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

Enhancing radioactive iodine (RAI) incorporation in RAI-refractory differentiated thyroid cancer: current insights

Metastatic differentiated thyroid cancer (DTC) is responsible for most thyroid cancer-related deaths, with an even worse prognosis for patients with radioactive iodine (RAI)-refractory DTC (RAIR-DTC). While multikinase inhibitors (MKIs) and tyrosine kinase inhibitors (TKIs) offer effective treatments for RAIR-DTC, most patients remain noncurative and eventually experience disease progression. In addition, long-term use of these medications is hindered by adverse events, drug resistance and high cost. Recently, the use of MKIs and TKIs has reignited interest in enhancing RAI incorporation. This approach aims to restore the effectiveness of RAI therapy in patients with RAIR-DTC by using agents that increase RAI uptake, potentially overcoming current treatment challenges. This review covers the molecular mechanisms behind RAI resistance, the definition of RAIR-DTC and the efforts to enhance RAI incorporation through various agents, including those currently undergoing clinical trials.

Clinical and Pathologic Characteristics of Cytologically Indeterminate Thyroid Nodules with Non-V600E BRAF Alterations

BACKGROUND

Molecular assays serve as a potential risk stratification tool for cytologically indeterminate thyroid nodules (ITNs). BRAF V600E mutations are nearly always associated with thyroid cancer. However, the malignancy risk for ITNs with other less common BRAF alterations is less well understood. In this retrospective cohort study, we examine the risk of malignancy (ROM), histopathologic diagnoses, and clinical outcomes for non-V600E BRAF-altered ITNs.

METHODS

Genomic profiling data obtained from 1034 pre-operative fine-needle aspiration samples from 955 patients were reviewed. Nodules harboring BRAF V600E were excluded. Clinical, radiographic, and histopathologic data were analyzed retrospectively from BRAF-altered ITNs managed surgically at one comprehensive cancer center (2014-2024). Diagnoses were subdivided based on American Thyroid Association (ATA) risk categories.

RESULTS

Thirty-seven patients (3.9%) with non-V600E BRAF-altered ITNs were identified (isolated BRAF mutation: n = 29 [78.4%], BRAF + other mutation: n = 3 [8.1%], BRAF fusion: n = 4 [10.8%], BRAF-like gene expression: n = 1 [2.7%]). All BRAF mutations identified in the cohort were class II (RAS-independent, intermediate to high kinase activity). Nodules had a median pre-operative diameter of 1.8 cm (interquartile range [IQR] 1.4-2.5). Patients presented with nodal metastases in 2.7% (n = 1) of cases, and local invasion was not identified in any patients in the cohort. Approximately half of patients (54.1%) were initially treated with a partial thyroidectomy (lobectomy: n = 17 [45.9%], isthmusectomy: n = 3 [8.1%]), and the remaining patients underwent total thyroidectomy (n = 17 [45.9%]). Median post-operative follow-up was 28 months (IQR 17.8-45.5). ROM for BRAF alterations was 73% (95%CI 59-87%; ATA low risk: 64.9%/ATA int risk: 5.4%/ATA high risk: 2.7%). There were no high-risk cancers identified in patients with isolated BRAF mutation (benign: n = 10 [34.5%], ATA low risk: n = 19 [65.5%]), and the most common isolated mutation was K601E (n = 17, 45.9%) which had a 58.8% ROM (all ATA low risk). Patients with isolated BRAF mutations had a significantly lower rate of ATA intermediate or high risk pathology when compared to all other BRAF alterations (0% vs. 37.5%, p = 0.0072). Only three patients were treated with radioactive iodine post-operatively (8.1%), and no completion thyroidectomy procedures were performed in those who did not initially undergo total thyroidectomy. No patients in the cohort were found to have distant metastatic disease or recurrence, and there were no deaths during the follow-up interval.

CONCLUSIONS

ITNs harboring non-V600E BRAF alterations were rare (3.9% of patients) and typically malignant (73%). Nearly all nodules were benign or ATA low-risk cancers. Only 8% of such nodules were ATA intermediate or high risk cancers. In ITNs with isolated non-V600E BRAF and no other genetic alterations, one-third were non-malignant, and all cancers were ATA low risk. In the appropriate clinical context, thyroid lobectomy or active surveillance can be considered for initial management of non-V600E BRAF-altered ITNs.

