Papillary carcinoma of the thyroid in Japan: subclassification of common type and identification of low risk group

Risk Stratification of Differentiated Thyroid Cancer at King Abdullah Specialized Children's Hospital Endocrinology Clinic in Riyadh, Saudi Arabia

Background Papillary thyroid cancer (PTC), a well-differentiated form of cancer, accounts for the majority of thyroid malignancies, and the incidence of PTC is on the rise. While the rate of PTC recurrence is considered to be low, there are broad spectrums of clinical and biological behavior that can lead to disease recurrence. The American Thyroid Association (ATA) risk stratification system for differentiated thyroid cancer is used as a prognostic tool to guide decision-making and management strategies most likely to achieve a favorable outcome. Aim This study aimed to estimate the prevalence of PTC recurrence in each category of the ATA risk stratification system and determine the appropriate iodine dose to be administered at the King Abdulaziz Medical City Endocrinology Clinic in Riyadh, Saudi Arabia. Methods A cross-sectional retrospective chart review was conducted on adult patients with PTC who underwent thyroidectomy procedures at the King Abdullah Specialized Children's Hospital (KASCH) Endocrinology Clinic in Riyadh between 2015 and 2023. IBM SPSS (Statistical Package for the Social Sciences) version 25 (IBM Corp., Armonk, NY) was used for data analysis. Results Of the 697 patients included in the study, 82.4% were females. About 5% had suffered from PTC recurrence, and 54.4% had low-risk stratification. In addition, more than half (52.1%) had received radioactive iodine (RAI). The recurrence of PTC was significantly associated with age (P = 0.019), ATA risk stratification (P = 0.0001), RAI therapy (P = 0.001), and iodine dosage (P = 0.013). Conclusion Both low PTC recurrence rates and low-risk stratification were observed among the PTC patients. The risk factors relating to PTC recurrence included high-risk stratification, advanced age, RAI therapy, and the dosage of RAI administered.

SKP2 Contributes to AKT Activation by Ubiquitination Degradation of PHLPP1, Impedes Autophagy, and Facilitates the Survival of Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common subtype of thyroid carcinoma. Despite a good prognosis, approximately a quarter of PTC patients are likely to relapse. Previous reports suggest an association between S-phase kinase-associated protein 2 (SKP2) and the prognosis of thyroid cancer. SKP1 is related to apoptosis of PTC cells; however, its role in PTC remains largely elusive. This study aimed to understand the expression and molecular mechanism of SKP2 in PTC. SKP2 expression was upregulated in PTC tissues and closely associated with clinical diagnosis. In vitro and in vivo knockdown of SKP2 expression in PTC cells suppressed cell growth and proliferation and induced apoptosis. SKP2 depletion promoted cell autophagy under glucose deprivation. SKP2 interacted with PH domain leucine-rich repeat protein phosphatase-1 (PHLPP1), triggering its degradation by ubiquitination. Furthermore, SKP2 activates the AKT-related pathways via PHLPP1, which leads to the cytoplasmic translocation of SKP2, indicating a reciprocal regulation between SKP2 and AKT. In conclusion, the upregulation of SKP2 leads to PTC proliferation and survival, and the regulatory network among SKP2, PHLPP1, and AKT provides novel insight into the molecular basis of SKP2 in tumor progression.

Hobnail Papillary Thyroid Carcinoma, A Systematic Review and Meta-Analysis

Although papillary thyroid carcinoma (PTC) is considered to have an excellent prognosis, some recently identified more aggressive variants show reduced overall survival rates. Hobnail PTC (HPTC) was newly recognized as one of these aggressive forms, affecting recurrence, metastasis, and overall survival rates. Herein, we performed a systematic review and meta-analysis of studies including cases or case series with patients with HPTC. Furthermore, we included our individual case series consisting of six patients. The pooled mortality rate in the cohort, consisting of 290 patients, was 3.57 (95% CI 1.67−7.65) per 100 person/years. No sex differences could be observed concerning mortality (p = 0.62), but older age and tumor size significantly affected mortality (p = 0.004 and p = 0.02, respectively). The percentage of hobnail cells did not affect mortality (p = 0.97), neither did the presence of BRAF mutations. Classical characteristics such as the presence of extrathyroidal extension (p = 0.001), distant metastases (p < 0.001), and lymph node metastases (p < 0.001) all had a significant impact on mortality. Thus, HPTC appears to correlate with worse overall survival, and all PTC cases should be carefully assessed for this variant.

Human Endogenous Retrovirus-H Long Terminal Repeat-Associating Protein 2 Possesses Prognostic Significance and Promotes Progression of Papillary Thyroid Cancer

Purpose

Patients and Methods

Results

Conclusion

Clinical-Pathological Features and Treatment Outcome of Patients With Hobnail Variant Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) with hobnail areas above 30% is classified as hobnail variant (HVPTC). Although it is widely accepted that HVPTC has a worse outcome than classical PTC, it is unclear whether PTC with hobnail features below 30% is as aggressive as HVPTC. We gathered the largest mono-institutional series of PTC with hobnail areas and HVPTC to evaluate differences in terms of pathological features of aggressiveness, molecular profile, and treatment outcome. A total of 99 PTC with hobnail features above 5% were retrospectively selected; 34 of them met the criteria for HVPTC (0.4% of all PTC diagnosed at our institution). All tumors showed high rates of extra-thyroidal extension (40.4%), lymph node metastasis (68.1% of patients with lymphadenectomy), and vascular emboli (49.5%), with no differences according to the 30% cutoff. On the other hand, distant metastases were present in HVPTC only (9.4%). Also, advanced age, advanced disease stage, and TERT promoter mutation were associated with HVPTC. More than half of the patients with follow-up had structural or biochemical persistence after 1 year from surgery. Structural persistence was significantly more common in patients with HVPTC (37.5% vs. 8.7%), while no differences were observed considering structural and biochemical persistence together. The presence of hobnail features identifies locally aggressive tumors, and, consequently, it should be always acknowledged in the pathological report. However, tumors with more than 30% hobnail areas frequently present TERT promoter mutations, advanced disease stage, and structural persistence after radioiodine ablation.

