Pediatric thyroid cancer after the Chernobyl disaster. Pathomorphologic study of 84 cases (1991-1992) from the Republic of Belarus

Management of aggressive variants of papillary thyroid cancer

PURPOSE OF REVIEW

The aim of this study was to provide a timely and relevant review of the latest findings and explore appropriate management of aggressive variants of papillary thyroid cancer (AVPTC).

RECENT FINDINGS

In general, AVPTCs tend to exhibit more invasive characteristics, a lack of responsiveness to radioiodine, increased occurrences of regional spreading, distant metastases and higher mortality rates. Meanwhile, each variant showcases unique clinical and molecular profiles.

SUMMARY

Given the elevated risk of recurrence postsurgery, a more aggressive strategy may be necessary when suspected preoperatively, particularly for those presenting with invasive features. Decision on the extent of surgical treatment and adjuvant therapy is individualized and made by experienced clinicians and multidisciplinary teams based on the clinical presentation, presence of aggressive features and molecular profile. Future studies on development of personalized medicine and molecular target therapy may offer tailored treatment options.

Prevalence of Differentiated High-Grade Thyroid Carcinoma Among Well-Differentiated Tumors: A Systematic Review and Meta-Analysis

Background: The current edition of the World Health Organization (WHO) classification of endocrine tumors introduced grading for follicular cell-derived thyroid cancer. Tumors with necrosis and/or high mitotic count but not fulfilling the Turin criteria for poorly differentiated carcinoma will be reclassified as differentiated high-grade thyroid carcinoma (DHGTC). However, the impact of this reclassification has not been evaluated. In this study, we performed a systematic review and meta-analysis to estimate the prevalence of this new entry across thyroid tumor subtypes. Methods: In this systematic review and meta-analysis, studies reporting data on necrosis and/or mitoses in well-differentiated thyroid carcinoma (WDTC) were used to estimate the prevalence of DHGTC. Heterogeneity and potential publication bias were also evaluated. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed, and quality assessment was performed using a modification of the Newcastle-Ottawa scale. The study has been registered in the International Prospective Register of Systematic Reviews (PROSPERO, ID: CRD42022378716). Results: In clinically unselected patients, the prevalence of DHGTC in WDTC was 0.072 [95% confidence interval, CI, = 0.045-0.113]. The proportion of high-grade tumors greatly varied across growth patterns and subtypes. Overall, the prevalence of DHGTC was higher in follicular thyroid carcinoma (FTC; 0.146 [CI = 0.101-0.205]) than in papillary thyroid carcinoma (PTC; 0.059 [CI = 0.036-0.097]). Diffuse sclerosing, follicular, and classic subtype PTC had the lowest rates of high-grade features (i.e., 0.018 [CI = 0.004-0.084]; 0.036 [CI = 0.010-0.124]; and 0.042 [CI = 0.027-0.066], respectively), while a greater proportion of solid trabecular and histologically aggressive PTC could be reclassified as DHGTC (i.e., 0.154 [CI = 0.067-0.314] and 0.168 [CI = 0.108-0.252], respectively). Similar proportions were obtained for minimally and widely invasive FTC (i.e., 0.136 [CI = 0.058-0.287] and 0.152 [CI = 0.086-0.254], respectively). Finally, in a cohort of patients with poor prognosis (i.e., fatal cases, metastatic and radioiodine resistant tumors, cases with biochemical recurrence), the proportion of DHGTC was 0.287 [CI = 0.155-0.469]. Conclusions: Following the current WHO indications, some tumors will be reclassified as DHGTC. The proportion of tumors with high-grade features is relevant in FTC, solid trabecular, and histologically aggressive PTC subtypes. A remarkable enrichment in DHGTC among patients with poor prognosis confirms the negative impact of high-grade features on outcome.

Radiation Dose Does Not Affect the Predictive Value of Thyroid Biopsy for Diagnosing Papillary Thyroid Cancer in a Belarusian Cohort Exposed to Chernobyl Fallout

INTRODUCTION

The Chernobyl nuclear accident exposed residents of contaminated territories to substantial quantities of radioiodines and was followed by an increase in thyroid cancer, primarily papillary thyroid cancer (PTC), among exposed children and adolescents. Although thyroid biopsy is an essential component of screening programs following accidental exposure to radioiodines, it is unknown whether the predictive value of biopsy is affected by different levels of environmental exposure.

METHODS

A cohort of 11,732 Belarusians aged ≤18 years at the time of the Chernobyl accident with individual thyroid radiation dose estimates was screened at least once 11-22 years later. Paired cytologic conclusions and histopathologic diagnoses were possible for 258 thyroid nodules from 238 cohort members. Cytologic conclusions were divided into five reporting categories, with all follicular lesion aspirates combined into a single indeterminate category. Standard performance indicators, risk of malignancy (ROM), and odds ratios for a correct cytologic conclusion were calculated, both overall and according to quintile of thyroid radiation dose.

RESULTS

The arithmetic mean thyroid dose estimate for the study group was 1.73 Gy (range: 0.00-23.64 Gy). The final histopathologic diagnosis was cancer for 136 of 258 biopsies (52.7%; 135 papillary and 1 follicular). The overall ROM was 96.7% for cytologies definite for PTC, 83.7% for suspicious for PTC, 33.0% for indeterminate, 8.1% for benign, and 31.0% for non-diagnostic. The ROM showed little change according to level of radiation exposure. Overall, there was no association between thyroid radiation dose and the odds ratio for a correct cytologic conclusion (p = 0.24). When analyzed according to dose quintile, the odds ratio for a correct conclusion increased two-fold at 0.10-0.29 Gy compared to a dose of 0.00-0.09 Gy and decreased at doses of 0.3-24 Gy (p value for linear trend = 0.99).

CONCLUSIONS

At radiation doses received by a cohort of young Belarusians exposed to radioiodines by the Chernobyl accident, the predictive value of thyroid biopsy for diagnosing PTC was not significantly affected by level of radiation exposure.

Evolving approaches in paediatric thyroid cytopathology: A review

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

The "GU-GU-RU" project to eliminate discrimination related to the health effects of the Fukushima nuclear accident

BACKGROUND

Although 12 years have passed since Great East Japan Earthquake and following Fukushima nuclear accident, approximately 40% of Japanese citizen still believe that the current radiation exposure in Fukushima residents will likely/ very likely to cause genetic effects of radiation. This incorrect understanding could continue unexpected discrimination and prejudice towards those from Fukushima now and in the future. In order to provide updated knowledge and eliminate rumors related to radiation, Japanese Ministry of the Environment has launched "GU-GU-RU" project in 2021 with consisting of five sections.

OBJECTIVE

(1) To discuss the objectives and effects of the "GU-GU-RU" project (results after the first year), (2) to present administrative measures that may be effective in the long-term to prevent unjustified discrimination and prejudice, and (3) to eliminate rumors in the event of future large-scale disasters, including radiation disasters.

METHODS

We showed the contents of each sections carried out under the project and observed the result of first-year activities in each section.

RESULTS

Among the programs, the "Radiation College" has steadily produced positive results, with nearly 1,300 students participating and 50 students sharing their thoughts and ideas. In addition, the project has adopted strategies such as creating and broadcasting a TV program and collaborations with manga, which are expected to have a significant impact on society.

CONCLUSIONS

Compared to previous efforts on disseminating information related to health effect of radiation exposure, the "GU-GU-RU" project has taken a different approach in providing primary data of radiation and its health effects, which could become a better understanding of health effects of radiation for the general public, in order to eliminate rumors that may lead unjustified discrimination and prejudice.

