A detailed clinicopathologic study of ALK-translocated papillary thyroid carcinoma

Mechanisms of receptor tyrosine kinase activation in cancer

Receptor tyrosine kinases (RTKs) play an important role in a variety of cellular processes including growth, motility, differentiation, and metabolism. As such, dysregulation of RTK signaling leads to an assortment of human diseases, most notably, cancers. Recent large-scale genomic studies have revealed the presence of various alterations in the genes encoding RTKs such as EGFR, HER2/ErbB2, and MET, amongst many others. Abnormal RTK activation in human cancers is mediated by four principal mechanisms: gain-of-function mutations, genomic amplification, chromosomal rearrangements, and / or autocrine activation. In this manuscript, we review the processes whereby RTKs are activated under normal physiological conditions and discuss several mechanisms whereby RTKs can be aberrantly activated in human cancers. Understanding of these mechanisms has important implications for selection of anti-cancer therapies.

Molecular pathology of thyroid tumours of follicular cells: a review of genetic alterations and their clinicopathological relevance

Thyroid cancer is the most common endocrine malignancy. Knowledge of the molecular pathology of thyroid tumours originating from follicular cells has greatly advanced in the past several years. Common molecular alterations, such as BRAF p.V600E, RAS point mutations, and fusion oncogenes (RET-PTC being the prototypical example), have been, respectively, associated with conventional papillary carcinoma, follicular-patterned tumours (follicular adenoma, follicular carcinoma, and the follicular variant of papillary carcinoma/non-invasive follicular thyroid neoplasm with papillary-like nuclear features), and with papillary carcinomas from young patients and arising after exposure to ionising radiation, respectively. The remarkable correlation between genotype and phenotype shows how specific, mutually exclusive molecular changes can promote tumour development and initiate a multistep tumorigenic process that is characterised by aberrant activation of mitogen-activated protein kinase and phosphoinositide 3-kinase-PTEN-AKT signalling. Molecular alterations are becoming useful biomarkers for diagnosis and risk stratification, and as potential treatment targets for aggressive forms of thyroid carcinoma. What follows is a review of the principal genetic alterations of thyroid tumours originating from follicular cells and of their clinicopathological relevance.

Endocrine pathology: past, present and future

Endocrine pathology is the subspecialty of diagnostic pathology which deals with the diagnosis and characterisation of neoplastic and non-neoplastic diseases of the endocrine system. This relatively young subspecialty was initially focused mainly on thyroid and parathyroid pathology, with some participants also involved in studies of the pituitary, the endocrine pancreas, and the adrenal glands. However, the endocrine system involves much more than these traditional endocrine organs and the discipline has grown to encompass lesions of the dispersed neuroendocrine cells, including neuroendocrine tumours (NETs) of the lungs, gastrointestinal tract, thymus, breast and prostate, as well as paraganglia throughout the body, not just in the adrenals. Indeed, the production of hormones is the hallmark of the endocrine system, and some aspects of gynecological/testicular, bone and liver pathology also fall into the realm of this specialty. Many of the lesions that are the focus of this discipline are increasing in incidence and their pathology is becoming more complex with increased understanding of molecular pathology and a high incidence of familial disease. The future of endocrine pathology will demand a depth of understanding of structure, function, prognosis and prediction as pathologists play a key role in the multidisciplinary care team of patients with endocrine diseases. It is anticipated that new technologies will allow increased subspecialisation in pathology and growth of this important area of expertise.

Key signaling pathways in thyroid cancer

Whole genome sequencing approaches have provided unprecedented insights into the genetic lesions responsible for the onset, progression and dedifferentiation of various types of thyroid carcinomas. Through these efforts, the MAPK and PI3K signaling cascades have emerged as the main activation pathways implicated in thyroid tumorigenesis. The nature of these essential pathways is highly complex, with hundreds of components, multiple points of crosstalk, different subcellular localizations and with the ability to potentially regulate many cellular processes. Small-molecule inhibitors targeting key kinases of these pathways hold great promise as novel therapeutics and several have reached clinical trials. However, while some remarkable responses have been reported, the development of resistance remains a matter of concern and limits the benefit for patients. In this review, we discuss the latest findings on the major components of the MAPK and PI3K pathways, including their mechanisms of activation in physiological and pathological contexts, their genetic alterations with respect to the different types of thyroid carcinomas and the more relevant drugs designed to block their activity.

