Molecular characteristics in papillary thyroid cancers (PTCs) with no 131I uptake

Genetic alterations landscape in paediatric thyroid tumours and/or differentiated thyroid cancer: Systematic review

Differentiated thyroid cancer (DTC) is a rare disease in the paediatric population (≤ 18 years old. at diagnosis). Increasing incidence is reflected by increases in incidence for papillary thyroid carcinoma (PTC) subtypes. Compared to those of adults, despite aggressive presentation, paediatric DTC has an excellent prognosis. As for adult DTC, European and American guidelines recommend individualised management, based on the differences in clinical presentation and genetic findings. Therefore, we conducted a systematic review to identify the epidemiological landscape of all genetic alterations so far investigated in paediatric populations at diagnosis affected by thyroid tumours and/or DTC that have improved and/or informed preventive and/or curative diagnostic and prognostic clinical conduct globally. Fusions involving the gene RET followed by NTRK, ALK and BRAF, were the most prevalent rearrangements found in paediatric PTC. BRAF V600E was found at lower prevalence in paediatric (especially ≤ 10 years old) than in adults PTC. We identified TERT and RAS mutations at very low prevalence in most countries. DICER1 SNVs, while found at higher prevalence in few countries, they were found in both benign and DTC. Although the precise role of DICER1 is not fully understood, it has been hypothesised that additional genetic alterations, similar to that observed for RAS gene, might be required for the malignant transformation of these nodules. Regarding aggressiveness, fusion oncogenes may have a higher growth impact compared with BRAF V600E. We reported the shortcomings of the systematized research and outlined three key recommendations for global authors to improve and inform precision health approaches, glocally.

Relationship of Recurrence Rate with some Characteristics in Patients with Thyroid Carcinoma

Background

Determining the clinical and subclinical characteristics related to the recurrence status in patients with a thyroid carcinoma has great significance for prognosis, prediction of recurrence and monitoring of treatment outcomes. This study aimed to determine the association between recurrence rate and some characteristics in patients with thyroid carcinoma.

Patients and Methods

The study was conducted by descriptive method with longitudinal follow-up on 102 thyroid carcinoma patients at 103 Military Hospital, Hanoi, Vietnam, from July 2013 to December 2016.

Results

Univariate analysis showed that there was a relationship between the recurrence characteristics in the studied patients and the characteristics of lymph node metastasis (P = 0.026; OR = 15; 95% CI = 1.4-163.2) and BRAF V600E mutation status (P = 0.01; OR = 3.41; 95% CI = 1.31-8.88). When analysing the multivariable Logistic regression model, there was a positive correlation between the occurrence of BRAF V600E gene mutation (P = 0.032; OR = 17.649; 95% CI = 1.290-241.523) and male sex (P = 0.036; OR = 12.788; 95% CI = 1.185-137.961) and the occurrence of recurrence in study patients. The mean time to relapse was earlier in male patients than in female patients (P = 0.02). The mean time to relapse in patients with the BRAF V600E mutation (31.81 ± 1.14 months) was shorter than the mean time to relapse in the group without the mutation (57.82 ± 2.08 months) (P = 0.01). The group of patients with mutations in the BRAF V600E gene increased the risk of recurrence compared with the group without the mutation (HR = 9.14, P = 0.04).

Conclusion

There is a positive correlation between recurrence and masculinity, lymph node metastasis and the occurrence of BRAF V600E mutations in thyroid carcinoma patients.

Relationships of BRAF V600E Gene Mutation With Some Immunohistochemical Markers and Recurrence Rate in Patients With Thyroid Carcinoma

Background

The B-type rafkinase (BRAF) V600E gene mutation plays an important role in the pathogenesis, diagnosis, and prognosis of thyroid carcinoma. This study was conducted to investigate the rate of the BRAF V600E mutation, the relationships between the BRAF V600E gene mutation and some immunohistochemical markers, and recurrence rate in patients with differentiated thyroid cancer.

Method

The study was conducted by a descriptive and longitudinal follow-up method on 102 thyroid carcinoma patients at 103 Military Hospital, Hanoi, Vietnam. All patients were identified with the BRAF V600E gene mutation by real-time polymerase chain reaction.

Results

The rate of BRAF V600E gene mutation in patients with thyroid cancer was 60.8%. Patients with BRAF V600E gene mutation had a significantly higher rate of positive cyclooxygenase 2 (COX-2) and Ki67 markers than those without the mutation (COX-2: odds ratio [OR] = 2.93; 95% confidence interval [CI] = 1.27-6.74, P = .011; Ki67: OR = 3.41; 95% CI = 1.31-8.88, P = .01). A statistically significant relationship was identified between the rate of BRAF V600E mutation and the rate of positive Hector Battifora mesothelial 1 (HBME-1) (B = -1.040; P = .037) and COX-2 (B = -1.123; P = .023) markers. The recurrence rate in patients with BRAF V600E gene mutation was significantly higher than that in those without the mutation (P = .007). The mean of the recurrence time of patients with BRAF V600E mutation was significantly lower than that in those without the mutation (P = .011).

Conclusions

A high prevalence of BRAF V600E gene mutation was found in thyroid carcinoma patients. The rates of positive HBME-1, COX-2, and Ki67 markers were significantly correlated to BRAF V600E gene mutation. Patients with BRAF V600E gene mutation showed a significantly higher relapse rate and earlier relapse time than those without the mutation.

Validation of miRNAs as diagnostic and prognostic biomarkers, and possible therapeutic targets in medullary thyroid cancers

Introduction

Medullary thyroid cancer (MTC) is a rare type of neuroendocrine tumor that produces a hormone called calcitonin (CT). Thyroidectomy is the preferred treatment for MTC, as chemotherapy has been shown to have limited effectiveness. Targeted therapy approaches are currently being used for patients with advanced, metastatic MTC. Several studies have identified microRNAs, including miR-21, as playing a role in the development of MTC. Programmed cell death 4 (PDCD4) is a tumor suppressor gene that is an important target of miR-21. Our previous research has shown that high levels of miR-21 are associated with low PDCD4 nuclear scores and high CT levels. The aim of this study was to investigate the potential of this pathway as a novel therapeutic target for MTC.

Methods

We used a specific process to silence miR-21 in two human MTC cell lines. We studied the effect of this anti-miRNA process alone and in combination with cabozantinib and vandetanib, two drugs used in targeted therapy for MTC. We analyzed the effect of miR-21 silencing on cell viability, PDCD4 and CT expression, phosphorylation pathways, cell migration, cell cycle, and apoptosis.

Results

Silencing miR-21 alone resulted in a reduction of cell viability and an increase in PDCD4 levels at both mRNA and protein levels. It also led to a reduction in CT expression at both mRNA and secretion levels. When combined with cabozantinib and vandetanib, miR-21 silencing did not affect cell cycle or migration but was able to enhance apoptosis.

Conclusion

Silencing miR-21, although not showing synergistic activity with TKIs (tyrosine kinase inhibitors), represents a potential alternative worth exploring as a therapeutic target for MTC.

The role of BRAF V600E mutation in post-surgical 131I therapy in papillary thyroid carcinoma: a study based on SPECT-CT uptake analysis

BACKGROUND

The BRAF V600E mutation (BRAF mut) in papillary thyroid cancer (PTC) has been associated with poor response to therapy with ¹³¹I in patients with metastases but the results in postsurgical treatment are controversial. Our main objective is to investigate the impact of the mutation on the biokinetics of the administered ¹³¹I therapy after surgery.

METHODS

A prospective study was designed, from July 2015 to January 2018 which included patients with PTC receiving ¹³¹I therapy after surgical treatment. To study the biokinetics of the radioiodine in postoperative thyroid remnants, SPECT-CT images were acquired so as to obtain the following variables: percentage of remnant uptake at 2 and 7 days post-administration, effective half-life and time-integrated activity coefficient. All of them were compared depending on the mutational diagnosis and other clinical features and pathological variables.

RESULTS

Sixty-one patients, and in total 103 thyroid remnants, were included. About 59% of patients were BRAF mutated. The mutation was associated with classic variant (88.5% vs. 11.5%; P=0.0001), desmoplastic reaction (85.7% vs. 14.3%; P=0.002), smaller tumor size (1.5 vs. 2.1 cm; P=0.024), nodal disease (3.3 vs. 1; P=0.001) and advanced stages (76.9% vs. 23%; P=0.014). The BRAFmut group had a lower percentage of ¹³¹I uptake at 2 days (0.17% vs. 0.47%; P=0.001) and at 7 days (0.02% vs. 0.1%; P=0.013); and a lower time-integrated activity coefficient (0.05h vs. 0.17 h; P=0.002). In univariate analysis, in addition to the mutation, the histological variant was significant but only for time-integrated activity coefficient (P=0.04). In multivariate analysis, only mutation determined the 2-day uptake (P<0.001) and the time-integrated activity coefficient (P<0.001).

CONCLUSIONS

The BRAF V600E mutation is associated with lower ¹³¹I uptake in thyroid remnants. Furthermore, it is an independent factor that decreases the effect of post-surgical ¹³¹I therapy, and therefore, it could be used as a potential tool to optimize the treatment of PTC.

