RET/PTC Gene Rearrangements in Thyroid Carcinogenesis: Assessment and Clinico-Pathological Correlations

Tilianin regulates the proliferation, invasion and tumor immune microenvironment of thyroid cancer cells through the TLR4/NF-κB axis

Thyroid cancer is the most prevalent form of endocrine malignancy. Tilianin has demonstrated anti-tumor properties in ovarian cancer and non-small cell lung cancer (NSCLC), while its effects on thyroid cancer progression remain elusive. Hence, this research explored the role of Tilianin in thyroid cancer development and clarified the underlying mechanisms. The findings indicated that Tilianin reduced cell viability of TPC-1 (IC50 = 38.97 μM) and IHH4 (IC50 = 27.69 μM) cells dose-dependently and inhibited the expression of Ki-67. Additionally, Tilianin impaired the invasion capacity of TPC-1 and IHH4 cells, decreased the PD-L1 level, strengthened the CD8+T cell viability, and elevated the secretions of IFN-γ, IL-2, and TNF-α in CD8+T cells. Furthermore, Tilianin could suppress the activation of the TLR4/NF-κB pathway. The inhibitory effects of Tilianin on TPC-1 cell proliferation, invasion, and immune escape were reversed by overexpression of TLR4. In vivo, oral administration of Tilianin restrained thyroid cancer tumor growth, reduced the levels of Ki-67, PD-L1, TLR4, and p-NF-κB, and increased CD8+ T cell levels. In summary, Tilianin effectively restrained thyroid cancer cell proliferation, invasion, and tumor immune microenvironment through inactivating the TLR4/NF-κB pathway.

Detection of genetic mutations in 855 cases of papillary thyroid carcinoma by next generation sequencing and its clinicopathological features

OBJECTIVE

To investigate the genetic mutations in patients with papillary thyroid carcinoma (PTC) and their clinicopathological features by next generation sequencing (NGS).

METHODS

NGS technology was used to detect genetic mutations in PTC patients, and clinicopathological features were collected.

RESULTS

①Among 855 PTC patients, 810 patients had genetic mutations, and 45 patients had no genetic mutation. ②BRAF mutation was associated with tumor diameter (P < 0.001) and histological subtypes (P = 0.002). The abundance of V600E mutation was associated with gender (P = 0.004), tumor diameter (P < 0.001), bilateral presentation (P = 0.001), extrathyroidal extension (P < 0.001), lymphatic metastasis (P < 0.001), histological subtypes (P = 0.002) and TNM staging (P = 0.000); The different mutation abundance of V600E was associated with tumor diameter (P < 0.001), multifocal presentation (P = 0.047), bilateral presentation (P = 0.001), extrathyroidal extension (P = 0.001), lymphatic metastasis (P < 0.001), histological subtypes (P = 0.022) and TNM staging (P = 0.000). ③RET fusion was associated with tumor diameter (P < 0.001) and lymphatic metastasis (P = 0.005). ④TERT mutation was associated with gender (P = 0.043), tumor diameter (P < 0.001), extrathyroidal extension (P = 0.028) and TNM staging (P = 0.017). ⑤RAS mutation was associated with histological subtypes (P < 0.001). ⑥NTRK and PIK3CA mutations were not associated with clinicopathological features.

CONCLUSION

NGS technology can comprehensively analyze the genetic mutations in PTC patients, which provides important prompts for the occurrence, development, diagnosis and treatment of PTC. In addition, BRAF V600E mutation, RET fusion and TERT mutation are associated with a number of high-risk clinicopathological features. Detection of genetic mutations in PTC patients by NGS is of great significance.

Next-generation sequencing identified that RET variation associates with lymph node metastasis and the immune microenvironment in thyroid papillary carcinoma

BACKGROUND

To date, although most thyroid carcinoma (THCA) achieves an excellent prognosis, some patients experience a rapid progression episode, even with differentiated THCA. Nodal metastasis is an unfavorable predictor. Exploring the underlying mechanism may bring a deep insight into THCA.