Thyroid collision tumor containing oncocytic carcinoma, classical and hobnail variants of papillary carcinoma and areas of poorly differentiated carcinoma

Collision tumors are rare and may comprise components with different behavior, treatments, and prognosis. We report an unprecedented case of aggressive thyroid collision tumor containing widely invasive oncocytic carcinoma (OC), classical and hobnail (HPTC) variants of papillary carcinoma, and poorly differentiated carcinoma (PDTC). The patient underwent total thyroidectomy, radioactive iodine therapy, and within months progressed with local recurrence, and pulmonary metastases requiring neck dissection, external radiotherapy and systemic treatment with sorafenib. The rapid progression, dedifferentiated metastatic lesions, and failure to treatments resulted in the patient's death. The great variety of histological types and the evolution of this case were a challenge for the management of metastatic disease. Widely invasive OC, HPTC and PDTC are considered to have a worse prognosis. HPTC has never been reported as a component of a collision tumor. HPTC and PDTC should call attention to a possible higher-grade transformation.

A population-based study of the three major variants of papillary thyroid carcinoma

Objective

To explore the clinicopathological features and relative prognostic risks of the three major variants of papillary thyroid carcinoma (PTC).

Methods

We retrospectively analyzed the clinicopathological characteristics and prognoses of patients with the three major PTC variants, conventional papillary thyroid carcinoma (CPTC), follicular-variant papillary carcinoma (FVPTC), and tall-cell papillary thyroid carcinoma (TCPTC), based on data from the Surveillance, Epidemiology, and End Results database from 2005 to 2009.

Results

A total of 29,555 patients were enrolled. In terms of their demographic and clinicopathological characteristics, TCPTC had the highest prevalence of older patients, men, patients with locally advanced stage (T stage and N stage), and mortality, while FVPTC had the lowest prevalence in relation to these factors. The three variants differed significantly in terms of 5-year overall survival and 5-year disease-specific survival. Cox regression analysis identified male sex, age ≥45 years, and higher American Joint Committee on Cancer and TNM stage as independent factors predicting a poor prognosis in relation to both overall and disease-specific survival.

Conclusions

CPTC, FVPTC, and TCPTC have different clinicopathological characteristics and prognoses, indicating the need for different treatment strategies for these three variants of PTC.

Papillary thyroid carcinoma with hobnail features showing rapid progression and therapy resistance

BACKGROUND

Hobnail variant of papillary thyroid carcinoma (HVPTC), also designated as a micropapillary variant, is a rare but aggressive variant of PTC, representing <2% of all PTC. It was adopted in the newest World Health Organization classification. HVPTC is strongly associated with higher mortality in comparison to classic PTC and a high propensity for disease progression. This paper aimed to investigate the clinical course, cytological and histopathological features, and mutational profile of the hobnail variant from a unique case.

CASE REPORT

A case of a 38-year-old female patient with HVPTC is presented. Total thyroidectomy with central and bilateral, lateral lymphadenectomy was performed. The clinical course showed aggressive features, as lymph node metastasis and extrathyroidal extension were present at the presentation. Molecular and immunohistochemical features are addressed along with a review of the literature.

DISCUSSION

The cytological examination of FNA was in consonance with published literature. The cells showed hobnail features in several segments of both thyroidal lobes on histological examination. The tumour displayed a typical BRAF mutation and Gly12Ala mutation in the KRAS gene, previously not associated with PTC.

CONCLUSION

We aimed to highlight the aggressive, clinicopathological features of this high-risk variant. We emphasise the need to evaluate suspicious thyroid nodules as an adequate diagnosis can prevent delayed therapy. It directly impacts the tumour's stage and prognosis. In fine-needle aspiration cytology showing papillary architecture carcinomas, HVPTC has to be part of the differential diagnosis.

Hobnail variant of papillary thyroid carcinoma: a systematic review and meta-analysis

OBJECTIVE

The hobnail variant of papillary thyroid carcinoma (HVPTC) has emerged as a rare and aggressive variant of papillary thyroid carcinoma (PTC). We aim to determine the prevalence and clinicopathologic factors of HVPTC.

METHODS

A systematic review of the literature for studies examining HVPTC was performed. Four databases (PubMed, Scopus, OVID, Cochrane library) were queried from inception of databases through March 20th, 2020.

RESULTS

Sixteen studies with 124 cases of HVPTC were included. The mean age for all patients was 52.3 years. HVPTC had a prevalence of 1.08% out of all PTC cases, with a mean tumor size of 3.1 cm. In 62% and 50% of cases, lymphovascular invasion and extrathyroidal extension were present, respectively. Follow-up data, with a mean of 49.9 months, revealed a 66% rate of lymph node metastasis and 23% rate of distant metastasis. Tumors with ≥30% hobnail morphology had a 2.6-fold increased odds of developing lymph node metastasis compared with <30% hobnail morphology, however did not differ in rates of distant metastasis. Patients ≥55 years old had a 4.5-fold increased odds of distant metastasis and a 4.7-fold increased odds of lymphovascular invasion over patients <55.

CONCLUSIONS

High rates of locoregional and distant disease as well as high-risk pathological factors reveal the aggressive nature of HVPTC. Diagnostic criteria regarding percentage of hobnail morphology requires further refinement. Further studies are warranted in order to better understand how recognition of this high-risk variant impacts clinical treatment.

LncRNA-HCG18 regulates the viability, apoptosis, migration, invasion and epithelial-mesenchymal transition of papillary thyroid cancer cells via regulating the miR-106a-5p/PPP2R2A axis

The incidence of papillary thyroid cancer (PTC) has experienced a rapid increase in recent years. Long non-coding RNA-homo sapiens HLA complex group (HCG) 18 plays a regulatory role in cancers, but its role in PTC remained unknown. This study determined the expressions of HCG18, microRNA (miR)-106a-5p, and protein phosphatase 2 regulatory subunit B alpha (PPP2R2A) in PTC tissues and cells by qRT-PCR. ENCORI predicted the targeting relation between HCG18 and miR-106a-5p. TargetScan v7.2 predicted the targeting relation between miR-106a-5p and PPP2R2A. Dual-luciferase reporter assay was performed to validate the two targeting relations. The viability, migration, and invasion of PTC cells were detected by Cell Counting Kit-8, wound healing assay, and Transwell assay, respectively. The expressions of matrix metalloproteinase 2 (MMP-2), MMP-9, E-cadherin, N-cadherin, and Vimentin in TPC-1 and MDA-T68 cells were assessed by qRT-PCR and Western blot. It was found that HCG18 was down-regulated in PTC. Overexpressing HCG18 suppressed viability, migration, and invasion, promoted apoptosis, and inhibited miR-106a-5p expression in PTC cells. HCG18 interacted with miR-106a-5p, the expression of which was upregulated in PTC. Upregulating miR-106a-5p expression by lentivirus infection promoted viability, migration and invasion and inhibited apoptosis of PTC cells, reversed the effect of HCG18 on the biological behaviors of PTC cells, and promoted the expressions of MMP-2, MMP-9, E-cadherin, and Vimentin and downregulated E-cadherin expression in PTC cells. PPP2R2A, a direct target of miR-106a-5p, was downregulated in PTC, and HCG18 promoted PPP2R2A expression in PTC cells by sponging miR-106a-5p. Furthermore, PPP2R2A reversed the effects of miR-106a-5p on PTC cells. In conclusion, HCG18 suppressed viability, migration, invasion and epithelial-mesenchymal transition and promoted apoptosis of PTC cells via regulating the miR-106a-5p/PPP2R2A axis.

