The epigenetic landscape of differentiated thyroid cancer

A bibliometric analysis of follicular thyroid carcinoma: Current situation, hot spots, and global trends

BACKGROUND

Follicular thyroid carcinoma (FTC), the second most prevalent thyroid cancer after papillary thyroid cancer (PTC), tends to metastasize distantly, leading to poorer outcomes. Despite substantial research, a holistic bibliometric analysis of FTC literature is lacking. This study aims to fill this gap by employing bibliometric methods to track FTC research evolution.

METHODS

English FTC publications were systematically gathered from the Web of Science. Bibliometric analysis, using R, VOSviewer, CiteSpace, and Excel, synthesized data and explored global research trends and topics.

RESULTS

From 2000 to 2023, 9086 authors from 1953 institutions across 75 countries contributed to 1776 papers in 491 academic journals on FTC. The last two decades have witnessed a steady increase in publications related to FTC, with the United States leading in terms of publication volume. The United States dominated both in publications and citations, with the National Cancer Institute and Sheue-Yann Cheng as leading contributors. The journal 'Thyroid' featured the most publications, while the 'Journal of Clinical Endocrinology and Metabolism' ranked highest in citation frequency. Research focused on gene expression analysis and preoperative diagnostics, with recent trends shifting toward prognosis management and machine learning due to advances in medical technology and increased health awareness.

CONCLUSION

This comprehensive bibliometric analysis has mapped the landscape of FTC research, highlighting key contributors, institutions, and thematic trends. Current discourse predominantly revolves around genetic analysis, prognostic determinants, and preoperative diagnostics in FTC. This foundational work guides future FTC research, providing insights into its evolution.

BRAF mutation, selected miRNAs and genes expression in primary papillary thyroid carcinomas and local lymph node metastases

Mutations in cancer-related genes are now known to be accompanied by epigenetic events in carcinogenesis by modification of the regulatory pathways and expression of genes involved in the pathobiology. Such cancer-related mutations, miRNAs and gene expression may be promising molecular markers of the most common papillary thyroid carcinoma (PTC). However, there are limited data on their relationships. The aim of this study was to analyse the interactions between BRAF mutations, selected microRNAs (miR-21, miR-34a, miR-146b, and miR-9) and the expression of selected genes (LGALS3, NKX2-1, TACSTD2, TPO) involved in the pathogenesis of PTC. The study cohort included 60 primary papillary thyroid carcinomas (PTC) that were classified as classical (PTC/C; n=50) and invasive follicular variant (PTC/F; n=10), and 40 paired lymph node metastases (LNM). BRAF mutation status in primary and recurrent/persistent papillary thyroid carcinomas was determined. The mutation results were compared both between primary and metastatic cancer tissue, and between BRAF mutation status and selected genes and miRNA expression in primary PTC. Furthermore, miRNAs and gene expression were compared between primary PTCs and non-neoplastic tissue, and local lymph node metastatic tumor, respectively. All studied markers showed several significant mutual interactions and contexts. In conclusion, to the best our knowledge, this is the first integrated study of BRAF mutational status, the expression levels of mRNAs of selected genes and miRNAs in primary PTC, and paired LNM.

Epigenetic Targets and Their Inhibitors in Thyroid Cancer Treatment

Although biologically targeted therapies based on key oncogenic mutations have made significant progress in the treatment of locally advanced or metastatic thyroid cancer, the challenges of drug resistance are urging us to explore other potentially effective targets. Herein, epigenetic modifications in thyroid cancer, including DNA methylation, histone modifications, non-coding RNAs, chromatin remodeling and RNA alterations, are reviewed and epigenetic therapeutic agents for the treatment of thyroid cancer, such as DNMT (DNA methyltransferase) inhibitors, HDAC (histone deacetylase) inhibitors, BRD4 (bromodomain-containing protein 4) inhibitors, KDM1A (lysine demethylase 1A) inhibitors and EZH2 (enhancer of zeste homolog 2) inhibitors, are updated. We conclude that epigenetics is promising as a therapeutic target in thyroid cancer and further clinical trials are warranted.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

Tumor biomarkers are molecules at genetic or protein level, or certain evaluable characteristics. These help in perfecting patient management. Over the past decade, advanced and more sensitive techniques have led to the identification of many new biomarkers in the field of oncology. A knowledge of the recent developments is essential for their application to clinical practice, and furthering research. This review provides a comprehensive account of such various markers identified in thyroid carcinoma, the most common endocrine malignancy. While some of these have been brought into use in routine patient management, others are novel and need more research before clinical application.