Molecular Genetics of Diffuse Sclerosing Papillary Thyroid Cancer

CONTEXT

Diffuse sclerosing papillary thyroid cancer (DSPTC) is rare, with limited data on its molecular genetics.

OBJECTIVE

We studied the molecular genetics of a cohort of DSPTC.

METHODS

DNA was isolated from paraffin blocks of 22 patients with DSPTC (15 females, 7 males, median age 18 years, range 8-81). We performed polymerase chain reaction-based Sanger sequencing and a next-generation sequencing (NGS) gene panel to characterize the genomic landscape of these tumors. We classified genetic alterations to definitely or probably pathogenic. Definitely pathogenic are genetic alterations that are well known to be associated with PTC (e.g., BRAFV600E). Probably pathogenic are other alterations in genes that were reported in The Cancer Genome Atlas or the poorly differentiated and anaplastic thyroid cancer datasets.

RESULTS

Three tumors were tested only by Sanger sequencing and were negative for BRAFV600E, HRAS, KRAS, NRAS, TERT promoter, PTEN, and PIK3CA mutations. The other 19 tumors tested by NGS showed definitely pathogenic alterations in 10 patients (52.6%): 2/19 (10.5%) BRAFV600E, 5/19 (26.3%) CCDC6-RET (RET/PTC1), 1/19 (5.3%) NCOA4-RET (RET/PTC3), 1/19 (5.3%) STRN-ALK fusion, and 2/19 (10.6%) TP53 mutations. Probably pathogenic alterations occurred in 13/19 tumors (68.4%) and included variants in POLE (31.6%), CDKN2A (26%), NF1 (21%), BRCA2 (15.8%), SETD2 (5.3%), ATM (5.3%), FLT3 (5.3%), and ROS1 (5.3%). In 1 patient, the gene panel showed no alterations. No mutations were found in the RAS, PTEN, PIK3CA, or TERT promoter in all patients. There was no clear genotype/phenotype correlation.

CONCLUSION

In DSPTC, fusion genes are common, BRAFV600E is rare, and other usual point mutations are absent. Pathogenic and likely pathogenic variants in POLE, NF1, CDKN2A, BRCA2, TP53, SETD2, ATM, FLT3, and ROS1 occur in about two-thirds of DTPTC.

Top 10 Nested Pattern Head and Neck Lesions to Notice

BACKGROUND

Nested is defined as "cellular clusters arranged in small groupings with intervening vascular or stromal networks, lacking lumens or glandular formation." Using this definition, multiple neoplastic and non-neoplastic lesions of the head and neck come into the differential. We have broadly organized the differential diagnosis of "nested" tumors into entities with neuroendocrine differentiation, squamous differentiation, thyroid follicular cell differentiation, and other lesions.

METHODS

Review.

RESULTS

Many different entities have a nested appearance and the morphologic, immunohistochemical, clinical, and radiographic features contribute to the differential diagnosis. The different tumors covered in this review include neuroendocrine neoplasms, paraganglioma, middle ear neuroendocrine tumor (formerly known as middle ear adenoma), medullary thyroid carcinoma, poorly differentiated thyroid carcinoma, olfactory neuroblastoma, ectopic pituitary neuroendocrine tumor, hyalinizing trabecular tumor, solid subtype of papillary thyroid carcinoma, solid cell nests/C-cell hyperplasia, necrotizing sialometaplasia, and meningioma.

CONCLUSION

In this review, we discuss the morphologic and immunohistochemical features of the covered entities as a guide to differential diagnosis when nested-patterned head and neck lesions are encountered.

A Comprehensive Review of the Progress and Evaluation of the Thyroid Ultrasound Examination Program, the Fukushima Health Management Survey

The Great East Japan Earthquake on March 11, 2011, and the subsequent tsunami caused an accident at the Fukushima Daiichi Nuclear Power Plant, in which extensive damage to the nuclear power reactors resulted in massive radioactive contamination. Fukushima Prefecture implemented the Thyroid Ultrasound Examination (TUE) program as part of the Fukushima Health Management Survey project in response to residents' anxieties about health risks due to radiation exposure for residents aged 0-18 years at the time of the nuclear accident. This program consisted of the primary examination and the confirmatory examination. In the primary examination, thyroid nodules and cysts were examined using portable ultrasound apparatuses. The confirmatory examination was performed to have clinical or cytological diagnosis. As of June 30, 2021, 116, 71, 31, 36, and 9 examinees in the first, second, third, and fourth round of surveys, and the survey at age 25 years, respectively, were determined to have nodules cytologically diagnosed as malignant or suspicious for malignancy. The confirmatory examination of the fourth-round survey and the primary and confirmatory examination of fifth-round survey are currently in progress. Together with the low thyroid absorbed radiation dose estimated in the United Nations Scientific Committee on the Effects of Atomic Radiation 2020 report, our results suggested that the increased incidence of childhood thyroid cancer in Fukushima Prefecture was not caused by radiation exposure, but rather by the highly sensitive detection method. As detailed in this review, there were ongoing challenges in our program, such as actions against the risk of overdiagnosis and psychological support for participants and their families.

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.

Clinicopathological Implications of the BRAF V600E Mutation in Papillary Thyroid Carcinoma of Ukrainian Patients Exposed to the Chernobyl Radiation in Childhood: A Study for 30 Years After the Accident

With time after the Chernobyl accident, the number of papillary thyroid carcinomas (PTCs) driven by the BRAF^V600E oncoprotein is growing in patients exposed to radiation at a young age. Clinicopathological associations of BRAF^V600E in PTCs from patients with internal radiation history have not been sufficiently studied so far. This work analyzes the structural characteristics, proliferative activity, invasive features, clinical information, and dosimetric data in the BRAF^V600E-positive and BRAF^V600E-negative PTCs from the Ukrainian patients exposed to Chernobyl radiation and treated over 30 years after the accident. The study included 428 PTCs from patients aged 4-49 years at surgery who lived in the six northern regions of Ukraine most contaminated by ¹³¹I, were ≤18 years of age at the time of exposure, and were operated on from 1990 to 2017. Immunohistochemical staining for BRAF^V600E was performed with the VE1 antibody. The probability of causation (POC) of a tumor due to radiation was determined using an interactive online NIH/NCI software. BRAF^V600E was detected in 136/428 (31.8%) PTCs. In comparison with the BRAF^V600E-negative PTCs, the BRAF^V600E-positivity was associated with older patient age at the accident and at surgery, a longer period of latency, and lower POC. The BRAF^V600E-positive PTCs were characterized by smaller tumor size, higher Ki67 labeling index, more frequent oncocytic changes, multifocality, and dominant papillary growth pattern. Tumor invasive features were less frequent in the BRAF^V600E-positive PTCs and did not change with POC level. Despite a less aggressive tumor phenotype, BRAF^V600E was a risk factor for recurrence, namely radioiodine-refractory (RAI-R) recurrent metastases. Multivariate models of RAI-R included BRAF^V600E and/or histopathological parameters closely correlating with BRAF^V600E such as tumor size, multifocality, dominant papillary growth pattern, or oncocytic changes. Thus, the BRAF^V600E-positive PTCs from patients from a high-risk group for radiogenic thyroid cancer diagnosed in the 30 years after the Chernobyl accident did not display higher invasiveness regardless of POC level, but in view of the prognostic impact of this genetic alteration, knowledge of the BRAF status may be beneficial for middle-aged patients with radiogenic PTC considered for RAI therapy, and suggests more careful follow-up of patients with the BRAF^V600E-positive tumors.