METHODS

A total of 108 THCA from Chinese patients with next-generation sequencing (NGS) were recruited. It was used to explore the gene alteration spectrum of THCA and identify gene alterations related to nodal metastasis in papillary thyroid carcinoma (PTC). The Cancer Genome Atlas THCA cohort was further studied to elucidate the relationship between specific gene alterations and tumor microenvironment. A pathway enrichment analysis was used to explore the underlying mechanism.

RESULTS

Gene alteration was frequent in THCA. BRAF, RET, POLE, ATM, and BRCA1 were the five most common altered genes. RET variation was positively related to nodal metastasis in PTC. RET variation is associated with immune cell infiltration levels, including CD8 naïve, CD4 T and CD8 T cells, etc. Moreover, Step 3 and Step 4 of the cancer immunity cycle (CIC) were activated, whereas Step 6 was suppressed in PTC with RET variation. A pathway enrichment analysis showed that RET variation was associated with several immune-related pathways.

CONCLUSION

RET variation is positively related to nodal metastasis in Chinese PTC, and anti-tumor immune response may play a role in nodal metastasis triggered by RET variation.

Role of Genetic Testing in the Management of Indeterminate Thyroid Nodules in the Indian Setting

The increased detection of thyroid nodules in the human population has led to an increase in the number of thyroid surgeries without an improvement in survival outcomes. Though the choice for surgery is straightforward in malignant thyroid nodules, the decision is far more complex in those nodules that get categorized into indeterminate thyroid nodules (ITN) by fine needle aspiration. Therefore, there is a pressing need to develop a tool that will aid in decision-making among the ITN. In this context, the development of various molecular testing (MT) panels has helped to confirm or rule out malignancy, reducing unnecessary surgeries and potentially guiding the extent of surgery as well. Currently, such tests are widely used among the Western population but these MT panels are not used by the South Asian population because of non-availability of validated panels and the high cost involved. There is a need to develop a suitable panel which is population-specific and validate the same. In this review, we would focus on current trends in the management of ITN among the South Asian population and how to develop a novel MT panel which is cost-effective, with high diagnostic accuracy obviating the need for expensive panels that already exist.

Tetraspanin 1 regulates papillary thyroid tumor growth and metastasis through c-Myc-mediated glycolysis

Papillary thyroid cancer (PTC) is the most common form of thyroid cancer and is characterized by its tendency for lymphatic metastasis, leading to a poor prognosis. Tetraspanin 1 (TSPAN1) is a member of the tetra-transmembrane protein superfamily and has been implicated in tumorigenesis and cancer metastasis in various studies. However, the role of TSPAN1 in PTC tumor development remains unclear. In this study, we aimed to investigate the impact of TSPAN1 on PTC cell behavior. Our results demonstrate that knockdown of TSPAN1 inhibits PTC cell proliferation, migration, and invasion, while overexpression of TSPAN1 has the opposite effect. These findings suggest that TSPAN1 might play a role in the tumorigenesis and invasiveness of PTC. Mechanistically, we found that TSPAN1 activates the ERK pathway by increasing its phosphorylation, subsequently leading to upregulated expression of c-Myc. Additionally, we observed that TSPAN1-ERK-c-Myc axis activation promotes glycolytic activity in PTC cells, as evidenced by the upregulation of glycolytic genes such as LDHA. Taken together, our findings indicate that TSPAN1 acts as an oncogene in PTC by regulating glycolytic metabolism. This discovery highlights the potential of TSPAN1 as a promising therapeutic target for PTC treatment. Further research in this area could provide valuable insights into the development of targeted therapies for PTC patients.

Challenges in the care of patients with RET-altered thyroid cancer: a multicountry mixed-methods study

BACKGROUND

The discovery of driver oncogenes for thyroid carcinomas and the identification of genomically targeted therapies to inhibit those oncogenes have altered the treatment algorithm in thyroid cancer (TC), while germline testing for RET mutations has become indicated for patients with a family history of RET gene mutations or hereditary medullary TC (MTC). In the context of an increasing number of selective RET inhibitors approved for use, this paper aims to describe challenges and barriers affecting providers' ability to deliver optimal care for patients with RET-altered TC across the patient healthcare journey.