Inflammatory Myofibroblastic Tumors of the Female Genital Tract Are Under-recognized: A Low Threshold for ALK Immunohistochemistry Is Required

Inflammatory myofibroblastic tumor (IMT) of the female genital tract is under-recognized. We investigated the prevalence of ALK-positive IMT in lesions previously diagnosed as gynecologic smooth muscle tumors. Immunohistochemistry (IHC) for ALK was performed on tissue microarrays of unselected tumors resected from 2009 to 2013. Three of 1176 (0.26%) “leiomyomas” and 1 of 44 (2.3%) “leiomyosarcomas” were ALK IHC positive, confirmed translocated by fluorescence in situ hybridization (FISH) and therefore more appropriately classified as IMT. On review significant areas of all 4 tumors closely mimicked smooth muscle tumors morphologically, but all showed at least subtle/focal features suggesting IMT. Recognizing that the distinction between IMT and leiomyoma/leiomyosarcoma can be subtle, we then reviewed 1 hematoxylin and eosin slide from each patient undergoing surgery for “leiomyoma” from 2014 to 2017 and selected cases for ALK IHC with a low threshold. Of these, 30 of 571 (5.3%) underwent IHC. Two were confirmed to be IHC positive and FISH rearranged. Of the 6 IMTs, only 1 tumor with a previous diagnosis of leiomyosarcoma, an infiltrative margin and equivocal necrosis, metastasized. Of note it demonstrated a less aggressive clinical course compared with most metastatic leiomyosarcomas (alive with disease at 6 y). The patient was subsequently offered crizotinib to which she responded rapidly. In conclusion, IMTs may closely mimic gynecologic smooth muscle tumors. IMTs account for at least 5 of 1747 (0.3%) tumors previously diagnosed as leiomyoma and 1 of 44 (2.3%) as leiomyosarcoma. These tumors may be recognized prospectively with awareness of subtle/focal histologic clues, coupled with a low threshold for ALK IHC.

Anaplastic lymphoma kinase L1198F and G1201E mutations identified in anaplastic thyroid cancer patients are not ligand-independent

Activating mutations in full length anaplastic lymphoma kinase (ALK) have been reported in neuroblastoma and in anaplastic thyroid cancer. ALK-L1198F and ALK-G1201E mutations were originally identified in anaplastic thyroid cancer (ATC) and characterized as constitutively activating mutations. In this study, we employed in vitro cell culture assays together with biochemical and in vivo Drosophila analyses to characterize their sensitivity to either activation by the FAM150A (AUG-β) and FAM150B (AUG-α) ALK ligands or inhibition by ALK inhibitors. Here we report that neither ALK-L1198F nor ALK-G1201E mutations result in ligand independent gain-of-function (GOF) activity in either in vitro biochemical analysis or the various model systems employed. ALK-L1198F is activated by the FAM150 (AUG) ligands and its ligand-dependant activity is similar to the wild type full length ALK receptor. ALK-G1201E is only very weakly activated by the FAM150 (AUG) ligands, most likely due to impaired protein stability. We conclude that neither ALK-L1198F nor ALK-G1201E displays ligand independent kinase activity, with ALK-L1198F belonging to the class of ligand dependent ALK mutations which are not constitutively active but that responds to ligand activation, while the ALK-G1201E mutation generates an unstable receptor with very low levels of kinase activity.

Two Cases of Renal Cell Carcinoma Harboring a Novel STRN-ALK Fusion Gene

Anaplastic lymphoma kinase (ALK) translocation renal cell carcinomas (RCCs) have been reported by several independent groups in recent times. The clinical behavior and histopathologic characteristics of these carcinomas are not fully understood because of the paucity of cases reported. Here, we describe 2 cases of RCC harboring a novel striatin (STRN)-ALK fusion. The first case was a 33-year-old woman with no sickle cell trait who underwent nephrectomy for right renal mass and had late recurrence in para-aortic lymph nodes twice 10 and 12 years after initial surgery. After the second recurrence, she was carefully observed without any treatment. Twenty-six years after the initial nephrectomy, the second para-aortic lymphadenectomy was performed, and gastrectomy was performed for newly developed primary gastric cancer. The resected para-aortic lymph nodes were largely replaced by metastatic carcinoma. The second case was a 38-year-old man with no sickle cell trait who underwent cytoreductive nephrectomy followed by sunitinib therapy for metastatic RCC. In both cases, the tumor showed solid, papillary, tubular, and mucinous cribriform structures. Psammoma bodies were occasionally seen in the stroma. Tumor cells had a large nucleus and prominent nucleoli with predominantly eosinophilic cytoplasm. Rhabdoid cells and signet-ring cells were also observed. Intracytoplasmic mucin deposition and background mucinous stroma were confirmed. In the second case, tumor necrosis was seen in some areas. Tumor cells exhibited diffuse positive staining for ALK in both cases. ALK translocation was confirmed by fluorescent in situ hybridization, and further gene analysis revealed a STRN-ALK fusion. These cases provide great insights into ALK translocation RCCs.

