Correlation between genetic alterations and microscopic features, clinical manifestations, and prognostic characteristics of thyroid papillary carcinomas

Follicular cell thyroid neoplasia: insights from genomics and The Cancer Genome Atlas research network

PURPOSE OF REVIEW

The present review is focused on the recently published study on the genomics of papillary thyroid carcinoma performed by The Cancer Genome Atlas Research Network and its implications for the follicular variant of papillary carcinoma.

RECENT FINDINGS

The Cancer Genome Atlas study of papillary thyroid carcinoma comprehensively examined the cancer genome of nearly 500 primary tumors. Using a highly integrated bioinformatic analysis, papillary carcinoma was shown at the genomic level to consist of two highly distinct classes that reflected both tumor histology and underlying genotype. Tumors with true papillary architecture were dominated by BRAF(V600E) mutations and RET kinase fusions and were designated as BRAF(V600E)-like. Tumors with follicular architecture were conversely dominated by RAS mutations and were designated as RAS-like. Given the strong genotype:phenotype correlation known to be present in thyroid cancer, the separation of BRAF(V600E)-like and RAS-like tumors has profound implications for its classification, especially the follicular variant of papillary carcinoma.

SUMMARY

The recent genomic characterization of papillary thyroid carcinoma is challenging the established pathological classification of thyroid cancer with significance for the care of patients.

Associations between BRAF(V600E) and prognostic factors and poor outcomes in papillary thyroid carcinoma: a meta-analysis

Background

The objective of this study is to perform a meta-analysis to evaluate the associations between the BRAF^V600E mutation status and aggressive clinicopathological features and poor prognostic factors in papillary thyroid cancer.

Methods

A literature search was performed within the PubMed, MEDLINE, Web of Science databases, and EMBASE databases using the Medical Subject Headings and keywords from January 2003 to July 2015. Individual study-specific odds ratios and confidence intervals were calculated, as were the Mantel-Haenszel pooled odds ratios for the combined studies.

Results

Sixty-three studies of 20,764 patients were included in the final analysis. Compared with wild-type BRAF, the BRAF^V600E mutation was associated with aggressive clinicopathological factors, including extrathyroidal extension, higher TNM stage, lymph node metastasis, and recurrence, and was associated with reduced overall survival; however, there was no significant association between the presence of BRAF mutation and distant metastasis.

Conclusions

BRAF mutations are closely associated with aggressive clinicopathological characteristics and poorer prognosis in papillary thyroid cancer. Accordingly, aggressive treatment should be considered for papillary thyroid cancer patients with BRAF mutation.

Vemurafenib in patients with BRAF(V600E)-positive metastatic or unresectable papillary thyroid cancer refractory to radioactive iodine: a non-randomised, multicentre, open-label, phase 2 trial

BACKGROUND

About half of patients with papillary thyroid cancer have tumours with activating BRAF(V600E) mutations. Vemurafenib, an oncogenic BRAF kinase inhibitor approved for BRAF-positive melanoma, showed clinical benefit in three patients with BRAF(V600E)-positive papillary thyroid cancer in a phase 1 trial. We aimed to establish the activity of vemurafenib in patients with BRAF(V600E)-positive papillary thyroid cancer.

METHODS

We did an open-label, non-randomised, phase 2 trial at ten academic centres and hospitals worldwide in patients aged 18 years or older with histologically confirmed recurrent or metastatic papillary thyroid cancer refractory to radioactive iodine and positive for the BRAF(V600E) mutation. Participants either had never received a multikinase inhibitor targeting VEGFR (cohort 1) or had been treated previously with a VEGFR multikinase inhibitor (cohort 2). Patients received vemurafenib 960 mg orally twice daily. The primary endpoint was investigator-assessed best overall response in cohort 1 (confirmed on two assessments 4 weeks or longer apart). Analyses were planned to have a minimum median follow-up of 15 months (data cutoff April 18, 2014) and were done in safety, intention-to-treat, and per-protocol populations. This trial is closed and is registered at ClinicalTrials.gov, number NCT01286753.

FINDINGS

Between June 23, 2011, and Jan 15, 2013, 51 patients were enrolled to the study, 26 in cohort 1 and 25 in cohort 2. Median duration of follow-up was 18·8 months (IQR 14·2-26·0) in cohort 1 and 12·0 months (6·7-20·3) in cohort 2. Partial responses were recorded in ten of 26 patients in cohort 1 (best overall response 38·5%, 95% CI 20·2-59·4). Grade 3 or 4 adverse events were recorded in 17 (65%) of 26 patients in cohort 1 and 17 (68%) of 25 patients in cohort 2; the most common grade 3 and 4 adverse events were squamous cell carcinoma of the skin (seven [27%] in cohort 1, five [20%] in cohort 2), lymphopenia (two [8%] in each cohort), and increased γ-glutamyltransferase (one [4%] in cohort 1, three [12%] in cohort 2). Two individuals in cohort 2 died due to adverse events, one from dyspnoea and one from multiorgan failure, but neither was treatment related. Serious adverse events were reported for 16 (62%) of 26 patients in cohort 1 and 17 (68%) of 25 patients in cohort 2.

INTERPRETATION

Vemurafenib showed antitumour activity in patients with progressive, BRAF(V600E)-positive papillary thyroid cancer refractory to radioactive iodine who had never been treated with a multikinase inhibitor. As such, this agent represents a potential new treatment option for these patients.

FUNDING

F Hoffmann-La Roche.

Vanishing tumors of thyroid: histological variations after fine needle aspiration

BACKGROUND

Fine needle aspiration (FNA) can lead to changes that extensively replace cytological confirmed thyroid lesions. These lesions, so called "vanishing tumors" can be diagnostically challenging to pathologists and therapeutically challenging for endocrinologists and surgeons. We performed a retrospective analysis to identify these tumors.

METHODS

Data of 656 patients referred for thyroid surgery was reviewed. Patients with suspicious lesions on neck ultrasound (US) underwent FNA. We compared FNA cytological and surgical pathological findings to identify vanishing tumors. FNA-induced changes such as cystic degeneration, hemorrhage, calcification, cholesterol crystals, fibrosis and granulation tissue were identified.

RESULTS

Seventeen patients (2.5%) were identified with vanishing tumors. FNA cytology was indeterminate in seven (41.1%) and benign in ten (58.8%) patients. Surgical pathology in all nodules showed regressive changes partially or entirely replacing the tumor. The mean size of vanishing tumors was 2.4±1.5 cm in greatest dimension. Seven nodules (41.1%) were entirely replaced while remaining ten nodules showed partial replacement of tumors. Three (17.6%) nodules had focal areas of optically clear nuclei suspicious of papillary thyroid carcinoma (PTC); one showed an additional focus of follicular neoplasm (FN) of uncertain malignant potential.

CONCLUSIONS

FNA-induced changes can lead to obliteration of nodules rendering pathological diagnosis with no evidence of confirmed lesions. Pathologists and surgeons should be aware of this challenging scenario.

Prevalence and phenotypic correlations of EIF1AX mutations in thyroid nodules

The EIF1AX gene mutations have been recently found in papillary thyroid carcinoma (PTC) and anaplastic thyroid carcinoma (ATC). The prevalence of these mutations in other types of thyroid cancers and benign nodules is unknown. In this study, we analyzed the occurrence of EIF1AX mutations in exons 2, 5, and 6 of the gene in a series of 266 thyroid tumors and hyperplastic nodules by either Sanger or next-generation sequencing (ThyroSeq v.2). In addition, 647 thyroid fine-needle aspiration (FNA) samples with indeterminate cytology were analyzed. Using surgically removed samples, EIF1AX mutations were detected in 3/86 (2.3%) PTC, 1/4 (25%) ATC, 0/53 follicular carcinomas, 0/12 medullary carcinomas, 2/27 (7.4%) follicular adenomas, and 1/80 (1.3%) hyperplastic nodules. Among five mutation-positive FNA samples with surgical follow-up, one nodule was PTC and others were benign follicular adenomas or hyperplastic nodules. Overall, among 33 mutations identified, A113_splice mutation at the intron 5/exon 6 splice site of EIF1AX was the most common. All four carcinomas harbored A113_splice mutation and three of them had one or more coexisting mutations, typically RAS All PTC carrying EIF1AX mutations were encapsulated follicular variants. In summary, this study shows that EIF1AX mutations occur not only in thyroid carcinomas, but also in benign nodules. The most common mutation hotspot is the A113_splice, followed by a cluster of mutations in exon 2. When found in thyroid FNA samples, EIF1AX mutations confer ~20% risk of cancer; the risk is likely to be higher in nodules carrying a A113_splice mutation and when EIF1AX coexists with RAS mutations.