METHODS

A mixed-method educational and behavioral needs assessment was conducted in Germany (GER), Japan (JPN), the United Kingdom (UK), and the United States (US) prior to RET-selective inhibitor approval. Participants included medical oncologists (MO), endocrinologists (EN) and clinical pathologists (CP) caring for patients affected with TC. Data collection tools were implemented in three languages (English, German, Japanese). Qualitative data were coded and thematically analyzed in NVivo. Quantitative data were analyzed via frequency and crosstabulations in SPSS. The findings presented here were part of a broader study that also investigated lung cancer challenges and included pulmonologists.

RESULTS

A total of 44 interviews and 378 surveys were completed. Suboptimal knowledge and skills were self-identified among providers, affecting (1) assessment of genetic risk factors (56%, 159/285 of MOs and ENs), (2) selection of appropriate genetic biomarkers (59%, 53/90 of CPs), (3) treatment plan initiation (65%, 173/275 of MOs and ENs), (4) management of side effects associated with multitargeted tyrosine kinase inhibitors (78%, 116/149 of MOs and ENs), and (5) transfer of patients into palliative care services (58%, 160/274 of MOs and ENs). Interviews underscored the presence of systemic barriers affecting the use of RET molecular tests and selective inhibitors, in addition to suboptimal knowledge and skills necessary to manage the safety and efficacy of targeted therapies.

CONCLUSION

This study describes concrete educational needs for providers involved in the care of patients with RET-altered thyroid carcinomas. Findings can be used to inform the design of evidence-based education and performance improvement interventions in the field and support integration into practice of newly approved RET-selective inhibitors.

The Difference in Clinical Behavior of Gene Fusions Involving RET/PTC Fusions and THADA/IGF2BP3 Fusions in Thyroid Nodules

BACKGROUND

Molecular testing has been used as an adjunct to morphological evaluation in the workup of thyroid nodules. This study investigated the impact of two gene fusions, RET/PTC and THADA/IGF2BP3, that have been described as oncogenic events in thyroid neoplasms.

METHODS

We performed a retrospective, single-centered study at a McGill University teaching hospital in Montreal, Canada, from January 2016 to August 2021. We included patients who underwent surgery for thyroid nodules that pre-operatively underwent molecular testing showing either RET/PTC or THADA/IGF2BP3 gene fusion.

RESULTS

This study included 697 consecutive operated thyroid nodules assessed using molecular testing, of which five had the RET/PTC fusion and seven had the THADA/IGF2BP3 fusion. Of the five nodules in the RET/PTC group, 100% were malignant and presented as Bethesda V/VI. Eighty percent (4/5) were found to have lymph node metastasis. Twenty percent (1/5) had extrathyroidal extensions. Sixty percent (3/5) were a diffuse sclerosing variant of papillary thyroid carcinoma, and the rest were the classical variant. Of the seven THADA/IGF2BP3 nodules, all presented as Bethesda III/IV and 71.4% (5/7) were malignant based on the final pathology analysis, and 28.6% (2/7) were NIFTP. All the THADA/IGF2BP3 fusion malignancies were a follicular variant of papillary thyroid carcinoma. None had lymph node metastasis or displayed extrathyroidal extensions.

CONCLUSIONS

RET/PTC nodules presented as Bethesda V/VI and potentially had more aggressive features, whereas THADA/IGF2BP3 nodules presented as Bethesda III/IV and had more indolent behavior. This understanding may allow clinicians to develop more targeted treatment plans, such as the extent of surgery and adjuvant radioactive iodine treatment.

Could Oxidative Stress Play a Role in the Development and Clinical Management of Differentiated Thyroid Cancer?

Increased oxidative stress (OS) has been implicated as a relevant risk factor for cancer progression. Furthermore, patients diagnosed with differentiated thyroid cancer (DTC) have been characterized by an increased OS status. Therefore, assessing OS status could potentially be considered a useful tool in DTC clinical management. This measurement could be particularly valuable in personalizing treatment protocols and determining new potential medical targets to improve commonly used therapies. A literature review was conducted to gather new information on DTC clinical management, with a particular focus on evaluating the clinical utility of OS. These meta-analyses concentrate on novel approaches that employ the measurement of oxidative-antioxidant status, which could represent the most promising area for implementing clinical management.

