Glucose transporter 1 expression, tumor proliferation, and iodine/glucose uptake in thyroid cancer with emphasis on poorly differentiated thyroid carcinoma

MAPK Inhibitors Enhance HDAC Inhibitor-Induced Redifferentiation in Papillary Thyroid Cancer Cells Harboring BRAF V600E: An In Vitro Study

Clinical efficacy of redifferentiation therapy with histone deacetylase inhibitor (HDACi) for lethal radioiodine-refractory papillary thyroid cancer (RR-PTC) is urgently needed to be improved. Given that the impairment of histone acetylation is a mechanism in BRAF^V600E-mitogen-activated protein kinase (MAPK)-induced aberrant silencing of thyroid iodine-metabolizing genes, dual inhibition of HDAC and MAPK may produce a more favorable effect. In this study, we treated BRAF^V600E-mutant (BCPAP and K1) and BRAF-wild-type (BHP 2-7) cells with HDACi (panobinostat) and MAPK inhibitor (dabrafenib or selumetinib), alone or in combination, and we tested the expression of iodine- and glucose-metabolizing genes, radioiodine uptake and efflux, and toxicity. We found that panobinostat alone increased iodine-metabolizing gene expression, promoted radioiodine uptake and toxicity, and suppressed GLUT1 expression in all the cells. However, MAPKi (dabrafenib or selumetinib) induced these effects only in BRAF^V600E-mutant cells. Combined treatment with panobinostat and MAPKi (dabrafenib or selumetinib) displayed a more robust BRAF^V600E-dependent redifferentiation effect than panobinostat alone via further improving the acetylation level of histone at the sodium-iodide symporter (NIS) promoter. In conclusion, MAPK inhibitors enhance HDACi-induced redifferentiation in PTC cells harboring BRAF^V600E, warranting animal and clinical trials.

EGFR mutation decreases FDG uptake in non‑small cell lung cancer via the NOX4/ROS/GLUT1 axis

[18F]fluoro‑2‑deoxyglucose (FDG) positron emission tomography (PET)‑computed tomography (CT) is a functional imaging modality based on glucose metabolism. The association between the maximum standardized uptake value (SUVmax) from 18F‑FDG PET‑CT scanning and epidermal growth factor receptor (EGFR) mutation status has, to the best of our knowledge, not previously been fully elucidated, and the potential mechanisms by which EGFR mutations alter FDG uptake are largely unknown. A total of 157 patients who were pathologically diagnosed with non‑small cell lung cancer (NSCLC) who underwent EGFR mutation testing and PET‑CT pretreatment between June 2015 and October 2017 were retrospectively analyzed. χ2 and univariate analyses were performed to identify the contributors to EGFR mutation. The receiver operating characteristic (ROC) curve was analyzed, and the area under the curve (AUC) was calculated. Glucose transporter 1 (GLUT1) and NADPH oxidase 4 (NOX4) expression, and reactive oxygen species (ROS) activity were detected in the A549 (wild‑type), PC‑9 (EGFR mutation‑positive, EGFR exon 19del) and NCI‑H1975 (EGFR mutation‑positive, combined with L858R and T790M substitution) cell lines. A total of 109 patients who met the criteria were enrolled, and 63 of those tested as EGFR mutation‑positive. The SUVmax values were significantly lower in patients with EGFR mutations (mean, 6.52±0.38) compared with in patients with wild‑type EGFR (mean, 9.37±0.31; P<0.001). Using univariate analysis, EGFR mutation status was significantly associated with sex, smoking status, tumor histology and SUVmax of the primary tumor. In the multivariate analysis, smoking status (never‑smoking), histopathology (adenocarcinoma) and SUVmax (≤9.91) were the statistically significant predictors of EGFR mutations. ROC curve analysis identified that the SUVmax cut‑off point was 9.92, for which the AUC was 0.75 (95% confidence interval, 0.68‑0.83). Reverse transcription‑polymerase chain reaction indicated that the GLUT1 mRNA decreased in the PC‑9 and NCI‑H1975 cell lines compared with the A549 cell line (0.82±0.07 and 0.72±0.04 vs. 0.98±0.04, respectively; P<0.05) and decreased ROS activity was observed in the PC‑9 cell line. Furthermore, the expression of NOX4 mRNA decreased by 20% in PC‑9 (P<0.01) and by 14% (P<0.05) in NCI‑H1975 cells. In addition, NOX4 protein expression decreased by 13% in PC‑9 and by 16% in NCI‑H1975 cells (both P<0.05) compared with the A549 cell line. The SUVmax could be considered to effectively predict EGFR mutation status of patients with NSCLC, and the EGFR mutation status may alter FDG uptake partially via the NOX4/ROS/GLUT1 axis.