Radioiodine therapy in advanced differentiated thyroid cancer: Resistance and overcoming strategy

Thyroid cancer is the most prevalent endocrine tumor and its incidence is fast-growing worldwide in recent years. Differentiated thyroid cancer (DTC) is the most common pathological subtype which is typically curable with surgery and Radioactive iodine (RAI) therapy (approximately 85%). Radioactive iodine is the first-line treatment for patients with metastatic Papillary Thyroid Cancer (PTC). However, 60% of patients with aggressive metastasis DTC developed resistance to RAI treatment and had a poor overall prognosis. The molecular mechanisms of RAI resistance include gene mutation and fusion, failure to transport RAI into the DTC cells, and interference with the tumor microenvironment (TME). However, it is unclear whether the above are the main drivers of the inability of patients with DTC to benefit from iodine therapy. With the development of new biological technologies, strategies that bolster RAI function include TKI-targeted therapy, DTC cell redifferentiation, and improved drug delivery via extracellular vesicles (EVs) have emerged. Despite some promising data and early success, overall survival was not prolonged in the majority of patients, and the disease continued to progress. It is still necessary to understand the genetic landscape and signaling pathways leading to iodine resistance and enhance the effectiveness and safety of the RAI sensitization approach. This review will summarize the mechanisms of RAI resistance, predictive biomarkers of RAI resistance, and the current RAI sensitization strategies.

Non-Iodine-Avid Disease Is Highly Prevalent in Distant Metastatic Differentiated Thyroid Cancer With Papillary Histology

CONTEXT

Patients with radioactive iodine (RAI) refractory metastatic differentiated thyroid cancer (DTC) have poor prognosis. Early identification of RAI refractoriness may improve care.

OBJECTIVE

This work aimed to characterize DTC patients with distant metastases (DM) at diagnosis who presented with non-iodine-avid disease.

METHODS

Retrospective analyses of DTC patients with DM at diagnosis who presented between 2012 and 2020 were performed. Iodine uptake in DM was correlated with tumor histology and mutational profile. The difference in uptake between BRAFV600E-like (BVL) and RAS-like (RL) cancers based on insights from The Cancer Genome Atlas was evaluated.

RESULTS

Among 78 patients, 48.7% had negative uptake in DM on the first posttherapy scan. Negative scans were highly prevalent in papillary thyroid carcinoma (PTC) with papillary architecture, PTC with BRAFV600E mutation, and PTC with both BRAFV600E and TERT promoter mutations (71.1%, 80.9%, and 100%, respectively). BVL and RL tumors exhibited distinct uptake patterns with negative scan prevalence of 76.9% and 14.3% (P = .005). Multivariate logistical regression confirmed high odds of negative uptake in BVL tumors with either BVL mutations or papillary architecture, 19.8 (95% CI, 2.72-144), and low odds of negative uptake in RL tumors with either RL mutations or follicular architecture, 0.048 (95% CI, 0.006-0.344), after adjusting for age, sex, race, RAI preparation method, bone metastases, and RAI dose. Patients with negative scans were significantly older (62.4 vs 47.0 years, P = .03).

CONCLUSION

Among DTC patients with DM at diagnosis, non-iodine-avid disease is highly prevalent in patients with BVL cancers, particularly with BRAFV600E and TERT promoter mutations, and is associated with an older age. Better strategies are needed to improve RAI treatment response for these patients.

Overexpression of miR-375 and L-type Amino Acid Transporter 1 in Pheochromocytoma and Their Molecular and Functional Implications

Pheochromocytoma (Pheo) is a tumor derived from chromaffin cells. It can be studied using 18F-dihydroxyphenylalanine (DOPA)—positron emission tomography (PET) due to its overexpression of L-type amino acid transporters (LAT1 and LAT2). The oncogenic pathways involved are still poorly understood. This study examined the relationship between ¹⁸F-DOPA-PET uptake and LAT1 expression, and we explored the role of miR-375 and putative target genes. A consecutive series of 58 Pheo patients were retrospectively analyzed, performing ¹⁸F-DOPA-PET in 32/58 patients. Real-time quantitative PCR was used to assess the expression of LAT1, LAT2, phenylethanolamine N-methyltransferase (PNMT), miR-375, and the major components of the Hippo and Wingless/Integrated pathways. Principal germline mutations associated with hereditary Pheo were also studied. Pheo tissues had significantly higher LAT1, LAT2, and PNMT mRNA levels than normal adrenal tissues. MiR-375 was strongly overexpressed. Yes-associated protein 1 and tankyrase 1 were upregulated, while beta-catenin, axin2, monocarboxylate transporter 8, and Frizzled 8 were downregulated. A positive relationship was found between ¹⁸F-DOPA-PET SUV mean and LAT1 gene expression and for 24 h-urinary norepinephrine and LAT1. This is the first experimental evidence of ¹⁸F-DOPA uptake correlating with LAT1 overexpression. We also demonstrated miR-375 overexpression and downregulated (Wnt) signaling and identified the Hippo pathway as a new potentially oncogenic feature of Pheo.

The Association Between Radioiodine Refractory in Papillary Thyroid Carcinoma, Sodium/Iodide Symporter Expression, and BRAF V600E Mutation

Objective

To study the association between radioiodine refractory papillary thyroid carcinoma, sodium/iodide symporter (NIS) expression, and the BRAF ^V600E mutation.

Methods

A study was conducted on 30 radioiodine refractory papillary thyroid carcinoma patients and 30 radioiodine-avid papillary thyroid carcinoma patients. The expressions of sodium/iodide symporter and BRAF ^V600E mutated protein were determined by immunohistochemistry using formalin-fixed, paraffin-embedded tissue.

Results

The mutated BRAF ^V600E protein was identified in 26 radioiodine refractory papillary thyroid carcinoma subjects (86.7%) and 22 radioiodine-avid papillary thyroid carcinoma subjects (73.3%), with no significant difference between the 2 groups (P = 0.3). Sodium/iodide symporter expression was detected in 4 of 30 cases (13.3%) from the radioiodine-avid papillary thyroid carcinoma group but was negative for all radioiodine refractory cases. There was no association between sodium/iodide symporter expression and radioiodine refractory papillary thyroid carcinoma (P = 0.11). Cases with positive NIS expression were likely negative for BRAF ^V600E mutation (3/4; P = 0.02).

Conclusion

Papillary thyroid carcinomas with BRAF ^V600E mutation were more likely to be negative for NIS expression. BRAF ^V600E mutation and NIS expressions cannot be used to predict radioiodine sensitivity.

PET/CT in the management of differentiated thyroid cancer

The standard treatment of differentiated thyroid cancer (DTC) consists of surgery followed by iodine-131 (¹³¹I) administration. Although the majority of DTC has a very good prognosis, more aggressive histologic subtypes convey a worse prognosis. Follow-up consists of periodically measurements of serum thyroglobulin, thyroglobulin antibodies and neck ultrasound and ¹²³I/¹³¹I whole-body scan. However, undifferentiated thyroid tumors have a lower avidity for radioiodine and the ability of DTC to concentrate ¹³¹I may be lost in metastatic disease. Positron emission tomography (PET)/computed tomography (CT) has been introduced in the evaluation of patients with thyroid tumors and the 2-[18F]-fluoro-2-deoxyd-glucose (¹⁸F-FDG) has been largely validated as marker of cell's metabolism. According to the 2015 American Thyroid Association guidelines, ¹⁸F-FDG PET/CT is recommended in the follow-up of high-risk patients with elevated serum thyroglobulin and negative ¹³¹I imaging, in the assessment of metastatic patients, for lesion detection and risk stratification and in predicting the response to therapy. It should be considered that well-differentiated iodine avid lesions could not concentrate ¹⁸F-FDG, and a reciprocal pattern of iodine and ¹⁸F-FDG uptake has been observed. Beyond ¹⁸F-FDG, other tracers are available for PET imaging of thyroid tumors, such as Iodine-124 (¹²⁴I), ¹⁸F-tetrafluoroborate and Gallium-68 prostate-specific membrane antigen. Moreover, the recent introduction of PET/MRI, offers now several opportunities in the field of patients with DTC. This review summarizes the evidences on the role of PET/CT in management of patients with DTC, focusing on potential applications and on elucidating some still debating points.

Molecular mechanisms of radioactive iodine refractoriness in differentiated thyroid cancer: Impaired sodium iodide symporter (NIS) expression owing to altered signaling pathway activity and intracellular localization of NIS

The advanced, metastatic differentiated thyroid cancers (DTCs) have a poor prognosis mainly owing to radioactive iodine (RAI) refractoriness caused by decreased expression of sodium iodide symporter (NIS), diminished targeting of NIS to the cell membrane, or both, thereby decreasing the efficacy of RAI therapy. Genetic aberrations (such as BRAF, RAS, and RET/PTC rearrangements) have been reported to be prominently responsible for the onset, progression, and dedifferentiation of DTCs, mainly through the activation of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT signaling pathways. Eventually, these alterations result in a lack of NIS and disabling of RAI uptake, leading to the development of resistance to RAI therapy. Over the past decade, promising approaches with various targets have been reported to restore NIS expression and RAI uptake in preclinical studies. In this review, we summarized comprehensive molecular mechanisms underlying the dedifferentiation in RAI-refractory DTCs and reviews strategies for restoring RAI avidity by tackling the mechanisms.