Histopathological domain adaptation with generative adversarial networks: Bridging the domain gap between thyroid cancer histopathology datasets

Deep learning techniques are increasingly being used to classify medical imaging data with high accuracy. Despite this, due to often limited training data, these models can lack sufficient generalizability to predict unseen test data, produced in different domains, with comparable performance. This study focuses on thyroid histopathology image classification and investigates whether a Generative Adversarial Network [GAN], trained with just 156 patient samples, can produce high quality synthetic images to sufficiently augment training data and improve overall model generalizability. Utilizing a StyleGAN2 approach, the generative network produced images with an Fréchet Inception Distance (FID) score of 5.05, matching state-of-the-art GAN results in non-medical domains with comparable dataset sizes. Augmenting the training data with these GAN-generated images increased model generalizability when tested on external data sourced from three separate domains, improving overall precision and AUC by 7.45% and 7.20% respectively compared with a baseline model. Most importantly, this performance improvement was observed on minority class images, tumour subtypes which are known to suffer from high levels of inter-observer variability when classified by trained pathologists.

The Prevalence and Prognostic Implications of BRAF K601E Mutations in Thyroid Neoplasms: A Systematic Review and Meta-Analysis

BACKGROUND

Activating mutations in the BRAF oncogene occur in 45% of papillary thyroid carcinomas (PTCs). Though less studied, K601E may identify a clinically distinct subset of thyroid neoplasms.

METHODS

A bioinformatics assessment was conducted using the COSMIC database and in silico data analysis. A systematic search was conducted through August 2024 to identify studies reporting BRAF mutation in thyroid neoplasms. Pooled prevalence, histopathological subtype distribution, extrathyroidal extension, lymph node metastasis, recurrence, and survival were extracted/analyzed from 32 studies (13 191 patients).

RESULTS

In the COSMIC database, BRAF K601E was found in various tissue types but mainly in the thyroid. In silico data analysis revealed a structural and functional basis for differences between K601E and V600E. Upon systematic review, the BRAF K601E mutation was identified in 2.8% of PTCs compared to 22% with V600E. The stratified analysis revealed geographical differences, with higher rates in Italy (5.23%) and the United States of America (3.31%). The K601E mutant was enriched for follicular-patterned variants like NIFTP (11.2% of cases). Meta-analysis demonstrated significantly reduced extrathyroidal extension for K601E versus V600E mutants (RR = 0.22, 95% CI = 0.10-0.50, p = 0.0003).

CONCLUSION

K601E-mutated neoplasms could be a unique clinicopathological entity associated with low-risk histology and reduced extrathyroidal extension, consistent with a more indolent course than V600E mutants. Although detecting K601E may potentially guide conservative management, further prospective studies are needed.

BRAF V600E mutation in thyroid carcinoma: a large-scale study in Han Chinese population

BACKGROUND

The prevalence of genetic mutations in thyroid cancer varies significantly among different ethnic backgrounds. The present study aimed to investigate the clinical potential of BRAF V600E in a large group of homogenous Han Chinese patients.

METHODS

From 2018 to 2021, 6232 thyroid disease patients who underwent thyroidectomy at our hospital were enrolled. We measured the diagnostic value of BRAF and plotted ROC curves. Patients with full clinical-pathological data were selected and divided into the BRAF mutation and wild type groups. We conducted univariate and multivariate analyses to quantify the differences in potential predictive factors of papillary thyroid carcinoma (PTC) patients between the groups. Kaplan-Meier survival analysis was used to estimate overall recurrence and recurrence rate.

RESULTS

The prevalence of BRAF V600E mutation was 86.0% in PTCs. The sensitivity and specificity of BRAF mutation for diagnosing PTC from suspicious lesions were 85.5% and 100%, respectively. The sensitivity and specificity of BRAF analysis in the indeterminate cytology group were 72.5% and 100%, respectively. BRAF mutation showed an independent association with older age, negative HT, larger tumor size, extrathyroidal extension, and multifocality in PTCs. In micro-PTCs (tumor size ≤ 1), the mutation was also positively correlated with progressive phenotypes of extrathyroidal extension and multifocality. BRAF mutation was associated with poorer recurrence-free probability in Kaplan-Meier survival analysis.

CONCLUSIONS

This large single-center study reveals that BRAF V600E is highly prevalent in the Han Chinese population and demonstrates BRAF V600E mutation testing has high diagnostic accuracy and its strong association with the progress of aggressiveness in PTCs and a higher probability of recurrence. BRAF mutation can serve as an accurate marker for diagnosis and decision-making with great value.

LncRNA GAS8-AS1 dinucleotide genetic variantn.713A>G, n.714T>C is associated with early-stage disease, lymph node, and distant metastasis in differentiated thyroid cancer

PURPOSE

Long noncoding RNAs (lncRNAs) play an essential role in the epigenetic regulation of various key genes involved in vital cellular functions. A somatic dinucleotide mutation in the lncRNA GAS8-AS1 was reported in Chinese papillary thyroid cancer. However, GAS8-AS1 dinucleotide alteration and its impact have never been explored in differentiated thyroid cancers and other populations.