Updates in the Pathologic Classification of Thyroid Neoplasms: A Review of the World Health Organization Classification

Advances in medical sciences and evidence-based medicine have led to momentous changes in classification and management of thyroid neoplasms. Much progress has been made toward avoiding overdiagnosis and overtreatment of thyroid cancers. The new 2017 World Health Organization (WHO) classification of thyroid neoplasms updated the diagnostic criteria and molecular and genetic characteristics reflecting the biology and behavior of the tumors, and newly introduced the category of borderline malignancy or uncertain malignant potential. Some neoplasms were subclassified, renamed, or redefined as a specific entity. This review introduces changes in the fourth edition WHO classification of thyroid tumors and updates the contemporary diagnosis and classification of thyroid tumors. We also discuss several challenges with the proposal of new diagnostic entities, since they have unique histopathologic and molecular features and clinical relevance.

Association between BRAFV600E mutation and the clinicopathological features in incidental papillary thyroid microcarcinoma: A single-center study in Turkish patients

OBJECTIVE:

In this study, we evaluated the influences of BRAF^V600E mutation on clinicopathological features in incidentally found papillary thyroid microcarcinomas (PTMCs).

METHODS:

This retrospective cohort study included 72 patients with PTMC who underwent surgery from 2008 to 2012. The mean follow-up of the whole cohort was three years. DNA was isolated using QIAamp DNA formalin-fixed, paraffin-embedded (FFPE) tissue kit. BRAF gene was amplified by the polymerase chain reaction-restriction fragment length (PCR-RFL) polymorphism method with the following primers. The clinicopathologic features (age, gender, histologic subtype, tumor size, presence of tumor capsule, bilaterality, multifocality, extrathyroidal extension (ETE), thyroid capsular invasion, presence of Hashimoto’s thyroiditis, lymph node metastasis (LNM) and distant metastasis) were compared between the BRAF (+) and BRAF (-) patient groups.

RESULTS:

BRAF^V600E mutation was detected in 30 of the 72 patients (41.6%). The presence of the mutation was statistically significantly associated with classic variant (p=0.046), invasion of thyroid capsule (p=0.002) and absence of tumor capsule (p=0.003).

CONCLUSION:

Although incidental PTMCs positive for the BRAF^V600E mutation had more invasive behavior, the presence of the mutation was not associated with recurrences within three years of follow-up.

Papillary Thyroid Cancer-Aggressive Variants and Impact on Management: A Narrative Review

Introduction

Aggressive variants of papillary thyroid cancer (PTC) have been described with increasing frequency. These variants include diffuse sclerosing variant, tall cell variant, columnar cell variant, solid variant, and hobnail variant.

Methods

We have performed a review of the more aggressive variants of PTC with respect to main characteristics, histological and molecular features, and the consequences that the knowledge of these variants should have in the treatment of the patients.

Results

At the present time, we do not know the prognostic value of these aggressive PTC variants. The extent of the surgical treatment and adjuvant therapy necessary should be decided on the basis of the extent of the tumor at presentation and the opinion of experienced clinicians.

Conclusion

These aggressive variants should be known by clinicians, to avoid underdiagnosis, and treated according to the latest recommendations in the literature.

The evolving concept of aggressive histological variants of differentiated thyroid cancer

It is recommended by current clinical guidelines that pathologists identify and report aggressive histological variants of differentiated thyroid cancer (e.g., tall cell, columnar cell, and hobnail variants of papillary thyroid carcinoma; widely invasive follicular thyroid carcinoma). This review analyzes the historical evolution of these entities and highlights unresolved issues with respect to the diagnostic criteria for these tumors.

Active surveillance for patients with very low-risk thyroid cancer

Over the past 30 years in the United States, increasing identification of small thyroid nodules has led to a dramatic rise in the detection of small thyroid cancers, many of which are unlikely to progress to overt clinical disease. Because autopsy studies reveal that up to 30% of people harbor clinically occult thyroid cancers, the growing use of diagnostic technologies has identified an increasing number of small, clinically low risk papillary thyroid cancers (PTCs). In recent years, clinical practice has evolved to de-intensify the treatment for PTCs, with fewer total thyroidectomy and nodal dissection procedures being performed, in favor of more limited operations. In addition, vigilant observation of selected low risk cancers has demonstrated outcomes comparable to those patients who undergo immediate surgical intervention. Active surveillance has emerged as a new option within the treatment algorithm of PTCs. There is now robust data from cancer centers in Japan and Korea which have reported excellent oncologic outcomes among patients undergoing active surveillance for PTC, as well as more recent, similar data from the United States. American Thyroid Association guidelines now include the option of active surveillance for appropriately selected patients with low-risk PTC. With active surveillance now one option within the standard of care for patients with certain thyroid cancers, surgeons have become critical to facilitating shared decision-making for patients facing this diagnosis.

Hobnail cells in encapsulated papillary thyroid carcinoma: Report of 2 cases with immunohistochemical and molecular findings and literature analysis

Papillary thyroid carcinoma (PTC) is the most common malignant tumor of the thyroid gland with most tumors behaving in an indolent fashion. However, morphologic variants have been described, such as tall cell, diffuse sclerosing, columnar cell etc. which are biologically more aggressive. One of these variants includes the more recently described hobnail variant (HVPTC) which shows micropapillae and presence of large cells with apically placed hyperchromatic nuclei, reverse polarity, and eosinophilic cytoplasm, akin to hobnail cells. The presence of >30% hobnail cells in a PTC deserves categorization as a hobnail variant. This variant is usually associated with extra thyroidal extension, lymphovascular invasion and lymph node metastasis. We describe the pathologic and molecular features of two cases of encapsulated PTC with hobnail cells in a 68 year old male and a 22 year old female (30% and 10% hobnail cells respectively). Both cases presented as low stage (pT2) tumors and showed no aggressive features like lymph node metastasis, or extrathyroidal extension (ETE) at the time of presentation. Tumors in both cases showed presence of BRAFV600E mutation, absence of RAS and/or TP53 mutations, and were negative for RET and PAX88/PPARG gene rearrangements.