NTRK fusion oncogenes in pediatric papillary thyroid carcinoma in northeast United States

BACKGROUND

An increase in thyroid cancers, predominantly papillary thyroid carcinoma (PTC), has been recently reported in children.

METHODS

The histopathology of 28 consecutive PTCs from the northeast United States was reviewed. None of the patients (ages 6-18 years; 20 females, 8 males) had significant exposure to radiation. Nucleic acid from tumors was tested for genetic abnormalities (n = 27). Negative results were reevaluated by targeted next-generation sequencing.

RESULTS

Seven of 27 PTCs (26%) had neurotrophic tyrosine kinase receptor (NTRK) fusion oncogenes (NTRK type 3/ets variant 6 [NTRK3/ETV6], n =5; NTRK3/unknown, n = 1; and NTRK type 1/translocated promoter region, nuclear basket protein [NTRK1/TPR], n = 1), including 5 tumors that measured >2 cm and 3 that diffusely involved the entire thyroid or lobe. All 7 tumors had lymphatic invasion, and 5 had vascular invasion. Six of 27 PTCs (22%) had ret proto-oncogene (RET) fusions (RET/PTC1, n = 5; RET/PTC3, n = 1); 2 tumors measured >2 cm and diffusely involved the thyroid, and 5 had lymphatic invasion, with vascular invasion in 2. Thirteen PTCs had the B-Raf proto-oncogene, serine/threonine kinase (BRAF) valine-to-glutamic acid mutation at position 600 (BRAF(V) (600E)) (13 of 27 tumors; 48%), 11 measured <2 cm, and 6 had lymphatic invasion (46%), with vascular invasion in 3. Fusion oncogene tumors, compared with BRAF(V) (600E) PTCs, were associated with large size (mean, 2.2 cm vs 1.5 cm, respectively; P = .05), solid and diffuse variants (11 of 13 vs 0 of 13 tumors, respectively; P < .001), and lymphovascular invasion (12 of 13 vs 6 of 13 tumors, respectively; P = .02); BRAF(V) (600E) PTCs were predominantly the classic variant (12 of 13 vs 1 of 13 tumors). Two tumors metastasized to the lung, and both had fusion oncogenes (NTRK1/TPR, n = 1; RET/PTC1, n = 1).

CONCLUSIONS

Fusion oncogene PTC presents with more extensive disease and aggressive pathology than BRAF(V) (600E) PTC in the pediatric population. The high prevalence of the NTRK1/NTRK3 fusion oncogene PTCs in the United States is unusual and needs further investigation.

Histopathologic and Clinical Characterization of Thyroid Tumors Carrying the BRAF(K601E) Mutation

BACKGROUND

While the association of the BRAF(V600E) mutation with aggressive histopathological tumor features and clinical behavior has been extensively studied in papillary thyroid carcinoma (PTC), the BRAF(K601E) mutation has not been well characterized. This study reports what is currently the largest series of BRAF(K601E) mutated thyroid nodules.

METHODS

Histopathologic, cytologic, and molecular reports over a period of seven years (June 2007 to June 2014) were reviewed to identify thyroid cases with various types of BRAF mutations. All cases positive for the BRAF(K601E) mutation were reviewed to confirm histopathologic diagnosis and establish tumor variant, and clinical charts were reviewed to obtain clinical characteristics and follow-up information.

RESULTS

The BRAF(K601E) mutation was identified in 39 patients and comprised 5.3% of all BRAF mutations noted in thyroidectomy specimens. Twenty-seven out of 29 nodules (93%) with BRAF(K601E) mutated tumors with surgical pathology results available for review were PTC, one (3.4%) was a follicular thyroid carcinoma, and one (3.4%) was a follicular adenoma. The majority of K601E-mutant PTCs (20 cases) were follicular variant PTC. Encapsulation was present in all but one case, and one case showed capsular invasion. Coexisting mutations overall were not identified in BRAF(K601E) mutated thyroid nodules except in a case that exhibited a complex K601E + T599I mutation and had a classic PTC phenotype. The majority of K601E mutant nodules were T1 lesions (69%) and T2 lesions (28%) by TNM staging. With a median follow-up of 19.6 months, no structural or biochemical recurrence or metastases were found in patients with an isolated BRAF(K601E) mutation.

CONCLUSIONS

The BRAF(K601E) mutation is the second most common BRAF mutation found in thyroid nodules. Unlike BRAF(V600E), the most common mutation, K601E is strongly associated with follicular-patterned cancer, particularly with the encapsulated follicular variant of PTC, and may also be found in follicular thyroid carcinomas. Overall, BRAF(K601E) mutant tumors show better clinical outcomes than BRAF(V600E) positive tumors, and preoperative BRAF(K601E) analysis may provide important prognostic information for use in clinical management.

Herpes and polyoma family viruses in thyroid cancer

Thyroid cancer is considered the most common malignancy that affects the endocrine system. Generally, thyroid cancer derives from follicular epithelial cells, and thyroid cancer is divided into well-differentiated papillary (80% of cases) and follicular (15% of cases) carcinoma. Follicular thyroid cancer is further divided into the conventional and oncocytic (Hürthle cell) type, poorly differentiated carcinoma and anaplastic carcinoma. Both poorly differentiated and anaplastic carcinoma can arise either de novo, or secondarily from papillary and follicular thyroid cancer. The incidence of thyroid cancer has significantly increased for both males and females of all ages, particularly for females between 55–64 years of age, from 1999 through 2008. The increased rates refer to tumors of all stages, though they were mostly noted in localized disease. Recently, viruses have been implicated in the direct regulation of epithelial-mesenchymal transition (EMT) and the development of metastases. More specifically, Epstein-Barr virus (EBV) proteins may potentially lead to the development of metastasis through the regulation of the metastasis suppressor, Nm23, and the control of Twist expression. The significant enhancement of the metastatic potential, through the induction of angiogenesis and changes to the tumor microenvironment, subsequent to viral infection, has been documented, while EMT also contributes to cancer cell permissiveness to viruses. A number of viruses have been identified to be associated with carcinogenesis, and these include lymphotropic herpesviruses, namely EBV and Kaposi's sarcoma-associated herpesvirus [KSHV, also known as human herpesvirus type 8 (HHV8)]; two hepatitis viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV); human papillomaviruses (HPVs); human T cell lymphoma virus (HTLV); and a new polyomavirus, Merkel cell polyomavirus identified in 2008. In this review, we examined the association between thyroid cancer and two oncogenic virus families, the herpes and polyoma family viruses, and we discuss their potential role as causative agents in thyroid carcinogenesis.