Abstract

Thyroid cancer is the most common endocrine malignancy. Recent developments in molecular biological techniques have led to a better understanding of the pathogenesis and clinical behavior of thyroid neoplasms. This has culminated in the updating of thyroid tumor classification, including the re-categorization of existing and introduction of new entities. In this review, we discuss various molecular biomarkers possessing diagnostic, prognostic, predictive and therapeutic roles in thyroid cancer. A comprehensive account of epigenetic dysregulation, including DNA methylation, the function of various microRNAs and long non-coding RNAs, germline mutations determining familial occurrence of medullary and non-medullary thyroid carcinoma, and single nucleotide polymorphisms predisposed to thyroid tumorigenesis has been provided. In addition to novel immunohistochemical markers, including those for neuroendocrine differentiation, and next-generation immunohistochemistry (BRAF V600E, RAS, TRK, and ALK), the relevance of well-established markers, such as Ki-67, in current clinical practice has also been discussed. A tumor microenvironment (PD-L1, CD markers) and its influence in predicting responses to immunotherapy in thyroid cancer and the expanding arena of techniques, including liquid biopsy based on circulating nucleic acids and plasma-derived exosomes as a non-invasive technique for patient management, are also summarized.

Emerging Roles of Circular RNAs in Thyroid Cancer

Thyroid cancer (TC) has the highest incidence among endocrine malignancies. Thus, it is essential to achieve a deep understanding of various mechanisms of development and progression of TC. circRNAs are recognized by multiple studies as being dysregulated in TC. Accumulating evidences have revealed that circRNAs serve as regulatory molecules involved in various biological processes in TC, including cell proliferation, apoptosis, invasion/migration, metabolism, and chemoresistance. Furthermore, circRNA can also serve as an effective tool in TC researches of diagnosis, prognosis, and treatments. Thus, this review is to outline the characteristics of circRNAs, generalize their categories and functions, and highlight the expression of circRNAs in TC. Meanwhile, we are expecting to achieve a comprehensive understanding of new therapies based on circRNAs in treating or preventing TC.

Study of Essential and Toxic Metal Imbalances in the Scalp Hair of Thyroid Cancer Patients in Comparison with Healthy Donors

Thyroid cancer is among the most common type of head and neck cancer; diet, age, gender and environmental factors play vital roles in its malignancy. The present study was carried out to assess the imbalances in the contents of trace metals due to onset and progression of thyroid cancer. Scalp hair was used as matrix for the evaluation of toxic and trace metals. Quantification of the metals was done through atomic absorption spectrometry. In comparison with healthy subjects, the thyroid cancer patients revealed significantly higher median levels of Mn (71%), Co (64%), Cr (55%), K (49%), Fe (45%), Mg (42%), Pb (36%), Na (30%), and Ni (26%), while the median level of Zn was considerably lower in the patients. The correlation coefficients among the metals in the patients demonstrated significantly different communal relationships compared with the healthy counterparts. Multivariate methods exhibited noticeably dissimilar apportionment among the metals in the patients than the controls. Significant disparities in the metal levels were also noticed for various types (anaplastic thyroid cancer, follicular thyroid cancer, papillary thyroid cancer, and medullary thyroid cancer) as well as stages (I, II, III, and IV) among the thyroid cancer patients. Majority of the metals revealed perceptible disparities in their contents based on gender, habitat, dietary habits, and smoking habits of the patients and controls. Overall, the study showed significantly divergent distribution and associations of the essential and toxic metal levels in the scalp hair of the patients in comparison with the levels in controls.

Alterations of regulatory factors and DNA methylation pattern in thyroid cancer

PURPOSE

DNA methylation plays an important role in thyroid oncogenesis. The aim of this study was to investigate the connection between global and local DNA methylation status and to establish the levels of important DNA methylation regulators (TET family and DNMT1) in thyroid tumours: follicular adenoma-FA, papillary thyroid carcinoma-PTC (classic papillary thyroid carcinoma-cPTC and papillary thyroid carcinoma follicular variant fvPTC).