Papillary Thyroid Cancer: Genetic Alterations and Molecular Biomarker Investigations

Papillary thyroid cancer (PTC) is the most prevalent form of malignancy among all cancers of the thyroid. It is also one of the few cancers with a rapidly increasing incidence. PTC is usually contained within the thyroid gland and generally biologically indolent. Prognosis of the cancer is excellent, with less than 2% mortality at 5 years. However, more than 25% of patients with PTC developed a recurrence during a long term follow-up. The present article provides an updated condensed overview of PTC, which focuses mainly on the molecular alterations involved and recent biomarker investigations.

OPNa Overexpression Is Associated with Matrix Calcification in Thyroid Cancer Cell Lines

Osteopontin (OPN) spliced variants (OPN-SV: OPNa, OPNb, and OPNc) are aberrantly expressed in tumors and frequently associated with cancer progression. This holds true for papillary thyroid carcinoma (PTC), which is the most common type of thyroid cancer (TC). PTC often presents with desmoplasia and dystrophic calcification, including psammoma bodies (PB). This work aimed to investigate total OPN (tOPN) and OPN-SV expression and their association with the presence of PB in the PTC classical variants (cPTC), as well as the involvement of OPN-SV in matrix calcification of TC cell lines. We found that cPTC samples presenting PB showed higher OPN expression levels. In TC cell lines, OPNa overexpression promotes higher matrix calcification and collagen synthesis when compared to that of clones overexpressing OPNb or OPNc. In response to OPN knockdown, calcification was inhibited, paralleled with the downregulation of calcification markers. In conclusion, our data evidenced that OPN expression is associated with the presence of PB in cPTC samples. Among the OPN-SV, OPNa is the main contributor to matrix calcification in tested TC cells, providing clues to a better understanding on the biology and ethiopathogenesis of the calcification process in TC cells.

Mouse models of sporadic thyroid cancer derived from BRAFV600E alone or in combination with PTEN haploinsufficiency under physiologic TSH levels

The BRAF^V600E mutation is the most prevalent driver mutation of sporadic papillary thyroid cancers (PTC). It was previously shown that prenatal or postnatal expression of BRAF^V600E under elevated TSH levels induced thyroid cancers in several genetically engineered mouse models. In contrast, we found that postnatal expression of BRAF^V600E under physiologic TSH levels failed to develop thyroid cancers in conditional transgenic Tg(LNL-Braf^V600E) mice injected in the thyroid with adenovirus expressing Cre under control of the thyroglobulin promoter (Ad-TgP-Cre). In this study, we first demonstrated that Braf^CA/+ mice carrying a Cre-activated allele of Braf^V600E exhibited higher transformation efficiency than Tg(LNL-Braf^V600E) mice when crossed with TPO-Cre mice. As a result, most Braf^CA/+ mice injected with Ad-TgP-Cre developed thyroid cancers in 1 year. Histologic examination showed follicular or cribriform-like structures with positive TG and PAX staining and no colloid formation. Some tumors also had papillary structure component with lower TG expression. Concomitant PTEN haploinsufficiency in injected Braf^CA/+;Pten^f/+ mice induced tumors predominantly exhibiting papillary structures and occasionally undifferentiated solid patterns with normal to low PAX expression and low to absent TG expression. Typical nuclear features of human PTC and extrathyroidal invasion were observed primarily in the latter mice. The percentages of pERK-, Ki67- and TUNEL-positive cells were all higher in the latter. In conclusion, we established novel thyroid cancer mouse models in which postnatal expression of BRAF^V600E alone under physiologic TSH levels induces PTC. Simultaneous PTEN haploinsufficiency tends to promote tumor growth and de-differentiation.

Hobnail Variant of Papillary Thyroid Carcinoma: a Literature Review

Papillary thyroid carcinoma is the most common thyroid malignancy and it is usually associated with a good prognosis. However, recurrence, metastases, and cancer death may occur in 10 to 15% of patients with more aggressive types of papillary thyroid carcinoma, such as tall cell, columnar cell, solid variant, or the more recently described hobnail variant of papillary thyroid carcinoma. Papillary thyroid carcinoma with a prominent hobnail pattern is a moderately differentiated papillary thyroid carcinoma variant with aggressive clinical behavior and significant mortality. The hobnail variant of papillary thyroid carcinoma shows prominent hobnail features, which have also been referred to as micropapillary. The typical hobnail/micropapillary morphological features show loss of cellular polarity/cohesiveness and support an epithelial-mesenchymal transition as a possible mechanism of metastasis. BRAF p.V600E is the most common mutation in papillary thyroid carcinoma, including the hobnail variant; recent and continuing studies are focused on defining other molecular anomalies that may be useful for prognostic stratification and may provide therapeutic targets.

Prognostic implication of histological features associated with EHD2 expression in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is a heterogeneous tumor with various histological and molecular subtypes. EHD2 is involved in endocytosis and endosomal recycling. This study aimed to investigate the prognostic significance of EHD2 expression in PTC and develop a new model for predicting persistent/recurrent disease after thyroidectomy. Pathologic slides of 512 consecutive patients with PTC ≥ 1 cm were retrospectively reviewed. BRAF mutation analysis and immunohistochemistry for EHD2 were performed. Clinical significance of EHD2 mRNA expression was analyzed in 388 PTC patients using The Cancer Genome Atlas dataset. The presence of dyscohesive cells and psammoma bodies were found have significant association with persistent/recurrent disease (p = 0.049 and p = 0.038, respectively). The best discrimination of disease-free survival was found by dividing patients into three prognostic groups based on the following two risk factors according to the size category: psammoma bodies ≥ 4 and dyscohesive cells (≥ 1% and ≥ 20% in PTCs of < 2.0 cm and ≥ 2.0 cm, respectively). In PTCs of ≥ 2.0 cm, patients with the two risk factors had a hazard ratio of 13.303 (p = 0.005) compared to those without risk factors. High expression level of EHD2 was associated with BRAF V600E (p < 0.001), presence of dyscohesive cells (p = 0.010), and absence of psammoma bodies (p = 0.001). Increased EHD2 mRNA expression level was associated with extrathyroidal extension (p < 0.001), pT3-4 (p < 0.001), lymph node metastasis (p < 0.001), higher risk of recurrence (p < 0.001), and BRAF V600E (p < 0.001). Our prognostic model is useful for predicting persistent/recurrent disease after surgery of PTC. EHD2 mRNA expression could be a novel prognostic marker for PTC patients.