Role of gene expression profiling in defining indeterminate thyroid nodules in addition to BRAF analysis

Fine-needle aspiration (FNA) is routinely used in the preoperative evaluation of thyroid nodules. However, 15% to 30% of aspirations yield indeterminate cytologic findings. Because the assessment of BRAF mutations seems to improve the diagnostic accuracy, this study evaluated BRAF mutations with Sanger sequencing and real-time methods in 650 consecutive thyroid aspirates. In addition, the expression of a large number of genes involved in basement membrane remodeling, extracellular matrix proteolysis, and cell adhesion was studied in both benign and malignant nodules to identify new diagnostic tools. In this prospective series, despite the use of a very sensitive BRAF mutational testing method, the frequency of a BRAF alteration being identified in indeterminate FNA samples was 3 of 68. Expression analysis revealed several genes that were differentially expressed between benign and malignant nodules (transforming growth factor, cadherin 1, collagen α1, catenin α1, integrin α3, and fibronectin 1 [FN1]), between follicular adenomas and follicular variant of papillary thyroid carcinoma (FN1, laminin γ1, integrin β2, connective tissue growth factor, catenin δ1, and integrin αV), and between BRAF-wild-type and BRAF-mutated papillary thyroid carcinomas (TIMP metallopeptidase inhibitor 1; catenin α1; secreted phosphoprotein 1; FN1; ADAM metallopeptidase with thrombospondin type 1 motif, 1; and selectin L). These data were partially confirmed with real-time polymerase chain reaction analysis and immunohistochemistry. When the cost/benefit ratio of the procedures was taken into account, BRAF mutational testing failed to increase diagnostic accuracy in cytologically indeterminate nodules. However, the additional analysis of the expression of specific molecular markers could have possible utility as a diagnostic tool, although further evidence based on a large series of samples is needed before definitive conclusions can be drawn. Cancer Cytopathol 2016;124:340-9. © 2015 American Cancer Society.

Follicular cell-derived thyroid cancer

Follicular cell-derived thyroid cancers are derived from the follicular cells in the thyroid gland, which secrete the iodine-containing thyroid hormones. Follicular cell-derived thyroid cancers can be classified into papillary thyroid cancer (80-85%), follicular thyroid cancer (10-15%), poorly differentiated thyroid cancer (<2%) and undifferentiated (anaplastic) thyroid cancer (<2%), and these have an excellent prognosis with the exception of undifferentiated thyroid cancer. The advent and expansion of advanced diagnostic techniques has driven and continues to drive the epidemic of occult papillary thyroid cancer, owing to overdiagnosis of clinically irrelevant nodules. This transformation of the thyroid cancer landscape at molecular and clinical levels calls for the modification of management strategies towards personalized medicine based on individual risk assessment to deliver the most effective but least aggressive treatment. In thyroid cancer surgery, for instance, injuries to structures outside the thyroid gland, such as the recurrent laryngeal nerve in 2-5% of surgeries or the parathyroid glands in 5-10% of surgeries, negatively affect quality of life more than loss of the expendable thyroid gland. Furthermore, the risks associated with radioiodine ablation may outweigh the risks of persistent or recurrent disease and disease-specific mortality. Improvement in the health-related quality of life of survivors of follicular cell-derived thyroid cancer, which is decreased despite the generally favourable outcome, hinges on early tumour detection and minimization of treatment-related sequelae. Future opportunities include more widespread adoption of molecular and clinical risk stratification and identification of actionable targets for individualized therapies.

Are we really at the dawn of understanding sporadic pediatric thyroid carcinoma?

Data from the National Cancer Institute and from the literature have disclosed an increasing incidence of thyroid cancer in children, adolescents and adults. Although children and adolescents with thyroid cancer tend to present with more advanced disease than adults, their overall survival rate is excellent; however, there is no clear explanation for the differences observed in the clinicopathological outcomes in these age groups. There has been an ongoing debate regarding whether the clinicopathological differences may be due to the existence of distinct genetic alterations. Efforts have been made to identify these acquired genetic abnormalities that will determine the tumor's biological behavior and ultimately allow molecular prognostication. However, most of the studies have been performed in radiation-exposed pediatric thyroid carcinoma. Therefore, our understanding of the role of these driver mutations in sporadic pediatric differentiated thyroid cancer development is far from complete, and additionally, there is a strong need for studies in both children and adolescents. The aim of this review is to present an extensive literature review with emphasis on the molecular differences between pediatric sporadic and radiation-exposed differentiated thyroid carcinomas and adult population.

Evaluation and management of thyroid nodules with atypia/follicular lesion of undetermined significance on fine-needle aspiration

Since the introduction of the Bethesda System for Reporting Thyroid Cytopathology in 2008, the management of thyroid nodules has become more standardized, with clearly defined algorithms based on risk of malignancy for each of the six cytologic categories. However, the management of a thyroid nodule with a fine-needle aspiration biopsy classified as Bethesda III, or atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), remains controversial due to the cytologic heterogeneity and the variability in the reported rates of malignancy. In this review, the history and rationale for the new Bethesda III category is examined, the reported incidence and risk of malignancy from published studies is reviewed and recommendations for management of patients with a thyroid nodule and AUS/FLUS are provided. Recent advances in molecular analysis and their role in the evaluation of patients with AUS/FLUS are also discussed.

Identification of potential therapeutic targets for papillary thyroid carcinoma by bioinformatics analysis

The aim of the present study was to identify potential therapeutic targets for papillary thyroid carcinoma (PTC) and to investigate the possible mechanism underlying this disease. The gene expression profile, GSE53157, was downloaded from the Gene Expression Omnibus database. Only 10 chips, including 3 specimens of normal thyroid tissues and 7 specimens of well-differentiated thyroid carcinomas, were analyzed in the present study. Differentially-expressed genes (DEGs) between PTC patients and normal individuals were identified. Next, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of DEGs were performed. Modules in the protein-protein interaction (PPI) network were identified. Significant target genes were selected from the microRNA (miRNA) regulatory network. Furthermore, the integrated network was constructed with the miRNA regulatory and PPI network modules, and key target genes were screened. A total of 668 DEGs were identified. Modules M1, M2 and M3 were identified from the PPI network. From the modules, DEGs of cyclin-dependent kinase inhibitor 1A, S100 calcium binding protein A6 (S100A6), dual specificity phosphatase 5, keratin 19, met proto-oncogene (MET) and lectin galactoside-binding soluble 3 were included in the Malacards database. In the miRNA regulatory and integrated networks, genes of cyclin-dependent kinase inhibitor 1C (CDKN1C), peroxisome proliferator-activated receptor γ, aryl hydrocarbon receptor, basic helix-loop-helix family, member e40 and reticulon 1 were the key target genes. S100A6, MET and CDKN1C may exhibit key roles in the progression and development of PTC, and may be used as specific therapeutic targets in the treatment of PTC. However, further experiments are required to confirm these results.

BRAF V600E and decreased NIS and TPO expression are associated with aggressiveness of a subgroup of papillary thyroid microcarcinoma

BACKGROUND

Thyroid cancer incidence has dramatically increased worldwide over the last two decades. The rise is mostly due to an increased detection of small papillary thyroid carcinomas (PTCs) (≤20  mm), predominantly microPTC (≤10  mm). Although small tumors generally have an excellent outcome, a considerable percentage may have a more aggressive disease and worse prognosis. The clinical challenge is to preoperatively identify those tumors that are more likely to recur.

AIM

To improve risk stratification and patient management, we sought to determine the prognostic value of BRAF V600E, NRAS or RET/PTC mutations in patients with PTC measuring <20  mm, mainly microPTC.

METHODS

The prevalence of RET/PTC fusion genes was examined by quantitative RT-PCR. BRAF V600E and NRAS Q61 mutations were determined by PCR sequencing. To further elucidate why some small PTC are less responsive to radioactive iodine treatment therapy, we explored if these genetic alterations may modulate the expression of iodine metabolism genes (NIS, TPO, TG, TSHR and PDS) and correlated with clinico-pathological findings that are predictors of recurrence.

RESULTS

This study shows that tumors measuring ≤20  mm exhibited higher prevalence of BRAF V600E mutation, which correlated with aggressive histopathological parameters, higher risk of recurrence, and lower expression of NIS and TPO. Although this correlation was not found when microPTC were evaluated, we show that tumors measuring 7-10  mm, which were positive for BRAF mutation, presented more aggressive features and lower expression of NIS and TPO.

CONCLUSION

We believe that our findings will help to decide the realistic usefulness of BRAF V600E mutation as a preoperative marker of poor prognosis in small PTC, primarily in microPTC.