Recent Development of Nuclear Molecular Imaging in Thyroid Cancer

Therapies targeting specific tumor pathways are easy to enter the clinic. To monitor molecular changes, cellular processes, and tumor microenvironment, molecular imaging is becoming the key technology for personalized medicine because of its high efficacy and low side effects. Thyroid cancer is the most common endocrine malignancy, and its theranostic radioiodine has been widely used to diagnose or treat differentiated thyroid cancer. This article summarizes recent development of molecular imaging in thyroid cancer, which may accelerate the development of personalized thyroid cancer therapy.

Predicting 131I-avidity of metastases from differentiated thyroid cancer using 18F-FDG PET/CT in postoperative patients with elevated thyroglobulin

The quantitative relationship between iodine and glucose metabolism in metastases from differentiated thyroid cancer (DTC) remains unknown. Aim of the prospective study was to establish the value of ¹⁸F-FDG PET/CT in predicting ¹³¹I-avidity of metastases from DTC before the first radioiodine therapy. A total of 121 postoperative DTC patients with elevated stimulated serum thyroglobulin (ssTg) who underwent ¹³¹I adjuvant therapy or therapy after ¹⁸F-FDG PET/CT scan were enrolled. The Receiver operating characteristic curve was established to create an optimal cut-off point and evaluate the value of SUVmax for predicting ¹³¹I-avidity. In our study, the median SUVmax in ¹³¹I-nonavid metastatic target lesions was also significantly higher than that in ¹³¹I-avid metastatic target lesions (5.37 vs. 3.30; P = 0.000). At a cut-off value of 4.0 in SUVmax, the area under curve was 0.62 with the sensitivity, specificity, positive predictive value and negative predictive value of 75.3%, 56.7%, 76.1%, and 54.8%, respectively. These results suggest that ¹⁸F-FDG PET/CT may be of great value in identifying metastases in postoperative DTC patients with elevated ssTg before ¹³¹I administration, leading to an improved management of disease. ¹⁸F-FDG positive metastatic DTC with SUVmax of greater than 4.0 possesses higher probability of non-avidity to radioiodine.

Iodine/FDG "Flip-Flop" Phenomenon Inside a Large Metastatic Thyroid Cancer Lesion Better Characterized on SPECT/CT and PET/CT Studies

Iodine/FDG "flip-flop" phenomenon inside large metastatic thyroid cancer lesions has been rarely described. We present a case of this phenomenon better characterized using SPECT/CT and PET/CT studies.

Initial [18F]FDG PET/CT in high-risk DTC patients

In a previous paper, we published the impact of initial [18F]FDG PET/CT (FDG-PET/CT) in high-risk patients with differentiated thyroid cancer (DTC) and described the changes in therapy management. The aim of the present study was to evaluate the prognostic impact of the initial FDG-PET/CT on a patient’s follow-up over three years and the rate of complete remission. Patients, methods: This study included 109 DTC patients who underwent radioiodine treatment (RIT), including posttherapeutic whole-body scintigraphy with FDG-PET/CT and a follow-up over three years. The follow-up included high-resolution sonography of the neck and determination of serum Tg as well as Tg antibodies every six months. The results of initial FDG-PET/CT and whole-body scintigraphy were compared with the status after three years of follow-up. Results: 24/109 patients (22%) presented FDG-positive lesions, 22/109 patients (20%) only iodine-positive lesions, and 63/109 patients (58%) neither FDG-positive nor iodine-positive lesions. After three years, 83/109 patients (76%) revealed full remission, 15/109 patients (14%) tumour persistence and 11/109 patients (10%) a progressive disease. The negative predictive value (NPV) was calculated for patients without FDG-positive lesions (NPV 85%) and patients without any lesions (NPV 91%) regarding full remission in the follow-up. Conclusion: FDG-PET/CT has a high NPV (85% to 91%) in DTC patients regarding recurrence-free follow-up after three years. The change in patient management in patients with iodine-negative lesions can lead to a higher rate of full remissions in the follow-up after additional surgery. Therefore, FDG-PET/ CT should be performed in all high-risk DTC patients in the context of the first RIT to improve patient management and risk stratification.