Molecular Profiling of Papillary Thyroid Carcinoma in Korea with a High Prevalence of BRAFV600E Mutation

BACKGROUND

The BRAF^V600E mutation in papillary thyroid carcinoma (PTC) is particularly prevalent in Korea, and a considerable number of wild-type BRAF PTCs harbor RAS mutations. In addition, subsets of other genetic alterations clearly exist, but their prevalence in the Korean population has not been well studied. Recent increased insight into noninvasive encapsulated follicular variant PTC has prompted endocrine pathologists to reclassify this entity as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). This study analyzed the genetic alterations among the histologic variants of PTC, including NIFTP.

METHODS

Mutations of the BRAF and RAS genes and rearrangement of the RET/PTC1, NTRK1, and ALK genes using 769 preoperative fine-needle aspiration specimens and resected PTCs were analyzed.

RESULTS

Molecular alterations were found in 687 (89.3%) of 769 PTCs. BRAF^V600E mutation (80.8%) was the most frequent alteration, followed by RAS mutation and RET/PTC1, NTRK1, and ALK rearrangements (5.6%, 2.1%, 0.4%, and 0%, respectively). The low prevalence of NTRK1 fusions and the absence of an ALK fusion detected in Korea may also be attributed to the higher prevalence of the BRAF^V600E mutation. There were significant differences in the frequency of the genetic alterations among the histologic variants of PTC. The prevalence of NIFTP in PTC was 2.7%, and among the NIFTPs, 28.6% and 57.1% harbored BRAF and RAS mutations, respectively. Clinicopathologic factors and mutational profiles between NIFTP and encapsulated follicular variant PTC with capsular invasion group were not significantly different.

CONCLUSIONS

Genetic alterations in PTC vary among its different histologic variants and seem to be different in each ethnic group.

Molecular Pathology of Anaplastic Thyroid Carcinomas: A Retrospective Study of 144 Cases

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is a rare tumor, with poorly defined oncogenic molecular mechanisms and limited therapeutic options contributing to its poor prognosis. The aims of this retrospective study were to determine the frequency of anaplastic lymphoma kinase (ALK) translocations and to identify the mutational profile of ATC including TERT promoter mutations.

METHODS AND MATERIALS

One hundred and forty-four ATC cases were collected from 10 centers that are a part of the national French network for management of refractory thyroid tumors. Fluorescence in situ hybridization analysis for ALK rearrangement was performed on tissue microarrays. A panel of 50 genes using next-generation sequencing and TERT promoter mutations using Sanger sequencing were also screened.

RESULTS

Fluorescence in situ hybridization was interpretable for 90 (62.5%) cases. One (1.1%) case was positive for an ALK rearrangement with a borderline threshold (15% positive cells). Next-generation sequencing results were interpretable for 94 (65.3%) cases, and Sanger sequencing (TERT) for 98 (68.1%) cases. A total of 210 mutations (intronic and exonic) were identified. TP53 alterations were the most frequent (54.4%). Forty-three percent harbored a mutation in the (H-K-N)RAS genes, 13.8% a mutation in the BRAF gene (essentially p.V600E), 17% a PI3K-AKT pathway mutation, 6.4% both RAS and PI3K pathway mutations, and 4.3% both TP53 and PTEN mutations. Nearly 10% of the cases showed no mutations of the RAS, PI3K-AKT pathways, or TP53, with mutations of ALK, ATM, APC, CDKN2A, ERBB2, RET, or SMAD4, including mutations not yet described in thyroid tumors. Genes encoding potentially druggable targets included: mutations in the ATM gene in four (4.3%) cases, in ERBB2 in one (1.1%) case, in MET in one (1.1%) case, and in ALK in one (1.1%) case. A TERT promoter alteration was found in 53 (54.0%) cases, including 43 C228T and 10 C250T mutations. Three out of our cases did not harbor mutations in the panel of genes with therapeutic interest.