METHODS

Global DNA methylation profile in thyroid tumours tissue (41 paired samples) was assessed by 5-methylcytosine and 5-hydroxymethylcytosine levels evaluation (ELISA), along with TETs and DNMT1 genes expression quantification. Also, it was investigated for the first time TET1 and TET2 promoter's methylation in thyroid tumours. BRAF V600E mutation and RET/PTC translocation testing were performed on all investigated samples. In vitro studies upon DNA methylation in K1 thyroid cancer cells were performed with demethylating agents (5-AzaC and vitamin C).

RESULTS

TET1 and TET2 displayed a significantly reduced gene expression level in PTC, while DNMT1 gene presented a high level of expression. PTC samples presented increased levels of 5-methylcytosine and low levels of 5-hydroxymethylcytosine. 5-methylcytosine levels were associated with TET1/TET2 expression levels. TET1 gene expression was significantly lower in patients positive for BRAF mutation and with RET/PTC rearrangement. TET2 gene was found hypermethylated in thyroid carcinoma patients overall, especially in PTC-follicular variant samples (p= 0.0002), where TET2 gene expression levels were significantly reduced (p= 0.0031). Furthermore, the data indicate for all thyroid cancer patients a good sensitivity (81.08%) and specificity (86.49%) regarding the use of TET1 (p< 0.0001), and TET2 (71.79%, 64.10%, p= 0.0001) hypermethylation as biomarkers for thyroid oncogenesis.

CONCLUSIONS

These results suggest that TET1/TET2 gene expression and methylation may serve as potential diagnostic tools for thyroid neoplasia. Our study showed that the methylation of TET1 increases in malignant thyroid tumours. fvPTC patients presented lower methylation levels compared to cPTC and could be a discriminatory factor between two cancer types and benign lesions. TET2 is a poorer discriminator between FA and fvPTC, but it can be useful for cPTC identification. K1-cells treated with demethylating agents showed a demethylation effect, especially upon TET2 gene. The cumulative effect of L-AA and 5-AzaC proved to have a potent combined demethylating effect on genes promoter's activation and could open new perspectives for thyroid cancer therapy.

MOF Regulates TNK2 Transcription Expression to Promote Cell Proliferation in Thyroid Cancer

MOF is a well-known histone acetyltransferase to catalyze acetylation of histone H4 lysine 16 (K16), and it is relevant to diverse biological processes, such as gene transcription, cell cycle, early embryonic development and tumorigenesis. Here, we identify MOF as an oncogene in most thyroid cancer. It is found that expression level of MOF was significantly upregulated in most thyroid cancer tissue samples and cell lines. MOF-deficient in both BHP-10-3 and TT2609 cell lines inhibited cell proliferation by blocking the cell cycle in G1 phase and enhanced cell apoptosis. Mechanistically, MOF bound the TNK2 promoter to activate TNK2 transcription. Furthermore, the expression level of TNK2 was decreased with the histone acetyltransferase inhibitor. Besides, MOF promoted proliferation of thyroid cancer cells through increased phosphorylation of AKT, thus activating the PI3K/AKT pathway. Ultimately, our findings indicated that MOF played an oncogene role in development and progression of thyroid cancer and may be a potential novel target for the treatment of thyroid cancer.

The Prognostic Value of MicroRNAs in Thyroid Cancers-A Systematic Review and Meta-Analysis