Advances in Molecular Profiling and Their Potential Influence on the Extent of Surgery in Well-Differentiated Thyroid Carcinoma (WDTC)

Thyroid cancer surgery has evolved dramatically with advances in our understanding of the biological behaviour of WDTC. Molecular profiling is shedding light on the subset that may behave aggressively. In an era when thyroid cancer management is becoming increasingly conservative, decision making regarding the extent of surgery must be objectively guided by molecular markers. The aim of the present article is to summarise the current published literature and provide possible practice recommendations. An online search for relevant published articles was performed using several databases. Title, abstract, and full-text screening, along with data extraction, was performed by two independent reviewers after the inclusion and exclusion criteria were defined. A total of 1241 articles were identified, and 82 relevant articles were extracted and scrutinised. BRAF V600E and TERT promoter mutations were found to be associated with an increased risk of disease recurrence and distant metastases. Several other mutations have been identified that enhance disease aggressiveness (such as RET/PTC, PTEN, and TP53). One of the most important determinants of the outcome in WDTC is the extent of surgical resection. The evolution of molecular testing has reached a stage of personalised incorporation into surgical practice. Guidelines for molecular testing and surgery in WDTC will need to be clearly defined, arguably representing the next chapter in the management of the disease.

Identification of key immune genes related to lymphatic metastasis of papillary thyroid cancer via bioinformatics analysis and experimental validation

Objective

The current research aimed to development and validation in signature immune genes for lymphatic metastasis in papillary thyroid cancer (PTC).

Method

Weighted correlation network analysis (WGCNA) was performed to identify genes closely correlated with lymphatic metastasis in PTC from TCGA database. Information on immune-related genes (IRGs) was obtained from the ImmPort database. Crossover genes were used with the R package clusterProfiler for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment. Key genes in the protein-protein interaction network of cross-targets were obtained using Cytoscape. Lasso and Random Forest (RF) models were utilized to identify pivotal genes. We constructed a nomogram based on the hub genes. The correlation between hub genes and immune cell infiltration was explored. We collected and assessed clinical samples via immunohistochemistry to detect the expression of hub genes.

Result

In total, 122 IRGs were correlated with lymphatic metastases from PTC. There are 10 key IRGs in the protein-protein interaction network. Then, three hub genes including PTGS2, MET, and ICAM1 were established using the LASSO and RF models. The expression of these hub genes was upregulated in samples collected from patients with lymphatic metastases. The average area under the curve of the model reached 0.83 after a 10-fold and 200-time cross-validation, which had a good prediction ability. Immuno-infiltration analysis showed that the three hub genes were significantly positively correlated with resting dendritic cells and were negatively correlated with activated natural cells, monocytes, and eosinophils. Immunohistochemistry results revealed that lymph node metastasis samples had a higher expression of the three hub genes than non-metastasis samples.

Conclusion

Via bioinformatics analysis and experimental validation, MET and ICAM1 were found to be upregulated in lymph node metastasis from papillary thyroid carcinoma. Further, the two hub genes were closely correlated with activated natural killer cells, monocytes, resting dendritic cells, and eosinophils. Therefore, these two genes may be novel molecular biomarkers and therapeutic targets in lymph node metastasis from papillary thyroid carcinoma.

RET rearrangements are relevant to histopathologic subtypes and clinicopathological features in Thai papillary thyroid carcinoma patients

Background: Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. The RET gene rearrangements CCDC6::RET and NCOA4::RET are the most common RET gene rearrangements in PTC patients. Different RET::PTC rearrangements are associated with different PTC phenotypes. Methods: Eighty-three formalin-fixed paraffin-embedded (FFPE) PTC samples were examined. The prevalence and expression levels of CCDC6::RET and NCOA4::RET were determined using semi-quantitative polymerase chain reaction (qRT-PCR). The association of these rearrangements with clinicopathological data was investigated. Results: The presence of CCDC6::RET rearrangement was significantly associated with the classic subtype and absence of angio/lymphatic invasion (p < 0.05). While NCOA4::RET was associated with the tall-cell subtype, and presence of angio/lymphatic invasion and lymph node metastasis (p < 0.05). Multivariate analysis demonstrated that an absence of extrathyroidal extension and extranodal extension were independent predictive factors for CCDC6::RET, whereas the tall-cell subtype, large tumor size, angioinvasion, lymphatic invasion and perineural invasion were independent predictive factors for NCOA4::RET (p < 0.05). However, the mRNA expression level of CCDC6::RET and of NCOA4::RET were not significantly associated with clinicopathological data. Conclusion: CCDC6::RET was correlated with an innocent PTC subtype and characteristics, but NCOA4::RET correlated with an aggressive phenotype of PTC. Therefore, these RET rearrangements strongly associated with clinicopathological phenotypes and can be used as predictive markers in PTC patients.