CONCLUSION

This study confirms that ALK rearrangements in ATC are rare and that the mutational landscape of ATC is heterogeneous, with many genes implicated in the follicular epithelial cell dedifferentiation process. This may explain the limited effectiveness of targeted therapeutic options tested so far.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Update on the cytologic features of papillary thyroid carcinoma variants

Papillary thyroid cancer (PTC), which accounts for 85-90% of all thyroid cancers, is generally an indolent tumor with long term survival rates >95%. A reliable definitive diagnosis of PTC is usually straightforward in fine needle aspirates of conventional PTC whenever the characteristic papillary and/or flat honeycomb sheet-like architecture and the typical nuclear features of chromatin pallor, nuclear enlargement, crowding, grooves and pseudoinclusions are encountered. Conventional PTC, however, has diminished in relative frequency as compared to PTC variants, especially the noninvasive follicular variant of PTC, an indolent tumor which has recently been reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). These PTC variants are characterized by various architecture, cell type and shape, and stromal features, some of which can be recognized cytologically. Awareness of the cytomorphological spectrum and of the characteristic cytological features of these PTC variants is important to avoid diagnostic pitfalls. In this article, we review the different variants of PTC, including their cytomorphologic features, differential diagnosis, and salient molecular features. Diagn. Cytopathol. 2017;45:714-730. © 2017 Wiley Periodicals, Inc.

EWSR1 rearrangement is a frequent event in papillary thyroid carcinoma and in carcinoma of the thyroid with Ewing family tumor elements (CEFTE)

Carcinomas of the thyroid with Ewing family tumor element (CEFTEs) are small-cell thyroid tumors with epithelial differentiation that disclose p63 expression and EWSR1-FLI1 rearrangement, carry a favorable prognosis and may co-exist with papillary thyroid carcinoma (PTC) foci. Two histogenetic hypotheses have been advanced regarding the origin of CEFTEs: arising in PTCs or in solid cell nests (SCN). A total of 3 CEFTEs, 54 PTCs, and 10 SCNs were reviewed, and fluorescence in situ hybridization (FISH) technique was performed in all cases to search for the presence of EWSR1 rearrangements. The three CEFTEs disclosed the EWSR1-FLI1 rearrangement both in the small cell and in the PTC component. Out of the 54 PTC cases, 28 (51.9%) were positive, 20 (37.0%) were negative, and 6 (11.1%) were inconclusive for EWSR1 rearrangement; in two of the positive PTC cases, the EWSR1-FLI1 rearrangement was detected. Classic PTC disclosed more often the EWSR1 rearrangement than other PTC variants (p = 0.031). PTCs with EWSR1 rearrangement disclosed a lower percentage of nuclei with EWSR1 polysomy than those without EWSR1 rearrangement (p = 0.001). Out of the 10 SCNs, 7 (70.0%) were negative and 3 (30.0%) were inconclusive for the EWSR1 rearrangement. Monosomic nuclei were more frequent (mean of 44.3%) in SCNs than in PTCs (p < 0.001). The presence of the EWSR1-FLI1 rearrangement in PTC component of all studied CEFTEs and the existence of the EWSR1 rearrangement in some PTCs favor the origin of CEFTE from PTC. The high frequency of EWSR1 rearrangements in PTC may represent a new diagnostic marker of these tumors.

The changing characteristics and molecular profiles of papillary thyroid carcinoma over time: a systematic review

BACKGROUND

The genetic alterations of papillary thyroid carcinoma (PTC) have been reported to change over the past few decades. We performed this systematic review to further examine the trends and modifications of patient demographic, clinicopathological features and molecular profiles of PTC over time.

METHODS

A literature search was performed within six electronic databases to identify relevant articles. The inclusion criteria were published studies investigating BRAF mutations, RET/PTC rearrangements or RAS mutations in PTCs or classical PTCs. Two teams of reviewers independently screened titles and abstracts of all articles. Full texts of potential articles were read and extracted data were listed and stratified into an excel file according to country, city, institution, and surgical time period. Student t test and Pearson Chi-square were used to analyze the trends of demographic and clinicopathological features of PTC patients and the prevalence of each genetic alteration in individual institutions.