Redefining the Solid Variant of Papillary Thyroid Carcinoma: A Multi-institutional Retrospective Study

AIMS

The definition of papillary thyroid carcinoma, solid variant (PTC-SV) varies from >50% to 100% of solid/trabecular/insular growth (STI). We aimed to identify prognostic factors and to establish an appropriate STI cutoff for PTC-SV in this multi-institutional study of 156 PTCs with STI.

RESULTS

Nodal metastases were seen in 18% and were associated with higher percentage of papillary and STI. When substratified by infiltration/encapsulation status, STI percentage did not impact risk of nodal metastasis. pN1 stage was seen in 51% of infiltrative tumors and 1% of encapsulated lesions. Overall, PTC with STI had an excellent prognosis. The 10-year DFS was 87% in the entire cohort, 94% in encapsulated lesions, and 76% in infiltrative tumors. STI percentage did not impact DFS. Fifty-four patients had noninvasive encapsulated lesions with 2% to 100% STI. None developed recurrence. Encapsulated lesions were enriched with RAS mutations (54%), whereas infiltrative lesions lacked RAS mutations (4%). BRAF V600E mutation was an infrequent event, being seen in 11% of the entire cohort.

CONCLUSION

In PTC with STI, the determining factor for nodal metastasis and DFS is the encapsulation/infiltration status rather than STI percentage. Encapsulated noninvasive tumors with STI follow an indolent course with a very low risk of nodal metastasis and recurrence. Overall, PTC with STI has an excellent prognosis with a 10-year DSS and DFS of 96% and 87% respectively. Therefore, the classification of SV-PTC as an aggressive PTC subtype may be reconsidered.

Molecular profiling of papillary thyroid carcinomas in healthcare workers exposed to low dose radiation at the workplace

PURPOSE

Exposure to ionizing radiation, especially during childhood, is a well-established risk factor for thyroid cancer. The vast majority of radiation-induced cancers are papillary carcinomas (PTCs). These tumors typically have gene fusions in contrast to point mutations prevalent in sporadic PTCs. The aim of this study was to investigate the molecular profiles of PTC patients with workplace exposure to ionizing radiation.

METHODS

A retrospective review of 543 patients who underwent surgery with diagnosis of PTC was performed. A cohort of nine healthcare specialists previously exposed to radiation sources during their professional practice was selected and analyzed using the ThyroSeq mutation panel for point mutations and gene fusions associated with thyroid cancer.

RESULTS

The molecular analysis of surgical samples of PTCs was informative and revealed genetic alterations in five patients. BRAF V600E was found in four (67%) cases whereas RET/PTC1 fusion in one (17%) and one sample (17%) was wild type for point mutations and fusions. One sample completely failed molecular analysis while two others were negative for genes fusions but failed DNA analysis; these three samples were excluded.

CONCLUSIONS

In this limited cohort of healthcare workers exposed to low dose of ionizing radiation at the workplace and developed PTC, the molecular profiling determined BRAF V600E point mutation as the most common event, arguing against the role of workplace radiation exposure in the etiology of these tumors.

Single neonatal irradiation induces long-term gene expression changes in the thyroid gland, which may be involved in the tumorigenesis

Exposure to ionizing radiation in childhood has been recognized as a risk factor for thyroid cancer. We previously demonstrated that neonatal X-irradiation induced specific deformation of the thyroid follicles. Here, we further analyzed this model to understand the possible relationship with thyroid carcinogenesis. Wistar rats were subjected to cervical X-irradiation at different ages of 1–8 weeks old and at different doses of 1.5–12 Gy. For tumor promotion, rats were fed with an iodine-deficient diet (IDD). In cervically X-irradiated neonatal rats, the size of thyroid follicles decreased, accompanied by an increase in the number of TUNEL-positive cells. Fas and Lgals3 mRNA levels increased, while Mct8 and Lat4 expressions decreased. The co-administration of IDD induced the proliferation and the upregulation in Lgals3 expression, resulting in thyroid adenoma development at 28 weeks post-exposure. Our data demonstrated that single neonatal X-irradiation induced continuous apoptotic activity in the thyroid with the long-term alternation in Fas, Mct8, Lat4, and Lgals3 mRNA expressions. Some of these changes were similar to those induced by IDD, suggesting that neonatal X-irradiation may partially act as a thyroid tumor promoter. These radiation-induced thyroidal changes may be enhanced by the combined treatment with IDD, resulting in the early development of thyroid adenoma.

Clinical and molecular characterization of thyroid cancer when seen as a second malignant neoplasm

BACKGROUND

Second malignant neoplasms (SMN) are among the most serious long-term adverse health conditions in cancer survivors. The aim of this study was to characterize clinical findings of patients who developed thyroid cancers as SMN, and to examine genomic alterations in thyroid cancer tissue.

METHODS

Retrospective analysis of medical records from patients seen for management of thyroid cancer over 10-year period was performed. Clinical and pathologic data were retrieved from their medical charts. Tumor DNA and RNA were extracted from formalin-fixed, paraffin-embedded tissue and subjected to next-generation sequencing (NGS) using Ion Torrent Oncomine Focus Assay. Microfluidic digital polymerase chain reactions (PCRs) were performed using QIAcuity Digital PCR System to identify BRAF ^V600E mutations and RET/PTC fusions.

RESULTS

Sixteen of 620 patients operated for thyroid cancer had history of previously diagnosed malignancy. Eight patients were male and eight patients were female, with a median age at diagnosis of 58.5 years (range, 4-78). Four patients had history of pediatric malignancy (PedCa), and 12 patients had a history of prior malignancy as an adult (AdCa). The latency periods for development of SMN in PedCa and AdCa patients were 10.8 (±5.2) years and 9.5 (±5.2) years, respectively. Histopathology revealed papillary thyroid cancers in 15 cases, and follicular thyroid cancer in 1 case. All tumors were classified as T1 or T2, and there were no patients presenting with metastases at the time of surgery. Genomic alterations were detected in 13/16 (81.2%) tumors including eight gene mutations (BRAF ^V600E (N = 4), RAS (N = 2), PI3CA (N = 2) and five gene fusions (RET/PTC1 (N = 4) and STRN/ALK (N = 1). In patients with PedCa and AdCa, mutations were detected in 1/4 (25%) and 7/12 (58.3%), respectively, p = 0.56; and fusions were detected in 3/4 (75%) and 2/12 (16.6%), respectively, p = 0.06. In patients with and without history of therapeutic irradiation, mutations were detected with the same frequencies (5/10 (50%), and 3/6 (50%), respectively, p = 1.0). Gene fusions were detected in patients with and without history of irradiation in 5/10 (55.5%) and 0/6 (0%), respectively, p = 0.09.

CONCLUSIONS

Monitoring of cancer survivors for thyroid disorders allowed diagnosis of second thyroid cancers at early stages. Second thyroid cancers harbor genomic alterations that are typical for sporadic as well as for radio-induced thyroid cancers.

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.

Risk of thyroid cancer after therapeutic irradiation in adult patients: An Age-Based surveillance, epidemiology, and end results analysis

OBJECTIVES/HYPOTHESIS

One risk of radiation therapy exposure (XRTe) is second primary thyroid cancer (SPTC). Previous reports examined this in children, but no population-based studies have explored XRTe and SPTC across all ages or stratified by histological subtypes.

STUDY DESIGN

Database study.