Thyroid cancer (TC) includes various phenotypes, from indolent to highly aggressive cancer. The limitations of the current prognostication systems to predict the recurrence risk and the variability in expression of the genes involved in the thyroid carcinogenesis uncover the need for new prognostic biomarkers by taking into account potential epigenetic differences. We aimed to summarize the current knowledge regarding the prognostic impact of microRNAs (miRNAs) in TC. A literature search was conducted in PubMed, Embase, Scopus, and Web of Science databases. Both upregulated and downregulated miRNAs are significantly correlated with worse overall survival (hazard ratio (HR) = 5.94, 95% CI: 2.73-12.90, p < 0.001; HR = 0.51, 95% CI: 0.26-0.96, p = 0.048) disease/recurrence-free survival (HR = 1.58, 95% CI: 1.08-2.32, p = 0.003; HR = 0.37, 95%, CI: 0.24-0.60, p < 0.001). Sensitivity analysis revealed a significant association between the higher expression of miR-146b, miR-221, and miR-222 and the recurrence of papillary TC (OR = 9.11, 95% CI 3.00 to 27.52; p < 0.001; OR = 3.88, 95% CI 1.34 to 11.19, p < 0.001; OR = 6.56, 95% CI 2.75 to 15.64, p < 0.001). This research identified that miR-146b, miR-221, and miR-222 could serve as potential prognostic biomarkers in TC, particularly in PTC. Further studies are needed to strengthen these findings and sustain its clinical applicability.

Cancer Stem Cells in Thyroid Tumors: From the Origin to Metastasis

Thyroid tumors are extremely heterogeneous varying from almost benign tumors with good prognosis as papillary or follicular tumors, to the undifferentiated ones with severe prognosis. Recently, several models of thyroid carcinogenesis have been described, mostly hypothesizing a major role of the thyroid cancer stem cell (TCSC) population in both cancer initiation and metastasis formation. However, the cellular origin of TCSC is still incompletely understood. Here, we review the principal epigenetic mechanisms relevant to TCSC origin and maintenance in both well-differentiated and anaplastic thyroid tumors. Specifically, we describe the alterations in DNA methylation, histone modifiers, and microRNAs (miRNAs) involved in TCSC survival, focusing on the potential of targeting aberrant epigenetic modifications for developing novel therapeutic approaches. Moreover, we discuss the bidirectional relationship between TCSCs and immune cells. The cells of innate and adaptive response can promote the TCSC-driven tumorigenesis, and conversely, TCSCs may favor the expansion of immune cells with protumorigenic functions. Finally, we evaluate the role of the tumor microenvironment and the complex cross-talk of chemokines, hormones, and cytokines in regulating thyroid tumor initiation, progression, and therapy refractoriness. The re-education of the stromal cells can be an effective strategy to fight thyroid cancer. Dissecting the genetic and epigenetic landscape of TCSCs and their interactions with tumor microenvironment cells is urgently needed to select more appropriate treatment and improve the outcome of patients affected by advanced differentiated and undifferentiated thyroid cancers.

Overexpression of Histone H3 Lysine 27 Trimethylation Is Associated with Aggressiveness and Dedifferentiation of Thyroid Cancer

A variety of epigenetic dysregulations are observed in thyroid malignancies. EZH2, the catalytic subunit of polycomb repressive complex 2, is upregulated in advanced thyroid cancers. EZH2 can catalyze trimethylation of histone H3 at lysine 27 (H3K27me3) and contribute to transcriptional silencing of target genes. Here, we investigated the immunohistochemical expression of H3K27me3 in neoplastic and normal thyroid tissues. Normal thyroid epithelial cells typically exhibited nuclear staining of moderate intensity. A similar expression pattern was observed in nodular goiters and follicular adenomas. By contrast, strong H3K27me3 expression was evident in 80% (8/10) lymphocytic thyroiditis, 63% (80/127) papillary thyroid cancer, 41% (7/17) follicular thyroid cancer, and 73% (8/11) poorly differentiated and anaplastic thyroid cancer. In differentiated thyroid cancer, strong H3K27me3 expression was associated with extrathyroidal extension (p < 0.001), lymphovascular invasion (p = 0.029), lymph node metastasis (p = 0.006), and higher risk of recurrence (p = 0.003). Our results indicate that H3K27me3 overexpression may be implicated in aggressiveness and dedifferentiation of thyroid cancer. In addition to prognostication, the predictive value of H3K27me3 expression deserves further investigation given the recent development of epigenetic targeting agents.