Case report: Dramatic response to pralsetinib in an elderly patient with advanced RET-fusion positive papillary thyroid carcinoma

We are recently faced with a progressive evolution of the therapeutic paradigm for radioiodine refractory differentiated thyroid cancer (RAI-R DTC), since the advent of tissue agnostic inhibitors. Thus, tumor genotype assessment is always more relevant and is playing a crucial role into clinical practice. We report the case of an elderly patient with advanced papillary thyroid carcinoma (PTC) harboring RET-CCDC6 fusion with four co-occurring mutations involving PI3KCA, TP53, and hTERT mutations, treated with pralsetinib under a compassionate use program. Despite the high histological grade and the coexistence of aggressive RET co-mutations, an impressive metabolic and structural tumor response has been obtained, together with a patient's prolonged clinical benefit. A timely comprehensive molecular testing of those cases wild-type for the common thyroid carcinoma BRAF V600E-like and RAS-like driver mutations may uncover actionable gene rearrangements that can be targeted by highly selective inhibitors with great potential benefit for the patients.

Iodine nutrition and papillary thyroid cancer

Thyroid cancer (TC) is the most frequent endocrine malignancy. The incidence of TC, especially papillary thyroid carcinoma (PTC), has continued to rise all over the world during the past few years, for reasons that are not entirely clear. Though the phenomenon of overdiagnosis is occurring, it is not the sole driver of the substantial increase in incidence. Lifestyle, environmental factors, or complications are considered to be potential risk factors. Among these factors, iodine is a micronutrient that is vital to thyroid function. The effect of iodine intake on PTC has been controversial for many years and the epidemiological or experimental studies provided diametrically opposite conclusions. Combining all these studies, we found that iodine nutrition may affect the overall prevalence, distribution of the histological types, and clinicopathological aggressiveness of TC, especially PTC. However, the available evidence is poor due to the impact of various internal and external related factors. Therefore, this article sums up available results from both epidemiological and experimental studies, future studies are also warranted to expound on the relationship between overall PTC prevalence and iodine intake.

Ferroptosis-Related APOE, BCL3 and ALOX5AP Gene Polymorphisms are Associated with the Risk of Thyroid Cancer

Purpose

This study aimed to evaluate the association between polymorphisms in the ferroptosis-related genes apolipoprotein E (APOE), BCL3 transcription coactivator (BCL3) and arachidonate 5-lipoxygenase activating protein (ALOX5AP) and the risk of thyroid cancer.

Methods

Six single nucleotide polymorphisms (SNPs) of APOE (rs429358 and rs7412), BCL3 (rs34698726 and rs8100239) and ALOX5AP (rs4076128 and rs4073259) were genotyped in 520 papillary thyroid carcinoma cases and 520 healthy controls using the MassARRAY platform.

Results

The rs429358-TC, rs34698726-TA/TT, and rs8100239-AT/AA genotypes exhibited an elevated risk of thyroid cancer (p_rs429358 = 0.002, p_rs34698726 = 0.007, p_rs8100239 = 0.002), while rs7412-CT/TT and rs4076128-GA/GG were found to be protective genotypes against the risk of disease (p_rs7412 = 0.0003, p_rs4076128 = 0.0001). Genetic model analysis showed that APOE-rs429358 was correlated with an increased risk of disease under dominant and log-additive models (p_dominant = 0.0004, p_log-additive = 0.0006). BCL3-s34698726 and rs8100239 were associated with an elevated risk of disease under all three genetic models (p < 0.05). In contrast, APOE-rs7412 was related to a decreased risk of thyroid cancer under dominant and log-additive models (p_dominant = 0.0001, p_log-additive = 0.0001). Moreover, ALOX5AP-rs4076128 was also correlated with a reduced risk of disease under all three genetic models (p < 0.05).