METHODS

We extracted genomic DNA from 265 DTCs and 97 normal healthy subjects, PCR amplified and Sanger sequenced to examine the GAS8-AS1 dinucleotide alteration. Calculated genotype/allele frequency to test Hardy-Weinberg Equilibrium (HWE) and performed a genetic model of inheritance to determine its association with DTC risk. Correlated the GAS8-AS1 dinucleotide variant distribution with clinical characteristics to find the association. Predicted GAS8-AS1 RNA secondary structure for wild type and variant using RemuRNA and RNAfold to assess the conformational changes.

RESULTS

GAS8-AS1 dinucleotide alteration (n.713A > G, rs55742939; n.714T > C, rs61118444) identified in DTCs is a germline variant not somatic. The GAS8-AS1 genotype and allele frequency significantly deviated for HWE in DTCs (χ2 = 37.954; p = 0.0001) though not associated with its risk. Dinucleotide variant distribution was remarkably associated with early-stage disease (p = 0.002), lymph node (p = 0.01), and distant metastasis (p = 0.01) in DTCs. The GAS8-AS1 bearing dinucleotide variant markedly showed conformational change compared to that of its wild type.

CONCLUSIONS

These findings indicate that GAS8-AS1 is genetically deregulated and implicated in several stages of DTC tumorigenesis suggesting it could be a promising prognostic biomarker in DTCs.

Unveiling a rare BRAF mutation in minimally invasive follicular thyroid carcinoma: A case report

RATIONALE

Molecular testing is becoming more widely used; however, the accuracy of diagnostic testing remains a primary consideration, especially for molecular testing that detects specific mutations associated with cancers.

PATIENT CONCERNS

A 45-year-old female without documented comorbidities presented a thyroid nodule during a routine health examination. Initial evaluation revealed a 3.8-cm nodule in the left lobe of thyroid, classified as Bethesda System category III on fine needle aspiration cytology. Genetic molecular testing detected the BRAF V600E mutation via quantitative polymerase chain reaction assay, raising concern for papillary thyroid cancer (PTC).

DIAGNOSES

The preoperative impression was PTC based on the detection of BRAF V600E mutation.

INTERVENTIONS

The patient underwent thyroidectomy as well as lymph node dissection with the expectation to treat PTC.

OUTCOMES

The final pathology unexpectedly revealed minimally invasive follicular carcinoma. Confirmatory Sanger sequencing unveiled a novel sequence variation involving nucleotide duplication within the range of 1794 to 1802, a non-V600E BRAF mutation not previously reported in follicular thyroid carcinoma.

LESSONS

This case study demonstrates the clinical relevance of exercising caution in molecular testing and its interpretation of results. For genetic testing used for diagnostic purposes, rigorous validation or cross-checking using different methods should always be considered to ensure appropriate interpretation of molecular results.

Expression of RASSF1A, DIRAS3, and AKAP9 Genes in Thyroid Lesions: Implications for Differential Diagnosis and Prognosis of Thyroid Carcinomas

Thyroid carcinoma is the primary endocrine malignancy worldwide. The preoperative examination of thyroid tissue lesion is often unclear. Approximately 25% of thyroid cancers cannot be diagnosed definitively without post-surgery histopathological examination. The assessment of diagnostic and differential markers of thyroid cancers is needed to improve preoperative diagnosis and reduce unnecessary treatments. Here, we assessed the expression of RASSF1A, DIRAS3, and AKAP9 genes, and the presence of BRAF V600E point mutation in benign and malignant thyroid lesions in a Polish cohort (120 patients). We have also performed a comparative analysis of gene expression using data obtained from the Gene Expression Omnibus (GEO) database (307 samples). The expression of RASSF1A and DIRAS3 was decreased, whereas AKAP9's was increased in pathologically changed thyroid compared with normal thyroid tissue, and significantly correlated with e.g., histopathological type of lesion papillary thyroid cancer (PTC) vs follicular thyroid cancer (FTC), patient's age, tumour stage, or its encapsulation. The receiver operating characteristic (ROC) analysis for the more aggressive FTC subtype differential marker suggests value in estimating RASSF1A and AKAP9 expression, with their area under curve (AUC), specificity, and sensitivity at 0.743 (95% CI: 0.548-0.938), 82.2%, and 66.7%; for RASSF1A, and 0.848 (95% CI: 0.698-0.998), 54.8%, and 100%, for AKAP9. Our research gives new insight into the basis of the aggressiveness and progression of thyroid cancers, and provides information on potential differential markers that may improve preoperative diagnosis.

How do BRAFV600E and TERT promoter mutations interact with the ATA and TNM staging systems in thyroid cancer?