MKL1 overexpression predicts poor prognosis in patients with papillary thyroid cancer and promotes nodal metastasis

Papillary thyroid cancer (PTC), the most common thyroid malignancy, has a strong propensity for cervical lymph node metastasis (LNM), which increases the risk of locoregional recurrence and decreases survival probability in some high-risk groups. Hence, there is a pressing requirement for a reliable biomarker to predict LNM in thyroid cancer. In the present study, MKL1 (also known as MRTFA) expression was significantly increased in PTC patients with LNM compared with those without. Further receiver operating characteristic (ROC) analysis showed that MKL1 expression had a diagnostic value in the differentiation of LNM in PTC. Furthermore, Kaplan-Meier analysis revealed that high MKL1 expression was associated with significantly decreased survival in PTC. Additionally, our study indicated that MKL1 promoted the migration and invasion of PTC cells. MKL1 interacted with and recruited Smad3 to the promoter of MMP2 to activate MMP2 transcription upon treatment with TGF-β. Moreover, there was significant correlation between expression of TGF-β, MKL1 and MMP2 in our clinical cohort of specimens from individuals with PTC. Our results suggest that the detection of MKL1 expression could be used to predict cervical LNM and inform post-operative follow-up in individuals with PTC.

Systems Biology Approaches to Investigate Genetic and Epigenetic Molecular Progression Mechanisms for Identifying Gene Expression Signatures in Papillary Thyroid Cancer

Thyroid cancer is the most common endocrine cancer. Particularly, papillary thyroid cancer (PTC) accounts for the highest proportion of thyroid cancer. Up to now, there are few researches discussing the pathogenesis and progression mechanisms of PTC from the viewpoint of systems biology approaches. In this study, first we constructed the candidate genetic and epigenetic network (GEN) consisting of candidate protein–protein interaction network (PPIN) and candidate gene regulatory network (GRN) by big database mining. Secondly, system identification and system order detection methods were applied to prune candidate GEN via next-generation sequencing (NGS) and DNA methylation profiles to obtain the real GEN. After that, we extracted core GENs from real GENs by the principal network projection (PNP) method. To investigate the pathogenic and progression mechanisms in each stage of PTC, core GEN was denoted in respect of KEGG pathways. Finally, by comparing two successive core signaling pathways of PTC, we not only shed light on the causes of PTC progression, but also identified essential biomarkers with specific gene expression signature. Moreover, based on the identified gene expression signature, we suggested potential candidate drugs to prevent the progression of PTC with querying Connectivity Map (CMap).

The Current Histologic Classification of Thyroid Cancer

Thyroid cancers of follicular cell derivation provide excellent phenotype-genotype correlations. Current morphologic classifications are complex and require simplification. Benign adenomas have follicular or papillary architecture and bland cytology. Well-differentiated thyroid carcinomas exhibit follicular architecture, expansile growth, and variable cytologic atypia and invasiveness; low-risk tumors have excellent prognosis after surgical resection whereas widely-invasive and angioinvasive tumors warrant total thyroidectomy and radioablation. Papillary carcinoma is less differentiated; indolent microcarcinomas can be managed by active surveillance, whereas clinical lesions with local or distant spread require therapy. Progression gives rise to poorly differentiated and anaplastic carcinomas that are less common but far more aggressive.

Human telomerase reverse transcriptase in papillary thyroid cancer: gene expression, effects of silencing and regulation by BET inhibitors in thyroid cancer cells

PURPOSE

Mutations in TERT promoter have been detected in the more aggressive papillary thyroid cancers (PTCs). To elucidate the role of TERT as an eligible molecular target in these tumors, the expression of hTERT was analyzed in a series of PTCs and the effects of both pharmacological and RNA-interference-induced hTERT silencing were investigated in two human PTC cell lines (K1 and BCPAP).

METHODS

The expression levels of hTERT mRNA and protein were evaluated by real-time PCR and western blot assays, respectively. Effects of hTERT silencing on PTC cell lines were analyzed by MTT, migration and western blot assays. Pharmacological inhibition of hTERT was performed using two bromodomain and extra-terminal (BET) inhibitors, JQ1 and I-BET762.

RESULTS

hTERT expression results increased in 20 out of 48 PTCs, including tumors either positive or negative for the presence of hTERT promoter and/or BRAF mutations. In K1 and BCPAP cells, hTERT silencing determined a reduction in cell viability (~50% for K1 and ~70%, for BCPAP, vs control) and migration properties that were associated with a decrease of AKT phosphorylation and β-Catenin expression. Moreover, hTERT mRNA levels were down-regulated by two BET inhibitors, JQ1 and I-BET762, which at the same dosage (0.5 and 5 µM) reduced the growth of these thyroid cancer cells.