The role of the size in thyroid cancer risk stratification

Only a minority of cases of differentiated thyroid carcinoma (DTC) have a poor clinical outcome. Clinical outcomes and molecular aspects were assessed in: 144 DTC ≤ 40 mm without distant metastases (group 1); 50 DTC > 40 mm without distant metastases (group 2); and 46 DTC with distant metastases (group 3). Group 3 had a worse outcome than the other two groups: during the follow-up, patients more frequently had persistent disease, died, or underwent further treatment. The outcomes did not differ between groups 1 and 2. Group 3 had a higher prevalence of TERT promoter mutations than group 2 (32.6% vs 14%). Group 1 had a higher frequency of BRAF mutations than groups 2 or 3 (61.1% vs 16.0% and 26.1%, respectively), while RAS mutations were more common in group 2 than in groups 1 and 3 (16.0% vs 2.1% and 6.5%, respectively). Groups 1 and 2 shared the same outcome, but were genetically distinct. Only lymph node involvement, distant metastases, older age and (among the molecular markers) TERT promoter mutations were independent predictors of a worse outcome. Metastatic DTC had the worst outcome, while the outcome was identical for large and small non-metastatic DTC, although they showed different molecular patterns. TERT promoter mutations emerged as an independent factor pointing to a poor prognosis.

Thyroid Carcinoma: Phenotypic Features, Underlying Biology and Potential Relevance for Targeting Therapy

Thyroid carcinoma consists a group of phenotypically heterogeneous cancers. Recent advances in biological technologies have been advancing the delineation of genetic, epigenetic, and non-genetic factors that contribute to the heterogeneities of these cancers. In this review article, we discuss new findings that are greatly improving the understanding of thyroid cancer biology and facilitating the identification of novel targets for therapeutic intervention. We review the phenotypic features of different subtypes of thyroid cancers and their underlying biology. We discuss recent discoveries in thyroid cancer heterogeneities and the critical mechanisms contributing to the heterogeneity with emphases on genetic and epigenetic factors, cancer stemness traits, and tumor microenvironments. We also discuss the potential relevance of the intratumor heterogeneity in understanding therapeutic resistance and how new findings in tumor biology can facilitate designing novel targeting therapies for thyroid cancer.

Relationship between clinicopathologic factors and FDG avidity in radioiodine-negative recurrent or metastatic differentiated thyroid carcinoma

BACKGROUND

In this study, we investigated the relationship between clinicopathologic factors, BRAFV600E mutation status and [18F] F-fluoro-2-deoxyglucose (FDG) avidity in patients with radioiodine (RAI)-negative recurrent or metastatic differentiated thyroid cancer (DTC).

METHODS

From 2015 to 2018 all patients with suspected recurrent or metastatic radioiodine-negative DTC patients who underwent FDG positron emission tomography/computed tomography (PET/CT) were retrospectively reviewed. Suspected lesions on FDG PET/CT were biopsied and underwent BRAFV600E mutation testing by immunohistochemistry and real-time PCR. Tumor size, recurrent versus metastatic disease, histopathologic features including classical type versus aggressive subtypes (poorly differentiated, tall cell, columnar cell, hobnail variants) and BRAFV600E mutation status were correlated with the SUVmax of highest hypermetabolic lesions on FDG PET/CT by the univariate analysis using logistic regression.

RESULTS

Sixty-three consecutive patients, 55 (87.3%) female, with median age of 48 (range 17-81) were included. The majority of patients had BRAFV600E mutation and classical subtype, 55/63 (87.3%) and 45/63(71.4%), respectively. Thyroglobulin at the time of suspected recurrence was 262.7 ng/ml (range 16.3-1000) and patients received a median 3 prior RAI treatments. Fifty-four patients (85.7%) had local recurrence. The majority of patients 58/63 (92.1%) had FDG-avid disease on PET/CT. On univariate analysis, tumor size aggressive histopathologic types and distant metastasis are the significant factors for predicting FDG uptake, p = 0.04, p = 0.001 and p = 0.004 respectively. Although FDG uptake of BRAFV600E bearing recurrent/metastatic RAIR DTC lesions was higher than those without the mutation, the difference did not reach statistical significance, SUVmax of 7.11 versus 4.91, respectively, p = 0.2.

CONCLUSION

The majority of recurrent or metastatic RAI-negative DTC have BRAFV600E mutation and detectable disease on FDG PET/CT. FDG avidity of the recurrent or metastatic RAI-negative DTC is independently associated with the aggressive histopathologic features.

Serum miR-375 for Diagnostic and Prognostic Purposes in Medullary Thyroid Carcinoma

PURPOSE

Having previously demonstrated that tissue miR-375 expression in medullary thyroid carcinoma (MTC) tissues is linked to prognosis, the aim of this study was to assess the diagnostic and prognostic value of circulating miR-375 levels in MTC patients.

METHODS

A series of 68 patients with MTC was retrospectively retrieved and assessed in terms of their clinicopathological characteristics. MiR-375 levels were measured in all patients' presurgical blood samples. Both serum and tissue levels were tested prior to surgery in a subgroup of 57 patients. Serum miR-375 levels were also measured in serum from 49 patients with non-C-cell thyroid nodular diseases (non-CTN), 14 patients with pheochromocytoma, and 19 healthy controls.

RESULTS

Circulating miR-375 levels were 101 times higher in the serum of patients with MTC than in all other patients and controls, with no overlap (P < 0.01). No correlation emerged between serum and tissue miR-375 levels. Serum miR-375 levels were higher in MTC patients with N0 than in those with N1 disease (P = 0.01), and also in patients who were biochemically cured than in those who were not (P = 0.02). In the whole series of patients and controls, calcitonin (CT) and serum miR-375 levels were correlated at diagnosis (R² = 0.40, P < 0.01), but in a U-shaped manner: a positive correlation was found with low CT levels, then the correlation turns negative as CT rises (in MTC patients). A negative correlation was indeed found in MTC patients between serum miR-375 and CT (R² = -0.10, P = 0.01). On ROC curve analysis, a cut-off of 2.1 for serum miR-375 proved capable of distinguishing between MTC patients and the other patients and controls with a 92.6% sensitivity and a 97.6% specificity (AUC: 0.978, P < 0.01).

CONCLUSIONS

Serum miR-375 levels can serve as a marker in the diagnosis of MTC, with a remarkable specificity. Serum miR-375 also proved a novel marker of prognosis in this disease. Further in vitro experiments to corroborate our results are currently underway.

Physiological and Pathophysiological Roles of Ion Transporter-Mediated Metabolism in the Thyroid Gland and in Thyroid Cancer

Thyroid cancer is the most common type of endocrine tumor and has shown an increasing annual incidence, especially among women. Patients with thyroid cancer have a good prognosis, with a high five-year survival rate; however, the recurrence rate and disease status of thyroid cancer remain a burden for patients, which compels us to further elucidate the pathogenesis of this disease. Recently, ion transporters have gradually become a hot topic in the field of thyroid gland biology and cancer research. Additionally, alterations in the metabolic state of tumor cells and protein molecules have gradually become the focus of scientific research. This review focuses on the progress in understanding the physiological and pathophysiological roles of ion transporter-mediated metabolism in both the thyroid gland and thyroid cancer. We also hope to shed light on new targets for the treatment and prognosis of thyroid cancer.

The molecular and gene/miRNA expression profiles of radioiodine resistant papillary thyroid cancer

Background

Papillary thyroid cancer (PTC) is the most frequent endocrine tumor. Radioiodine (RAI) treatment is highly effective in these tumors, but up to 60% of metastatic cases become RAI-refractory. Scanty data are available on either the molecular pattern of radioiodine refractory papillary thyroid cancers (PTC) or the mechanisms responsible for RAI resistance.

Methods

We analyzed the molecular profile and gene/miRNA expression in primary PTCs, synchronous and RAI-refractory lymph node metastases (LNMs) in correlation to RAI avidity or refractoriness.

We classified patients as RAI+/D+ (RAI uptake/disease persistence), RAI−/D+ (absent RAI uptake/disease persistence), and RAI+/D- (RAI uptake/disease remission), and analyzed the molecular and gene/miRNA profiles, and the expression of thyroid differentiation (TD) related genes.

Results

A different molecular profile according to the RAI class was observed: BRAF^V600E cases were more frequent in RAI−/D+ (P = 0.032), and fusion genes in RAI+/D+ cases. RAI+/D- patients were less frequently pTERT mutations positive, and more frequently wild type for the tested mutations/fusions. Expression profiles clearly distinguished PTC from normal thyroid. On the other hand, in refractory cases (RAI+/D+ and RAI−/D+) no distinctive PTC expression patterns were associated with either tissue type, or RAI uptake, but with the driving lesion and BRAF−/RAS-like subtype. Primary tumors and RAI-refractory LNMs with BRAF^V600E mutation display transcriptome similarity suggesting that RAI minimally affects the expression profiles of RAI-refractory metastases. Molecular profiles associated with the expression of TPO, SLC26A4 and TD genes, that were found more downregulated in BRAF^V600E than in gene fusions tumors.

Conclusions

The present data indicate a different molecular profile in RAI-avid and RAI-refractory metastatic PTCs. Moreover, BRAF^V600E tumors displayed reduced differentiation and intrinsic RAI refractoriness, while PTCs with fusion oncogenes are RAI-avid but persistent, suggesting different oncogene-driven mechanisms leading to RAI refractoriness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01757-x.

Circ_PSD3 promotes the progression of papillary thyroid carcinoma via the miR-637/HEMGN axis

AIMS

In the present study, we aimed to uncover the potential functions of circular RNA (circRNA) pleckstrin and Sec7 domain containing 3 (circ_PSD3) in papillary thyroid carcinoma (PTC) development.

MAIN METHODS

The abundance of circ_PSD3, PSD3 messenger RNA (mRNA), microRNA-637 (miR-637) and hemogen (HEMGN; EDAG-1) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Flow cytometry was employed to measure cell cycle progression and cell apoptosis. Western blot assay was used to examine protein expression. The proliferation ability and motility of PTC cells were analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and transwell assays, respectively. The interaction between miR-637 and circ_PSD3 or HEMGN was tested by dual-luciferase reporter assay. Animal experiments were used to explore the role of circ_PSD3 in PTC progression in vivo.