The association of papillary thyroid cancer with microcalcification in thyroidnodules with indeterminate cytology based on fine-needle aspiration biopsy

BACKGROUND/AIM

Microcalcifications are generally accepted as highly specific for thyroid malignancy, especially for papillary thyroid carcinoma (PTC). The aim of this study was to determine the significance of microcalcification within nodules that were classified as being of &ldquo;indeterminate cytology&rdquo; (IC) according to fine-needle aspiration biopsy.

MATERIALS AND METHODS

Patients who underwent thyroidectomy between January 2010 and 2013 were included in the study. Nodules identified as &ldquo;atypia/follicular lesion of undetermined significance", "follicular neoplasm/suspicious for follicular neoplasm", or "suspicious for malignancy" were categorized as IC. Patients were subcategorized depending on the presence of microcalcification (Group 1) or its absence (Group 2). The relationship between microcalcification and PTC was evaluated in the IC group retrospectively.

RESULTS

Indeterminate cytology was detected in 135 (28.5%) of 473 patients. Microcalcification was detected in 27 (20%) of 135 nodules and classified as Group 1, while the remaining 108 (80%) patients were classified as Group 2. According to the final pathology results, PTC was diagnosed in 13 of 27 (48.1%) patients in Group 1 and 29 of 108 (26.8%) patients in Group 2. A statistically significant relation between microcalcification and malignancy was determined in the IC group (P < 0.05).

CONCLUSION

Surgery might be considered primarily for patients harboring nodule(s) with IC accompanied by microcalcification due to increased risk of PTC.

Clinicopathological features for predicting central and lateral lymph node metastasis in papillary thyroid microcarcinoma: Analysis of 66 cases that underwent central and lateral lymph node dissection

Currently the surgical approach for papillary thyroid microcarcinoma (PTMC), particularly the range of lymph node dissection, remains controversial. The present study aims to evaluate the risk factors for central and lateral lymph node metastasis (CLNM and LLNM) for appropriate clinical decision of neck lymph node dissection in PTMC. A total of 66 cases of PTMC that underwent unilateral or bilateral lobectomy plus prophylactic cervical lymph node dissection were collected for clinicopathological evaluation, including age, gender, tumor size, subtypes, extrathyroidal invasion, multifocality, calcifications, loss of cellular polarity/cohesiveness (LOP/C) in the invasive front, CLNM and LLNM, and retrospectively analysis. Univariate analysis revealed that LOP/C was significantly associated with CLNM (P=0.001) and LLNM (P<0.0001). The male gender was a risk factor of CLNM (P=0.04), while the age <45 years, tumor size >0.5 cm and multifocality were high-risk factors of LLNM (P=0.022, 0.044 and 0.005, respectively). Multivariable analysis revealed that LOP/C was significantly associated with CLNM [P=0.007, odds ratio (OR)=7.765, 95% confidence interval (CI)=1.773–33.996] and LLNM [P=0.029, OR=5.717, 95% CI=1.190–27.470]. Both multivariable analysis and χ² test revealed that CLNM was another important high-risk factor of LLNM (P=0.021, OR=5.444, 95% CI=1.290–22.969, χ²=17.867, P<0.001). The present study revealed that prophylactic central lymph node dissection is essential for PTMC surgery and that prophylactic lateral lymph node dissection is recommend for patients with LOP/C and CLNM, which can be performed by intraoperative frozen section pathological examination. This must be considered discreetly in the case of patients with age <45 years, tumor size >0.5 cm and multifocal lesions.

Tissue and serum samples of patients with papillary thyroid cancer with and without benign background demonstrate different altered expression of proteins

Background

Papillary thyroid cancer (PTC) is mainly diagnosed using fine-needle aspiration biopsy. This most common form of well-differentiated thyroid cancer occurs with or without a background of benign thyroid goiter (BTG).

Methods

In the present study, a gel-based proteomics analysis was performed to analyse the expression of proteins in tissue and serum samples of PTC patients with (PTCb; n = 6) and without a history of BTG (PTCa; n = 8) relative to patients with BTG (n = 20). This was followed by confirmation of the levels of proteins which showed significant altered abundances of more than two-fold difference (p < 0.01) in the tissue and serum samples of the same subjects using ELISA.

Results

The data of our study showed that PTCa and PTCb distinguish themselves from BTG in the types of tissue and serum proteins of altered abundance. While higher levels of alpha-1 antitrypsin (A1AT) and heat shock 70 kDa protein were associated with PTCa, lower levels of A1AT, protein disulfide isomerase and ubiquitin-conjugating enzyme E2 N seemed apparent in the PTCb. In case of the serum proteins, higher abundances of A1AT and alpha 1-beta glycoprotein were detected in PTCa, while PTCb was associated with enhanced apolipoprotein A-IV and alpha 2-HS glycoprotein (AHSG). The different altered expression of tissue and serum A1AT as well as serum AHSG between PTCa and PTCb patients were also validated by ELISA.

Discussion

The distinctive altered abundances of the tissue and serum proteins form preliminary indications that PTCa and PTCb are two distinct cancers of the thyroid that are etiologically and mechanistically different although it is currently not possible to rule out that they may also be due other reasons such as the different stages of the malignant disease. These proteins stand to have a potential use as tissue or serum biomarkers to discriminate the three different thyroid neoplasms although this requires further validation in clinically representative populations.

Prognostic classification of thyroid follicular cell tumors using Ki-67 labeling index: risk stratification of thyroid follicular cell carcinomas

This review emphasizes that the so-called high-risk thyroid carcinoma is not a distinct tumor entity, but a group of tumors with different histologies. High-grade histological features, such as tumor necrosis, increased mitoses, and nuclear pleomorphism, together with high Ki-67 labeling index (more than 10%), are good indicators of high-risk thyroid carcinoma and suggest a possible risk for anaplastic transformation. This review proposes the stratification of patients with thyroid carcinoma into low-, moderate-, and high-risk groups based on Ki-67 labeling index, which should be useful for the clinical management of patients, even after initial surgery. Currently, both the aggressive variant of papillary carcinoma and poorly differentiated carcinoma are aggressively treated by a completion of total thyroidectomy with prophylactic lymph node dissection followed by radioactive iodine treatment. Therefore, patients with moderate-risk or high-risk thyroid carcinoma based on Ki-67 labeling index should also be considered candidates for this treatment strategy.