Conclusion

The results help us better understand how genetic polymorphisms in ferroptosis-related genes are relevant to thyroid cancer susceptibility.

lncRNA GAS8-AS1 genetic alterations in papillary thyroid carcinoma and their clinical significance

The long non-coding RNA (lncRNA) GAS8-AS1 is the second-most frequently altered gene, following the BRAF gene, in papillary thyroid carcinoma (PTC). We aimed to study the specificity and significance of genetic alterations in GAS8-AS1 in PTC. In this study, we reported the prevalence of genetic alterations of GAS8-AS1 in tissues of 48 nodular goiter, 573 papillary thyroid cancer, 95 colorectal cancer, 101 non-small cell lung cancer, 92 glioma, and 69 gastrointestinal stromal tumor patients, and in peripheral white blood cells of 286 healthy volunteers. We observed that the genomic sequence of GAS8-AS1 had a high frequency of genetic alterations in addition to the previously reported c.713A>G/714T>C substitution. Substitution of c.713A>G was completely linked with four other loci at c.714T>C, c.728A>G, c.737G>A, and c.752G>A. Two novel substitutions at c.749G>A and c.826A>G were also found. Interestingly, evidence from different samples indicated that these variations were not unique variants for PTC; they were also found in other malignant tissues and white blood cells of healthy volunteers. The c.713A>G substitution was associated with the T stage of PTC, while c.749G>A was more likely to occur in younger patients with PTC. PTC patients carrying heterozygous variants at the c.749 and c.826 loci had a higher risk of developing multiple lesions. These associations were also observed in patients with PTC and concomitant benign thyroid disease. Notably, the rare homozygous GG at the c.826 site conferred a higher risk of developing T2 PTC without benign thyroid disease, and a lower risk of developing T2 PTC with benign thyroid disease. Alterations of c.749G>A and c.826A>G had higher levels of serum TSH (thyroid stimulating hormone) in PTC subjects. Our study provides evidence that the detection of GAS8-AS1 genetic alterations would be useful in diagnostic screening and prognostic assessment of PTC.

Intratumoral Heterogeneity in Differentiated Thyroid Tumors: An Intriguing Reappraisal in the Era of Personalized Medicine

Differentiated thyroid tumors (DTTs) are characterized by significant molecular variability in both spatial and temporal intra-tumoral heterogeneity (ITH), that could influence the therapeutic management. ITH phenomenon appears to have a relevant role in tumor growth, aggressive behavior and drug resistance. Accordingly, characteristics and consequences of ITH in DTTs should be better analyzed and understood in order to guide clinical practice, improving survival. Consequently, in the present review, we investigated morphological and molecular ITH of DTTs in benign, borderline neoplasms and in malignant entities, summarizing the most significant data. Molecular testing in DTTs documents a high risk for recurrence of cancer associated with BRAF^V600E, RET/PTC 1/3, ALK and NTRK fusions, while the intermediate risk may be related to BRAF^K601E, H/K/N RAS and PAX8/PPARγ. In addition, it may be suggested that tumor genotype is associated with peculiar phenotype.

Kinase gene fusions: roles and therapeutic value in progressive and refractory papillary thyroid cancer

The incidence of papillary thyroid cancer (PTC), the major type of thyroid cancer, is increasing rapidly around the world, and its pathogenesis is still unclear. There is poor prognosis for PTC involved in rapidly progressive tumors and resistance to radioiodine therapy. Kinase gene fusions have been discovered to be present in a wide variety of malignant tumors, and an increasing number of novel types have been detected in PTC, especially progressive tumors. As a tumor-driving event, kinase fusions are constitutively activated or overexpress their kinase function, conferring oncogenic potential, and their frequency is second only to BRAF^V600E mutation in PTC. Diverse forms of kinase fusions have been observed and are associated with specific pathological features of PTC (usually at an advanced stage), and clinical trials of therapeutic strategies targeting kinase gene fusions are feasible for radioiodine-resistant PTC. This review summarizes the roles of kinase gene fusions in PTC and the value of clinical therapy of targeting fusions in progressive or refractory PTC, and discusses the future perspectives and challenges related to kinase gene fusions in PTC patients.