KEY FINDINGS

Circ_PSD3 was aberrantly up-regulated in PTC tumor tissues compared with adjacent normal tissues. Circ_PSD3 and HEMGN promoted the cell cycle progression, proliferation and metastasis and impeded the apoptosis of PTC cells. MiR-637 was a direct target of circ_PSD3, and miR-637 directly interacted with HEMGN mRNA in PTC cells. Circ_PSD3 silencing-induced effects in PTC cells were partly attenuated by the addition of anti-miR-637 or HEMGN overexpression plasmid. Circ_PSD3/miR-637/HEMGN regulated the activity of PI3K/Akt signal pathway in PTC cells. Circ_PSD3 silencing inhibited the tumor growth in vivo.

SIGNIFICANCE

Circ_PSD3 promoted the progression of PTC through regulating miR-637/HEMGN axis and activating PI3K/Akt signaling. Circ_PSD3/miR-637/HEMGN signaling axis might be a potential target for PTC therapy.

Clinical and Translational Challenges in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy and it accounts for 1% of all newly diagnosed tumors. Approximately 10% of patients with differentiated thyroid carcinomas (DTC) and 30% with medullary thyroid carcinoma (MTC) could not be cured with locoregional treatment and could develop metastatic disease. In addition, one of the most aggressive solid tumors can arise from the thyroid gland, the anaplastic thyroid carcinoma, with a median overall survival of less than 6 months. Currently, only four drugs are approved for the treatment of DTC and MTC and several unmet needs are focusing the scientific discussions, including the resistant setting, the off-target side effects that may reduce the efficacy and the molecular knowledge-based combinations. In this review, we aimed to discuss the current molecular landscape and treatment of thyroid cancers, and the ongoing clinical and translational research lines focusing on new drugs and drug combinations to improve the inhibition of driver mutations, such as BRAF and RET, and how systemic therapies that improved outcomes of other cancer types, like immunotherapy and peptide receptor radionuclide therapy, may play a role in the future management of advanced thyroid cancers.

A Novel Tyrosine Kinase Inhibitor Can Augment Radioactive Iodine Uptake Through Endogenous Sodium/Iodide Symporter Expression in Anaplastic Thyroid Cancer

Background: Radioactive iodine (RAI) therapy is an important strategy in the treatment of thyroid cancer. However, anaplastic thyroid cancer (ATC), a rare malignancy, exhibits severe dedifferentiation characteristics along with a lack of sodium iodide symporter (NIS) expression and function. Therefore, RAI therapy is ineffective and contributes toward poor prognosis of these patients. Recently, small-molecule tyrosine kinase inhibitors (TKIs) have been used to treat thyroid cancer patients for restoring NIS expression and function and RAI uptake capacity. However, most results reported thus far are associated with differentiated thyroid cancer. In this study, we identified a new TKI and investigated its effects on cell redifferentiation, NIS function, and RAI therapy in ATC. Methods: We identified a new TKI, "5-(5-{4H, 5H,6H-cyclopenta[b]thiophen-2-yl}-1,3,4-oxadiazol-2-yl)-1-methyl-1,2-dihydropyridin-2-one" (CTOM-DHP), using a high-throughput screening system. CTOM-DHP was exposed to 8505C ATC cells at different concentrations and time points. Concentrations of 12.5 and 25 μM and an incubation time of 72 hours were chosen as the conditions for subsequent NIS promoter assays and NIS mRNA and protein expression experiments. In addition, we examined factors related to iodide metabolism after CTOM-DHP treatment as well as the signaling pathways mediating the effects of CTOM-DHP on endogenous NIS expression. RAI uptake and ¹³¹I cytotoxicity effects caused by CTOM-DHP pretreatment were also evaluated in vitro and in vivo. Results: Promoter assays as well as mRNA and protein expression analyses confirmed that NIS expression was augmented by treatment of 8505C ATC cells with CTOM-DHP. Moreover, CTOM-DHP treatment robustly increased the expression of other thyroid-specific proteins and thyroid transcription factors related to iodide metabolism. Enhancement of NIS function was demonstrated by an increase in ¹²⁵I uptake and ¹³¹I cytotoxicity. Increased endogenous NIS expression was associated with the inhibition of PI3K/Akt and MAPK signaling pathways. In vivo results also demonstrated an increase in NIS promoter activity and RAI avidity in response to CTOM-DHP treatment. Furthermore, ¹³¹I-mediated therapeutic effects preferentially improved in a tumor xenograft mice model. Conclusions: CTOM-DHP, a new TKI identified in this study, enhances endogenous NIS expression and thereby is a promising compound for restoring RAI avidity in ATC.

Telomerase: Key regulator of inflammation and cancer

The telomerase holoenzyme, which has a highly conserved role in maintaining telomere length, has long been regarded as a high-profile target in cancer therapy due to the high dependency of the majority of cancer cells on constitutive and elevated telomerase activity for sustained proliferation and immortality. In this review, we present the salient findings in the telomerase field with special focus on the association of telomerase with inflammation and cancer. The elucidation of extra-telomeric roles of telomerase in inflammation, reactive oxygen species (ROS) generation, and cancer development further complicated the design of anti-telomerase therapy. Of note, the discovery of the unique mechanism that underlies reactivation of the dormant telomerase reverse transcriptase TERT promoter in somatic cells not only enhanced our understanding of the critical role of TERT in carcinogenesis but also opens up new intervention ideas that enable the differential targeting of cancer cells only. Despite significant effort invested in developing telomerase-targeted therapeutics, devising efficacious cancer-specific telomerase/TERT inhibitors remains an uphill task. The latest discoveries of the telomere-independent functionalities of telomerase in inflammation and cancer can help illuminate the path of developing specific anti-telomerase/TERT therapeutics against cancer cells.

BRAF Inhibitors in Thyroid Cancer: Clinical Impact, Mechanisms of Resistance and Future Perspectives

The Kirsten rat sarcoma viral oncogene homolog (RAS)/v-raf-1 murine leukemia viral oncogene homolog 1 (RAF)/mitogen-activated protein kinase 1 (MAPK) signaling cascade is the most important oncogenic pathway in human cancers. Tumors leading mutations in the gene encoding for v-raf murine sarcoma viral oncogene homolog B (BRAF) serine-threonine kinase are reliant on the MAPK signaling pathway for their growth and survival. Indeed, the constitutive activation of MAPK pathway results in continuous stimulation of cell proliferation, enhancement of the apoptotic threshold and induction of a migratory and metastatic phenotype. In a clinical perspective, this scenario opens to the possibility of targeting BRAF pathway for therapy. Thyroid carcinomas (TCs) bearing BRAF mutations represent approximately 29–83% of human thyroid malignancies and, differently from melanomas, are less sensitive to BRAF inhibitors and develop primary or acquired resistance due to mutational events or activation of alternative signaling pathways able to reactivate ERK signaling. In this review, we provide an overview on the current knowledge concerning the mechanisms leading to resistance to BRAF inhibitors in human thyroid carcinomas and discuss the potential therapeutic strategies, including combinations of BRAF inhibitors with other targeted agents, which might be employed to overcome drug resistance and potentiate the activity of single agent BRAF inhibitors.

Radioactive Iodine-Refractory Differentiated Thyroid Cancer and Redifferentiation Therapy

The retained functionality of the sodium iodide symporter (NIS) expressed in differentiated thyroid cancer (DTC) cells allows the further utilization of post-surgical radioactive iodine (RAI) therapy, which is an effective treatment for reducing the risk of recurrence, and even the mortality, of DTC. Whereas, the dedifferentiation of DTC could influence the expression of functional NIS, thereby reducing the efficacy of RAI therapy in advanced DTC. Genetic alternations (such as BRAF and the rearranged during transfection [RET]/papillary thyroid cancer [PTC] rearrangement) have been widely reported to be prominently responsible for the onset, progression, and dedifferentiation of PTC, mainly through activating the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling cascades. These genetic alternations have been suggested to associate with the reduced expression of iodide-handling genes in thyroid cancer, especially the NIS gene, disabling iodine uptake and causing resistance to RAI therapy. Recently, novel and promising approaches aiming at various targets have been attempted to restore the expression of these iodine-metabolizing genes and enhance iodine uptake through in vitro studies and studies of RAI-refractory (RAIR)-DTC patients. In this review, we discuss the regulation of NIS, known mechanisms of dedifferentiation including the MAPK and PI3K pathways, and the current status of redifferentiation therapy for RAIR-DTC patients.

BRAF V600E Status and Stimulated Thyroglobulin at Ablation Time Increase Prognostic Value of American Thyroid Association Classification Systems for Persistent Disease in Differentiated Thyroid Carcinoma

BACKGROUND

Stimulated thyroglobulin levels measured at the time of remnant ablation (A-hTg) and BRAFV600E mutation had shown prognostic value in predicting persistent disease in differentiated thyroid cancer (DTC). The aim of this study was to evaluate the prognostic role of A-hTg combined with the BRAFV600E status in association with the revised American Thyroid Association (ATA) risk stratification.

MATERIAL AND METHODS

620 patients treated for a DTC were included in this study with a median follow-up duration of 6.1 years. All patients underwent total thyroidectomy followed by radioiodine ablation. Patients with positive anti-thyroglobulin antibodies were excluded. The predictive value of A-hTg was calculated by receiver operating characteristic curve (ROC curve) analysis. The Cox proportional hazard regression model, including the BRAF status, A-hTg, and ATA classification system, was assessed to evaluate the existing persistent disease risk.