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.

Hobnail variant of papillary thyroid carcinoma: an institutional case series and molecular profile

BACKGROUND

Papillary thyroid carcinoma (PTC) is increasing in incidence while mortality is unchanged. Identifying patients with higher risk of recurrence and death is essential. Case series identify the hobnail variant of PTC (HVPTC), which is characterized by micropapillary architecture, apocrine features, and loss of cellular polarity. Herein, we describe the clinical course, pathologic features, and mutational profile of patients at our institution with HVPTC.

METHODS

A query into the surgical pathologic database (2009-2012) was performed, and clinicopathologic data were collected on all patients carrying the diagnosis of HVPTC. BRAF(V600E) testing was performed on paraffin-embedded blocks using SNaPshot mutational analysis.

RESULTS

Twelve patients with HVPTC were identified, with an average age of 54.1±18.8 years. Seven patients (63.6%) were AJCC Stage III or IV at presentation. Tumors were large (3.7±2.0 cm), some were multifocal (33.3%), and frequently with extrathyroidal extension (58.3%), lymphovascular invasion (41.7%), and lymph node metastasis (75%). Forty percent of the patients had concomitant tall cell features (TCF), and two had small foci of undifferentiated (anaplastic) thyroid carcinoma (ATC). Eighty percent of tumors undergoing mutational analysis had the BRAF(V600E) mutation, and the remaining 20% harbored a RET/PTC1 gene rearrangement. No other known thyroid cancer mutations were identified on SNaPshot analysis. At median follow-up of 26 months, four patients had recurrent or persistent disease, one of whom died from the disease one year after surgery.

CONCLUSIONS

The hobnail variant of PTC has an aggressive behavior, with a high incidence of infiltrative tumors and metastatic disease. Strikingly, all tumors in our series harbored a PTC-associated genetic abnormality, either a BRAF(V600E) mutation (80%) or a RET/PTC1 rearrangement (20%). This histologic variant warrants further study, and patients with this diagnosis should be observed closely for recurrence.

A study on inorganic elements in psammomas from ovarian & thyroid cancer

BACKGROUND & OBJECTIVES

Concentric lamellar calcifications known as psammoma bodies (PB) are found in benign and malignant tumours. Whether or not the inorganic element concentrations in psammomas are similar to serous adenocarcinoma of the ovary and thyroid papillary cancer tissues has not yet been ascertained. We undertook this retrospective study to establish if there is any difference in the concentrations of inorganic ions found in psammomas in serous adenocarcinoma of the ovary, and those found in thyroid papillary cancer tissue.

METHODS

PB samples from patients with adenocarcinoma of the ovary (n = 10) and with thyroid papillary cancer (n = 10) were analyzed through inductively-coupled plasma spectroscopy (ICP).

RESULTS

There were no significant differences in the concentrations of inorganic elements in PB from thyroid papillary cancer than in those PB from ovarian cancer.

INTERPRETATION & CONCLUSIONS

Differences in the concentrations of inorganic elements may be due to the variation in environmental pollution. Our study had limitation of small sample size. Our results suggest that some inorganic elements can participate in the origin of psammoma bodies.

Encapsulated papillary thyroid carcinoma, follicular variant: a misnomer

Papillary thyroid carcinoma (PTC) has long been diagnosed based on its unique nuclear features (PTC-N); however, significant observer discrepancies have been reported in the diagnosis of encapsulated follicular patterned lesions (EnFPLs), because the threshold of PTC-N is subjective. An equivocal PTC-N may often occur in non-invasive EnFPLs and benign/malignant disagreements often create serious problems for patients' treatment. This review collects recent publications focusing on the so-called encapsulated follicular variant of papillary thyroid carcinoma (EnFVPTC) and tries to emphasize problems in the histopathological diagnosis of this spectrum of tumors, which covers encapsulated common-type PTC (EncPTC), EnFVPTC, well-differentiated tumor of uncertain malignant potential (WDT-UMP), follicular adenoma (FA) with equivocal PTC-N and minimally invasive follicular carcinoma (mFTC). We propose that EnFVPTC and other EnFPLs with equivocal PTC-N should be classified into a unified category of borderline malignancy, such as well-differentiated tumor of uncertain behavior (WDT-UB), based on their homogeneous excellent outcome. It is suggested that the unified nomenclature of these lesions may be helpful to reduce significant observer disagreements in diagnosis, because complete agreement in the diagnosis of an EncPTC, EnFVPTC or FA by all pathologists may be not possible for this problematic group of tumors. In conclusion, a malignant diagnosis of EnFVPTC should not be used to cover this spectrum of tumors until uncertainty about the nature of this lesion is settled, whether it is benign, precancerous or malignant.

Classification of thyroid follicular cell tumors: with special reference to borderline lesions

We propose a new classification of thyroid follicular cell tumors which is correlated with patient's prognosis. It is unique as to two new categories: borderline malignancy between benign and malignant, and moderately differentiated adenocarcinoma (MDA) as a differentiation classification to stratify tumor aggressiveness. As to diagnostic criteria, we recommend invasiveness (capsular and vascular invasion) to separate benign and malignant and it should not be based on presence or absence of papillary thyroid carcinoma (PTC) type nuclear features (PTC-N). Thus borderline malignancy in our new classification includes some of the formerly malignant tumors and they are 1) papillary microcarcinoma, 2) encapsulated conventional PTC (EncPTC), 3) encapsulated follicular variant PTC (EnFVPTC), 4) well differentiated tumor of uncertain malignant potential (WDT-UMP), 5) follicular tumors of uncertain malignant potential (FT-UMP), and 6) capsular invasion only follicular thyroid carcinoma (FTC). Review of the literature revealed that those thyroid tumors have consistently excellent outcome. Well differentiated follicular cell adenocarcinoma (WDA) in our classification includes common type PTC and low-risk follicular carcinoma (FTC). They are invasive (diffuse infiltrative) common type PTC and minimally invasive type FTC with less than 4 foci of angioinvasion. Moderately differentiated follicular cell adenocarcinoma (MDA) includes FTC with angioinvasion (more than 4), aggressive variants of PTC, such as tall cell, columnar cell, solid, loss of cellular polarity/cohesiveness (hobnail) variants and encapsulated carcinoma with high grade histology. Poorly differentiated carcinoma (PDC) includes PDC of WHO definition, insular carcinoma, tumors with minor anaplastic transformation and tumors with distant metastasis at presentation.

