC.

Results

We included 41 patients, 34 females and 7 males, diagnosed with papillary DTC at a mean (SD) age of 16.2 (1.8) years. Based on the ATA pediatric risk classification, patients were categorized as low (61%), intermediate (10%), or high risk (29%). The median follow-up period was 7.3 (1-41) years. After initial treatment, disease free status was achieved in 92%, 50%, and 42% of the low, intermediate, and high risk groups, respectively (P <0.01). At the last visit, persistent disease was present in 12%, 25%, and 33% (P=0.27). Assessing other risk factors, only the presence of distant metastases at diagnosis resulted in increased presence of persistent disease at last follow-up (P=0.03).

Conclusion

This study supports the clinical relevance of the ATA risk classification for predicting the response to initial treatment. There was no clear prediction of long-term outcome, but this may be due to limited power caused by the small number of patients.

DIFFERENTIATED THYROID CANCER IN PEDIATRIC POPULATION (≤18 YEARS): POSTOPERATIVE TREATMENT WITH RADIOACTIVE IODINE (I-131)

The aim is to present data on the treatment and follow-up in a cohort of patients with pediatric thyroid cancer who underwent total thyroidectomy and received postoperative radioactive iodine (I-131) therapy. The study was conducted in a tertiary high-volume thyroid center, in pediatric patients with differentiated thyroid cancer who were consecutively treated during the 1965-2015 period. A total of 45 patients aged ≤18 years having undergone total thyroidectomy with or without selective neck dissection were included in the study. Decision on postoperative I-131 ablation was based on tumor characteristics, postoperative thyroglobulin level, preablative whole body scintigraphy, and/or neck ultrasound. Median age at diagnosis was 15 years. The presence of cervical lymph node metastases was significantly associated with papillary thyroid cancer, larger tumor size, involvement of two thyroid lobes, and multifocal disease. The presence of distant metastases was significantly associated with larger tumor size. None of the patients died during follow-up period, and the 5-year and 10-year overall survival rates were 100%. The 5-year and 10-year progression-free survival (PFS) rates were 87% and 73%, respectively. Male gender (p=0.046), age ≤15 years (p=0.029) and tumor size >15 mm (p=0.042) were significantly associated with inferior PFS. A significant positive trend of increase in the number of newly diagnosed patients was observed over time (p=0.011). Clinical management of pediatric thyroid cancer is challenging, especially in the light of increasing incidence in this population. Male patients younger than 15 years and with tumors of more than 15 mm in size require additional caution due to lower PFS observed.

Lung Metastasis in Pediatric Thyroid Cancer: Radiological Pattern, Molecular Genetics, Response to Therapy, and Outcome

CONTEXT

Lung metastases are common in pediatric thyroid cancer (TC). We present an analysis of a series of lung metastases in pediatric TC.

PATIENTS AND METHODS

Data from 20 patients (16 females, 4 males; median age, 14.5 years; range 10 to 18 years) were analyzed. The tumors included differentiated TC in 19 patients and poorly differentiated TC in 1 patient.

RESULTS

Lung metastasis presented with three distinct radiological patterns: lung uptake on diagnostic radioactive iodine whole body scan (DxWBS) only in 3 patients (15%); lung uptake on DxWBS and CT scan as micrometastases (≤1 cm) in 16 patients (80%); and lung uptake on DxWBS and CT scan as macrometastases (>1 cm) in 1 patient (5%). Iodine-131 therapies were administered to all patients (median, three; range one to eight) with a median cumulative administered activity of 317.5 mCi (range, 109 to 682 mCi). None of the patients achieved a complete response but the biochemical response was substantial. During a median follow-up period of 8.2 years (range, 0.75 to 16.3 years), 1 patient (5%) died, 1 patient (5%) had a biochemically incomplete response, 2 patients (10%) had an indeterminate response, 1 patient (5%) had progressive structural disease, and 14 patients (70%) had stable structural disease. Mutational testing of 10 of 20 tumors revealed only two PIK3CA mutations in a single tumor.