RESULTS

Taken together, the BRAF status and A-hTg levels improve the ATA risk classification in all categories. In particular, in the low-risk ATA classification, only the combination of BRAFV600E+A-hTg > 8.9ng/ml was associated with persistent disease (P = 0.001, HR 60.2, CI 95% 5.28-687). In the intermediate-risk ATA classification, BRAFWT+A-hTg > 8.9ng/ml was associated with persistent disease (P = 0.029, HR 2.71, CI 95% 1.106-6.670) and BRAFV600E+A-hTg > 8.9ng/ml was also associated with persistent disease (P < 0.001, HR 5.001, CI 95% 2.318-10.790). In the high-risk ATA classification, both BRAFV600E+A-hTg < 8.9ng/ml and BRAFV600E+A-hTg > 8.9 ng/ml were associated with persistent disease (P = 0.042, HR 5.963, CI 95% 1.069-33.255 and P = 0.002, HR 11.564, CI 95% 2.543-52.576, respectively).

CONCLUSIONS

The BRAF status and stimulated thyroglobulin levels at ablation time improve the ATA risk stratification of differentiated thyroid cancer; therefore, even A-hTg could be included in risk classification factors.

Novel Prognostic Factors Associated with Cell Cycle Control in Sporadic Medullary Thyroid Cancer Patients

BACKGROUND

Medullary thyroid cancer (MTC) is a rare neuroendocrine-derived malignancy. It is represented by sporadic and familiar forms, and both can have RET oncogene mutations. Numerous markers can be used to define MTC; however, none is generally approved for predicting the outcome of sporadic MTC.

AIM

The aim of this work was to analyze PTTG1/securin and Aurora kinase A expressions in MTC patients, both at the gene and protein levels, and to define their prognostic role in MTC assessing their association with lab and clinical parameters.

PATIENTS AND METHODS

Seventy-one sporadic MTC human samples were analyzed for RET mutations and by qPCR for PTTG1 and AURKA (Aurora kinase A) expression. Ki-67 levels and western blot reactivity for PTTG1 and Aurora kinase A were also determined in a selected cohort of patients.

RESULTS

RET somatic mutations were found in 48% of the patients (34/71). PTTG1 expression was statistically different among the groups with or without regional lymph node metastasis (p < 0.0001) and advanced stage disease (p < 0.01). PTTG1 and AURKA expressions were statistically higher than those of controls (p = 0.01 and p < 0.002, respectively). PTTG1 expression and Ki-67 levels were statistically different among the groups with remitted or persistent disease (p < 0.05 and p < 0.01, respectively). We found a significant correlation between the expressions of AURKA and PTTG1 (p < 0.0002, r = 0.5298) and between the expressions of PTTG1 and Ki-67 (p = 0.01). Ki-67 levels were statistically different among the groups with or without metastatic lymph nodes (p = 0.01) or distant metastases (p = 0.003).

CONCLUSION

The presence of an altered expression of PTTG1 and AURKA is a negative prognostic factor associated with a more aggressive course of disease, such as an advanced stage or disease persistence. It emerges as a cell cycle process mediated by the 2 factors, in addition to the RET pathway, which can be altered in MTC patients.

Telomerase reverse transcriptase induced thyroid carcinoma cell proliferation through PTEN/AKT signaling pathway

Thyroid carcinoma is the most common endocrine malignant tumor in the world, and so, there is a requirement to develop novel molecular targets for thyroid cancer diagnosis and treatment. Telomerase reverse transcriptase (TERT) was revealed to promote cell proliferation in a number of types of cell. To evaluate whether and how TERT functioned on papillary thyroid cancer (PTC) cell proliferation, the present study constructed TERT over‑expression [recombined (r)TERT plasmid group] and interference [small interfering RNA (si)‑TERT group] models by liposome transfection respectively to study the molecular mechanisms. The transfection efficiency was first detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting to analyze TERT levels compared with the negative control (NC) and control groups. Then MTT and carboxyfluorescein diacetate succinimidyl ester assays were performed to determine living cell proliferation and total cell proliferation respectively. Propidium iodide assay was used to detect alterations in cell cycle progression. RT‑qPCR and western blotting were performed to detect associated factor variation. The results demonstrated that, following the generation of TERT overexpression or silencing PTC cells, the living cells and also total cell proliferation increased significantly in the rTERT group, and decreased significantly in siTERT group, when compared with the NC and control groups. The cell cycle was accelerated in the rTERT group, and blocked in the G1/S transition in the siTERT group. The mRNA and protein levels of P27, P53 and phosphatase and tensin homolog (PTEN) decreased significantly in the rTERP group and increased in the siTERP group, while cyclin dependent kinase 2 and Cyclin D1 increased significantly in the rTERP group and decreased in the siTERP group. The expression of cell division cycle 25A did not alter significantly. The protein levels of β‑catenin and retinoblastoma were also unaltered. Protein kinase B (AKT) was detected once activated by TERT, and there were increased phosphorylated (p)‑AKT protein levels in the rTERT group, and decreased p‑AKT protein levels in the siTERT group. In conclusion, TERT could induce thyroid carcinoma cell proliferation mainly through the PTEN/AKT signaling pathway.

Molecular Profiling of Follicular Variant of Papillary Thyroid Cancer Reveals Low-Risk Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: A Paradigm Shift to Reduce Aggressive Treatment of Indolent Tumors

INTRODUCTION

Encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) has been reclassified into noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and invasive EFVPTC. NIFTP is considered a low-risk neoplasm. Therefore, follicular variant of papillary thyroid cancer (FVPTC) presently has two distinct histopathological subtypes - invasive EFVPTC and infiltrative/diffuse FVPTC. Molecular characteristics of these groups remain unclear.

METHODOLOGY

Thirty FVPTCs (10 NIFTPs, 12 invasive EFVPTCs, and 8 infiltrative/diffuse variants) were reviewed and screened for BRAF and RAS mutations by restriction fragment length morphism-polymerase chain reaction (PCR) and Sanger sequencing. The mRNA expression levels of iodine-metabolizing genes were analyzed using real-time PCR. The mutations status and mRNA expression levels were correlated with clinicopathological features.

RESULTS

All 10 NIFTPs had predominant follicular pattern. One case showed NRAS mutation, whereas none showed BRAF mutation. All invasive EFVPTC had capsular and/or lymphovascular invasion and 4/12 showed lymph node metastasis. BRAF and NRAS were seen in three cases each of invasive FVPTC. All eight infiltrating/diffuse FVPTCs showed infiltration into adjacent thyroid parenchyma and lymph node metastasis.

CONCLUSION

BRAF mutation was observed in 62.5% of cases; however, no NRAS mutation was found. Sodium iodide symporter (NIS) expressions in NIFTP were similar to that of normal thyroid tissue, whereas it was downregulated in invasive and infiltrative/diffuse FVPTC. Our study supports the argument that NIFTP can be considered as low-risk follicular thyroid neoplasm. Those tumors that harbor BRAF mutations may be offered a complete thyroidectomy because they show decreased expression of NIS gene which confers a tendency to lose radioactive iodine avidity and further recurrence of the tumor.

The Role of the NIS (SLC5A5) Gene in Papillary Thyroid Cancer: A Systematic Review

Papillary thyroid cancer (PTC) is the most common thyroid malignancy. Genetic and epigenetic alterations play a decisive role in the onset of several human neoplasms. Mutations and polymorphisms are two frequent genetic alterations. Located on chromosome 19 (19p13.11), the NIS SLC5A5 (solute carrier family 5 member 5) gene encodes a highly specialized and efficient 80-90 kDa transmembrane glycoprotein that mediates active transport of iodide from the bloodstream into the follicular cells. Given the highly significant role of NIS in the physiology and the cancer pathogenesis process, this paper's objective is to provide a comprehensive assessment of the associations between NIS gene and protein with papillary thyroid cancer.

NIS expression in thyroid tumors, relation with prognosis clinicopathological and molecular features

Thyroid cancer therapy is based on surgery followed by radioiodine treatment. The incorporation of radioiodine by cancer cells is mediated by sodium iodide symporter (NIS) (codified by the SLC5A5 gene), that is functional only when targeted to the cell membrane. We aimed to evaluate if NIS expression in thyroid primary tumors would be helpful in predicting tumor behavior, response to therapy and prognosis. NIS expression was addressed by qPCR and immunohistochemistry. In order to validate our data, we also studied SLC5A5 expression on 378 primary papillary thyroid carcinomas from The Cancer Genome Atlas (TCGA) database. In our series, SLC5A5 expression was lower in carcinomas with vascular invasion and with extrathyroidal extension and in those harboring BRAFV600E mutation. Analysis of SLC5A5 expression from TCGA database confirmed our results. Furthermore, it showed that larger tumors, with locoregional recurrences and/or distant metastases or harboring RAS, BRAF and/or TERT promoter (TERTp) mutations presented significantly less SLC5A5 expression. Regarding immunohistochemistry, 12/211 of the cases demonstrated NIS in the membrane of tumor cells, those cases showed variable outcomes concerning therapy success, prognosis and all but one were wild type for BRAF, NRAS and TERTp mutations. SLC5A5 mRNA lower expression is associated with features of aggressiveness and with key genetic alterations involving BRAF, RAS and TERTp. Mutations in these genes seem to decrease protein expression and its targeting to the cell membrane. SLC5A5 mRNA expression is more informative than NIS immunohistochemical expression regarding tumor aggressiveness and prognostic features.