CONCLUSIONS

These findings demonstrate that hTERT may represent an excellent therapeutic target in subgroups of aggressive PTCs.

ZNF677 Suppresses Akt Phosphorylation and Tumorigenesis in Thyroid Cancer

The zinc finger protein 677 (ZNF677) belongs to the zinc finger protein family, which possesses transcription factor activity by binding sequence-specific DNA. Previous studies have reported its downregulated by promoter methylation in non-small cell lung cancer. However, its biological role and exact mechanism in human cancers, including thyroid cancer, remain unknown. In this study, we demonstrate that ZNF677 is frequently downregulated by promoter methylation in primary papillary thyroid cancers (PTC) and show that decreased expression of ZNF677 is significantly associated with poor patient survival. Ectopic expression of ZNF677 in thyroid cancer cells dramatically inhibited cell proliferation, colony formation, migration, invasion, and tumorigenic potential in nude mice and induced cell-cycle arrest and apoptosis. Conversely, knockdown of ZNF677 promoted thyroid cancer cell proliferation and colony formation. ZNF677 exerted its tumor suppressor functions in thyroid cancer cells through transcriptional repression of two targets CDKN3 and HSPB1 (or HSP27), thereby inhibiting phosphorylation and activation of Akt via distinct mechanisms. Taken together, our data show that ZNF677 functions as a tumor suppressor and is frequently silenced via promoter methylation in thyroid cancer.Significance: These findings report a tumor suppressive role of the zinc-finger protein ZNF677 in primary papillary thyroid cancer through inhibition of Akt phosphorylation. Cancer Res; 78(18); 5216-28. ©2018 AACR.

Immunohistochemical Biomarkers in Thyroid Pathology

The application of immunohistochemistry to the diagnosis of thyroid lesions has increased as new biomarkers have emerged. In this review, we discuss the biomarkers that are critical for accurate diagnosis, prognosis, and management. Immunohistochemical markers are used to confirm that an unusual tumor in the thyroid is indeed of thyroid origin, either of follicular epithelial or C-cell differentiation; the various mimics include nonthyroidal lesions such as parathyroid tumors, paragangliomas, thymic neoplasms, and metastatic malignancies. Tumors of thyroid follicular epithelial cells can be further subclassified using a number of immunohistochemical biomarkers that can distinguish follicular-derived from C-cell lesions and others that support malignancy in borderline cases. The use of mutation-specific antibodies can distinguish papillary carcinomas harboring a BRAF^V600E mutation from RAS-like neoplasms. Immunostains have been developed to further identify molecular alterations underlying tumor development, including some rearrangements. Altered expression of several biomarkers that are known to be epigenetically modified in thyroid cancer can be used to assist in predicting more aggressive behavior such as a propensity to develop locoregional lymphatic spread. Immunohistochemistry can assist in identifying lymphatic and vascular invasion. Biomarkers can be applied to determine dedifferentiation and to further classify poorly differentiated and anaplastic carcinomas. The rare tumors associated with genetic predisposition to endocrine neoplasia can also be identified using some immunohistochemical stains. The application of these ancillary tools allows more accurate diagnosis and better understanding of pathogenesis while improving prediction and prognosis for patients with thyroid neoplasms.

Increased Global DNA Hypomethylation in Distant Metastatic and Dedifferentiated Thyroid Cancer

CONTEXT

Global DNA hypomethylation is a major event for the development and progression of cancer, although the significance in thyroid cancer remains unclear. Therefore, we aimed to investigate its role in thyroid cancer progression and its potential as a prognostic marker.

METHODS

Global hypomethylation of Alu repeats was used as a surrogate marker for DNA global hypomethylation, and was assessed using the Quantification of Unmethylated Alu technique. Mutations in BRAF and RAS were determined by Sanger sequencing.