CONCLUSIONS

Lung metastases are common in pediatric TC and present most frequently with bilateral radioiodine-avid micrometastases. Known single point mutations in adult TC are rare in pediatric TC. The biochemical response to iodine-131 can be substantial but resolution of structural abnormalities is rare.

Management outcomes of pediatric and adolescent papillary thyroid cancers with a brief review of literature

Background

Papillary carcinoma of thyroid (PTC) is a rare disease in children and adolescents and contributes to about 1.5%-3% of all pediatric malignancies. To date, no randomized trial has ever been performed in the pediatric population and management of these patients has been extrapolated from adult practice.

Materials and Methods

Retrospective analysis of the patients treated for PTC in the age <21 years, between the years 1998-2013 at a tertiary cancer center from India.

Results

Sixty-seven patients were treated in the above said period with a male:female ratio of 1:1.6 and a median age of 18 years. Fifty-two (77.6%) patients clinically presented as a thyroid swelling with or without nodal swelling while 13 (19.4%) presented with isolated nodal swelling. Surgery was performed in 30 patients at a nononcological hospital and was subsequently referred to our center; more than half of them needed a completion surgery at our center. Pathologically, multifocal tumors were found in close to a quarter of the patients. Among the pathological variants, classical, follicular, and tall cell variants comprised 65.7%, 28.4%, and 5.9% of the cases, respectively. Nodal positivity was noted 71.6% of the cases of which 14.5% were N1a disease and the vast majority (85.5%) harboring N1b disease. The median follow-up period of the study cohort was 104 months during which there were 3 local, 6 nodal, and 2 systemic recurrences. The 5- and 10-year disease-free survival were found to be 85.9% and 81.4%, respectively. Univariate and multivariate analysis has shown no significant clinical and pathological feature defining the disease outcomes except for the T-stage. Logistic regression revealed extrathyroidal invasion and the age ≤ 15 years correlated with nodal positivity.

Conclusion

Being a rare malignancy, pediatric and adolescent PTCs tend to behave differently from adult PTC with a seemingly aggressive clinical presentation; however, they are associated with excellent survival outcomes.

Up-regulated lipocalin-2 in pediatric thyroid cancer correlated with poor clinical characteristics

BACKGROUND

The incidence of thyroid cancer is fast increasing in both adults and children. The pediatric thyroid cancer had often already progressed to a more advanced stage of the disease at diagnosis. Early detection of pediatric thyroid cancer has been a problem for many years. Lipocalin-2 (Lcn2) has been reported to be over-expressed in cancers of diverse histological origin and it facilitates tumorigenesis by promoting survival, growth, and metastasis.

METHODS

The plasma Lcn2 concentration of 28 Chinese papillary thyroid cancer (PTC) children and 24 healthy controls was measured. Immunostaining for Ki-67 of tumor tissue from PTC children was performed. The expression levels of Lcn2 and NFκB in PTC tissue and peri-carcinoma tissue of PTC children were measured through Western blot.

RESULTS

The plasma concentration of Lcn2 was significantly elevated in pediatric PTC patients compared with healthy controls. Besides, the plasma Lcn2 concentration significantly correlated with clinical characteristics, NFκB level, and Ki-67 positive rate of nucleus in tissue of PTC.

CONCLUSION

This is the first study to evaluate the plasma Lcn2 in pediatric PTC patients. It is possible that the plasma Lcn2 may be a new biomarker of pediatric thyroid cancer. Further studies are needed to explore the definite role and mechanism of Lcn2 in thyroid cancer, which will help to explore novel diagnostic or therapeutic strategies.

Treatment outcomes in pediatric differentiated thyroid carcinoma

Background Until the American Thyroid Association (ATA) guidelines on management of pediatric differentiated thyroid carcinoma (DTC) became available in 2015, all children with DTC were treated like adults. This study aims to investigate the outcome of pediatric DTC and factors predicting the response to therapy in pediatric DTC managed according to adult guidelines. Methods Clinical records of 41 children less than 18 years of age diagnosed with DTC followed from 2007 in a single center were reviewed. According to the new ATA classification for pediatric DTC, five had low-risk, 28 had intermediate-risk and eight had high-risk disease at presentation. Results There was no mortality or recurrence in this cohort of pediatric DTC patients and the cure rate was 46% during a mean follow-up of 44 months when they were managed according to adult guidelines. Neither the new ATA risk classification nor any clinicopathological character was identified which could predict the response to therapy. The new ATA guidelines would have avoided 27% of the radioiodine therapies given. Conclusions This study showed that DTC in children managed according to adult guidelines had a good cure rate. The new ATA guidelines on pediatric DTC might have drastically reduced the number of radioiodine therapies in the affected children. Long term prospective studies are needed to validate the benefits and risks of both these approaches.