A Series of RET Fusion Spitz Neoplasms With Plaque-Like Silhouette and Dyscohesive Nesting of Epithelioid Melanocytes

ABSTRACT

Two distinct studies have shown that RET fusions are found in 3%-4% of Spitz neoplasms. RET fusions have been well described in papillary thyroid cancer, non-small-cell lung cancer, breast cancer, and soft-tissue mesenchymal tumors as well as some other neoplasms. However, there are no comprehensive descriptions to date of the characteristic morphologic, clinical, or genomic findings in RET fusion Spitz neoplasms. In this study, we identified 5 cases of RET fusion Spitz neoplasms. These tumors showed characteristic morphologic features which included plaque-like silhouette and monotonous epithelioid cytology with expansile and dyscohesive nesting. Four of 5 patients including 1 diagnosed as Spitz melanoma had clinical follow-up all of which was uneventful. Furthermore, we describe the genomic sequences in 4 of these cases, 2 of which have previously described KIF5B-RET fusion and 2 of which had a novel LMNA-RET fusion. We believe this report significantly contributes to our current knowledge regarding Spitz neoplasms and describes characteristics features which can help with recognition of the RET subgroup of Spitz.

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

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

[The role of molecular testing in thyroid tumors]

&sup1;I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; &sup2;Endocrinology Research Centre, Moscow, Russia Thyroid cancer is the most common endocrine gland cancer. In the last few decades, the molecular diagnostics for thyroid tumors have been widely researched. It is one of the few cancers whose incidence has increased in recent years from microcarcinomas to common, large forms, in all age groups, from children to the elder people. Most researches focus on the genetic basis, since our current knowledge of the genetic background of various forms of thyroid cancer is far from being complete. Molecular and genetic research has several main directions: firstly, differential diagnosis of thyroid tumors, secondly, the prognostic value of detected mutations in thyroid cancer, and thirdly, targeted therapy for aggressive or radioactive iodine-resistant forms of thyroid cancer. In this review, we wanted to update our understanding and describe the prevailing advances in molecular genetics of thyroid cancer, focusing on the main genes associated with the pathology and their potential application in clinical practice.

Molecular Markers Guiding Thyroid Cancer Management

The incidence of thyroid cancer is rapidly increasing, mostly due to the overdiagnosis and overtreatment of differentiated thyroid cancer (TC). The increasing use of potent preclinical models, high throughput molecular technologies, and gene expression microarrays have provided a deeper understanding of molecular characteristics in cancer. Hence, molecular markers have become a potent tool also in TC management to distinguish benign from malignant lesions, predict aggressive biology, prognosis, recurrence, as well as for identification of novel therapeutic targets. In differentiated TC, molecular markers are mainly used as an adjunct to guide management of indeterminate nodules on fine needle aspiration biopsies. In contrast, in advanced thyroid cancer, molecular markers enable targeted treatments of affected signalling pathways. Identification of the driver mutation of targetable kinases in advanced TC can select treatment with mutation targeted tyrosine kinase inhibitors (TKI) to slow growth and reverse adverse effects of the mutations, when traditional treatments fail. This review will outline the molecular landscape and discuss the impact of molecular markers on diagnosis, surveillance and treatment of differentiated, poorly differentiated and anaplastic follicular TC.

Recurrent RET gene fusions in paediatric spindle mesenchymal neoplasms

AIMS

The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of so-called 'infantile fibrosarcoma' has expanded to include tumours with NTRK, BRAF and MET gene fusions. RET-rearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET-rearranged paediatric spindle cell tumours with fusion partners MYH10, KIAA1217 and CLIP2.

METHODS AND RESULTS

The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients' ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high-power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy.

CONCLUSIONS

Our findings help to define RET-rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.