Context

The American Thyroid Association risk stratification (ATA) and the American Joint Committee on Cancer Tumor Node Metastases (TNM) predict recurrence and mortality of differentiated thyroid cancer (DTC). BRAFV600E and TERT promoter mutations have been shown to correlate with the histopathological features and outcome of DTC. Our objectives were to study the correlation of these molecular markers with these clinicopathological-staging systems.

Patients and methods

We studied 296 unselected patients, 214 females and 82 males with a median age of 36 years (IQR 23.3-49.0). BRAFV600E and TERT promoter mutations were tested by PCR-based Sanger sequencing. Data were extracted from medical records and analysed using Chi-Square and Fisher Exact tests and Kaplan Meier analysis.

Results

Of 296 patients tested, 137 (46.3%) had BRAFV600E-positive tumors and 72 (24.3%) were positive for TERT promoter mutations. The BRAFV600E mutation did not correlate with the ATA and TNM staging, being non-significantly different in various stages of these systems and did not predict the development of persistent disease (PD) (P 0.12). Unlike BRAFV600E, TERT promoter mutations were more frequent in the ATA high-risk than in intermediate- or low-risk tumors (P 0.006) and in TNM stages III and IV than lower stages (P <0.0001). TERT promoter mutations also predicted the outcome, being present in 37.2% of patients with PD compared to only 15.4% in those without evidence of disease (P <0.0001). The same pattern was also seen when BRAFV600E and TERT promoter mutations were combined.

Conclusion

TERT promoter mutations alone or in combination with BRAFV600E mutation, but not BRAFV600E mutation alone, correlated well with the ATA and TNM staging and predicted development of PD, especially in higher stages of these systems.

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.

Molecular diagnosis and targeted treatment of advanced follicular cell-derived thyroid cancer in the precision medicine era

Most malignant thyroid tumours are initially treated with surgery or a combination of surgery and radioactive iodine (RAI) therapy. However, in patients with metastatic disease, many tumours become refractory to RAI, and these patients require alternative treatments, such as locoregional therapies and/or systemic treatment with multikinase inhibitors. Improvements in our understanding of the genetic alterations that occur in thyroid cancer have led to the discovery of several targeted therapies with clinical efficacy. These alterations include NTRK (neurotrophic tyrosine receptor kinase) gene fusions, with the tropomyosin receptor kinase inhibitors larotrectinib and entrectinib both approved by the European Medicines Agency and in other markets worldwide. Inhibitors of aberrant proteins resulting from alterations in RET (rearranged during transfection) and BRAF (B-Raf proto-oncogene) have also shown promising efficacy, and so far have received approval by the US Food and Drug Administration. Selpercatinib, a RET kinase inhibitor, was approved for use in Europe in early 2021. With the discovery of multiple actionable targets, it is imperative that effective testing strategies for these genetic alterations are integrated into the diagnostic armamentarium to ensure that patients who could potentially benefit from targeted treatments are identified. In this review, we offer our recommendations on the optimal testing strategies for detecting genetic alterations in thyroid cancer that have the potential to be targeted by molecular therapy. We also discuss the future of treatments for thyroid cancers, including the use of immune checkpoint inhibitors, and new generations of targeted treatments that are being developed to counter acquired tumour resistance.

Identification of prognostic signature with seven LncRNAs for papillary thyroid carcinoma

PURPOSE

With the increasing incidence of thyroid cancer (TC), the prognostic risk assessment of thyroid cancer has been becoming more and more important. The aim of this study was to screen TC-related biomarkers and identify key multi-long non coding RNA (lncRNA) signature for prognostic risk assessment of papillary TC.

MATERIAL AND METHODS

The lncRNAs differentially expressed between TC tissue and adjacent normal tissue was identified by R language. Bioinformatics analysis was applied to screen the lncRNAs significantly associated with prognosis in TC patients and build the multi-lncRNA signature. The lncRNAs were annotated by co-expression and enrichment analysis to demonstrate the underlying mechanism of their effect on prognosis.

RESULTS

285 up-regulated and 174 down-regulated differently expressed lncRNAs were identified. Based on seven signature lncRNAs (AL591846.2, AC253536.3, AC004112.1, LINC00900, AC008555.1, TNRC6C-AS1, LINC01736) a prognostic risk assessment model was built. The model can segregate the patients into the high-risk and low-risk groups (P value <0.0001, CI: 0.02∼0.14). ROC analysis revealed that the area under the curve reached 0.86, indicating that this model had an excellent sensitivity and specificity. Also, the model could act as an independent prognostic indication (HR ​= ​2.90, P value ​= ​0.0094 with multivariate analysis). Annotation results further supported and enriched our understanding of the seven signature lncRNAs. Importantly, expression levels of three of the seven lncRNAs were confirmed in Gene Expression Omnibus (GEO) data.

CONCLUSIONS

This study has provided a promising method for the prognostic risk assessment in patients with TC.