Metabolic Alterations of Thyroid Cancer as Potential Therapeutic Targets

Thyroid cancer (TC) is the most frequent endocrine tumor with a growing incidence worldwide. Besides the improvement of diagnosis, TC increasing incidence is probably due to environmental factors and lifestyle modifications. The actual diagnostic criteria for TC classification are based on fine needle biopsy (FNAB) and histological examination following thyroidectomy. Since in some cases it is not possible to make a proper diagnosis, classical approach needs to be supported by additional biomarkers. Recently, new emphasis has been given to the altered cellular metabolism of proliferating cancer cells which require high amount of glucose for energy production and macromolecules biosynthesis. Also TC displays alteration of energy metabolism orchestrated by oncogenes activation and tumor suppressors inactivation leading to abnormal proliferation. Furthermore, TC shows significant metabolic heterogeneity within the tumor microenvironment and metabolic coupling between cancer and stromal cells. In this review we focus on the current knowledge of metabolic alterations of TC and speculate that targeting TC metabolism may improve current therapeutic protocols for poorly differentiated TC. Future studies will further deepen the actual understandings of the metabolic phenotype of TC cells and will give the chance to provide novel prognostic biomarkers and therapeutic targets in tumors with a more aggressive behavior.

HER inhibitor promotes BRAF/MEK inhibitor-induced redifferentiation in papillary thyroid cancer harboring BRAFV600E

Redifferentiation therapy with BRAF/MEK inhibitors to facilitate treatment with radioiodine represents a good choice for radioiodine-refractory differentiated thyroid carcinoma, but recent initial clinical outcomes were modest. MAPK rebound caused by BRAF/MEK inhibitors-induced activation of HER2/HER3 is a resistance mechanism, and combination with HER inhibitor to prevent MAPK rebound may sensitize BRAF^V600E-mutant thyroid cancer cells to redifferentiation therapy. To evaluate if inhibiting both BRAF/MEK and HER can produce stronger redifferetiation effect, we tested the effects of BRAF/MEK inhibitor dabrafenib/selumetinib alone or in combination with HER inhibitor lapatinib on the expression and function of iodine- and glucose-handling genes in BRAF^V600E-positive BCPAP and K1 cells, using BHP 2-7 cells harboring RET/PTC1 rearrangement as control. Herein, we showed that lapatinib prevented MAPK rebound and sensitized BRAFV600E-positive papillary thyroid cancer cells to BRAF/MEK inhibitors. Dabrafenib/selumetinib alone increased iodine-uptake and toxicity and suppressed glucose-metablism in BRAF^V600E-positive papillary thyroid cancer cells. When lapatinib was added, more significant effects on iodine- and glucose-handling gene expression, cell membrane location of sodium/iodine symporter as well as radioiodine uptake and toxicity were observed. Thus, combined therapy using HER inhibitor and BRAF/MEK inhibitor presented more significant redifferentiation effect on papillary thyroid cancer cells harboring BRAF^V600E than BRAF/MEK inhibitor alone. In vivo and clinical studies assessing such combined targeted redifferentiation strategy were warranted.

The incidence of thyroid cancer in focal hypermetabolic thyroid lesions: an 18F-FDG PET/CT study in more than 6000 patients

BACKGROUND

The clinical significance of incidental thyroid abnormalities discovered in fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) (FDG PET/CT) studies remains controversial. The aim of this large retrospective study was to (a) determine the prevalence of focal F-FDG thyroid uptake on whole-body F-FDG PET/CT studies carried out for nonthyroid cancers and (b) to test whether intense focal F-FDG thyroid uptake is associated with malignancy.

MATERIALS AND METHODS

A total of 11 921 F-FDG PET/CT studies in 6216 patients carried out at our institution between January 2012 and December 2014 were analyzed. We retrospectively reviewed the medical records of these patients. Eight hundred and forty-five/6216 (13.6%) patients had a thyroid incidentaloma on the basis of the clinical F-FDG PET/CT report. One hundred and sixty/845 (18.9%) of these underwent ultrasound and 98 (61.3%) of these underwent a fine-needle aspiration (FNA). Twenty-six of these 98 (26.5%) patients underwent thyroidectomy. Thyroid lesion and background standardized uptake value (SUVs) for each patient were measured upon review of the F-FDG PET/CT study. We measured maximum standardized uptake value (SUVmax), thyroid to background TL/TBG, thyroid to bloodpool TL/BP and thyroid to liver TL/L ratios in benign and malignant lesions. Receiver operating curves were calculated to determine optimal cut-off values between malignant and benign lesions.