BRAF V600E and risk stratification of thyroid microcarcinoma: a multicenter pathological and clinical study

Studies from single institutions have analyzed BRAF in papillary microcarcinomas, sometimes with contradictory results. Most of them have provided limited integration of histological and clinical data. To obtain a comprehensive picture of BRAF V600E-mutated microcarcinomas and to evaluate the role of BRAF testing in risk stratification we performed a retrospective multicenter analysis integrating microscopical, pathological, and clinical information. Three hundred and sixty-five samples from 300 patients treated at six medical institutions covering different geographical regions of Italy were analyzed with central review of all cases. BRAF V600E statistical analysis was conducted on 298 microcarcinomas from 264 patients after exclusion of those that did not meet the required criteria. BRAF V600E was identified in 145/298 tumors (49%) including the following subtypes: 35/37 (95%, P<0.0001) tall cell and 72/114 (64%, P<0.0001) classic; conversely 94/129 follicular variant papillary microcarcinomas (73%, P<0.0001) were BRAF wild type. BRAF V600E-mutated microcarcinomas were characterized by markedly infiltrative contours (P<0.0001) with elongated strings of neoplastic cells departing from the tumor, and by intraglandular tumor spread (P<0.0001), typically within 5 mm of the tumor border. Multivariate analysis correlated BRAF V600E with specific microscopic features (nuclear grooves, optically clear nuclei, tall cells within the tumor, and tumor fibrosis), aggressive growth pattern (infiltrative tumor border, extension into extrathyroidal tissues, and intraglandular tumor spread), higher American Thyroid Association recurrence risk group, and non-incidental tumor discovery. The following showed the strongest link to BRAF V600E: tall cell subtype, many neoplastic cells with nuclear grooves or with optically clear nuclei, infiltrative growth, intraglandular tumor spread, and a tumor discovery that was non-incidental. BRAF V600E-mutated microcarcinomas represent a distinct biological subtype. The mutation is associated with conventional clinico-pathological features considered to be adverse prognostic factors for papillary microcarcinoma, for which it could be regarded as a surrogate marker. BRAF analysis may be useful to identify tumors (BRAF wild type) that have negligible clinical risk.

The Impact of Noninvasive Follicular Variant of Papillary Thyroid Carcinoma on Rates of Malignancy for Fine-Needle Aspiration Diagnostic Categories

BACKGROUND

Increased recognition of the indolent nature of noninvasive follicular variant of papillary thyroid carcinoma (NFVPTC) along with greater insight into the molecular alterations of these tumors has prompted endocrine pathologists to question whether these tumors warrant a diagnosis of carcinoma. However, a change in terminology would affect the rates of malignancy of fine-needle aspiration (FNA) diagnostic categories. Therefore, the aim of this study was to determine the percentage decrease in associated risk of malignancy for each FNA diagnostic category if NFVPTCs were no longer termed carcinomas.

METHODS

We evaluated a cohort of 655 FNAs with subsequent resection specimens over a 22-month time period. The diagnoses of the preceding FNAs were recorded according to the Bethesda System for Reporting Thyroid Cytopathology. For cases with more than one preceding FNA, the FNA diagnosis associated with the highest risk of malignancy was identified. Slides for all resection specimens with a diagnosis of FVPTC were reviewed to identify noninvasive tumors. By definition, all of these tumors were encapsulated, partially encapsulated, or well circumscribed and lacked any indication of infiltrative growth, capsular penetration, or lymphovascular invasion.

RESULTS

Our cohort of 655 FNAs with subsequent resection specimens included 53 (8.1%) nondiagnostic (ND), 167 (25.5%) benign, 97 (14.8%) atypia/follicular lesion of undetermined significance (AUS/FLUS), 88 (13.4%) suspicious for follicular neoplasm (SFN), 94 (14.4%) suspicious for malignancy (SUS), and 156 (23.8%) malignant cases (POS). Surgical resections demonstrated benign findings in 309 (47.2%) and malignant tumors in 346 (52.8%), including 85 NFVPTCs accounting for 24.6% of malignancies. Our rates of malignancy for ND, benign, AUS/FLUS, SFN, SUS, and POS were 18.9%, 13.2%, 39.2%, 45.5%, 87.2%, and 98.7%, respectively. If NFVPTC were no longer termed carcinoma, these rates would drop to 17.0% (10% decrease), 5.4% (59% decrease), 21.6% (45% decrease), 37.5% (18% decrease), 45.7% (48% decrease), and 93.6% (5% decrease), respectively.

CONCLUSION

Our findings demonstrate that if terminology were changed and NFVPTCs were not considered carcinomas, the rates of malignancy for FNA diagnostic categories would be substantially decreased, with the most clinically significant decrease seen in the SUS category, which demonstrated a relative decrease of nearly 50%.

The utility of molecular markers in pre-operative assessment of thyroid nodules

The pre-operative diagnosis of thyroid tumors is determined by gold standard fine needle aspiration (FNA) biopsy. This has been widely accepted and offers the most cost-effective approach for evaluation of thyroid nodules. However, its diagnostic accuracy can pose a challenging scenario to surgeons. These diagnostic difficulties may subject patients to unnecessary thyroidectomies for benign thyroid nodules. Thus, additional molecular tests are needed to improve the sensitivity and specificity of FNA. The role of molecular markers is being proposed to predict the type and risk of malignancy to abate the need for diagnostic thyroidectomies. This review discusses their utility and validity in pre-operative diagnosis of thyroid nodules and how these markers can enhance the accuracy of FNA cytology.

Genetic Alterations in Hungarian Patients with Papillary Thyroid Cancer

The incidence of thyroid cancers is increasing worldwide. Some somatic oncogene mutations (BRAF, NRAS, HRAS, KRAS) as well as gene translocations (RET/PTC, PAX8/PPAR-gamma) have been associated with the development of thyroid cancer. In our study, we analyzed these genetic alterations in 394 thyroid tissue samples (197 papillary carcinomas and 197 healthy). The somatic mutations and translocations were detected by Light Cycler melting method and Real-Time Polymerase Chain Reaction techniques, respectively. In tumorous samples, 86 BRAF (44.2%), 5 NRAS (3.1%), 2 HRAS (1.0%) and 1 KRAS (0.5%) mutations were found, as well as 9 RET/PTC1 (4.6%) and 1 RET/PTC3 (0.5%) translocations. No genetic alteration was seen in the non tumorous control thyroid tissues. No correlation was detected between the genetic variants and the pathological subtypes of papillary cancer as well as the severity of the disease. Our results are only partly concordant with the data found in the literature.

American Thyroid Association Statement on Surgical Application of Molecular Profiling for Thyroid Nodules: Current Impact on Perioperative Decision Making

BACKGROUND

Recent advances in research on thyroid carcinogenesis have yielded applications of diagnostic molecular biomarkers and profiling panels in the management of thyroid nodules. The specific utility of these novel, clinically available molecular tests is becoming widely appreciated, especially in perioperative decision making by the surgeon regarding the need for surgery and the extent of initial resection.

METHODS

A task force was convened by the Surgical Affairs Committee of the American Thyroid Association and was charged with writing this article.

RESULTS/CONCLUSIONS

This review covers the clinical scenarios by cytologic category for which the thyroid surgeon may find molecular profiling results useful, particularly for cases with indeterminate fine-needle aspiration cytology. Distinct strengths of each ancillary test are highlighted to convey the current status of this evolving field, which has already demonstrated the potential to streamline decision making and reduce unnecessary surgery, with the accompanying benefits. However, the performance of any diagnostic test, that is, its positive predictive value and negative predictive value, are exquisitely influenced by the prevalence of cancer in that cytologic category, which is known to vary widely at different medical centers. Thus, it is crucial for the clinician to know the prevalence of malignancy within each indeterminate cytologic category, at one's own institution. Without this information, the performance of the diagnostic tests discussed below may vary substantially.

Comparison of presentation and clinical outcome between children and young adults with differentiated thyroid cancer

BACKGROUND

The aim of the present study was to evaluate the presentation, clinical course and outcome between children and young adults with differentiated thyroid cancer (DTC) treated in our hospital.