Usefulness of dynamic risk stratification in pediatric patients with differentiated thyroid carcinoma

Purpose

Recently, the American Thyroid Association (ATA) dynamic risk stratification (DRS) has been verified to be more valuable than the static anatomical staging system for predicting prognosis in patients with differentiated thyroid carcinoma (DTC). The purpose of this retrospective study was to compare the clinical usefulness of DRS, which is based on the response to initial treatment, with that of ATA initial risk stratification in pediatric patients.

Methods

A total of 144 pediatric patients underwent thyroid operation from August 1982 to December 2013 at Yonsei University Hospital (Seoul, Korea). Among them, 128 patients with complete clinical data were enrolled in this study. Clinicopathologic features and surgical outcomes were retrospectively analyzed by medical chart review. The mean follow-up duration was 11.5 years.

Results

The mean tumor size was 2.1 cm; 80.4% of patients were diagnosed with conventional papillary thyroid carcinoma, and 7.0% of patients were diagnosed with follicular thyroid carcinoma. Low-risk patients had the highest probability of an excellent response to initial treatment (66.6%). High-risk patients had the highest probability of a structural incomplete response (100%) and the lowest probability of an excellent response (11.1%). The ATA risk stratification and the DRS system were independent risk factors for disease-free survival (DFS) (P = 0.041 and P < 0.001, respectively).

Conclusion

The DRS system, which is based on the response to initial treatment, can offer more useful prognostic information compared with ATA risk stratification in pediatric patients with DTC.

Differentiated thyroid cancer in children: Heterogeneity of predictive risk factors

OBJECTIVE

To correlate clinical and pathological characteristics at diagnosis with patient long-term outcomes and to evaluate ongoing risk stratifications in a large series of paediatric differentiated thyroid cancers (DTC).

STUDY DESIGN

Retrospective analysis of clinical and pathological prognostic factors of 124 paediatric patients with DTC (age at diagnosis <19 years) followed up for 10.4 ± 8.4 years. Patients with a follow-up >3 years (n = 104) were re-classified 18 months after surgery on the basis of their response to therapy (ongoing risk stratification).

RESULTS

Most patients had a papillary histotype (96.0%), were older than 15 years (75.0%) and were diagnosed because of clinical local symptoms (63.7%). Persistent/recurrent disease was present in 31.5% of cases during follow-up, but at the last evaluation, only 12.9% had biochemical or structural disease. The presence of metastases in the lymph nodes of the lateral compartment (OR 3.2, 95% CI, 1.28-7.16, P = 0.01) was the only independent factor associated with recurrent/persistent disease during follow-up. At the last evaluation, biochemical/structural disease was associated with node metastases (N1a, N1b) by univariate but not multivariate analysis. Ongoing risk stratification compared to the initial risk classification method better identified patients with a lower probability of persistent/recurrent disease (NPV = 100%).

CONCLUSIONS

In spite of the aggressive presentations at diagnosis, paediatric patients with DTC show an excellent response to treatment and often a favourable outcome. N1b status should be considered a strong predictor of persistent/recurrent disease which, as in adults, is better predicted by ongoing risk stratification.

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.

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.

Prognostic Factors for Early and Long-Term Remission in Pediatric Differentiated Thyroid Carcinoma: The Role of Sex, Age, Clinical Presentation, and the Newly Proposed American Thyroid Association Risk Stratification System

BACKGROUND

The incidence of pediatric differentiated thyroid carcinoma (DTC) has been rising in recent years, and the main risk factors for recurrence are lymph node and distant metastasis at diagnosis. Other clinical features remain unclear, such as the impact of age, sex, and puberty. Furthermore, until now, this population has been treated using the same strategies used to treat adults. In 2015, the American Thyroid Association (ATA) published the first guidelines targeted at this age group. The aims of this study were to investigate the prognostic factors for early and long-term remission and also to validate the ATA risk stratification proposal in a population outside the United States.