RESULTS

Ninety primary thyroid tumors were included [28 low-risk differentiated thyroid cancer (DTC), 13 pediatric DTC, 33 distant metastatic DTC, 7 poorly differentiated thyroid cancer (PDTC), and 9 anaplastic thyroid cancer (ATC)], as well as 24 distant metastases and 20 normal thyroid tissues. An increasing hypomethylation was found for distant metastatic DTC [median, 4.0; interquartile range (IQR), 3.1 to 6.2] and PDTC/ATC (median, 9.3; IQR, 7.0 to 12.1) as compared with normal thyroid tissue (median, 2.75; IQR, 2.30 to 3.15), whereas low-risk and pediatric DTC were not affected by hypomethylation. Alu hypomethylation was similar between distant metastases and matched primary tumors. Within distant metastatic DTC, Alu hypomethylation was increased in BRAF vs RAS mutated tumors. Kaplan-Meier and Cox regression analyses showed that thyroid cancer-related and all-cause mortality were associated with tumor hypomethylation, but this association was lost after adjustment for thyroid cancer risk category.

CONCLUSION

Distant metastatic DTC, PDTC, and ATC were increasingly affected by global Alu hypomethylation, suggesting that this epigenetic entity may be involved in thyroid cancer progression and dedifferentiation.

Active Surveillance for Papillary Thyroid Microcarcinoma: Challenges and Prospects

Active surveillance (AS) can be considered as an alternative to immediate surgery in low-risk papillary thyroid microcarcinoma (PTMC) without clinically apparent lymph nodes, gross extrathyroidal extension (ETE), and/or distant metastasis according to American Thyroid Association. However, in the past AS has been controversial, as evidence supporting AS in the management of PTMC was scarce. The most prominent of these controversies included, the limited accuracy and utility of ultrasound (US) in the detection of ETE, malignant lymph node involvement or the advent of novel lymph node malignancy during AS, and disease progression. We summarized publications and indicated: (1) US, performer-dependent, could not accurately diagnose gross ETE or malignant lymph node involvement in PTMC. However, the combination of computed tomography and US provided more accurate diagnostic performance, especially in terms of selection sensitivity. (2) Compared to immediate surgery patients, low-risk PTMC patients had a slightly higher rate of lymph node metastases (LNM), although the overall rate for both groups remained low. (3) Recent advances in the sensitivity and specificity of imaging and incorporation of diagnostic biomarkers have significantly improved confidence in the ability to differentiate indolent vs. aggressive PTMCs. Our paper reviewed current imagings and biomarkers with initial promise to help select AS candidates more safely and effectively. These challenges and prospects are important areas for future research to promote AS in PTMC.

Preclinical Imaging for the Study of Mouse Models of Thyroid Cancer

Thyroid cancer, which represents the most common tumors among endocrine malignancies, comprises a wide range of neoplasms with different clinical aggressiveness. One of the most important challenges in research is to identify mouse models that most closely resemble human pathology; other goals include finding a way to detect markers of disease that common to humans and mice and to identify the most appropriate and least invasive therapeutic strategies for specific tumor types. Preclinical thyroid imaging includes a wide range of techniques that allow for morphological and functional characterization of thyroid disease as well as targeting and in most cases, this imaging allows quantitative analysis of the molecular pattern of the thyroid cancer. The aim of this review paper is to provide an overview of all of the imaging techniques used to date both for diagnosis and theranostic purposes in mouse models of thyroid cancer.

Epigenetic Modifications: Novel Therapeutic Approach for Thyroid Cancer

The incidence of thyroid cancer is growing the fastest among all cancers in the United States, especially in women. The number of patients with thyroid neoplasm is part of an even larger number of patients who often need to undergo an operation to exclude a cancer diagnosis. While differentiated thyroid cancer (papillary thyroid cancer and follicular thyroid cancer) accounts for most cases of thyroid cancer and has a relatively good prognosis, effective treatments for patients with de-differentiated and anaplastic thyroid cancer are still gravely needed. Despite progress in the identification of genetic changes in thyroid cancer, the impact of aberrant epigenetic alterations on thyroid cancer remains to be fully elucidated. Understanding of the roles of epigenetic changes in thyroid cancer could open new opportunities for the identification of innovative molecular targets for novel treatment modalities, especially for anaplastic thyroid cancer for which treatment is very limited. This article briefly reviews the studies that exemplify the potential for and promise of using epigenetic regulators in the treatment of thyroid cancer.