MATERIALS AND METHODS

The medical records of 145 patients with DTC who underwent surgery followed by radioiodine and thyroid hormone (TSH) suppression were retrospectively reviewed. The follow up was between January 2006 and June 2012. These patients consisted of 38 children (age ≤ 18 y) and 107 young adult patients (age ≤ 30 y). The clinical characteristics and outcome were analyzed and compared, and the progression-free survival (PFS) was evaluated using the Kaplan-Meier method.

RESULTS

At initial diagnosis, a greater degree of extra thyroidal extension was found in children than adults patients (p<0.001). However, there was no significant difference between the two groups with regard to the tumor size and the presence of lymph node or distant metastasis (p=0.172, p=0.050 and p=0.068, respectively). The extent of surgery and the cumulative or mean dose of radioiodine were similar in both groups. During the follow up, the overall survival rate was 100% for both groups, and the PFS rate was similar in children and in young adults group (log rank test, χ2=0.126, p=0.723).

CONCLUSIONS

In comparison to the young adult patients, DTC in children presents with more aggressive behavior, but outcomes are similar between the two groups after the intensive management of surgery followed by radioiodine and TSH suppression therapy.

Lenvatinib: a new option for the treatment of advanced iodine refractory differentiated thyroid cancer?

ABSTRACT 

Lenvatinib mesylate (E7080; 4-[3-chloro-4-(N′-cyclopropylureido) phenoxy] 7-methoxyquinoline-6-carboxamide mesylate) is an oral molecule that inhibits multiple tyrosine kinase receptors such as VEGF-R-1–3, FGF-R-1–4, RET, c-KIT and PDGF-R-β. Phase I studies identified the maximum tolerated dose to be 25 mg daily that, in fasting treated patients, is rapidly absorbed with maximum concentrations achieved within 3 h of administration. In these studies, lenvatinib showed activity in solid tumors. Subsequently, Phase II studies in thyroid cancer, in particular differentiated thyroid cancer (DTC), confirmed good clinically significant activity and the recently published Phase III SELECT trial reported median progression-free survival was 18.3 months with lenvatinib versus 3.6 months with placebo (hazard ratio for progression or death: 0.21; 99% CI: 0.14–0.31; p < 0.001). Treatment-related adverse effects occurred in more than 40% of patients on lenvatinib. These were hypertension (in 67.8% of the patients), diarrhea (in 59.4%), fatigue or asthenia (in 59.0%), decreased appetite (in 50.2%), decreased weight (in 46.4%) and nausea (in 41.0%). Discontinuations of lenvatinib because of adverse effects occurred in 37 patients (14.2%) compared with three patients who received placebo (2.3%). Six of 20 deaths in patients on lenvatinib were considered to be drug-related. Lenvatinib has been licensed by the US FDA and EMA based on these data and provides an option for the treatment of radioiodine refractory DTC.

Molecular Assays in Cytopathology for Thyroid Cancer

Background

Despite lack of adequate, validated, independently performed clinical studies, several molecular tests are commercially available on the market and are being used on indeterminate thyroid nodules to guide patient-care decisions.

Methods

We summarize the current evidence on the role and limitations of molecular tests used in combination with thyroid cytopathology to refine the presurgical diagnosis of thyroid nodules.

Results

The clinical performance of molecular tests depends on the pretest risk of malignancy within the specific cytological group being assessed. This risk is variable and should be assessed at each institution to optimize the selection of the molecular test and the interpretation of its results. Next-generation sequencing has increased the sensitivity of oncogene panels while maintaining high specificity. Tests assessing the gene expression pattern have shown promising results, with high sensitivity but low specificity. The impacts of molecular markers on clinical practice remains in flux and their effect on health care costs remains poorly understood.

Conclusions

Further large, independent, confirmatory, clinical validation studies and real-world, cost-effectiveness studies are necessary before the widespread adoption of these tests can be endorsed as standard of care.

Integrated genomic characterization of papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. Here, we describe the genomic landscape of 496 PTCs. We observed a low frequency of somatic alterations (relative to other carcinomas) and extended the set of known PTC driver alterations to include EIF1AX, PPM1D, and CHEK2 and diverse gene fusions. These discoveries reduced the fraction of PTC cases with unknown oncogenic driver from 25% to 3.5%. Combined analyses of genomic variants, gene expression, and methylation demonstrated that different driver groups lead to different pathologies with distinct signaling and differentiation characteristics. Similarly, we identified distinct molecular subgroups of BRAF-mutant tumors, and multidimensional analyses highlighted a potential involvement of oncomiRs in less-differentiated subgroups. Our results propose a reclassification of thyroid cancers into molecular subtypes that better reflect their underlying signaling and differentiation properties, which has the potential to improve their pathological classification and better inform the management of the disease.

Vitamin D-neutralizing CYP24A1 expression, oncogenic mutation states and histological findings of human papillary thyroid cancer

OBJECTIVE

The aims of the present study were to examine gene and protein expression of the vitamin D-inactivating 24-hyroxylase (CYP24A1) and the activating 1-alpha-hydroxylase (CYP27B1) enzyme in human papillary thyroid cancer (PTC), furthermore, to investigate the association between CYP24A1 expression and numerous clinical, histological parameters and somatic oncogene mutation status of thyroid tumor tissues.

MATERIALS AND METHODS

Gene expression analysis was carried out in 100 Hungarian thyroid samples, both normal and papillary tumor tissue sections of the same patient. The specific mRNA to the selected genes was analyzed by TaqMan probe-based quantitative real-time RT-PCR. The somatic oncogene mutation states of BRAF, NRAS, HRAS and KRAS were also tested.

RESULTS

CYP24A1 mRNA expression was markedly increased in 52 cases (52%) of the examined papillary cancers compared with that of normal thyroid tissue. There was a tendency toward difference in the distribution of high-level CYP24A1 in the PTC accompanied with somatic oncogene mutation. Positive correlation was seen between increased CYP24A1 expression rate and a group of variables reflecting tumor malignity (mainly vascular invasion, lymph node metastasis, tumor size, hypothyreosis) by principal components analysis. No significant alteration was seen in CYP27B1 gene expression between neoplastic and normal tissues.

CONCLUSIONS

A definite alteration was seen in vitamin D3-inactivating CYP24A1 gene activity in PTC compared to their normal tissues on a relatively large patient population. Our findings raise the possibility that CYP24A1 may also directly be involved in thyroid carcinogenesis.

Investigation of BK virus, Epstein-Barr virus and human papillomavirus sequences in postoperative thyroid gland specimens

BACKGROUND

Although recent evidence has implicated viruses in the regulation of epithelial-to-mesenchymal transition and tumor progression, little is known regarding viral infections in thyroid malignancies. Thus the aim of this study was to detect sequences of 3 potentially oncogenic viruses - BK virus (BKV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) - in a series of postoperative thyroid gland specimens.

METHODS

Thirty patients with thyroid nodules who underwent surgery for thyroid disease within a 3-year period were enrolled. Both nodular and adjacent normal thyroid tissue was surgically excised from each patient. Viral gene sequences of BKV (VP1), EBV (LMP1, EBNA2 and EBER1) and HPV were amplified by PCR. The PCR results were confirmed by direct sequencing analysis.

RESULTS

VP1 gene sequences were detected in 60% (18/30) of thyroid cancer or multinodular hyperplasia lesions compared with in 43.3% (13/30) of adjacent normal thyroid tissue specimens. Fifteen of thirty (50%) of thyroid cancer or multinodular hyperplasia samples revealed LMP1 sequences compared with 46.7% (14/30) of corresponding normal thyroid tissues. EBNA2 gene sequences were detected in 90% (27/30) of thyroid cancer or multinodular hyperplasia samples, compared with 90% (27/30) of adjacent normal thyroid tissue specimens. All samples were negative for EBER1 sequences, while HPV DNA was not detected in either nodular or normal thyroid tissue.

CONCLUSIONS

This study suggests that BKV and EBV "infection" is an early event, occurring within normal tissue. Our findings do not show a clear role for the viruses examined, instead they suggest an "endemicity" pattern rather than a causal effect.