Isocitrate Dehydrogenase IDH1 and IDH2 Mutations in Human Cancer: Prognostic Implications for Gliomas

Background: There are isolated reports of mutations in genes for isocitrate dehydrogenases (IDH1 and IDH2), but few have been examined in a large number of different malignancies. We aimed to analyze mutational prevalence of these genes in a large series of cancers and determine their significance in most mutated phenotype.

Methods: We analyzed the frequencies of IDH1 and IDH2 mutations in 14,726 malignancies of 37 cancers. Furthermore, we examined these mutations in the most frequent cancer (gliomas, 923 cases) from a single cohort, and determined their clinical significance.

Results:IDH1 mutations were present in 3% (473/14,726) of cancers. The highest frequencies were in oligodendrogliomas (91/102, 89%), anaplastic oligodendrogliomas (40/46, 87%), and diffuse astrocytomas (89/116, 77%). IDH2 mutation was detected in <1% (83/14,726) of cancers, but were present in 13% (6/46) of anaplastic oligodendrogliomas, 9% (9/102) of oligodendrogliomas, and in 5% (2/39) of cutaneous squamous cell carcinomas. Further analyses of 923 gliomas revealed 34 and 1% of IDH1 and IDH2 mutations, respectively. In up to 342 months of follow-up, IDH1 and IDH2 mutations were significantly linked with better overall (OS) (both p = 0.01) and progression-free survival (PFS) (p = 0.01; p = 0.004), respectively.

Conclusion:IDH1 and IDH2 are often mutated in a tissue-specific manner, most commonly in gliomas. Mutation in both genes is linked to OS and PFS. Our findings suggest that these genes are promising therapeutic targets and strong prognostic biomarkers in gliomas.

Analysis of ALK, IDH1, IDH2 and MMP8 somatic mutations in differentiated thyroid cancers

Anaplastic lymphoma kinase (ALK), isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) and matrix metalloproteinase 8 (MMP8) gene mutations have been frequently reported in human cancers; however, to the best of our knowledge, they have not been specifically examined in differentiated thyroid cancers (DTCs). Therefore, the present study aimed to determine the somatic mutational frequencies of these genes in DTCs. Mutational analysis of the ALK (exons 23, 24 and 25), IDH1 (exon 4), IDH2 (exon 4), and MMP8 (all exons 1-10) was performed in 126, 271, 271 and 50 DTCs, respectively. All the indicated exons were PCR-amplified and the PCR products were directly sequenced by Sanger sequencing. The present study identified a high frequency (86%; 43/50) of MMP8 single nucleotide polymorphism (SNP) and also found some rare SNPs of this gene (S3C, T32I, L310P and K460T) in DTCs but no somatic mutation in ALK, IDH1, IDH2 and MMP8. Analyses of 414 DTCs from The Cancer Genome Atlas revealed rare ALK (1%) and MMP8 (0.24%) mutations and none in IDH1 and IDH2. Conversely, analyses of 117 aggressive thyroid cancers [84, poorly differentiated thyroid cancer (PDTC); 33, anaplastic thyroid cancer (ATC)] from the Memorial Sloan Kettering Cancer Center cohort revealed ALK mutations in 3% of ATCs and fusions in 3.6% of PDTCs. IDH1 mutation was identified in 1.25% of PDTCs but not in ATC. IDH2 mutation was identified in 3% of ATCs but not in PDTC. The present study demonstrated that these genes are less frequently mutated in DTCs, but common in ATCs and PDTCs. It suggests that these genes serve a role in a small portion of DTCs and a more important role in ATCs and PDTCs and may serve as potential therapeutic targets in these subsets.

Novel Therapeutics in Radioactive Iodine-Resistant Thyroid Cancer

Iodine-resistant cancers account for the vast majority of thyroid related mortality and, until recently, there were limited therapeutic options. However, over the last decade our understanding of the molecular foundation of thyroid function and carcinogenesis has driven the development of many novel therapeutics. These include FDA approved tyrosine kinase inhibitors and small molecular inhibitors of VEGFR, BRAF, MEK, NTRK and RET, which collectively have significantly changed the prognostic outlook for this patient population. Some therapeutics can re-sensitize de-differentiated cancers to iodine, allowing for radioactive iodine treatment and improved disease control. Remarkably, there is now an FDA approved treatment for BRAF-mutated patients with anaplastic thyroid cancer, previously considered invariably and rapidly fatal. The treatment landscape for iodine-resistant thyroid cancer is changing rapidly with many new targets, therapeutics, clinical trials, and approved treatments. We provide an up-to-date review of novel therapeutic options in the treatment of iodine-resistant thyroid cancer.