A six-gene panel to label follicular adenoma, low- and high-risk follicular thyroid carcinoma

The distinction between follicular thyroid carcinomas (FTCs) and follicular-patterned benign lesions is almost impossible on fine-needle aspiration cytology. Furthermore, minimally invasive FTCs (MI-FTCs) with less than 4 vascular invasion foci generally have an excellent prognosis, but there are exceptions and, so far, no molecular marker appears able to identify them reliably. We aimed to distinguish benign lesions from low- and high-risk FTCs by a small-scale combination of genes. The expression analysis of 75 selected genes was performed on 18 follicular adenomas (FAs), 14 MI-FTCs and 6 widely invasive FTC (WI-FTCs). The mutational status of the RAS genes, TERT promoter and PAX8-PPARG rearrangements was also investigated. Seven samples were mutated, namely 3 MI-FTCs and 4 WI-FTCs. Twenty-five genes were differentially expressed (FDR <0.05) between FAs and WI-FTCs. Six of these (ECM1, RXRG, SDPR, SLC26A4, TIFF3, TIMP1) were also differently expressed among MI-FTCs and FAs or WI-FTCs and were considered to build a classification model, which was tested to classify samples according to their histological class. Hence, 31 out of 38 were correctly classified, and accuracy remained high after cross-validation (27/38). The 2 MI-FTCs incorrectly classified as WI-FTCs harbored both RAS and TERT promoter mutations. The capability of these six genes to stratify benign, low- and high-risk lesions appears to be promising in supporting the diagnosis of indeterminate thyroid nodules.

Response to therapy of papillary thyroid cancer of known BRAF status

OBJECTIVE

A dynamic risk stratification with modified initial estimated risk based on response to therapy and disease course is one of the crucial changes adopted recently by the American Thyroid Association (ATA). This approach focuses on an individualized risk-adapted approach to the management of differentiated thyroid cancer. The BRAF V600E mutation is the most common genetic alteration in papillary thyroid cancer (PTC). However, the prognostic value of this mutation remains unclear. The aim of this study was to examine the relation between the BRAF V600E status in PTC and all ATA response-to-therapy categories, as well as the recurrence and persistence of both biochemical disease and structural disease.

PATIENTS

Unselected PTC cases with known BRAF status diagnosed from 2000 to 2013 and actively monitored at one institution (n=723) were reviewed retrospectively. The association between the BRAF V600E mutation and clinicopathological characteristics, ATA 2015 response-to-therapy category, recurrence after a period of no evidence of disease (NED) and persistent biochemical or structural disease, was analysed.

RESULTS

BRAF V600E was found in 65.7% (475/723) of PTC cases. Although BRAF mutation status correlated significantly with certain clinicopathological prognostic factors, there was no correlation with any of the response-to-therapy categories. Recurrences and persistent biochemical or structural disease were not associated with BRAF status.

CONCLUSIONS

Our data are consistent with those of other studies reporting a positive relation between BRAF V600E mutation and poor prognostic factors in PTC; however, the BRAF status did not significantly correlate with a response to therapy.

Association of NF-κB polymorphisms with clinical outcome of non-medullary thyroid carcinoma

The NF-κB inflammatory pathway plays a major role in cancer development and clinical progression. Activation of NF-κB signaling is promoted by NFKB1 and inhibited by NFKBIA. The present study aimed to determine the relevance of NFKB1 rs4648068 and NFKBIA rs2233406 genetic variants for non-medullary thyroid cancer (NMTC) susceptibility, progression and clinical outcome. This case-control and cohort study consists of a Romanian discovery cohort (157 patients and 258 controls) and a Dutch validation cohort (138 patients and 188 controls). In addition, patient cohorts were analyzed further for the association of genetic variants with clinical parameters. Functional studies were performed on human peripheral blood mononuclear cells. No associations were observed between the studied genetic variants and TC susceptibility. Although no statistically significant associations with clinical parameters were observed for NFKB1 rs4648068, the heterozygous genotype of NFKBIA rs2233406 was correlated with decreased radioactive iodide sensitivity requiring higher cumulative dosages to achieve clinical response. These findings were discovered in the Romanian cohort (P < 0.001) and confirmed in the Dutch cohort (P = 0.01). Functional studies revealed that this NFKBIA rs2233406 genotype was associated with elevated TLR4-mediated IL-1β production. In conclusion, genetic variation in NFKBIA, an inhibitor of NF-κB signaling, is associated with clinical response to RAI therapy and with increased production of the pro-inflammatory cytokine IL-1β, providing a potential mechanism for the observed clinical associations. These data suggest that NF-κB signaling is involved in NMTC pathogenesis and that the inflammatory tumor microenvironment could contribute to RAI resistance.

Recurrence-associated genes in papillary thyroid cancer: An analysis of data from The Cancer Genome Atlas

BACKGROUND

Recurrence of papillary thyroid cancer is not uncommon, but incorporating clinicopathologic parameters to predict recurrence is suboptimal. The aim of this study was to identify systemically recurrence-associated genes using The Cancer Genome Atlas RNA sequencing database.

METHODS

A total of 504 patients with transcriptome sequencing data of the primary neoplasm were included in this study. High and low levels of expression of each gene were defined by median splits. Differences in recurrence-free survival were compared using Kaplan-Meier curves and log-rank tests. Recurrence-associated genes were subjected to functional enrichment analyses with Kyoto Encyclopedia of Genes and Genomes annotation databases and Ingenuity Pathway Analysis.

RESULTS

We found that 1,807 genes were associated with recurrence-free survival. There were 676 genes of which high expression was associated with a greater risk of recurrence. These genes were enriched in pathways involved in cell cycle regulation and DNA repair. Among 1,131 genes of which low expression was associated with recurrence, Kyoto Encyclopedia of Genes and Genomes-annotated functions were metabolism, calcium signaling, glycan biosynthesis, and the Notch signaling pathway. Canonical pathways identified by Ingenuity Pathway Analysis included RXR function, nitric oxide signaling, interleukin-8 signaling, and nutrient sensing. In addition, low expression of the majority of thyroid differentiation genes was associated with a significantly less recurrence-free survival.

CONCLUSION

Upregulation of cell cycle-regulating and DNA repair genes appears to have a negative impact on recurrence-free survival in patients with papillary thyroid cancer. Furthermore, recurrence is associated with thyroid dedifferentiation.

Does Molecular Genotype Provide Useful Information in the Management of Radioiodine Refractory Thyroid Cancers? Results of a Retrospective Study

INTRODUCTION

Whether mutation status should be used to guide therapy is an important issue in many cancers. We correlated mutation profile in radioiodine-refractory (RAIR) metastatic thyroid cancers (TCs) with patient outcome and response to tyrosine kinase inhibitors (TKIs), and discussed the results with other published data.

MATERIALS AND METHODS

Outcome in 82 consecutive patients with metastatic RAIR thyroid carcinoma prospectively tested for BRAF, RAS and PI3KCA mutations was retrospectively analyzed, including 55 patients treated with multikinase inhibitors.

RESULTS

Papillary thyroid carcinomas (PTCs) were the most frequent histological subtype (54.9 %), followed by poorly differentiated thyroid carcinoma [PDTC] (30.5 %) and follicular thyroid carcinoma [FTC] (14.6 %). A genetic mutation was identified in 23 patients (28 %) and BRAF was the most frequently mutated gene (23 %). Median progression-free survival (PFS) on first-line TKI treatment was 14.6 months (95% CI 9.9-18.4). BRAF mutation positively influenced median PFS, both in the entire TKI-treated cohort (median PFS 34.7 months versus 11.6 months; hazard ratio [HR] 0.29; 95% CI 0.09-0.98; p = 0.03) and in the TKI-treated PTC cohort (n = 22) [log-rank p = 0.086; HR 2.95; 95 % CI 0.81-10.70). However, in TKI-treated patients, PDTC histologic subtype was the only independent prognostic factor for PFS identified in the multivariate analysis (HR 2.36; 95% CI 1.01-5.54; p = 0.048).

CONCLUSION

Patients with BRAF-mutant PTC had a significantly longer PFS than BRAF wild-type when treated with TKIs. However, due to the small number of BRAF-mutant patients, further investigations are required, especially to understand the potential positive effect of BRAF mutations in RAIR TC patients while having a negative prognostic impact in RAI-sensitive PTC patients.

Modulation of thyroidal radioiodide uptake by oncological pipeline inhibitors and Apigenin

Targeted radioiodine therapy for thyroid cancer is based on selective stimulation of Na+/I- Symporter (NIS)-mediated radioactive iodide uptake (RAIU) in thyroid cells by thyrotropin. Patients with advanced thyroid cancer do not benefit from radioiodine therapy due to reduced or absent NIS expression. To identify inhibitors that can be readily translated into clinical care, we examined oncological pipeline inhibitors targeting Akt, MEK, PI3K, Hsp90 or BRAF in their ability to increase RAIU in thyroid cells expressing BRAFV600E or RET/PTC3 oncogene. Our data showed that (1) PI3K inhibitor GDC-0941 outperformed other inhibitors in RAIU increase mainly by decreasing iodide efflux rate to a great extent; (2) RAIU increase by all inhibitors was extensively reduced by TGF-β, a cytokine secreted in the invasive fronts of thyroid cancers; (3) RAIU reduction by TGF-β was mainly mediated by NIS reduction and could be reversed by Apigenin, a plant-derived flavonoid; and (4) In the presence of TGF-β, GDC-0941 with Apigenin co-treatment had the highest RAIU level in both BRAFV600E expressing cells and RET/PTC3 expressing cells. Taken together, Apigenin may serve as a dietary supplement along with small molecule inhibitors to improve radioiodine therapeutic efficacy on invasive tumor margins thereby minimizing future metastatic events.