METHODS

We report patient characteristics of a Surveillance, Epidemiology, and End Results (SEER) dataset of SPTC (n = 4,669) using χ² and t tests. Odds ratio (OR) for SPTC was determined based on age, histology, and XRTe compared to expected values in the SEER database. Kaplan-Meier survival and Cox proportional hazard ratios were reported to determine factors influencing latent survival (LS; time from initial diagnosis to SPTC) and overall survival in univariate and multivariate models.

RESULTS

Extrathyroid extension and node status based on XRTe were similar (P = .684 and P = .776, respectively). XRTe patients were more likely to have smaller tumors (17.6 vs. 19.3 mm, P = .007). XRTe patients were diagnosed with SPTC at younger ages (59.8 vs. 62.7 years, P < .001) without a difference in LS (7.45 vs. 7.50 years, P = .426). Patients aged 1 to 14 years and 15 to 29 years at diagnosis of first cancer are at higher risk of SPTC after XRTe (OR = 1.89, P = .005 and OR = 2.35, P = .001, respectively), unlike patients age 30 to 44 years and 45+ years (OR = 1.03, P = .823 and OR = 0.97, P = .624, respectively). This difference is not present for follicular and medullary SPTC.

CONCLUSIONS

Patients aged 30+ years receiving radiation therapy (XRT) do not have an increased risk of SPTC. Deliberation is necessary in recommending, planning, and delivering XRT to minimize risk of subsequent malignancy in younger patients.

LEVEL OF EVIDENCE

NA Laryngoscope, 130: 2081-2086, 2020.

Papillary Thyroid Cancer-Aggressive Variants and Impact on Management: A Narrative Review

Introduction

Aggressive variants of papillary thyroid cancer (PTC) have been described with increasing frequency. These variants include diffuse sclerosing variant, tall cell variant, columnar cell variant, solid variant, and hobnail variant.

Methods

We have performed a review of the more aggressive variants of PTC with respect to main characteristics, histological and molecular features, and the consequences that the knowledge of these variants should have in the treatment of the patients.

Results

At the present time, we do not know the prognostic value of these aggressive PTC variants. The extent of the surgical treatment and adjuvant therapy necessary should be decided on the basis of the extent of the tumor at presentation and the opinion of experienced clinicians.

Conclusion

These aggressive variants should be known by clinicians, to avoid underdiagnosis, and treated according to the latest recommendations in the literature.

THE COMPARISON OF THE EXTERNAL DOSE RATE MEASUREMENT OF CHILDREN AND ADOLESCENT PATIENTS WITH ADULT PATIENTS TREATED WITH RADIOIODINE THERAPY

The aim of this study is to evaluate the radiation safety of caregiving people contacting the child and adolescent patients with thyroid cancer who received radioactive iodine-131 (RIT) treatment by comparison with external dose rate measurements of adult patients according to their administered activities and days of hospitalization. We retrospectively evaluated external dose rate measurement of 158 children and adolescent patients and 158 adult patients. During the RIT, the hospitalization time were grouped as 2, 3 and 4 d, and the administered activities as <3700, 3700 and >3700 MBq. The values of external dose rate measurements of children and adolescents were statistically significantly higher than the adult group. Different approaches in radiation safety rules are required for children and adolescents. In terms of radiation safety, we suggest that more specific regulations for family members and caregivers should be established and informed.

Subtle excess in lifetime cancer risk related to CT scanning in Spanish young people

BACKGROUND

CT scan is a life-saving medical diagnostic tool, entailing higher levels of ionising radiation exposure than conventional radiography, which may result in an increase in cancer risk, particularly in children. Information about the use and potential health effects of CT scan imaging among young people in Spain is scarce.

OBJECTIVE

This paper aims to estimate the number of radiation-related cancer cases which can be expected due to the use of CT scanning in Spanish children and young adults in a single year (2013).

METHODS

The 2013 distribution of number and types of CT scans performed in young people was obtained for Catalonia and extrapolated to the whole Spain. Organ doses were estimated based on the technical characteristics of 17,406 CT examinations extracted from radiology records. Age and sex-specific data on cancer incidence and life tables were obtained for the Spanish population. Age and sex-specific risk models developed by the Committee on Health Risks of Exposure to Low Levels of Ionizing Radiations (BEIR VII) and Berrington de Gonzalez were used, together, with the dose estimates to derive the lifetime attributable risks of cancer in Spain due to one year of CT scanning and project the number of future cancer cases to be expected.

RESULTS

In 2013, 105,802 CT scans were estimated to have been performed in people younger than age 21. It was estimated that a total of 168.6 cancer cases (95% CrI: 30.1-421.1) will arise over life due to the ionising radiation exposure received during these CTs. Lifetime attributable risks per 100,000 exposed patients were highest for breast and lung cancer. The largest proportion of CTs was to the head and neck and hence the highest numbers of projected cancer cases were of thyroid and oral cavity/pharynx.

CONCLUSIONS

Despite the undeniable medical effectiveness of CT scans, this risk assessment suggests a small excess in cancer cases which underlines the need for justification and optimisation in paediatric scanning. Given the intrinsic uncertainties of these risk projection exercises, care should be taken when interpreting the predicted risks.

Special types of thyroid carcinoma

This article reviews the small percentage of thyroid tumours that are not classified as classic papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. It includes subtypes of papillary thyroid carcinoma, including, tall-cell, hobnail/micropapillary, columnar cell, diffuse sclerosing and solid variants. Poorly differentiated carcinoma, high-grade carcinoma and anaplastic thyroid carcinoma are reviewed. Also discussed are entities that are unusual but need to be recognized as primary thyroid neoplasms, i.e. mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, and mammary analogue secretory carcinoma/secretory carcinoma. The pathological features and prognostic factors are described; a brief review of molecular correlates of these neoplasms is included.

[DICER1 mutated, solid/trabecular thyroid papillary carcinoma in an 11-year-old child]

We report the case of an 11-year-old patient diagnosed with a solid variant of papillary thyroid carcinoma. Papillary thyroid carcinoma (PTC) is the most common thyroid cancer, representing 80-90% of all newly diagnosed thyroid cancers. Among the many variants described, solid/trabecular variant of papillary thyroid carcinoma is a rare entity and account for 3% of thyroid cancers. It is more common in children and young adults, and it is seen in higher proportion in post radiation papillary thyroid carcinoma cases. Histologically, solid variant papillary carcinoma is characterized by a predominantly solid, trabecular or insular growth pattern, and the presence of cytological features typical of PTC. Its main differential diagnosis is poorly differentiated thyroid carcinoma. It has a less favorable prognosis than the classical papillary type, with a higher risk of distant metastasis, extrathyroidal extension and lympho-vascular invasion. It is associated with a slightly lower long-term survival in adult cases, but not in children. The management of solid variant PTC includes surgery, associated or not with postoperative radioiodine ablation, according to the aggressiveness criteria. Our patient had a DICER1 somatic mutation. Carriers of germline DICER1 mutations are predisposed to a rare cancer syndrome, the DICER1 syndrome, with a higher risk of numerous tumors and infrequently differentiated thyroid carcinomas.

Increased risk of thyroid cancer in female residents nearby nuclear power plants in Korea: was it due to detection bias?