METHODS

Clinical records from 118 patients <18 years old followed in two referral centers were reviewed. The median age was 12 years (range 4-18 years), and 20.3% (24 patients) were <10 years old at diagnosis. The median follow-up was 9.1 years. The majority were female (72%) and received total thyroidectomy and radioiodine therapy (RAI), and 61.8% were treated with more than one dose of RAI. The majority were classified as high risk (48.3%) by the new ATA pediatric guidelines due to distant metastasis (30 patients) or extensive lymph node involvement (27 patients). The remained were classified as low risk (31.3%) and intermediate risk (20.4%).

RESULTS

Females with no lymph node or distant metastasis and low ATA pediatric risk were more likely to have no evidence of disease (p < 0.05) within the first year and also in the long term. In this study, age did not significantly predict outcomes. Furthermore, patients also benefitted from multiple doses of RAI, but when the cumulative activity was >400 mCi, this benefit was diminished.

CONCLUSIONS

This study shows that the ATA risk stratification proposal for pediatric patients is useful in predicting early and long-term outcomes in pediatric patients with DTC. In addition, it shows that sex and metastatic disease are important prognostic factors in pediatric populations.

Classical V600E and other non-hotspot BRAF mutations in adult differentiated thyroid cancer

BACKGROUND

BRAF is the most frequently mutated gene in differentiated thyroid cancer (DTC). Previous studies on DTC have well documented high rates of the BRAF (V600E) mutation in patients of mixed ages. Previous studies either included a mix of pediatric and adult patients or pediatric patients only. However, the prevalence of hotspot and non-hotspot BRAF mutations and its significance in pure adult DTCs is not yet well determined. In this study we determine the frequency of this classical BRAF mutation and other rare BRAF mutations in pure adult DTCs.

METHODS

A total of 204 adult DTC samples (Age >18 years) were analyzed for mutations in exon 15 of the BRAF gene by performing polymerase chain reaction (PCR) amplification of tumor genomic DNAs and direct sequencing of amplicons using Sanger sequencing. Obtained results were correlated to clinical and pathological characteristics of DTCs. Statistical analyses were performed using SPSS (The Statistical Package for Social Sciences) version 20 software.

RESULTS

Overall, BRAF mutations were identified in 48.5 % (99/204) of adult DTCs. Three rare non-hotspot mutations (T599I, T599dup and K601E) were detected in four tumor samples (2 %). One (K601E) of these non-hotspot mutations occurred in conventional papillary thyroid cancer (CPTC) and other three (T599I, T599dup and K601E) were found in follicular variant PTC. We found significant association between BRAF (V600E) mutation and age (P < 0.0001), extrathyroidal invasion (P = 0.017), lymph node metastasis (P = 0.038) and TNM stage III/IV (P = 0.001).

CONCLUSIONS

Our study is the first to report BRAF mutations in a pure adult sample of DTCs of Saudi Arabian ethnicity. Our results show a high rate and a strong prognostic role of the classical BRAF (V600E) mutation and also suggest a common occurrence of non-hot spot mutations in adult DTC from this highly inbred population.

HABP2 Gene Mutations Do Not Cause Familial or Sporadic Non-Medullary Thyroid Cancer in a Highly Inbred Middle Eastern Population

BACKGROUND

Familial non-medullary thyroid cancer (NMTC) occurs either as part of known hereditary syndromes or as a non-syndromic isolated hereditary tumor. Although the genes underlying the syndromic type of NMTC have been identified in most syndromes, no clear underlying gene has been identified in the non-syndromic NMTC. Recently, a c.1601G>A, p.G534E mutation in the HABP2 gene was reported to be the underlying genetic defect in a family with seven members affected by NMTC. The G534E variant has also been reported to occur in about 4.7% of cases of the Thyroid Cancer Genome Atlas (TCGA) database.