Hybrid Imaging in Oncology

In oncology various imaging modalities play a crucial role in diagnosis, staging, restaging, treatment monitoring and follow up of various cancers. Stand-alone morphological imaging like computerized tomography (CT) and magnetic resonance imaging (MRI) provide a high magnitude of anatomical details about the tumor but are relatively dumb about tumor physiology. Stand-alone functional imaging like positron emission tomography (PET) and single photon emission tomography (SPECT) are rich in functional information but provide little insight into tumor morphology. Introduction of first hybrid modality PET/CT is the one of the most successful stories of current century which has revolutionized patient care in oncology due to its high diagnostic accuracy. Spurred on by this success, more hybrid imaging modalities like SPECT/CT and PET/MR were introduced. It is the time to explore the potential applications of the existing hybrid modalities, developing and implementing standardized imaging protocols and train users in nuclear medicine and radiology. In this review we discuss three existing hybrid modalities with emphasis on their technical aspects and clinical applications in oncology.

Overexpression of L-Type Amino Acid Transporter 1 (LAT1) and 2 (LAT2): Novel Markers of Neuroendocrine Tumors

Background

6-18F-fluoro-L-3,4-dihydroxyphenylalanine (¹⁸F-FDOPA) PET is a useful tool in the clinical management of pheochromocytoma (PHEO) and medullary thyroid carcinoma (MTC). ¹⁸F-FDOPA is a large neutral amino acid biochemically resembling endogenous L-DOPA and taken up by the L-type amino acid transporters (LAT1 and LAT2). This study was conducted to examine the expression of the LAT system in PHEO and MTC.

Methods

Real-time PCR and Western blot analyses were used to assess LAT1 and LAT2 gene and protein expression in 32 PHEO, 38 MTC, 16 normal adrenal medulla and 15 normal thyroid tissue samples. Immunohistochemistry method was applied to identify the proteins’ subcellular localization.

Results

LAT1 and LAT2 were overexpressed in both PHEO and MTC by comparison with normal tissues. LAT1 presented a stronger induction than LAT2, and their greater expression was more evident in PHEO (15.1- and 4.1-fold increases, respectively) than in MTC (9.9- and 4.1-fold increases, respectively). Furthermore we found a good correlation between LAT1/2 and GLUT1 expression levels. A positive correlation was also found between urinary noradrenaline and adrenaline levels and LAT1 gene expression in PHEO. The increased expression of LAT1 is also confirmed at the protein level, in both PHEO and MTC, with a strong cytoplasmic localization.

Conclusions

The present study is the first to provide experimental evidence of the overexpression in some NET cancers (such as PHEO or MTC) of L-type amino acid transporters, and the LAT1 isoform in particular, giving the molecular basis to explain the increase of the DOPA uptake seen in such tumor cells.

Molecular genetics of thyroid cancer

The pathogenesis of the development and progression of thyroid cancer (TC) is far from being clear at present. Accumulated evidence suggests that it is a complex polygenic disorder for which genetic factors play an important role in disease aetiology. Here we review the literature to report the genetic variations and alterations that have been described in the aetiology of TC. The functional effects of some mutations and single nucleotide polymorphisms on TC are validated, establishing the role of sequence variations in this cancer. However, large prospective studies are still required to evaluate the diagnostic and prognostic value of these genetic determinants in clinical practice.

Clinical Manifestations and Gene Expression in Patients with Conventional Papillary Thyroid Carcinoma Carrying the BRAF(V600E) Mutation and BRAF Pseudogene

BACKGROUND

The association of BRAF(V600E) with the clinical manifestations of papillary thyroid carcinoma (PTC) remains controversial. Recent studies have shown that the BRAF pseudogene can activate the MAPK pathway and induce tumorigenesis. This study investigated the association of BRAF(V600E), the BRAF pseudogene, and their mRNA levels with clinical features and thyroid-specific gene expression in conventional PTCs.

MATERIALS AND METHODS

A total of 78 specimens were collected from patients with conventional PTCs. RNA was isolated, and quantitative polymerase chain reaction was used to measure the mRNA levels of BRAF, the BRAF pseudogene, and thyroid-specific and tumor-related genes. Immunohistochemical (IHC) staining of BRAF, ERK, sodium-iodide symporter (NIS), thyrotropin receptor, glucose transporter 1, and Ki67 was also performed.

RESULTS

BRAF(V600E) and the BRAF pseudogene were detected in 73.0% (57/78) and 91.7% (44/48), respectively, of the conventional PTCs. The presence of BRAF(V600E) was not associated with the multiple clinical features assessed or the recurrence rate during 76.9 ± 47.2 months of follow-up. Neither was it associated with IHC staining or tumor-related/thyroid-specific gene expression, except for decreased NIS gene expression. The BRAF pseudogene was not associated with clinical characteristics or thyroid-specific gene expression, except for decreased decoy receptor 3 (DCR3) expression. High BRAF mRNA levels were associated with bilateral and multifocal lesions, and BRAF-pseudogene mRNA levels were positively correlated with BRAF mRNA levels (r = 0.415, p = 0.009).

CONCLUSION

These results do not support the use of the BRAF(V600E) mutation as a prognostic marker of conventional PTC. However, the association of high BRAF mRNA levels with more advanced clinical features suggests that BRAF mRNA levels might be a more useful clinical marker of PTCs, independent of the BRAF(V600E) mutation status. The correlation between BRAF-pseudogene mRNA levels and BRAF mRNA levels in PTCs is in agreement with the hypothesis that the BRAF pseudogene regulates BRAF expression during tumorigenesis by acting as competitive noncoding RNA. However, additional studies with larger sample sizes are required to confirm these findings.

B-Raf mutation and papillary thyroid carcinoma patients

Thyroid carcinoma is the most prevalent endocrine neoplasm globally. In the majority of thyroid carcinoma cases, a positive prognosis is predicted following administration of the appropriate treatment. A wide range of genetic alterations present in thyroid carcinoma exert their oncogenic actions partially through the activation of the mitogen-activated protein kinase pathway, with the B-Raf mutation in particular being focused on by experts for decades. The B-Raf gene has numerous mutations, however, V600E presents with the highest frequency. It is believed that the existence of the V600E mutation may demonstrate an association with the clinicopathological characteristics of patients, however, inconsistencies remain in the literature. A number of explanatory theories have been presented in order to resolve these discrepancies. Recently, it has been suggested that the V600E mutation may function as a target in a novel approach that may aid the diagnosis and prognosis of thyroid carcinoma, with a number of vying methods put forward to that effect. The current review aims to assist researchers in further understanding the possible association between B-Raf mutations and thyroid carcinoma.

Relationships between transporter expression and the status of BRAF V600E mutation and F-18 FDG uptake in papillary thyroid carcinomas

PURPOSE

The purpose of this study was to evaluate the expression of the glucose transporters GLUT1 and GLUT3 in papillary thyroid carcinomas (PTCs) and to elucidate their relationship with the BRAF V600E mutation and F-18 FDG uptake.

MATERIALS AND METHODS

We retrospectively analyzed data of 52 PTC patients (41 women and 11 men; mean age, 52.4 ± 14.5 years). F-18 FDG PET/CT was performed preoperatively, and the maximum standardized uptake value (SUVmax) was calculated. GLUT1/GLUT3 expression was determined immunohistochemically, and the BRAF V600E mutation was detected using DNA sequencing.

RESULTS

GLUT1 and GLUT3 were expressed in 82.7% (43/52) and 59.6% (31/52) PTCs, respectively. The BRAF V600E mutation was detected in 65.4% (34/52) PTCs. The odds ratio between GLUT1 expression and the BRAF V600E mutation was 5.2 (95% CI, 1.11-24.05; p < 0.05), and that between GLUT3 expression and the BRAF V600E mutation was 3.8 (95% CI, 1.14-12.53; p < 0.05). The SUVmax of PTCs was significantly higher if they carried the BRAF V600E mutation (11.3 ± 2.0, compared with 5.7 ± 1.4 for wild type BRAF tumors, Mann-Whitney test, p = 0.016). Neither GLUT1 nor GLUT3 expression was significantly associated with the SUVmax of F-18 FDG PET/CT in PTCs.

CONCLUSIONS

Our findings confirmed that both GLUT1 and GLUT3 are strongly expressed by PTCs, although their expression was not significantly associated with the SUVmax of F-18 FDG PET/CT. However, GLUT1 and GLUT3 expressions were significantly associated with the presence of the BRAF V600E mutation, and the SUVmax of tumors was significantly higher in the presence of the mutated BRAF gene.

Outcomes and Prognostic Factors in Radioiodine Refractory Differentiated Thyroid Carcinomas

BACKGROUND

Outcomes vary among patients with radioiodine refractory (RR) differentiated thyroid cancer (DTC). The prognostic factors for survival are not well-known, resulting in difficulty in selecting patients for new targeted therapies. We assessed overall survival (OS) and cancer-specific survival (CSS) from RR-DTC to identify prognostic factors associated with survival.

PATIENTS AND METHODS

The data on all cases of metastatic RR-DTC treated in our center from 1990 to 2011 were retrospectively reviewed. Survival was estimated using the Kaplan-Meier method; associated prognostic factors were assessed using Cox's model.