Background

The Korea Radiation Effect & Epidemiology Cohort - The resident cohort (KREEC-R) study concluded that there is no epidemiological or causal evidence supporting any increase in cancer risks resulting from radiation from Korean nuclear power plants (NPPs). But the risks of thyroid cancer in women were significantly higher in residents living near NPPs than control. Debate about the cause of the pattern of thyroid cancer incidence in women is ongoing and some researchers argue that detection bias influenced the result of KREEC-R study. Therefore there was a need to investigate whether residents living near NPPs who were assessed in the KREEC-R were actually tested more often for thyroid cancer. We evaluated the possibility of detection bias in the finding of the KREEC-R study based on materials available at this time.

Methods

Using the KREEC-R raw data, we calculated age standardized rates (ASRs) of female thyroid cancer and re-analyzed the results of survey on the use of medical services. We also marked the administrative districts of residents who received the Radiation Health Research Institute (RHRI) health examinations and those in which thyroid cancer case occurred as per the Chonnam National University Research Institute of Medical Sciences (RIMS) final report on maps where the locations of NPPs and 5 km-radii around them were also indicated. And we compared the incidence rates of Radiation-induced cancer measured between the first period when RHRI health examinations were not yet implemented, and the second period when the RHRI health examinations were implemented.

Results

The ASR for the far-distance group, which comprised residents living in areas outside the 30 km radius of the NPPs, increased rapidly after 2000; however, that of the exposed group, which comprised residents living within a 5 km radius of the NPPs, started to increase rapidly even before 1995. The frequencies of the use of medical services were significantly higher in the intermediate proximate group, which comprised residents living within a 5-30 km radius of the NPPs, than in the exposed group in women. In case of female thyroid cancer, the second period ASR was higher than the first period ASR, but in case of female liver cancer and female stomach cancer no significant difference were observed between the periods. On map, many administrative districts of residents who received RHRI health examinations and most administrative districts in which thyroid cancer case occurred on RIMS final report were outside 5 km-radii around NPPs.

Conclusions

We could not find any evidence supporting the assertion that detection bias influenced the increased risks of female thyroid cancer observed in the exposed group of the KREEC-R study, as opposed to the control group.

Hormesis and radiation safety norms: Comments for an update

Hormesis can be explained by evolutionary adaptation to the current level of a factor present in the natural environment or to some average from the past. This pertains also to ionizing radiation as the natural background has been decreasing during the time of the life existence. DNA damage and repair are normally in a dynamic balance. The conservative nature of the DNA repair suggests that cells may have retained some capability to repair damage from higher radiation levels than that existing today. According to this concept, the harm caused by radioactive contamination would tend to zero with a dose rate tending to a wide range level of the natural radiation background. Existing evidence in favor of hormesis is substantial, experimental data being partly at variance with results of epidemiological studies. Potential bias, systematic errors, and motives to exaggerate risks from low-dose low-rate ionizing radiation are discussed here. In conclusion, current radiation safety norms are exceedingly restrictive and should be revised on the basis of scientific evidence. Elevation of the limits must be accompanied by measures guaranteeing their observance.

Is hypothyroidism in idiopathic pleuroparenchymal fibroelastosis a novel lung-thyroid syndrome?

BACKGROUND

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a rare type of interstitial pneumonia characterized by fibroelastosis. Patients with IPPFE as well as idiopathic interstitial pneumonia often have autoimmune diseases, which sometimes coincide with hypothyroidism (HypoT). However, there have been no reports on the association between IPPFE and HypoT. The purpose of this study was to evaluate the correlation between IPPFE and HypoT. We also examined the pathological features of the thyroid glands from autopsied cases.

METHODS

Thirteen patients diagnosed with IPPFE from among 255 consecutive cases of idiopathic interstitial pneumonia were included in this study; pertinent data were obtained from our hospital's clinical library. We examined the prevalence of HypoT and compared the clinical, radiological, and pathological features between the patients with and those without HypoT. Histological analyses of the lungs and thyroid glands were performed in 4 and 3 cases, respectively.

RESULTS

HypoT was identified in 7 of 13 patients (53.8%). Sex, body mass index, survival time, and laboratory test results were not significantly different between patients with and those without HypoT. Radiological and pathological lung findings were similar between both groups of patients. Thyroid gland histology demonstrated perifollicular or interlobular fibrosis without inflammation in all three cases, including a euthyroid case.

CONCLUSIONS

Although we only analyzed a small number of IPPFE cases, HypoT was prevalent among all of them. Characteristic fibrosis in the thyroid gland was observed even in a euthyroid case. Therefore, patients with IPPFE may potentially have thyroid gland dysfunction through a common pathogenesis in both organs.

Radionuclide Imaging of Infection and Inflammation in Children: a Review

With the exception of radiolabeled monoclonal antibodies, antibody fragments and radiolabeled peptides which have seen little application in the pediatric population, the nuclear medicine imaging procedures used in the evaluation of infection and inflammation are the same for both adults and children. These procedures include (1) either a two- or a three-phase bone scan using technetium-99m methylene diphosphonate; (2) Gallium 67-citrate; (3) in vitro radiolabeled white blood cell imaging (using ¹¹¹Indium-oxine or ^99mTechnetium hexamethyl-propylene-amine-oxime-labeled white blood cells); and (4) hybrid imaging with ¹⁸F-FDG. But children are not just small adults. Not only are the disease processes encountered in children different from those in adults, but there are developmental variants that can mimic, but should not be confused with, pathology. This article discusses some of the differences between adults and children with osteomyelitis, illustrates several of the common developmental variants that can mimic disease, and, finally, focuses on the increasing use of ¹⁸F-FDG PET/CT in the diagnosis and response monitoring of children with infectious and inflammatory processes. The value of and need for pediatric specific imaging protocols are reviewed.

Poorly Differentiated and Anaplastic Thyroid Cancer

BACKGROUND

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic (undifferentiated) thyroid carcinoma (ATC) comprise a small subset of thyroid tumors that are associated with a poor prognosis and account for a significant portion of the morbidity and mortality related to thyroid cancer. Since management strategies vary between these two entities, it is important for clinicians to be able to differentiate PDTC from ATC.

METHODS

We reviewed the literature on PDTC and ATC and compared clinical and histopathologic features important in defining the disease process.

RESULTS

Both PDTC and ATC display aggressive behavior with increased locoregional and distant disease. In most cases, patients are older and have large, locally advanced tumors. PDTC may represent an intermediate entity in the progression of well-differentiated thyroid carcinoma to ATC. The use of surgical management may be curative or palliative and differs between PDTC and ATC. The roles of radiotherapy and chemotherapy have not been well described.

CONCLUSIONS

PDTC and ATC are rare diseases that carry a poor prognosis. Recognition of their different clinicopathologic features is important to the optimal management of these tumors.

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.

Prognostic significance of diffuse sclerosing variant papillary thyroid carcinoma: a systematic review and meta-analysis

OBJECTIVE

Diffuse sclerosing variant papillary thyroid carcinoma (DSVPTC) is an uncommon variant of papillary thyroid carcinoma (PTC). The biological behaviors and prognostic outcomes of this variant, however, are still controversial. The aim of this systematic review and meta-analysis is to investigate the prognostic significance and outcomes of DSVPTCs in comparison with classical PTCs (cPTCs).

METHODS

An electronic search was performed in five libraries: PubMed, Scopus, ISI, World Health Organization Global Health Library (WHO GHL) and Virtual Health Library (VHL) in June 2016. Published data were extracted and were pooled into odds ratios (OR), mean differences and corresponding 95% confidence intervals (CI) using random-effect model. Publication bias was analyzed using Egger's regression test and funnel plot observation.