RESULTS

From 3139 articles, we included 16 articles for final analysis. Our results showed an increasing trend of BRAF and a decreasing trend of RET/PTC prevalence over time in PTCs and classical PTCs, accompanied by an older age of PTC patients, an increase in proportion of PTMC and less aggressive behaviours of tumours.

CONCLUSIONS

The demographic and clinicopathological characteristics and molecular profile of PTCs have been changing over the past few decades. These modifications suggest changes in etiologies and risk factors of thyroid cancer that influence the tumorigenesis of PTCs.

ALK: a tyrosine kinase target for cancer therapy

The anaplastic lymphoma kinase (ALK) gene plays an important physiologic role in the development of the brain and can be oncogenically altered in several malignancies, including non-small-cell lung cancer (NSCLC) and anaplastic large cell lymphomas (ALCL). Most prevalent ALK alterations are chromosomal rearrangements resulting in fusion genes, as seen in ALCL and NSCLC. In other tumors, ALK copy-number gains and activating ALK mutations have been described. Dramatic and often prolonged responses are seen in patients with ALK alterations when treated with ALK inhibitors. Three of these—crizotinib, ceritinib, and alectinib—are now FDA approved for the treatment of metastatic NSCLC positive for ALK fusions. However, the emergence of resistance is universal. Newer ALK inhibitors and other targeting strategies are being developed to counteract the newly emergent mechanism(s) of ALK inhibitor resistance. This review outlines the recent developments in our understanding and treatment of tumors with ALK alterations.

Nucleophosmin-anaplastic lymphoma kinase: the ultimate oncogene and therapeutic target

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase physiologically expressed by fetal neural cells. However, aberrantly expressed ALK is involved in the pathogenesis of diverse malignancies, including distinct types of lymphoma, lung carcinoma, and neuroblastoma. The aberrant ALK expression in nonneural cells results from chromosomal translocations that create novel fusion proteins. These protein hybrids compose the proximal part of a partner gene, including its promoter region, and the distal part of ALK, including the coding sequence for the entire kinase domain. ALK was first identified in a subset of T-cell lymphomas with anaplastic large cell lymphoma (ALCL) morphology (ALK+ ALCL), the vast majority of which harbor the well-characterized nucleophosmin (NPM)-ALK fusion protein. NPM-ALK co-opts several intracellular signal transduction pathways, foremost being the STAT3 pathway, normally activated by cytokines from the interleukin-2 (IL-2) family to promote cell proliferation and to inhibit apoptosis. Many genes and proteins modulated by NPM-ALK are also involved in evasion of antitumor immune response, protection from hypoxia, angiogenesis, DNA repair, cell migration and invasiveness, and cell metabolism. In addition, NPM-ALK uses epigenetic silencing mechanisms to downregulate tumor suppressor genes to maintain its own expression. Importantly, NPM-ALK is capable of transforming primary human CD4⁺ T cells into immortalized cell lines indistinguishable from patient-derived ALK+ ALCL. Preliminary clinical studies indicate that inhibition of NPM-ALK induces long-lasting complete remissions in a large subset of heavily pretreated adult patients and the vast majority of children with high-stage ALK+ ALCL. Combining ALK inhibition with other novel therapeutic modalities should prove even more effective.

High endothelial venule-like vessels and lymphocyte recruitment in diffuse sclerosing variant of papillary thyroid carcinoma

Diffuse sclerosing variant of papillary thyroid carcinoma (DSPTC) is a rare subtype of papillary thyroid carcinoma with a high incidence of lymph node metastasis. One of its characteristic histological features is the presence of dense lymphocyte infiltrates; however, how these lymphocytes are recruited in this pathological setting remains unclear. Here, we analysed 17 DSPTC cases immunohistologically for cell adhesion molecules expressed on endothelial cells. We found that venules morphologically similar to high endothelial venules (HEVs) in secondary lymphoid organs were induced in lymphoid aggregates in DSPTC, and such HEV-like vessels expressed 6-sulfo sialyl Lewis X (sLeX) glycans as well as intercellular adhesion molecule 1 (ICAM-1). Triple immunohistochemistry revealed that CD8⁺ cytotoxic T cells were the major lymphocyte subset attached to the luminal surface of HEV-like vessels. sLeX-type glycans were also expressed on DSPTC carcinoma cells, which in binding assays were decorated with E-selectin•IgM chimaeras calcium-dependently. These findings collectively suggest that 6-sulfo sLeX glycans, together with ICAM-1, on HEV-like vessels may function to recruit CD8⁺ cytotoxic T cells in DSPTC. Additionally, sLeX-type glycans on carcinoma cells might partly contribute to highly metastatic properties of DSPTC through interaction with E-selectin expressed on endothelial cells.