BRAF V600E mutation-specific antibody: A review

The significance of BRAF mutations in neoplasia was first recognized in 2002 when mutations were discovered in a broad range of cancers. Numerous subsequent studies expanded our understanding of BRAF V600E as a critical diagnostic, prognostic, and predictive biomarker in many cancers. Additionally, the advent of small-molecule inhibitors of BRAF V600E rendered assessment of BRAF mutation status essential in tumors such as melanoma. In clinical practice, evaluation of BRAF mutation status has routinely been performed by DNA-based assays utilizing polymerase chain reaction (PCR). However, molecular testing is not available at many hospitals since it is time-consuming, expensive, and requires expertise in molecular techniques. The first BRAF V600E-specific antibody was reported in 2011 (clone VE1). A purified version of this antibody as well as a second monoclonal antibody targeted to BRAF V600E is now commercially available. In this review, clinicopathologic characteristics associated with BRAF-mutant tumors will be highlighted, and the prognostic and predictive implications of a BRAF V600E mutation will be discussed with a focus on melanoma, thyroid carcinoma and colorectal carcinoma. Additionally, we will review the correlation between immunohistochemistry and molecular results and deliberate how BRAF immunohistochemistry might be utilized in the evaluation of these tumors.

Invasion rather than nuclear features correlates with outcome in encapsulated follicular tumors: further evidence for the reclassification of the encapsulated papillary thyroid carcinoma follicular variant

The prognosis of the encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) and its relationship to encapsulated follicular carcinoma (EFC) and follicular adenoma (FA) is subject to controversy. All EFVPTCs, EFCs, and FAs identified at a single institution between 1981 and 2003 were analyzed microscopically. A cohort of FAs from a different hospital was also examined. EFVPTCs were subdivided into noninvasive EFVPTC (NIEFVPTC) and invasive EFVPTC (IEFVPTC) displaying capsular/vascular invasion. There were 83 EFVPTCs (57 noninvasive, 26 invasive), 14 EFCs, and 52 FAs. Similar to FA, over a median follow-up of 9.5 years, none of the NIEFVPTCs manifested lymph node metastasis (LNM) or recurred. Furthermore, with a median follow-up of 10.5 years, none of 39 NIEFVPTCs without radioactive iodine therapy recurred. Four (15%) of 26 IEFVPTCs and none of 14 EFCs harbored distant metastasis (P = .29). There was no difference in LNM rate and degree of vascular or capsular invasion between IEFVPTC and EFC (P > .1). All 4 IEFVPTCs with adverse behavior presented with distant metastasis and no LNM. Sixteen percent of IEFVPTCs had poor outcome, whereas there was none in the NIEFVPTCs (P = .007). In conclusion, NIEFVPTC seems to behave similarly to FA, whereas IEFVPTC can metastasize and spread like EFC. Thus, invasion rather than nuclear features drives outcome in encapsulated follicular tumors. Non-IEFVPTC could be treated in a conservative manner sparing patients unnecessary total thyroidectomy and radioactive iodine therapy. The position of the EFVPTC in the classification of thyroid neoplasia should be reconsidered.

Preoperative RAS mutational analysis is of great value in predicting follicular variant of papillary thyroid carcinoma

Follicular variant of papillary thyroid carcinoma (FVPTC), particularly the encapsulated subtype, often causes a diagnostic dilemma. We reconfirmed the molecular profiles in a large number of FVPTCs and investigated the efficacy of the preoperative mutational analysis in indeterminate thyroid nodules. BRAF V600E/K601E and RAS mutational analysis was performed on 187 FVPTCs. Of these, 132 (70.6%) had a point mutation in one of the BRAF V600E (n = 57), BRAF K601E (n = 11), or RAS (n = 64) genes. All mutations were mutually exclusive. The most common RAS mutations were at NRAS codon 61. FNA aspirates from 564 indeterminate nodules were prospectively tested for BRAF and RAS mutation and the surgical outcome was correlated with the mutational status. Fifty-seven and 47 cases were positive for BRAF and RAS mutation, respectively. Twenty-seven RAS-positive patients underwent surgery and all except one patient had FVPTC. The PPV and accuracy of RAS mutational analysis for predicting FVPTC were 96% and 84%, respectively. BRAF or RAS mutations were present in more than two-thirds of FVPTCs and these were mutually exclusive. BRAF mutational analysis followed by N, H, and KRAS codon 61 mutational analysis in indeterminate thyroid nodules would streamline the management of patients with malignancies, mostly FVPTC.

Management of recurrent/persistent nodal disease in patients with differentiated thyroid cancer: a critical review of the risks and benefits of surgical intervention versus active surveillance

BACKGROUND

The primary goals of this interdisciplinary consensus statement are to define the eligibility criteria for management of recurrent and persistent cervical nodal disease in patients with differentiated thyroid cancer (DTC) and to review the risks and benefits of surgical intervention versus active surveillance.

METHODS

A writing group was convened by the Surgical Affairs Committee of the American Thyroid Association and was tasked with identifying the important clinical elements to consider when managing recurrent/persistent nodal disease in patients with DTC based on the available evidence in the literature and the group's collective experience.

SUMMARY

The decision on how best to manage individual patients with suspected recurrent/persistent nodal disease is challenging and requires the consideration of a significant number of variables outlined by the members of the interdisciplinary team. Here we report on the consensus opinions that were reached by the writing group regarding the technical and clinical issues encountered in this patient population.

CONCLUSIONS

Identification of recurrent/persistent disease requires a team decision-making process that includes the patient and physicians as to what, if any, intervention should be performed to best control the disease while minimizing morbidity. Several management principles and variables involved in the decision making for surgery versus active surveillance were developed that should be taken into account when deciding how best to manage a patient with DTC and suspected recurrent or persistent cervical nodal disease.

Autophagy in thyroid cancer: present knowledge and future perspectives

Thyroid cancer is the most common endocrine malignancy. Despite having a good prognosis in the majority of cases, when the tumor is dedifferentiated it does no longer respond to conventional treatment with radioactive iodine, the prognosis worsens significantly. Treatment options for advanced, dedifferentiated disease are limited and do not cure the disease. Autophagy, a process of self-digestion in which damaged molecules or organelles are degraded and recycled, has emerged as an important player in the pathogenesis of different diseases, including cancer. The role of autophagy in thyroid cancer pathogenesis is not yet elucidated. However, the available data indicate that autophagy is involved in several steps of thyroid tumor initiation and progression as well as in therapy resistance and therefore could be exploited for therapeutic applications. The present review summarizes the most recent data on the role of autophagy in the pathogenesis of thyroid cancer and we will provide a perspective on how this process can be targeted for potential therapeutic approaches and could be further explored in the context of multimodality treatment in cancer and personalized medicine.

Best practice of BRAF V600E mutation testing for the diagnosis and management of thyroid cancers

BRAF V600E mutation is the single most common genetic alteration identified in papillary thyroid carcinoma. There is significant association between BRAF V600E mutation and aggressive tumor behavior. BRAF V600E mutation has also been found to be an independent predictor of treatment failure and tumor recurrence even in patients with low-stage disease. Pre-operative BRAF mutation testing of thyroid fine needle aspiration specimens has become a routine clinical practice that enhances the predictability of malignancy in indeterminate fine needle aspiration cytology specimens especially those in the follicular lesion of undetermined significance/atypia of undetermined significance category. In addition to histological evaluation of subsequent core needle biopsy and BRAF immunohistochemistry, an expanded panel of mutation testing including BRAF V600E, NRAS, HRAS, RET/papillary thyroid carcinoma and PAX8/PPARγ rearrangements are currently advocated to further improve the diagnostic predictability in the detection of thyroid carcinomas using cytological specimens.

BRAF mutation analysis in thyroid nodules with indeterminate cytology: our experience on surgical management of patients with thyroid nodules from an area of borderline iodine deficiency

PURPOSE

Fine-needle aspiration (FNA) with cytologic evaluation is the most reliable tool for malignancy prediction in thyroid nodules, but cytologic diagnosis remains indeterminate for 12-18 % of nodules. BRAF V600E mutation has been reported to show a high specificity for malignant thyroid nodules and the use of this marker to refine indeterminate FNA cytology results may be a useful diagnostic adjunctive tool in the pre-operative evaluation of thyroid nodules. The aim of this study was to estimate the prevalence of BRAF exon 15 mutation (V600E) and its clinical value as a diagnostic tool in a series of thyroid nodules with indeterminate cytology from an area of borderline iodine deficiency.