Histological subtype is the most important determinant of survival in metastatic papillary thyroid cancer

BACKGROUND

Papillary thyroid cancer (PTC) comprises the commonest type of thyroid cancer and carries the highest rate of survival. However, when metastatic disease occurs, survival is significantly affected.

METHODS

We aimed to identify prognostic histopathological and clinical factors that modify survival in metastatic PTC. All cases of metastatic PTC treated at our department in the last 20 years were reviewed and analyzed.

RESULTS

Histological subtype was the most important determinant of survival, as classic PTC demonstrated clearly improved survival compared to follicular subtype of PTC and other less frequently seen histological subtypes. The instant risk of death for the other histological subtypes was 4.56 times higher than the risk for the classic papillary type. Overall, a 10-year survival of 76.6% in our patients was seen.

CONCLUSIONS

Patients with aggressive variants of PTC are more at risk for the development of metastatic disease. In these patients, established treatment modalities (surgery, radioiodine therapy) should be offered promptly, as well as close follow-up.

Loss of cellular polarity/cohesiveness in the invasive front of papillary thyroid carcinoma, a novel predictor for lymph node metastasis; possible morphological indicator of epithelial mesenchymal transition

BACKGROUND

Loss of cellular polarity/cohesiveness (LOP/C) in the invasive front of papillary thyroid carcinoma (PTC) results in a high recurrence risk of PTC.

AIMS

To investigate the immunohistochemical features of LOP/C in PTC and to show that this feature is linked to a high association of lymph node metastasis (LNM) at surgery and tumour recurrence.

METHODS

The degree of LOP/C of the PTCs was evaluated histologically using a cut-off value of 20% and the immunohistochemical features of LOP/C were analysed using immunohistochemical staining for E-cadherin, β-catenin and vimentin. The relationship between the LOP/C and the other clinicopathological parameters was analysed.

RESULTS

43 cases of PTC with LOP/C (≥20%) were selected and 27 cases with LOP/C (<20%) were included as control tumours. 11/44 cases (25%) were observed to develop recurrence, LNM or distant metastasis at an average follow-up of 31 months. Less expression of E-cadherin and aberrant localisation of β-catenin and vimentin were observed in PTC tumour cells with LOP/C. LOP/C (≥20%) was significantly correlated with extrathyroid invasion (r=0.336, p=0.003), advanced tumour stage (r=0.275, p=0.017), LNM (r=0.389, p<0.001) and recurrence after surgery (r=0.302, p=0.036). Both extrathyroid invasion and LOP/C were independent significant predictors of LNM.

CONCLUSIONS

LOP/C may be a useful morphological feature of epithelial mesenchymal transition under H&E observation, and it is an important indicator of lymph node metastasis and aggressive clinical behaviour of PTC.

Papillary thyroid carcinoma variants

Papillary thyroid carcinomas are the most common thyroid cancers and constitute more than 70% of thyroid malignancies. The most common etiologic factor is radiation, but genetic susceptibility and other factors also contribute to the development of papillary thyroid carcinoma. The most common variants include conventional, follicular variant and tall cell variant. However, many other uncommon variants have been described including oncocytic, columnar cell, diffuse sclerosing and solid forms. Immunohistochemical staining with TTF-1 and thyroglobulin is very useful in confirming the diagnosis of papillary thyroid carcinoma especially in metastatic sites. Markers such as HBME-1 and CITED1 can assist in separating some difficult cases of follicular variants of papillary thyroid carcinomas from follicular adenomas. Molecular studies have shown that the BRAF V600E mutation is found mainly in papillary and anaplastic thyroid carcinomas. Other molecular markers such as HMGA2 and insulin-like growth factor II mRNA binding protein 3 have been used recently as molecular tests to separate papillary thyroid carcinoma and its variants from follicular adenomas and other benign thyroid nodules.

Clinicopathologic and molecular disease prognostication for papillary thyroid cancer

Despite its increasing incidence over the last 30 years, the mortality rate of papillary thyroid cancer (PTC) has decreased significantly. Nevertheless, a minority of patients still present with an aggressive form of PTC that can lead to death, even after a prolonged period of survival. Many classifications exist that allow one to stratify the clinical risk of recurrence and death in patients with PTC; however, the parameters upon which they are established are pathological and molecular and, therefore, are revealed only after surgery. The preoperative identification of these aggressive variants of PTC would allow one to schedule a more aggressive operation (e.g., total thyroidectomy together with central and/or mono- or bi-lateral node dissections) in patients with high-risk PTC. This article reviews the parameters used most commonly to differentiate low-risk PTCs from their more aggressive variants and describes some of the newest molecular therapies for this latter group of tumors.

Classification of follicular cell tumors of the thyroid gland: analysis involving Japanese patients from one institute

Prognostic analyses of thyroid carcinomas of follicular cell origin were carried out on patients treated at Kuma Hospital, Kobe, Japan. A new histopathological classification based on the prognostic evidence is proposed in this study, and it is applicable to the patients treated curatively. Major histological types of papillary carcinoma, follicular carcinoma and poorly differentiated carcinoma were combined into one single entity of follicular cell adenocarcinoma because (i) they have the same cell origin (follicular cell); (ii) clear-cut separation of papillary and follicular carcinoma is not always possible, and 10 year cause-specific survival was essentially similar when the patients were treated curatively; and (iii) poorly differentiated carcinoma usually has a background of either papillary or follicular carcinoma. This adenocarcinoma together with undifferentiated carcinoma was stratified into four prognostic groups using pure morphological criteria of the degree of cellular differentiation and histological grade. They are termed well-differentiated adenocarcinoma, moderately differentiated adenocarcinoma, poorly differentiated carcinoma and undifferentiated carcinoma of the thyroid. The 10 year disease-free survival rates were 86.3-93.1%, 65.4-78.7%, and 43.0-53.8%, and 0%, respectively. The 10 year cause-specific survival rates were 97.2-100%, 91.5-97.4%, and 71.2-80.0%, and 0%, respectively.