RESULTS

From 315 articles, we included 16 articles comprising 732 DSVPTCs for meta-analysis. Overall, DSVPTC manifested more aggressive clinicopathological behaviors than cPTC such as higher rate of vascular invasion (OR: 5.33; 95% CI: 3.08-9.23), extrathyroidal extension (OR: 2.96; 95% CI: 2.04-4.30), lymph node metastasis (OR: 5.40; 95% CI: 2.82-10.35), distant metastasis (OR: 3.61; 95% CI: 1.89-6.88) and were more likely to relapse (OR: 2.83; 95% CI: 1.59-5.05). DSVPTC patients were associated with a worsened overall survival (HR: 1.89; 95% CI: 1.36-2.62).

CONCLUSION

DSVPTCs should be considered high-risk PTCs because of high propensity for tumor invasion, metastasis, relapse and mortality. Aggressiveness of DSVPTCs might be related to a different molecular pathway than that in cPTCs.

Radiation-associated neoplasia: clinical, pathological and genomic correlates

Ionizing radiation is an established risk factor for the development of benign and malignant tumours. The epidemiology of radiation-associated neoplasia has been studied over the decades in diverse populations, including Japanese atomic bomb survivors, exposed communities following the Chernobyl nuclear power plant disaster, and paediatric and adult populations receiving therapeutic irradiation. Radiation has been associated with an increased risk of neoplasia throughout the human body, with some sites showing a markedly increased relative risk of developing tumours (thyroid; soft tissues), depending on patient age and the context of exposure. Although the mechanisms of cellular injury and repair resulting from ionizing radiation are well described, the genomics of radiation-induced tumours are still relatively poorly understood, with some exceptions, such as RET rearrangement in thyroid carcinomas following iodine-131 exposure and MYC amplification in cutaneous angiosarcoma following chest wall irradiation for breast cancer. This review will provide a general overview of the epidemiology, molecular mechanism, pathology and genomics of radiation-associated neoplasia in humans.

Previous External Beam Radiation Treatment Exposure Does Not Confer Worse Outcome for Patients with Differentiated Thyroid Cancer

BACKGROUND

Radiation exposure, especially in childhood, is known to increase the risk for the development of thyroid cancer. However, the prognosis of patients with thyroid cancer with a history of radiation treatment exposure remains unclear.

METHODS

One hundred and sixteen patients with a previous history of radiotherapy in the head and neck region were identified from an institutional database of 3664 patients with differentiated thyroid cancer treated between 1986 and 2010. Using the Kaplan-Meier method, disease-specific survival and recurrence-free survival were compared between patients with (RT; n = 116) and without (No RT; n = 3509) a prior history of radiation exposure.

RESULTS

The median ages of the RT and No RT cohorts were 52 and 47 years. The median follow-up for both groups was 54 months. Patients who had a prior history of radiation treatment exposure were more likely to be male (38.8% vs. 26.9%; p = 0.005) and older than 45 years of age (67.2% vs. 53.9%; p = 0.005). Other patient, tumor, and treatment characteristics were similar between the groups. There was no difference in the five-year disease-specific survival of the RT and No RT patients (97.4% vs. 98.7%; p = 0.798). The five-year recurrence-free survival was also similar between the RT and No RT patients (97.8% vs. 94.9%; p = 0.371).

CONCLUSION

The findings suggest that differentiated thyroid cancer patients with a history of prior radiation treatment exposure have similar outcomes to those with no history of head and neck radiation exposure.

Application of molecular biology of differentiated thyroid cancer for clinical prognostication

Although cancer outcome results from the interplay between genetics and environment, researchers are making a great effort for applying molecular biology in the prognostication of differentiated thyroid cancer (DTC). Nevertheless, role of molecular characterisation in the prognostic setting of DTC is still nebulous. Among the most common and well-characterised genetic alterations related to DTC, including mutations of BRAF and RAS and RET rearrangements, BRAF^V600E is the only mutation showing unequivocal association with clinical outcome. Unfortunately, its accuracy is strongly limited by low specificity. Recently, the introduction of next-generation sequencing techniques led to the identification of TERT promoter and TP53 mutations in DTC. These genetic abnormalities may identify a small subgroup of tumours with highly aggressive behaviour, thus improving specificity of molecular prognostication. Although knowledge of prognostic significance of TP53 mutations is still anecdotal, mutations of the TERT promoter have showed clear association with clinical outcome. Nevertheless, this genetic marker needs to be analysed according to a multigenetic model, as its prognostic effect becomes negligible when present in isolation. Given that any genetic alteration has demonstrated, taken alone, enough specificity, the co-occurrence of driving mutations is emerging as an independent genetic signature of aggressiveness, with possible future application in clinical practice. DTC prognostication may be empowered in the near future by non-tissue molecular prognosticators, including circulating BRAF^V600E and miRNAs. Although promising, use of these markers needs to be refined by the technical sight, and the actual prognostic value is still yet to be validated.

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.

Association between single nucleotide polymorphisms of upstream transcription factor 1 (USF1) and susceptibility to papillary thyroid cancer

BACKGROUND

Thyroid cancer, predominantly by papillary thyroid cancer (PTC), is a malignant tumour of endocrine system with increasing incidence rate worldwide. Upstream transcription factor 1 (USF1) regulates a variety of biological processes by transactivation of functional genes. In this study, we investigated the association between USF1 polymorphisms and PTC risk.

MATERIAL & METHODS

A total of 334 patients with PTC, 186 patients with benign nodules (BN) and 668 healthy controls were enrolled in our study. Tag-SNPs were identified in Chinese Han in Beijing (CHB) from International HapMap Project Databases. Genomic DNAs were extracted by TaqMan Blood DNA kits. SNPs of USF1 were genotyped by TaqMan SNPs genotyping assay. Odds ratios (OR) and corresponding 95% confidence interval (CI) were used to assess the association between USF1 genetic variants and PTC risk. The statistical analyses were carried out with spss 13.0 software.

RESULTS

Five tag-SNPs were retrieved to capture all the genetic variants of USF1. Among the five tag-SNPs, genetic variants in rs2516838, rs3737787 and rs2516839 have significant association with PTC risk. The rs2516838 polymorphisms dominant model (CG+GG vs CC: OR = 0·71; 95% CI: 0·52-0·97; P = 0·033) and allelic model (C vs G: OR = 0·031; 95% CI: 0·56-0·97; P = 0·031) indicated it may act as a protective factor against PTC. On the contrary, the results of rs3737787 polymorphisms: dominant model (CT+TT vs CC: OR = 1·55; 95%CI: 1·09-2·02; P = 0·001) and allelic model (C vs T: OR = 1·35; 95%CI: 1·10-1·64; P = 0·003), as well as the results of rs2516839 polymorphisms: dominant model (GA+AA vs GG: OR = 1·77; 95%CI: 1·31-2·38; P < 0·001) and allelic model (G vs A: OR = 1·36; 95%CI: 1·13-1·63; P = 0·014), revealed that they may act as risk factors for PTC.

CONCLUSION

In this study, we found the SNPs of rs2516838 (mutant G alleles vs wild C alleles), rs3737787 (mutant T alleles vs wild C alleles) and rs2516839 (mutant A alleles vs wild G alleles) were significantly associated with PTC risk. Further large-scale studies with different ethnicities are still needed to validate our findings and explore the underlying mechanism of USF1 in PTC development.

Trends in Thyroid Cancer Incidence in Korean Children (1999-2012) Based on Palpation and Nonpalpation Detection Methods

BACKGROUND

The incidence of childhood thyroid cancer is increasing in several populations; however, contributing factors have not been adequately discussed.