RESULTS

Of 153 cases of metastatic DTC, 59% (n = 91) met a criterion for RR: that is, 60% (n = 55) had at least 1 metastasis without (131)I uptake; 21% (n = 19) had progressive disease (PD) despite (131)I; 19% (n = 17) had persistent disease despite a cumulative activity of (131)I of ≥600 mCi. After the diagnosis of RR, median OS was 8.9 years (95% confidence interval [CI]: 5.4-NR); median CSS was 9.6 years (95% CI: 6.01-NR). In multivariate analyses, PD despite (131)I as a criterion for RR disease and the time from initial diagnosis of DTC to diagnosis of RR <3 years were the only independent prognostic factors for poor OS and CSS. Thyroglobulin doubling time (Tg-DT) was assessed in 31 of 91 cases. Among the 11 patients with Tg-DT for <1 year or undetectable Tg, 6 deaths occurred, whereas only 3 died of 20 patients with Tg-DT >1 year or negative Tg-DT.

CONCLUSION

The identification of prognostic factors for decreased survival in RR-DTC may improve the selection of patients for targeted agents.

IMPLICATIONS FOR PRACTICE

This study shows a great heterogeneity in terms of prognosis in radioiodine refractory differentiated thyroid carcinoma. Poorer prognosis is observed in patients with tumor progression or with a diagnosis of radioiodine resistance within 3 years after the initial diagnosis of thyroid cancer. Those findings could lead to improvements in the selection of patients for targeted therapies.

Relation Between F-18 FDG Uptake of PET/CT and BRAFV600E Mutation in Papillary Thyroid Cancer

BRAFV600E mutation and F-18 fluorodeoxyglucose (FDG) uptake are potential prognostic factors of papillary thyroid cancer (PTC). This study was performed to investigate the relationship between the BRAFV600E mutation and F-18 FDG uptake in PTC.We retrospectively included 169 PTC patients who underwent F-18 FDG positron emission tomography/computed tomography (PET/CT) before thyroidectomy from May 2009 to August 2012. Subjects were classified into overt PTC (>1 cm, n = 76) and papillary thyroid microcarcinoma (PTMC, n = 93) groups. Univariate and multivariate analyses were performed to assess the relationship between maximum standardized uptake value (SUVmax) of the primary tumors and clinicopathologic variables.The BRAFV600E mutation was detected in 82.2% (139/169). In all subjects, the BRAFV600E mutation and tumor size were independently related to SUVmax by multivariate analysis (P = 0.048 and P < 0.001, respectively). SUVmax was significantly higher in tumors with the BRAFV600E mutation than in those with wild-type BRAF (9.4 ± 10.9 vs 5.0 ± 4.1, P < 0.001). Similarly, in overt PTC group, the BRAFV600E mutation and tumor size were independently correlated with SUVmax (P = 0.032 and P = 0.001, respectively). By contrast, in PTMC group, only tumor size was significantly associated with SUVmax (P = 0.010). The presence of the BRAFV600E mutation is independently associated with high F-18 FDG uptake on preoperative PET/CT in patients with overt PTC, but this relationship was not evident in PTMC. This study provides a better understanding of the relationship between F-18 FDG uptake and BRAFV600E mutation in patients with PTC.

Detection of Circulating BRAF(V600E) in Patients with Papillary Thyroid Carcinoma

BRAF(V600E) is a common mutation in papillary thyroid carcinoma (PTC) correlated with aggressive features. Our objective was to assess the feasibility and accuracy of a novel RNA-based blood assay to identify individuals with a high-risk tumor mutation in patients with PTC. Patients with benign or malignant thyroid disorders were included between September 2013 and July 2014 before either thyroidectomy (n = 62) or treatment of recurrent or metastatic PTC (n = 8). RNA was isolated from peripheral blood lymphocytes and reverse transcribed and followed by two rounds of nested PCR amplification with a restriction digest specific for wild-type BRAF. BRAF(V600E) levels were quantified with standardization curves. Circulating BRAF(V600E) levels were compared with BRAF mutation status from surgical pathologic DNA-based tissue assays. Testing characteristics and receiving-operator curve using tissue results as the gold standard were assessed. Matched blood and tissue assays for BRAF(V600E) were performed on 70 patients with PTC (stages I to IV, n = 48) or other (n = 22) thyroid tumors. Sixty-three percent of PTC patients tested positive for BRAF(V600E) with conventional tissue assays on surgical specimens. The correlation between the RNA-based blood assay and tissue BRAF status was 0.71. PTC patients harbor detectable BRAF(V600E) circulating tumor cells. This blood assay is feasible and has potential as a biomarker for prognosis, surveillance, clinical decision making, and assessment of treatment response to BRAF-targeted therapies.

Association Between (18)F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

PURPOSE

The BRAF mutation, a potential prognostic factor in papillary thyroid carcinoma (PTC), is associated with a high expression of the glucose transporter gene. We investigated which clinicopathologic factors, including BRAF mutation status, influence (18)F-fluoro-2-deoxyglucose ((18)F-FDG) avidity.

METHODS

We retrospectively reviewed 55 patients who underwent BRAF analysis from biopsy-confirmed PTC and (18)F-FDG positron emission tomography/computed tomography within 6 months before undergoing thyroid surgery from September 2008 to August 2014. Tumors were considered to be (18)F-FDG avid if the uptake was greater than that of the liver. (18)F-FDG uptake of PTCs was also analyzed semiquantitatively using SUVmax. The association between (18)F-FDG avidity and clinicopathologic variables (age, tumor size, perithyroidal extension, cervical lymph node status, and BRAF mutation status) was investigated.

RESULTS

Twenty-nine (52.7 %) of 55 patients had (18)F-FDG-avid PTCs. PTCs with the BRAF mutation showed higher (18)F-FDG avidity (24/38, 63.2 %) than those without (5/17, 29.4 %). The BRAF mutation (p = 0.025) and tumor size (p = 0.003) were significantly associated with (18)F-FDG avidity in univariate analysis, and the BRAF mutation status remained significant after adjusting for tumor size in multivariate analysis (p = 0.015). In the subgroup of tumor size ≥ 1 cm, the BRAF mutation was the only factor significantly associated with (18)F-FDG avidity (p = 0.021). The mean SUVmax of PTCs with the BRAF mutation was significantly higher than that of those without (4.89 ± 6.12 vs. 1.96 ± 1.10, p = 0.039).

CONCLUSIONS

The BRAF mutation must be one of the most important factors influencing (18)F-FDG avidity in PTCs, especially in those with a tumor size ≥ 1 cm.

BRAFV600E mutation associated with non-radioiodine-avid status in distant metastatic papillary thyroid carcinoma

PURPOSE

It was reported that BRAF mutation correlates with radioactive iodine refractory papillary thyroid carcinoma (PTC) in local recurrence, whereas its relationship with I uptake status in distant metastatic PTC remains uncertain. This prospective study tried to explore the association between I uptake in distant metastases (DM) of PTC and BRAF mutation status in their primary tumor.

METHODS

Seventy-three patients with DM were divided into BRAF mutation group (n = 19) and wild-type BRAF group (n = 54) according to the BRAF mutation status. After posttherapy I whole-body scan was performed, the relation between I uptake in DM, BRAF mutation status, and clinicopathological characteristics of 2 groups were compared.

RESULTS

The mean age of mutation group was older than that of the wild-type group (P < 0.05). In the mutation group, 16 patients (84.2%, 16 of 19) were found to be with non-iodine-avid DM, whereas in wild-type group, only 5.6% (3 of 54) were with non-iodine-avid DM. The sensitivity and specificity of using BRAF mutation for the identification of non-iodine-avid DM were 84.2% and 94.4%, respectively.

CONCLUSIONS

BRAF mutation in primary tumor might be a promising molecular marker to predict the status of I uptake in distal metastases.

Prognostic role of 18F-FDG PET/CT in the postoperative evaluation of differentiated thyroid cancer patients

PURPOSE

The aim of this study was to evaluate the role of F-FDG PET/CT performed after surgery but before radioiodine therapy in patients with differentiated thyroid cancer.

PROCEDURES

FDG PET/CT was performed off l-thyroxine in 60 newly diagnosed differentiated thyroid cancer patients. Clinical and hematological evaluation as well as high-resolution neck ultrasound were performed. All patients underwent a complete follow-up (range, 6-67 months; mean [SD], 31.7 [20.6] months). The date of recurrence or the most recent office visit was recorded. Progression-free survival (PFS) is the primary end point of this study. Analysis was performed by Cox proportional hazards model. Survival curves were generated using Kaplan-Meier estimates, and the log-rank test was used to assess significance.

RESULTS

FDG PET/CT was negative in 63% of patients, 20% had FDG thyroid bed uptake, 5% distant metastases, and 12% lymph node FDG uptake. In patients with positive FDG PET/CT scan (ie, those with distant metastases or lymph node uptake), a higher rate of recurrence was observed (50% vs 6%, P < 0.05). Thyroglobulin, neck ultrasound, stage, and FDG PET/CT correlated with PFS at univariate analysis. At multivariate analysis, only thyroglobulin and FDG PET/CT continued to be predictors of PFS. Patients with a negative FDG PET/CT scan have a better PFS either in the whole group or in those with elevated thyroglobulin level (both >2 ng/mL and >10 ng/mL).

CONCLUSIONS

FDG PET/CT was abnormal in 17% of patients. Moreover, FDG PET/CT has an independent prognostic role, with a better PFS in patients with a negative scan.