Survival impact of psammoma body, stromal calcification, and bone formation in papillary thyroid carcinoma

The presence of calcification is the most significant ultrasonographic finding in evaluating thyroid nodules. Calcifications are more frequently detected in papillary thyroid carcinoma than in other thyroid lesions. However, the clinical significance of calcification, including clinical correlations and impact on survival, and the molecular mechanism responsible for calcification in papillary thyroid carcinoma remain uncertain. We performed a retrospective study of patients with primary common-type papillary thyroid carcinoma to determine the clinical correlations of calcification and its impact on survival. Histologically, calcification was classified as either psammoma bodies, stromal calcification, or bone formation. They were identified in 25, 47, and 13% of all 229 cases of papillary thyroid carcinoma, respectively. The presence of psammoma bodies was significantly correlated with gross lymph node metastasis and stage grouping. Both stromal calcification and bone formation were significantly correlated with patient age. In addition, stromal calcification was associated with pT classification and gross lymph node metastasis. Papillary thyroid carcinoma with, compared to that without, psammoma bodies was associated with poorer disease-free survival. We examined the quantitative expression of BMP-1, a metalloproteinase that is reported to be involved in bone and extracellular matrix formations, and found that its expression was significantly higher in tumors with psammoma bodies or with stromal calcification (P=0.0464 and 0.0272, respectively). These results suggest that the presence of psammoma bodies is a useful predictor of outcome for patients suffering from papillary thyroid carcinoma.

Prognostic values of thyroid tumours

Thyroid cancer accounts for approximately 1% of total cancer cases in developed countries. The aim of this study has been to analyze the histopathological variants of thyroid tumours with regard to gender and age. Despite their relative rarity in our material, they exhibit a wide range of morphological patterns and biological behaviour. During the period from 2001-2007, 138 biopsy cases of thyroid tumours, which were fixed in buffered neutral formalin and embedded in paraffin, have been reviewed. Tissue sections (4microm thick) were cut and stained with hematoxylin and eosin (H&E). Follicular adenomas have been found in 39, 1% of cases, thyroid carcinomas in 60, 12%, whereas thyroid secondary carcinomas have been found in 0, 72% of cases. As far as histological variants of thyroid carcinomas are concerned, most frequently found were papillary carcinomas in 39,85% of cases; followed by follicular carcinomas in 9,42% of cases; follicular variants of papillary carcinomas in 5,79% of cases; medullary carcinomas in 3,62% of cases, while anaplastic and Hurthle cell carcinomas have been found in 0,72% of cases each. All histological variants of thyroid tumours occurred more frequently in women than in men. Papillary carcinoma has been found in 80% of female cases. Thyroid tumours in our material mainly occurred in the third, the fourth and the fifth decade of life. Our data indicate that apart from the fact that papillary carcinomas, well differentiated, and characterised by relatively good prognosis, were most frequent variants, certain morphological variants of it were associated with poor prognosis.

Loss of cellular polarity/cohesiveness in the invasive front of papillary thyroid carcinoma and periostin expression

Loss of cellular polarity/cohesiveness and periostin expression are involved in the epithelial-mesenchymal transition in the epithelial malignancies. Their roles in papillary thyroid carcinoma were studied. There was a significant correlation between the loss of cellular polarity/cohesiveness in the invasive front and the up-regulation of periostin in tumors. Both of them were significantly correlated with extrathyroid invasion, pT and lymph node metastasis. Our results suggest that the loss of cellular polarity/cohesiveness is a useful parameter for predicting prognosis of patients with papillary thyroid carcinoma, and periostin could be a candidate gene for therapeutic targeting for the blockage of tumor invasion.

Subclassification of non-solid-type papillary thyroid carcinoma identification of high-risk group in common type

Two hundred and sixty-three cases of primary human papillary thyroid carcinoma (PTC) were analyzed. All cases met the following parameters: tumor size > or = 10 mm, no distant metastasis at presentation, and no coexistence of other histological type. The histological features of the solid/trabecular component, encapsulation, tall/columnar cell component and loss of polarity/cohesiveness were utilized to subclassify the 263 cases of PTC into five groups: solid type (15.6%), encapsulated group (9.5%), tall/columnar cell group (7.2%), micropapillary/discohesive group (19.8%) and not-otherwise-specified group (47.9%). We focused on the latter four non-solid groups and compared their prognosis with the solid type. The tall/columnar cell group showed the worst disease-free survival rate (DFS) analyzed by the Kaplan-Meier method, followed by the micropapillary/discohesive group. The not-otherwise-specified group and encapsulated group showed a better DFS rate than the solid type. Cancer-related death was noted in the tall/columnar cell group (21.1%) and micropapillary/discohesive group (3.8%), but not in the other groups. The four non-solid histological groups were further categorized into two prognostic groups: high-risk group (including tall/columnar cell group and micropapillary/discohesive group); and low-risk group (including encapsulated group and not-otherwise-specified group). Their 10-year disease-free survival rates were 78.7% and 93.1%, respectively. In the present study, histological grouping was significantly correlated with prognosis in the multivariate analysis according to the Cox proportional hazards regression model in addition to clinical parameters of extrathyroid invasion and gross lymph node metastasis, which predicts the patient outcome in terms of tumor recurrence and cancer-related death more precisely.

BRAF mutation in papillary thyroid cancer: pathogenic role, molecular bases, and clinical implications

In recent years, the T1799A B-type Raf kinase (BRAF) mutation in thyroid cancer has received enthusiastic investigation, and significant progress has been made toward understanding its tumorigenic role and clinical significance. Among various thyroid tumors, this mutation occurs uniquely in papillary thyroid cancer (PTC), the most common endocrine malignancy, and some apparently PTC-derived anaplastic thyroid cancers. Many studies have found this mutation to be associated with those clinicopathological characteristics of PTC that are conventionally known to predict tumor progression and recurrence, including, for example, old patient age, extrathyroidal invasion, lymph node metastasis, and advanced tumor stages. Direct association of BRAF mutation with the clinical progression, recurrence, and treatment failure of PTC has also been demonstrated. The BRAF mutation has even been correlated with PTC recurrence in patients with conventionally low-risk clinicopathological factors. Some molecular mechanisms determining BRAF mutation-promoted progression and the aggressiveness of PTC have recently been uncovered. These include the down-regulation of major tumor suppressor genes and thyroid iodide-metabolizing genes and the up-regulation of cancer-promoting molecules, such as vascular endothelial growth factor, matrix metalloproteinases, nuclear transcription factor kappaB, and c-Met. Thus, BRAF mutation represents a novel indicator of the progression and aggressiveness of PTC. Significant advances have also occurred in the preclinical testing of new therapeutic strategies targeting the MAPK pathway aberrantly activated by BRAF mutation and other related mutations. New mitogen extracellular kinase (MEK) inhibitors developed recently are particularly promising therapeutic agents for thyroid cancer. With these advances, it has become clearer that BRAF mutation will likely have significant impact on the clinical management of PTC.