SUBJECTS AND METHODS

One hundred and fifty-three thyroid samples obtained by FNA of thyroid nodules from 151 patients were subjected to the analysis of BRAF V600E mutation by direct sequencing. In the study 54 nodules with indeterminate cytology, 56 benign and 43 malignant thyroid nodules were included.

RESULTS

V600E BRAF gene mutation was demonstrated in 19/43 malignant nodules, in 0/56 benign nodules and in only 1/54 indeterminate nodules that, after histology, turned out to be at a papillary thyroid carcinoma.

CONCLUSIONS

The application of BRAF exon 15 analysis showed limitations when applied to discriminate thyroid nodules with indeterminate cytology if wild-type BRAF is found, and there is no role for avoiding diagnostic thyroid surgery.

Molecular approaches to thyroid cancer diagnosis

Thyroid nodules are common, and the accurate diagnosis of cancer or benign disease is important for the effective clinical management of patients. Molecular markers are a helpful diagnostic tool, particularly for cytologically indeterminate thyroid nodules. In the past few years, significant progress has been made in developing molecular markers for clinical use in fine-needle aspiration specimens, including gene mutation panels and gene expression classifiers. With the availability of next generation sequencing technology, gene mutation panels can be expanded to interrogate multiple genes simultaneously and to provide yet more accurate diagnostic information. In addition, recently several new molecular markers of thyroid cancer have been identified that offer diagnostic, prognostic, and therapeutic information that might be of value in guiding individualized management of patients with thyroid nodules.

Pax-8-PPAR-γ fusion protein in thyroid carcinoma

Thyroid carcinoma is the most common endocrine malignancy, and its incidence is continuing to increase. Most thyroid carcinomas contain one of several known driver mutations, such as the Val600Glu substitution in B-Raf, Ras mutations, RET gene fusions, or PAX8-PPARG gene fusions. The PAX8-PPARG gene fusion results in the production of a Pax-8-PPAR-γ fusion protein (PPFP), which is found in approximately one-third of follicular thyroid carcinomas, as well as some follicular-variant papillary thyroid carcinomas. In vitro and in vivo evidence indicates that PPFP is an oncoprotein. Although specific mechanisms of action remain to be defined, PPFP is considered to act as a dominant-negative inhibitor of wild-type PPAR-γ and/or as a unique transcriptional activator of subsets of PPAR-γ-responsive and Pax-8-responsive genes. Detection of the fusion transcript in thyroid nodule biopsy specimens can aid clinical decision-making when cytological findings are indeterminate. The PPAR-γ agonist pioglitazone is highly therapeutic in a transgenic mouse model of PPFP-positive thyroid carcinoma, suggesting that PPAR-γ agonists might be beneficial in patients with PPFP-positive thyroid carcinomas.

BRAF mutation in follicular variant of papillary thyroid carcinoma is associated with unfavourable clinicopathological characteristics and malignant features on ultrasonography

OBJECTIVE

Follicular variant of papillary thyroid carcinoma (FVPTC) is a common variant of papillary thyroid carcinoma (PTC), but the association between BRAF mutation and the clinicopathological and ultrasonographical characteristics of FVPTC has not been well studied. The aim of this study was to determine the significance of BRAF mutation in FVPTC.

PATIENTS

The medical records of the 137 patients with >5 mm FVPTCs and known BRAF mutation status in the interested nodule were reviewed. BRAF mutation analysis was performed routinely and prospectively by Sanger sequencing. Clinicopathological and ultrasonographical characteristics were compared between BRAF mutation-positive and BRAF mutation-negative groups.

RESULTS

BRAF mutation was detected in 35 (25·5%) patients. The BRAF mutation-positive group was associated with smaller tumour size (P = 0·022), extrathyroidal extension (P = 0·001), multifocality (P = 0·046) and higher (III/IV) TNM stages (P = 0·005). In multivariable analysis, higher (III/IV) TNM stage was an independent predictive factor for BRAF mutation-positive status (adjusted OR 2·966, 95% CI 1·321-6·663). In diagnosis of FVPTC, the presence of BRAF mutation was associated with malignant features on ultrasonography (P < 0·001) and higher incidence of suspicious for malignancy or malignant diagnosis on the fine needle aspiration cytology (P = 0·023). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of US for detecting BRAF mutation were 82·9%, 57·8%, 40·3%, 90·8% and 64·2%, respectively. Conclusions BRAF mutation in FVPTC is associated with unfavourable clinicopathological characteristics and malignant features on ultrasonography and may be a potential prognostic factor as it is in classical PTC.

Synchronous occurrence of medullary and papillary carcinoma of the thyroid in a patient with cutaneous melanoma: determination of BRAFV600E in peripheral blood and tissues. Report of a case and review of the literature

The purpose of this study is to describe a case of concurrent medullary and papillary thyroid carcinoma (MTC and PTC) and cutaneous melanoma and to analyze BRAF(V600E) mutation in plasma and tissues. We report the clinical history and the laboratory, imaging, and histopathological findings of a 47-year-old man affected by multinodular goiter. BRAF(V600E)-mutated DNA was quantified in plasma samples and in cancer sections by quantitative real-time polymerase chain reaction (qPCR). At ultrasound examination, the dominant right nodule of the thyroid was weakly hyperechoic and hypervascularized, while the left one was hypoechoic without internal vascularization. Regional lymphadenomegalia was not detected. Basal plasma calcitonin was elevated, and the patient underwent total thyroidectomy and resection of central cervical lymph nodes. Histopathological examination identified two distinct foci of MTC and PTC and micrometastasis of well-differentiated carcinoma in one of the six resected lymph nodes. RET proto-oncogene germline mutations were not detected. Cutaneous melanoma of the thorax was subsequently diagnosed. BRAF(V600E) tissue DNA was detected in PTC and melanoma but not in MTC. The cell-free plasma percentage of BRAF(V600E) DNA was detected in pre-thyroidectomy peripheral blood and was drastically reduced after cancer treatments. This study confirms the occurrence of synchronous MTC and PTC and is the first evidence of the co-existence of melanoma and distinct thyroid cancers of different origin. BRAF(V600E) allele was detected in PTC and melanoma but not in MTC tissues. BRAF(V600E) molecular quantification in pre- and post-treatment blood supports our previous data, suggesting its possible role in diagnosis and follow-up of BRAF-positive tumors.

Follicular variant of papillary thyroid carcinoma: accuracy of FNA diagnosis and implications for patient management

Follicular variant of papillary thyroid carcinoma (FVPTC) creates a continuous diagnostic dilemma among pathologists because of the paucity of nuclear changes of papillary carcinoma and overlapping features with benign and other neoplastic follicular lesions. Current guidelines for the management of thyroid nodules recommend surgery for confirmed PTC, suspicious for PTC, and follicular neoplasm cases, while further immediate diagnostic studies or treatment are not routinely required if the nodule is benign on cytology. This study is designed to determine the accuracy of cytology in the diagnosis of FVPTC, based on the Bethesda classification system, and determine the implications for patient management based on the current recommendation. Based on a retrospective review of cytologic diagnoses between January 2008 and December 2011, thyroid fine needle aspiration (FNA) cytology specimens with subsequent surgical intervention and a final diagnosis of FVPTC were selected. The cytologic diagnoses were compared with the final diagnoses, and the percentage of cases contributing to the final diagnosis of FVPTC was calculated for each diagnostic category. Triage efficiency and diagnostic accuracy were calculated. One hundred and fifty-two cases with histologic confirmation of FVPTC were identified (representing 128 patients-101 female, 27 male). All patients had undergone either lobectomy with completion thyroidectomy or total thyroidectomy. The cytologic diagnosis of "positive for malignancy" accounted for only 27 % of the final histologic diagnosis of FVPTC, while suspicious for carcinoma, follicular neoplasm, follicular lesion of undetermined significance, and benign accounted for 11, 23, 23, and 16 % of the final diagnosis of FVPTC, respectively. Only 18 % of the 55 cases tested were positive for BRAF mutation. The subtle nuclear features of FVPTC pose challenges for an accurate diagnosis. Therefore, a better approach is to triage these cases for surgical intervention and/or further evaluation of the particular nodule. Our triage efficacy for FVPTC was 84 %; however, the diagnostic accuracy of PTC was 38 %. A negative diagnosis on FNA has diagnostic and management implications for up to 16 % of cases because they may have no further immediate diagnostic studies or treatment. BRAF mutation analysis provides minimal effect on diagnostic accuracy.