High Genetic Diversity and No Evidence of Clonal Relation in Synchronous Thyroid Carcinomas Associated with Hashimoto's Thyroiditis: A Next-Generation Sequencing Analysis

The close association between pre-existing Hashimoto’s thyroiditis and thyroid cancer is well established. The simultaneous occurrence of multiple neoplastic foci within the same organ suggests a common genotoxic effect potentially contributing to carcinogenesis, the nature of which is still not clear. Next-generation sequencing (NGS) provides a potent tool to demonstrate and compare the mutational profile of the independent neoplastic foci. Our collection of 47 cases with thyroid carcinoma and Hashimoto’s thyroiditis included 14 with at least two tumorous foci. Detailed histological analysis highlighted differences in histomorphology, immunoprofile, and biological characteristics. Further, a 67-gene NGS panel was applied to demonstrate the mutational diversity of the synchronic tumors. Significant differences could be detected with a wide spectrum of pathogenic gene variants involved (ranging between 5 and 18, cutoff >5.0 variant allele frequencies (VAF)). Identical gene variants represented in both synchronous tumors of the same thyroid gland were found in only two cases (BRAF and JAK3 genes). An additional set of major driver mutations was identified at variable allele frequencies in a highly individual setup suggesting a clear clonal independence. The different BRAF statuses in coincident thyroid carcinoma foci within the same organ outline a special challenge for molecular follow-up and therapeutic decision-making.

Update on Fundamental Mechanisms of Thyroid Cancer

The incidence of thyroid cancer (TC) has increased worldwide over the past four decades. TC is divided into three main histological types: differentiated (papillary and follicular TC), undifferentiated (poorly differentiated and anaplastic TC), and medullary TC, arising from TC cells. This review discusses the molecular mechanisms associated to the pathogenesis of different types of TC and their clinical relevance. In the last years, progresses in the genetic characterization of TC have provided molecular markers for diagnosis, risk stratification, and treatment targets. Recently, papillary TC, the most frequent form of TC, has been reclassified into two molecular subtypes, named BRAF-like and RAS-like, associated to a different range of cancer risks. Similarly, the genetic characterization of follicular TC has been proposed to complement the new histopathological classification in order to estimate the prognosis. New analyses characterized a comprehensive molecular profile of medullary TC, raising the role of RET mutations. More recent evidences suggested that immune microenvironment associated to TC may play a critical role in tumor invasion, with potential immunotherapeutic implications in advanced and metastatic TC. Several types of ancillary approaches have been developed to improve the diagnostic value of fine needle aspiration biopsies in indeterminate thyroid nodules. Finally, liquid biopsy, as a non-invasive diagnostic tool for body fluid genotyping, brings a new prospective of disease and therapy monitoring. Despite all these novelties, much work remains to be done to fully understand the pathogenesis and biological behaviors of the different types of TC and to transfer this knowledge in clinical practice.

Influencers on Thyroid Cancer Onset: Molecular Genetic Basis

Thyroid cancer, a cancerous tumor or growth located within the thyroid gland, is the most common endocrine cancer. It is one of the few cancers whereby incidence rates have increased in recent years. It occurs in all age groups, from children through to seniors. Most studies are focused on dissecting its genetic basis, since our current knowledge of the genetic background of the different forms of thyroid cancer is far from complete, which poses a challenge for diagnosis and prognosis of the disease. In this review, we describe prevailing advances and update our understanding of the molecular genetics of thyroid cancer, focusing on the main genes related with the pathology, including the different noncoding RNAs associated with the disease.

GDNF and the RET Receptor in Cancer: New Insights and Therapeutic Potential

The Glial cell line-derived neurotrophic Family Ligands (GFL) are soluble neurotrophic factors that are required for development of multiple human tissues, but which are also important contributors to human cancers. GFL signaling occurs through the transmembrane RET receptor tyrosine kinase, a well-characterized oncogene. GFL-independent RET activation, through rearrangement or point mutations occurs in thyroid and lung cancers. However, GFL-mediated activation of wildtype RET is an increasingly recognized mechanism promoting tumor growth and dissemination of a much broader group of cancers. RET and GFL expression have been implicated in metastasis or invasion in diverse human cancers including breast, pancreatic, and prostate tumors, where they are linked to poorer patient prognosis. In addition to directly inducing tumor growth in these diseases, GFL-RET signaling promotes changes in the tumor microenvironment that alter the surrounding stroma and cellular composition to enhance tumor invasion and metastasis. As such, GFL RET signaling is an important target for novel therapeutic approaches to limit tumor growth and spread and improve disease outcomes.