Prevalence of BRAFV600E mutation in Asian series of papillary thyroid carcinoma-a contemporary systematic review

Papillary thyroid carcinoma (PTC), the most common malignancy of the endocrine system, is frequently driven by BRAFV600E mutation, which was reported in 35-60% cases in Western series. Numerous studies have recently emerged from Asian countries and regions; however sufficient summary is lacking to date. BRAF mutation serves as a diagnostic and prognostic tool in thyroid cancer, therefore establishing a rate of BRAF on the national scale could be of practical significance. We performed systematic reviews of available literature to investigate the prevalence of BRAF mutation in series of PTC from various Asian countries and regions. Out of the total 3,966 reports identified via initial screening, 138 studies encompassing over 40,000 PTCs were included for the final analysis. A vast majority (90.2%) of PTCs with known BRAF status were from East Asia, including China, South Korea, and Japan, with BRAF mutation rates of 71.2%, 75.5%, and 70.6%, respectively. Less abundant Indian and Saudi Arabian series found 45.6% and 46.3% prevalence of BRAFV600E in PTC, respectively. Much limited evidence was available from Thailand, Iran, Kazakhstan, Taiwan, Singapore, Indonesia, Hong Kong, Philippines, Vietnam, Iraq, and Myanmar. No relevant publications were found from other highly populated countries, such as Pakistan, Bangladesh, and Malaysia. After grouping by geographic region, we found that the highest rate of BRAFV600E was reported in the PTC series from East Asia (76.4%). Much lower rate (45-48%) was seen in PTC cohorts from South Asia, Central Asia, and the Middle East while the Southeast Asian series were in between (57%). Further subgroup analysis revealed that studies employing fresh frozen tissue and fine-needle aspirates showed higher rates of BRAF compared to those used formalin-fixed paraffin-embedded tissues. We found that the PTC series enrolled patients' cohorts after 2010 demonstrated a higher rate of BRAF compared to the earlier series. Finally, pediatric PTCs had lower BRAF prevalence compared to the baseline rate for the country. In conclusion, despite considerable among and within countries heterogeneity, the Asian PTC series showed a higher prevalence of BRAFV600E mutation than that in Western series. Causes of geographic heterogeneity, whether genuine (etiology, genetics) or methodology-related should be further investigated.

Case of aggressive metastatic follicular variant papillary thyroid carcinoma with BRAF K601E and BCORL1 mutations

BCL6 corepressor like-1 (BCORL1) mutation has rarely been described in thyroid cancer or in association with BRAF mutations in any malignancy. However, we report a 49-year-old woman who had aggressive follicular variant papillary thyroid carcinoma (FV-PTC) with both the BRAF K601E and BCORL1 mutations. The patient underwent a total thyroidectomy for a 3.6 cm right thyroid nodule and a smaller lesion in the left lobe in 2007; both were FV-PTCs with no lymphovascular invasion or metastases. In 2015, a positron emission tomography-CT scan showed a small defect in the left posterior lateral fifth rib with mild increased hypermetabolic activity with standardised uptake value of 3.9 and another lesion in the right hip at the junction of the femoral neck and trochanter. Tumour biopsy and genetic analysis revealed an uncommon BRAF K601E and a rare BCORL1 mutation. While rare, we report a case of aggressive FV-PTC with both the BRAF K601E and BCORL1 mutations.

Radioiodine-Refractory Thyroid Cancer: Molecular Basis of Redifferentiation Therapies, Management, and Novel Therapies

Recurrent, metastatic disease represents the most frequent cause of death for patients with thyroid cancer, and radioactive iodine (RAI) remains a mainstay of therapy for these patients. Unfortunately, many thyroid cancer patients have tumors that no longer trap iodine, and hence are refractory to RAI, heralding a poor prognosis. RAI-refractory (RAI-R) cancer cells result from the loss of thyroid differentiation features, such as iodide uptake and organification. This loss of differentiation features correlates with the degree of mitogen-activated protein kinase (MAPK) activation, which is higher in tumors with BRAF (B-Raf proto-oncogene) mutations than in those with RTK (receptor tyrosine kinase) or RAS (rat sarcoma) mutations. Hence, inhibition of the mitogen-activated protein kinase kinase-1 and -2 (MEK-1 and -2) downstream of RAF (rapidly accelerated fibrosarcoma) could sensitize RAI refractivity in thyroid cancer. However, a significant hurdle is the development of secondary tumor resistance (escape mechanisms) to these drugs through upregulation of tyrosine kinase receptors or another alternative signaling pathway. The sodium iodide symporter (NIS) is a plasma membrane glycoprotein, a member of solute carrier family 5A (SLC5A5), located on the basolateral surfaces of the thyroid follicular epithelial cells, which mediates active iodide transport into thyroid follicular cells. The mechanisms responsible for NIS loss of function in RAI-R thyroid cancer remains unclear. In a study of patients with recurrent thyroid cancer, expression levels of specific ribosomal machinery-namely PIGU (phosphatidylinositol glycan anchor biosynthesis class U), a subunit of the GPI (glycosylphosphatidylinositol transamidase complex-correlated with RAI avidity in radioiodine scanning, NIS levels, and biochemical response to RAI treatment. Here, we review the proposed mechanisms for RAI refractivity and the management of RAI-refractive metastatic, recurrent thyroid cancer. We also describe novel targeted systemic agents that are in use or under investigation for RAI-refractory disease, their mechanisms of action, and their adverse events.