Molecular features of follicular variant papillary carcinoma of thyroid: comparison of areas with or without classical nuclear features

We aimed to compare the genetic background of different areas in follicular variant papillary thyroid carcinomas (FVPTC) with or without classical nuclear changes. Sixteen cases of FVPTC were included in our study. All tumors were well demarcated from surrounding thyroid tissue and had both areas with nuclear features (WNF) and areas without nuclear features (WONF) of papillary carcinoma. DNA is obtained by laser microdissection from WNF and WONF areas of each case. Point mutations for NRAS codon 61, HRAS codon 61, and BRAF were investigated by direct sequencing. In 11 cases, reverse transcription PCR was performed for the presence of PAX8-PPARɣ and RET/PTC1-3 gene rearrangements. Point mutation for NRAS codon 61 was also studied in 15 colloidal nodules. Seven cases (44 %) showed at least one mutation; two cases (13 %) revealed the same mutation in both WNF and WONF areas, while in the rest only WNF areas were mutated. None of the studied 11 cases demonstrated RET/PTC1-3 gene rearrangement and in only one case PAX8-PPARɣ gene rearrangement was found. Six cases (38 %) showed NRAS codon 61 mutation, involving only WNF areas in five cases and both WNF and WONF areas in one case. Neither HRAS codon 61 nor BRAF mutations were present. Fifteen colloidal nodules were also wild type for NRAS codon 61. Our findings suggest that NRAS codon 61 point mutations and PAX8-PPARɣ gene rearrangement play a role in the FVPTC pathogenesis and may be established before the morphological/phenotypical features fully develop.

Molecular markers for thyroid cancer diagnosis, prognosis, and targeted therapy

Molecular markers including gene expression profiles, somatic gene alterations, and circulating peripheral markers have augmented diagnostic, prognostic, and therapeutic options for thyroid cancer patients.

Up-regulation of urinary-type plasminogen activator correlates with high-risk papillary thyroid carcinoma with BRAF(V600E) mutation and its possible molecular mechanism

The aim of the present study is to investigate the relationship between urinary-type plasminogen activator (uPA) expression and clinicopathological features in papillary thyroid carcinoma (PTC) and to determine the signal transduction of PTC cells in vitro. PTC tissues from 42 patients were analyzed for the expression of uPA and the BRAF(V600E) mutation. BCPAP, a PTC cell line harboring the BRAF(V600E) mutation, was used to study MAPK signaling. PCR and direct sequencing were applied to analyze BRAF(V600E) mutation status. uPA mRNA expression was measured using a quantitative RT-PCR method, and uPA protein was localized using an immunohistochemical method. The ERK protein status was detected by Western blot analysis. uPA gene expression was significantly increased in PTC tissues as compared to the corresponding non-tumor tissues. Furthermore, the up-regulation of uPA mRNAs was correlated with high-risk clinicopathological features, including extrathyroid invasion, loss of cellular polarity/cohesiveness, and the BRAF(V600E) mutation. Marked dephosphorylation of ERK1/2 and down-regulation of uPA expression were detected when BCPAP was treated with a MEK inhibitor, U0126. MEK inhibitors might be a potential treatment strategy for aggressive PTC with BRAF(V600E) through inhibition of uPA expression.

High-sensitivity BRAF mutation analysis: BRAF V600E is acquired early during tumor development but is heterogeneously distributed in a subset of papillary thyroid carcinomas

CONTEXT

The homogeneous distribution of BRAF V600E in papillary thyroid carcinoma (PTC) has been called into question by recent reports. These studies claim that BRAF V600E is heterogeneous and is limited to tumor cell subsets in the majority of PTCs.

OBJECTIVE

The objective of the study was to understand the allele distribution of BRAF V600E by evaluating the percentage of mutated neoplastic cells in a group of PTCs using two different highly sensitive analytical approaches: allele-specific locked nucleic acid PCR and 454 next-generation sequencing targeted to BRAF exon 15.

STUDY DESIGN

BRAF V600E was investigated using allele-specific locked nucleic acid PCR on 155 consecutive samples of PTC. Mutated cases were reanalyzed by 454 next-generation sequencing and immunohistochemistry. Because the evaluation of genetic heterogeneity in tumor samples can be profoundly biased by contamination with normal cells, all mutation frequency data were normalized to the real amount of neoplastic cells within each tumor.

RESULTS

Eighty-five of 155 PTCs (54.8%) were BRAF V600E mutated. The distribution of mutated neoplastic cells within the tumor was as follows: greater than 80% in 37 of 85 (43.5%), 30-80% in 39 of 85 (45.9%), and less than 30% in 9 of 85 (10.6%). In most of the PTCs with less than 80% BRAF V600E-positive neoplastic cells, the mutation was present in large neoplastic cell subpopulations. Tumors with less than 30% mutated neoplastic cells were smaller than tumors with a percentage of mutated cells greater than 80% or between 30% and 80% (P < .05).

CONCLUSIONS

BRAF V600E is heterogeneously distributed in some PTCs. The large BRAF V600E neoplastic cell subpopulations found in mutated cases is consistent with the view that the BRAF V600E is acquired early during PTC development.

Follicular variant of papillary thyroid carcinoma with B-type Raf(V600E) showing higher frequency of suspicious sonographic features and multifocality

BACKGROUND

The purpose of this study was to investigate the correlation between B-type Raf (BRAF) kinase mutation and clinicopathological features of follicular variant of papillary thyroid carcinoma (PTC).

METHODS

Eighty-four patients with pathologically confirmed follicular variant of PTC, who underwent a preoperative BRAF(V600E) study, were analyzed. Clinicopathological parameters and ultrasonographic features were compared between the BRAF(V600E) -positive and negative groups.

RESULTS

A total of 41.7% of the patients showed BRAF(V600E) . The BRAF(V600E) -positive group showed the smaller tumor size (7.3 ± 3.6 mm vs 10.7 ± 8.9 mm; p = .018) and the more frequent multifocality (25.7% vs 8.2%; p = .028). Follicular variant of PTC with BRAF(V600E) showed suspicious ultrasonographic features (88.6% vs 57.1%; p = .002) more frequently. BRAF(V600E) positivity is associated with multifocality after adjusting for age, sex, the presence of suspicious ultrasonographic features, pathological tumor size, and thyrotropin level.

CONCLUSION

BRAF(V600E) was correlated with smaller tumor size and suspicious ultrasonographic features in follicular variant of PTC. BRAF(V600E) was a significant parameter for predicting multifocality of follicular variant of PTC.

Role of molecular diagnostic markers in the management of indeterminate and suspicious thyroid nodules

Incidental thyroid nodules are commonly found during routine neck examination. Fine needle aspiration (FNA) followed by cytological examination is currently considered as the most reliable method for evaluation of thyroid nodules. However, 10–40% of FNA results are inconclusive, and are reported as indeterminate or suspicious. Approximately 20% of indeterminate or suspicious nodules are malignant. Therefore, there has been an increasing trend in use of molecular markers as an adjunctive measure for more accurate preoperative diagnosis of indeterminate or suspicious nodules. Molecular markers can be used alone or as a part of molecular panels. Although some investigations revealed promising findings regarding the potential use of molecular markers in the management of thyroid nodules, their true impact on management of patients with indeterminate nodules is still unclear.