Classic Architecture with Multicentricity and Local Recurrence, and Absence of TERT Promoter Mutations are Correlates of BRAF (V600E) Harboring Pediatric Papillary Thyroid Carcinomas

This study is aimed to investigate the BRAF (V600E) and TERT promoter mutation profile of 50 pediatric papillary thyroid carcinomas (PTCs) to refine their clinicopathological correlates. The median age at the time of surgery was 16 years (range, 6-18). No TERT promoter mutations were identified in this series. The BRAF (V600E) mutation was present in 15 (30 %) tumors. From genotype-histologic variant correlation perspective, 13 of 24 classic variant PTCs and 2 of 7 diffuse sclerosing variant PTCs were found to harbor BRAF (V600E) mutation. One cribriform-morular variant, 3 solid variant, and 15 follicular variant PTCs were BRAF wild type. While tumors with distant metastasis were BRAF wild type, two of five tumors with extrathyroidal extension (ETE) harbored BRAF (V600E) mutation. Nine of 15 BRAF (V600E) harboring tumors had central lymph node metastases. There was no significant correlation with BRAF (V600E) mutation and age, gender, tumor size, ETE, central lymph node metastasis, the status of pT, pN1a-b, and distant metastasis. An adverse correlation between BRAF (V600E) mutation and disease-free survival (DFS) was noted in the entire cohort; however, the predictive value of BRAF (V600E) mutation disappeared within the group of tumors displaying classic architecture as well as classic variant PTCs. The present cohort identifies that the classic architecture with multicentricity and local recurrence are correlates of BRAF (V600E) harboring pediatric PTCs. While the small size of this cohort is one of the limitations, neither the BRAF mutation status nor the classic tumor architecture does seem to be an independent prognosticator of DFS in this series. Evidence also suggests that TERT promoter mutations do not seem to play a major role in the pathogenesis of pediatric PTCs.

Clinical utility of TERT promoter mutations and ALK rearrangement in thyroid cancer patients with a high prevalence of the BRAF V600E mutation

Background

Mutations in the TERT promoter, ALK rearrangement, and the BRAF V600E mutation are associated with aggressive clinicopathologic features in thyroid cancers. However, little is known about the impact of TERT promoter mutations and ALK rearrangement in thyroid cancer patients with a high prevalence of BRAF mutations.

Methods

We performed Sanger sequencing to detect BRAF V600E and TERT promoter mutations and both immunohistochemistry and fluorescence in situ hybridization to identify ALK rearrangement on 243 thyroid cancers.

Results

TERT promoter mutations were not present in 192 well-differentiated thyroid carcinomas (WDTC) without distant metastasis or in 9 medullary carcinomas. However, the mutations did occur in 40 % (12/30) of WDTC with distant metastasis, 29 % (2/7) of poorly differentiated carcinomas and 60 % (3/5) of anaplastic carcinomas. ALK rearrangement was not present in all thyroid cancers. The BRAF V600E mutation was more frequently found in WDTC without distant metastasis than in WDTC with distant metastasis (p = 0.007). In the cohort of WDTC with distant metastasis, patients with wild-type BRAF and TERT promoter had a significantly higher response rate after radioiodine therapy (p = 0.024), whereas the BRAF V600E mutation was significantly correlated with progressive disease (p = 0.025).

Conclusions

The TERT promoter mutation is an independent predictor for distant metastasis of WDTC, but ALK testing is not useful for clinical decision-making in Korean patients with a high prevalence of the BRAF V600E mutation. Radioiodine therapy for distant metastasis of WDTC is most effective in patients without BRAF V600E and TERT promoter mutations.

Anaplastic Thyroid Carcinoma, Version 2.2015

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Thyroid Carcinoma focuses on anaplastic carcinoma because substantial changes were made to the systemic therapy recommendations for the 2015 update. Dosages and frequency of administration are now provided, docetaxel/doxorubicin regimens were added, and single-agent cisplatin was deleted because it is not recommended for patients with advanced or metastatic anaplastic thyroid cancer.