GPCR-mediated PI3K pathway mutations in pediatric and adult thyroid cancer

Whole exome sequencing (WES) recently identified frequent mutations in the genes of GPCR-mediated PI3K pathway (LPAR4, PIK3CA, and PTEN) in a Chinese population with papillary thyroid cancers (PTCs). The study found LPAR4 mutations as novel gene mutations in adult population with differentiated thyroid cancer (DTC). Here, we determine the prevalence of somatic mutations in this pathway (LPAR4 (exon 1), PIK3CA (exons 9 and 20) and PTEN (exons 5, 6, 7 and 8) in 323 thyroid samples consisting of 17 multinodular goiters (MNG), 89 pediatric DTCs, 204 adult DTCs, and 13 aggressive thyroid cancers including 10 poorly differentiated (PDTC) and 3 anaplastic thyroid cancer (ATC) from another ethnic population. We found 3.37% and 2.45% (includes Q214H, a novel PTEN mutation) in GPCR-mediated PI3K pathway of pediatric and adult DTCs, respectively. Analyses of 507 DTCs from thyroid Cancer Genome Atlas data (TCGA) revealed a low prevalence of mutations in this pathway (1.18%). In 13 cases with PDTC and ATC, we found no mutation in genes of this pathway. By contrast, analyses of 117 aggressive thyroid cancers (PDTC and ATC) from TCGA showed 13% of mutations in this pathway. Moreover, analyses of 1080 pan-cancer cell lines and 9020 solid tumors of TCGA data revealed high rates of mutations in this pathway (cell lines, 24.8%; tumors, 24.8%). In addition, PIK3CA + PTEN (p = <0.001) and LPAR4 + PIK3CA (p = 0.003) significantly co-occurred. Our study reveals a low prevalence of GPCR-mediated PI3K pathway mutations both in pediatric and adult DTCs corroborating the TCGA data and suggests a significant role of this pathway only in a small portion of DTCs. The high prevalence of mutations in this pathway in other solid malignancies suggests an important role in their pathogenesis making it an attractive target for therapeutic intervention both in a small subset of DTCs and other solid cancers.

Low Prevalence of TERT Promoter, BRAF and RAS Mutations in Papillary Thyroid Cancer in the Greek Population

Thyroid cancer is a common endocrine malignancy and displays a variety of histological patterns ranging from adenoma to malignant tumors. Molecular diagnostics have given significant insights into the genetic basis of thyroid tumorigenesis, known to be linked with signaling pathways affected by oxidative stress. We report for the first time a genotype study of TERT promoter combined with BRAF and RAS mutations in Papillary Thyroid Cancer (PTC) cases in the Greek population. Polymerase Chain Reaction and sequencing were used to identify TERT promoter (C228T, C250T, CC243-243TT) mutations, the BRAF (T1799A) mutation and mutations in codons 12, 13, 61 of the HRAS, KRAS and NRAS genes. The most common C228T TERT promoter mutation was identified in 2 PTC cases co-existing with the BRAF mutation. The BRAF T1799A mutation was detected in 10 PTC cases, while two different NRAS mutations in codon 61 (C181A and A182G) were found in 2 PTC cases. These mutations occur in a mutually exclusive manner. Our results indicate that despite the low frequencies, the study of the specific mutations should be encouraged because they are indicative of aggressive forms of thyroid cancer of the papillary histotype in this patient cohort, thus providing insights towards their therapeutic management.

Genome sequencing identifies somatic BRAF duplication c.1794_1796dupTAC;p.Thr599dup in pediatric patient with low-grade ganglioglioma

Gangliogliomas (WHO grade I) are rare tumors affecting the central nervous system and are most frequently observed in children. Next-generation sequencing of tumors is being utilized at an increasing rate in both research and clinical settings to characterize the genetic factors that drive tumorigenesis. Here, we report a rare BRAF somatic mutation (NM_004333.4:c.1794_1796dupTAC; p.Thr599dup) in the tumor genome from a pediatric patient in her late teens, who was initially diagnosed with low-grade ganglioglioma at age 13. This duplication of 3 nt introduces a second threonine residue at amino acid 599 of the BRAF protein. Based on previous studies, this variant is likely to increase kinase activity, similar to the well-characterized BRAF p.Val600Glu (V600E) pathogenic variant. In addition, although the p.T599dup somatic mutation has been documented rarely in human cancers, the variant has not been previously reported in ganglioglioma. The identification of this variant presents an opportunity to consider targeted therapy (e.g., BRAF inhibitor) for this patient.