OBJECTIVES

Our aim was to identify trends of childhood thyroid cancer based on the Korea Central Cancer Registry (KCCR) database and to elucidate changes in detection methods of cancers using a single-center database.

METHODS

Data from the KCCR and Statistics Korea between 1999 and 2012 were used to calculate the crude incidence of thyroid cancer in children. To analyze detection methods for cancers, pediatric patients (aged 0-19 years, n = 126) who underwent thyroid surgery for thyroid cancers at our institution were identified. Subjects were divided into two groups by detection method: (1) palpation group and (2) screening group.

RESULTS

The crude incidence of childhood thyroid cancer increased from 0.5 per 100,000 in 1999 to 1.7 in 2012. The proportion of thyroid cancer among total cancers also increased from 4.4% in 1999 to 10.6% in 2012. Among 126 children from our institution, 91 cases (72%) were identified as palpable neck masses, and the remainder were discovered during imaging studies. The numbers in both groups gradually increased during the study period.

CONCLUSIONS

The incidence of childhood thyroid cancer has steadily increased in Korea. Regarding the detection methods of cancers, most tumors are detected by palpation rather than screening, although the rate of masses identified during screening has increased.

Diagnostic accuracy of fine needle aspiration biopsy for detection of malignancy in pediatric thyroid nodules: protocol for a systematic review and meta-analysis

BACKGROUND

Fine needle aspiration biopsy (FNAB) is an accurate test commonly used to determine whether thyroid nodules are malignant in adults. However, less is known about its diagnostic accuracy for this purpose in children, where conduct of FNAB is less frequent, more technically challenging, and pre-test probabilities of malignancy are often higher. The purpose of this systematic review is to evaluate the diagnostic accuracy of FNAB for the detection of malignancy in pediatric thyroid nodules.

METHODS

We will search electronic bibliographic databases (MEDLINE, EMBASE, the Cochrane Library, and Evidence-Based Medicine) from their date of inception, reference lists of included articles, proceedings from relevant conferences, and the table of contents of the Journal of Pediatric Surgery (January 2007-present). Two reviewers will independently screen titles and abstracts and identify diagnostic accuracy studies involving FNAB of the thyroid in children. We will include studies comparing FNAB to a reference standard of surgical histopathology or clinical follow-up for detection of malignancy in pediatric thyroid nodules. Two investigators will independently extract data and assess risk of bias using the Quality of Diagnostic Accuracy Studies-II tool. Pooled estimates of sensitivity, specificity, and positive and negative likelihood ratios will be calculated using bivariate random-effects and hierarchical summary receiver operating characteristic models. In the presence of between-study heterogeneity, we will conduct stratified meta-analyses and meta-regression to determine whether diagnostic accuracy estimates vary by country of origin, use of ultrasound guidance during FNAB, qualifications of the individuals performing/interpreting FNAB, adherence to the Bethesda criteria for cytology classification, length of clinical follow-up, timing of data collection, patient selection methods, and presence of verification bias.

DISCUSSION

This meta-analysis will determine the diagnostic accuracy of FNAB for detection of malignancy in pediatric thyroid nodules and explore whether heterogeneity observed across studies may be explained by variations in patient population, FNAB technique or interpretation, and/or study-level risks of bias. This will be the first study to determine the accuracy of Bethesda cytological classification levels of FNAB (benign, atypical, follicular, suspicious, malignant). We expect that our results will help in guiding clinical decision-making in children with thyroid nodules.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO No. CRD42014007140.

Genetic GIScience: Toward a Place-Based Synthesis of the Genome, Exposome, and Behavome

The exposome, defined as the totality of an individual's exposures over the life course, is a seminal concept in the environmental health sciences. Although inherently geographic, the exposome as yet is unfamiliar to many geographers. This article proposes a place-based synthesis, genetic geographic information science (Genetic GISc) that is founded on the exposome, genome+ and behavome. It provides an improved understanding of human health in relation to biology (the genome+), environmental exposures (the exposome), and their social, societal and behavioral determinants (the behavome). Genetic GISc poses three key needs: First, a mathematical foundation for emergent theory; Second, process-based models that bridge biological and geographic scales; Third, biologically plausible estimates of space-time disease lags. Compartmental models are a possible solution; this article develops two models using pancreatic cancer as an exemplar. The first models carcinogenesis based on the cascade of mutations and cellular changes that lead to metastatic cancer. The second models cancer stages by diagnostic criteria. These provide empirical estimates of the distribution of latencies in cellular states and disease stages, and maps of the burden of yet to be diagnosed disease. This approach links our emerging knowledge of genomics to cancer progression at the cellular level, to individuals and their cancer stage at diagnosis, to geographic distributions of cancer in extant populations. These methodological developments and exemplar provide the basis for a new synthesis in health geography: genetic geographic information science.

Normal vs cancer thyroid stem cells: the road to transformation

Recent investigations in thyroid carcinogenesis have led to the isolation and characterisation of a subpopulation of stem-like cells, responsible for tumour initiation, progression and metastasis. Nevertheless, the cellular origin of thyroid cancer stem cells (SCs) remains unknown and it is still necessary to define the process and the target population that sustain malignant transformation of tissue-resident SCs or the reprogramming of a more differentiated cell. Here, we will critically discuss new insights into thyroid SCs as a potential source of cancer formation in light of the available information on the oncogenic role of genetic modifications that occur during thyroid cancer development. Understanding the fine mechanisms that regulate tumour transformation may provide new ground for clinical intervention in terms of prevention, diagnosis and therapy.

The thyroid status of children and adolescents in Fukushima Prefecture examined during 20-30 months after the Fukushima nuclear power plant disaster: a cross-sectional, observational study

Background

A possible increase in thyroid cancer in the young represents the most critical health problem to be considered after the nuclear accident in Fukushima, Japan (March 2011), which is an important lesson from the Chernobyl disaster (April 1986). Although it was reported that childhood thyroid cancer had started to increase 3–5 yr after the Chernobyl accident, we speculate that the actual period of latency might have been shorter than reported, considering the delay in initiating thyroid surveillance in the then Soviet Union and also the lower quality of ultrasonographic testing in the 1980s. Our primary objectives in the present study were to identify any possible thyroid abnormality in young Fukushima citizens at a relatively early timepoint (20–30 months) after the accident, and also to strive to find a possible relationship among thyroid ultrasonographic findings, thyroid-relevant biochemical markers, and iodine-131 ground deposition in the locations of residence where they stayed during very early days after the accident.

Methods and Findings

This is a cross-sectional study. We targeted the Fukushima residents who were 18 yr old or younger (including fetuses) at the time of the accident. Our examinations comprised a questionnaire, thyroid ultrasonography, thyroid-related blood tests, and urinary iodine measurement. We analyzed a possible relationship among thyroid ultrasonographic findings (1,137 subjects), serum hormonal data (731 subjects), urinary iodine concentrations (770 subjects), and iodine-131 ground deposition (1,137 subjects). We did not find any significant relationship among these indicators, and no participant was diagnosed to contract thyroid cancer.

Conclusions

At the timepoint of 20–30 months after the accident, we did not confirm any discernible deleterious effects of the emitted radioactivity on the thyroid of young Fukushima residents. This is the first report in English detailing the thyroid status of young Fukushima residents after the nuclear disaster.