OBJECTIVES

The aim of this study was to explore whether the recent finding of G534E genetic variant can be replicated in a large sample of NMTC, including 11 members of four unrelated families with familial NMTC and 509 cases of sporadic pediatric (63 cases) and adult NMTC (446 cases).

METHODS

All exons and exon-intron boundaries of HABP2 were screened in 11 members of four families with familial non-syndromic NMTC using DNA isolated from peripheral leucocytes, polymerase chain reaction, and direct sequencing. The G534E variant was also screened for specifically in 229 cases of sporadic NMTC using DNA isolated from peripheral leucocytes and an additional 217 cases of NMTC using DNA isolated from formalin-fixed paraffin-embedded tumor tissues. As a control cohort, 190 healthy individuals without known thyroid disease were also studied for the presence of the G534E variant using DNA isolated from peripheral leucocytes.

RESULTS

None of the familial NMTC carried HABP2 mutations. Of 509 sporadic NMTC, only one case (0.2%) harbored the G534E variant. Similarly, only one case (0.5%) of the control group harbored the G534E variant.

CONCLUSION

In this study, HABP2 mutations were not found in familial NMTC, and the G534E variant is not the underlying genetic defect in a large sample of sporadic NMTC from the Middle East.

Radioactive iodine ablation may not decrease the risk of recurrence in intermediate-risk papillary thyroid carcinoma

The use of radioactive iodine (RAI) ablation in patients with intermediate-risk papillary thyroid carcinoma (PTC) who show microscopic extrathyroidal extension (ETE), regional lymph node (LN) metastasis, tumors with aggressive histology, or vascular invasion has been debated due to the lack of data regarding long-term prognosis in this risk group. Therefore, the purpose of this study was to resolve the controversy surrounding the prognostic benefit of RAI ablation, especially in intermediate-risk PTC patients. We retrospectively reviewed the medical records of 8297 intermediate-risk PTC patients who underwent primary total thyroidectomy with or without neck dissection at the Thyroid Cancer Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea, between January 1997 and June 2015. Of these 8297 patients, 7483 (90.2%) received RAI ablation. After adjusting for clinicopathological characteristics, RAI ablation did not significantly decrease the risk of loco-regional recurrence (LRR) (adjusted hazard ratio (HR) 0.852, P 0.413). Moreover, RAI ablation did not decrease the risk of LRR even in intermediate-risk PTC patients with aggressive features such as BRAF positivity (adjusted HR 0.729, P 0.137), tumor size >1 cm (adjusted HR 0.762, P 0.228), multifocality (adjusted HR 1.032, P 0.926), ETE (adjusted HR 0.870, P 0.541), and regional LN metastasis (adjusted HR 0.804, P 0.349). Furthermore, high-dose RAI ablation (>100 mCi) did not significantly decrease the risk of LRR (adjusted HR 0.942, P 0.843). Therefore, RAI ablation in intermediate-risk PTC patients should be considered on the basis of tailored risk restratification.

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.

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.

Are we really at the dawn of understanding sporadic pediatric thyroid carcinoma?

Data from the National Cancer Institute and from the literature have disclosed an increasing incidence of thyroid cancer in children, adolescents and adults. Although children and adolescents with thyroid cancer tend to present with more advanced disease than adults, their overall survival rate is excellent; however, there is no clear explanation for the differences observed in the clinicopathological outcomes in these age groups. There has been an ongoing debate regarding whether the clinicopathological differences may be due to the existence of distinct genetic alterations. Efforts have been made to identify these acquired genetic abnormalities that will determine the tumor's biological behavior and ultimately allow molecular prognostication. However, most of the studies have been performed in radiation-exposed pediatric thyroid carcinoma. Therefore, our understanding of the role of these driver mutations in sporadic pediatric differentiated thyroid cancer development is far from complete, and additionally, there is a strong need for studies in both children and adolescents. The aim of this review is to present an extensive literature review with emphasis on the molecular differences between pediatric sporadic and radiation-exposed differentiated thyroid carcinomas and adult population.