Long noncoding RNAs: emerging players in thyroid cancer pathogenesis

Thyroid cancer continues to be the most common malignancy of endocrine glands. The incidence of thyroid cancer has risen significantly over the past 4 decades and has emerged as a major health issue. In recent years, significant progress has been achieved in our understanding of the molecular mechanisms of thyroid carcinogenesis, resulting in significant diagnostic, prognostic and therapeutic implications; yet, it has not reached a satisfactory level. Identifying novel molecular therapeutic targets and molecules for diagnosis and prognosis is expected to advance the overall management of this common malignancy. Long noncoding RNAs (lncRNAs) are implicated in the regulation of various key cellular genes involved in cell differentiation, proliferation, cell cycle, apoptosis, migration and invasion mainly through modulation of gene expression. Recent studies have established that lncRNAs are deregulated in thyroid cancer. In this review, we discuss extensively the tumor-suppressive (for example, LINC00271, MEG3, NAMA, PTCSC1/2/3, etc.) and oncogenic (for example, ANRIL, FAL1, H19, PVT1, etc.) roles of various lncRNAs and their possible disease associations implicated in thyroid carcinogenesis. We briefly summarize the strategies and mechanisms of lncRNA-targeting agents. We also describe the potential role of lncRNAs as prospective novel therapeutic targets, and diagnostic and prognostic markers in thyroid cancer.

Thyroid Cancer in Saudi Arabia: A Histopathological and Outcome Study

Most data on differentiated thyroid cancer (DTC) came from the Western world. We describe its salient characteristics and outcome from a Middle Eastern country. Patients and Methods. We studied all cases of TC seen during a 2-year period (2004-2005) seen at our institution. Results. A total of 600 consecutive cases of DTC with a median age at diagnosis of 39 years (5-85) and the female : male ratio of 459 : 141 (76.5% : 23.5%). The cases included classical papillary thyroid cancer (PTC) in 77%, follicular variant PTC in 13.3%, follicular thyroid cancer in 3.2%, and other rare subtypes 6.5%. Total or near-total thyroidectomy was performed in 93%, central and/or lateral neck dissection in 64.5% of cases, and radioactive iodine ablation in 82% of cases. Additional therapies were administered to 154 patients (25.7%). At a median follow-up period of 7.63 years (0.22-13.1), 318 patients (53.3%) were in excellent response, 147 (24.5%) having an indeterminate response, 55 (9.2%) biochemically incomplete, 33 (5.5%) structurally incomplete, and 27 (4.5%) unclassifiable. Twenty cases died secondary to DTC (disease-specific mortality 3.3%). Conclusions. In Saudi Arabia, DTC is common and occurs at young age and predominantly in females. Although remission is common, persistent disease is also common but disease-specific mortality is low.

The micropapillary/hobnail variant of papillary thyroid carcinoma: A review of series described in the literature compared to a series from one southern Italy pathology institution

Papillary thyroid carcinoma (PTC) has a good prognosis with a 10-yr survival greater than 90%. Recently, a micro-papillary pattern with hobnail appearance (MPHC) in PTC has been indicated as associated with poor prognosis, but this suggestion is based only on a few cases from geographical areas different from ours. Two-hundred ninety-nine consecutive PTC cases were collected between the years of 1992 and 2014 at our institution. The corresponding histologic sections (at least 6 for each case) were stained with hematoxylin and eosin and reviewed independently by two pathologists to reach a consensus on the identification and quantification of the MPHC. As done in other cohorts, parallel serial sections were stained with antisera for thyroglobulin, epithelial membrane antigen, thyroid-transcription-factor-1 and Ki 67. BRAF gene mutation at codon 600 and RET/PTC1 gene rearrangements were searched. A comparative statistical analysis was done between the present series and previously published series. Of the 295 PTC, 124 (42.5%) were follicular, 104 (35%) classic, 34 (11.5%) sclerosing, 15 (5%) tall cells, 10 (3.4%) Warthin-like, and 8 (2.7%) MPHC. Four MHPC cases (50%) harbored the BRAF V600E variant, while one was positive for RET/PTC1 rearrangement. Our rate of MPHC-PTC (2.7%) is 2X to 8X greater than those reported previously for cohorts from North America + North Italy, Korea and Mexico. MPHC prognosis appears to be better compared to other cohorts, probably due to not only to the lower rate of the vascular invasion, but also to the smaller size of the MPHC-PTC nodule.