Poorly differentiated thyroid cancer

PURPOSE OF REVIEW

Poorly differentiated thyroid carcinomas (PDTCs) comprise a small subset of heterogeneous thyroid tumors, occupying an intermediate area between well differentiated follicular or papillary carcinoma and anaplastic carcinomas, from both a histopathogenetic and a clinical point of view. PDTCs are more aggressive than the well differentiated, but less aggressive than the anaplastic thyroid cancers. They have a distinct biological behavior, and the classification of these tumors into a separate group appears justified.

RECENT FINDINGS

The criteria used to diagnose PDTC have been an area of controversy. The multiple definitions of PDTC make the literature difficult to interpret. No clinical features can accurately diagnose PDTCs. Thus, the results of histocytology, immunohistochemistry, and molecular genetics tests aid in diagnosis. Given the aggressiveness of PDTCs, with increased recurrence and decreased survival rates, a multimodality treatment approach is required.

SUMMARY

We conducted a comprehensive review of the current diagnostic and therapeutic tools in the management of patients with PDTCs. The present article aims to review the various aspects of this tumor type, from morphology to immunohistochemistry, and molecular abnormalities from a practical and daily practice-oriented point of view.

Analysis of thyroid malignant pathologic findings identified during 3 rounds of screening (1997-2008) of a cohort of children and adolescents from belarus exposed to radioiodines after the Chernobyl accident

BACKGROUND

Recent studies of children and adolescents who were exposed to radioactive iodine-131 (I-131) after the 1986 Chernobyl nuclear accident in Ukraine exhibited a significant dose-related increase in the risk of thyroid cancer, but the association of radiation doses with tumor histologic and morphologic features is not clear.

METHODS

A cohort of 11,664 individuals in Belarus who were aged ≤18 years at the time of the accident underwent 3 cycles of thyroid screening during 1997 to 2008. I-131 thyroid doses were estimated from individual thyroid activity measurements taken within 2 months after the accident and from dosimetric questionnaire data. Demographic, clinical, and tumor pathologic characteristics of the patients with thyroid cancer were analyzed using 1-way analysis of variance, chi-square tests or Fisher exact tests, and logistic regression.

RESULTS

In total, 158 thyroid cancers were identified as a result of screening. The majority of patients had T1a and T1b tumors (93.7%), with many positive regional lymph nodes (N1; 60.6%) but few distant metastases (M1; <1%). Higher I-131 doses were associated with higher frequency of solid and diffuse sclerosing variants of thyroid cancer (P < .01) and histologic features of cancer aggressiveness, such as lymphatic vessel invasion, intrathyroidal infiltration, and multifocality (all P < .03). Latency was not correlated with radiation dose. Fifty-two patients with self-reported thyroid cancers which were diagnosed before 1997 were younger at the time of the accident and had a higher percentage of solid variant cancers compared with patients who had screening-detected thyroid cancers (all P < .0001).

CONCLUSIONS

I-131 thyroid radiation doses were associated with a significantly greater frequency of solid and diffuse sclerosing variants of thyroid cancer and various features of tumor aggressiveness.

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children

PURPOSE

The purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS).

METHOD AND MATERIALS

A total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report.

RESULTS

Our study found the highest effective doses in neonates and the lowest effective doses were observed in the 10-18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk.

CONCLUSION

Multiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed.

Alpha particle induced DNA damage and repair in normal cultured thyrocytes of different proliferation status

Childhood exposure to ionizing radiation increases the risk of developing thyroid cancer later in life and this is suggested to be due to higher proliferation of the young thyroid. The interest of using high-LET alpha particles from Astatine-211 ((211)At), concentrated in the thyroid by the same mechanism as (131)I [1], in cancer treatment has increased during recent years because of its high efficiency in inducing biological damage and beneficial dose distribution when compared to low-LET radiation. Most knowledge of the DNA damage response in thyroid is from studies using low-LET irradiation and much less is known of high-LET irradiation. In this paper we investigated the DNA damage response and biological consequences to photons from Cobolt-60 ((60)Co) and alpha particles from (211)At in normal primary thyrocytes of different cell cycle status. For both radiation qualities the intensity levels of γH2AX decreased during the first 24h in both cycling and stationary cultures and complete repair was seen in all cultures but cycling cells exposed to (211)At. Compared to stationary cells alpha particles were more harmful for cycling cultures, an effect also seen at the pChk2 levels. Increasing ratios of micronuclei per cell nuclei were seen up to 1Gy (211)At. We found that primary thyrocytes were much more sensitive to alpha particle exposure compared with low-LET photons. Calculations of the relative biological effectiveness yielded higher RBE for cycling cells compared with stationary cultures at a modest level of damage, clearly demonstrating that cell cycle status influences the relative effectiveness of alpha particles.

Aggressive variants of follicular cell-derived thyroid carcinomas: a cytopathologist's perspective

Follicular cell-derived carcinomas of the thyroid gland comprise a heterogeneous group of malignant neoplasms of the thyroid gland with varied histologic appearance and molecular profiles. In most patients, these tumors represent relatively indolent neoplasms; however, certain subtypes/variants behave in an aggressive manner, and the recognition of this subset of tumors is essential because of their variable response to therapy and significant morbidity and mortality. Fine-needle aspiration is considered an essential tool for the diagnosis of suspicious thyroid nodules. In this review, the authors discuss the clinical, histologic, and molecular findings and the prognostic implications of aggressive thyroid neoplasms with emphasis on the characteristic cytomorphologic features on fine-needle aspiration smears.

ETV6-NTRK3 is a common chromosomal rearrangement in radiation-associated thyroid cancer

BACKGROUND

In their previous analysis of papillary thyroid carcinomas (PTCs) from an Ukrainian-American cohort that was exposed to iodine-131 ((131) I) from the Chernobyl accident, the authors identified RET/PTC rearrangements and other driver mutations in 60% of tumors.

METHODS

In this study, the remaining mutation-negative tumors from that cohort were analyzed using RNA sequencing (RNA-Seq) and reverse transcriptase-polymerase chain reaction to identify novel chromosomal rearrangements and to characterize their relation with radiation dose.

RESULTS

The ETS variant gene 6 (ETV6)-neurotrophin receptor 3 (NTRK3) rearrangement (ETV6-NTRK3) was identified by RNA-Seq in a tumor from a patient who received a high (131) I dose. Overall, the rearrangement was detected in 9 of 62 (14.5%) post-Chernobyl PTCs and in 3 of 151 (2%) sporadic PTCs (P = .019). The most common fusion type was between exon 4 of ETV6 and exon 14 of NTRK3. The prevalence of ETV6-NTRK3 rearrangement in post-Chernobyl PTCs was associated with increasing (131) I dose, albeit at borderline significance (P = .126). The group of rearrangement-positive PTCs (ETV6-NTRK3, RET/PTC, PAX8-PPARγ) was associated with significantly higher dose response compared with the group of PTCs with point mutations (BRAF, RAS; P < .001). In vitro exposure of human thyroid cells to 1 gray of (131) I and γ-radiation resulted in the formation of ETV6-NTRK3 rearrangement at a rate of 7.9 × 10(-6) cells and 3.0 × 10(-6) cells, respectively.

CONCLUSIONS

The authors report the occurrence of ETV6-NTRK3 rearrangements in thyroid cancer and demonstrate that this rearrangement is significantly more common in tumors associated with exposure to (131) I and has a borderline significant dose response. Moreover, ETV6-NTRK3 rearrangement can be directly induced in thyroid cells by ionizing radiation in vitro and, thus, may represent a novel mechanism of radiation-induced carcinogenesis.

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

Background

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

Methods

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

Results

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

Conclusions

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

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.