RESULTS

Twenty-one of the 98 patients who underwent FNA biopsy or thyroidectomy had malignant disease (21.4%). Malignant lesions had significantly higher thyroid lesion SUVmax, TL/TBG, TL/BP, and TL/L than benign nodules. The receiver operating curves derived cut-off ratio TL/TBG of more than 2.0 differentiated benign from malignant lesions best with a specificity and sensitivity of 0.76 and 0.88, respectively.

CONCLUSION

The incidence of malignancy in biopsied focal hypermetabolic thyroid lesions is 21.4%. Lesions on F-FDG PET/CT studies, with a ratio TL/TBG more than 2.0, warrant further work-up with ultrasound and FNA to exclude malignancy.

18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography for Other Thyroid Cancers: Medullary, Anaplastic, Lymphoma and So Forth

Positron emission tomography/computed tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose (FDG) is used in staging, restaging, and evaluation of therapy response in many cancers as well as differentiated thyroid carcinomas especially in non-iodine avid variants. Its potential in less frequent thyroid tumors like medullary, anaplastic thyroid cancers, thyroid lymphoma and metastatic tumors of the thyroid however, is not well established yet. The aim of this review is to provide an overview on the recent applications and indications of ¹⁸F-FDG PET/CT in these tumors and to focus on the controversies in the clinical setting.

Nuclear Molecular and Theranostic Imaging for Differentiated Thyroid Cancer

Traditional nuclear medicine is rapidly being transformed by the evolving concepts in molecular imaging and theranostics. The utility of new approaches in differentiated thyroid cancer (DTC) diagnostics and therapy has not been fully appreciated. The clinical information, relevant to disease management and patient care, obtained by scintigraphy is still being underestimated. There has been a trend towards moving away from the use of radioactive iodine (RAI) imaging in the management of the disease. This paradigm shift is supported by the 2015 American Thyroid Association Guidelines (1). A more systematic and comprehensive understanding of disease pathophysiology and imaging methodologies is needed for optimal utilization of different imaging modalities in the management of DTC. There have been significant developments in radiotracer and imaging technology, clinically proven to contribute to the understanding of tumor biology and the clinical assessment of patients with DTC. The research and development in the field continues to evolve, with expected emergence of many novel diagnostic and therapeutic techniques. The role for nuclear imaging applications will continue to evolve and be reconfigured in the changing paradigm. This article aims to review the clinical uses and controversies surrounding the use of scintigraphy, and the information it can provide in assisting in the management and treatment of DTC.

Correlation of BRAF mutation and SUVmax levels in thyroid cancer patients incidentally detected in 18F-fluorodeoxyglucose positron emission tomography

The prognostic importance of ¹⁸F-fluorodeoxyglucose avidity in primary thyroid tumor and molecular basis responsible for its mechanism has not yet been well characterized. In this study, we aimed to evaluate the correlation between the maximum standardized uptake levels and B-type Raf kinase mutation positivity in incidentally detected papillary thyroid cancer patients during ¹⁸F-fluorodeoxyglucose positron emission tomography examination. We retrospectively evaluated 6873 ¹⁸F-fluorodeoxyglucose-positron emission tomography scans of consecutive subjects from a database search for tumor staging in 2014 at our hospital Nuclear Medicine Center. In total, 135 patients had focal ¹⁸F-fluorodeoxyglucose uptake in the thyroid. Of these, 76 patients had fine-needle aspiration biopsy. ¹⁸F-fluorodeoxyglucose-maximum standardized uptake of the positron emission tomography-detected nodules was recorded. B-type Raf kinase (V600E) mutation and p53 protein expression were evaluated in papillary thyroid cancer patients. The incidence of thyroid incidentaloma in ¹⁸F-fluorodeoxyglucose-maximum standardized uptake scans was 2 % (135/6873). Of the 76 patients evaluated, 41 % (n = 31) were diagnosed papillary thyroid cancer. B-type Raf kinase mutation was positive in 51 % (17/30) of the papillary thyroid cancer patients. Maximum standardized uptake levels of the nodules (≥1 cm) were significantly higher in B-type Raf kinase-mutated papillary thyroid cancer patients than in non-mutated patients [16.6 (10.4-27.9) vs. 9.7 (6.8-11.1); P = 0.007]. Correlation analysis revealed that maximum standardized uptake was significantly associated with B-type Raf kinase mutation positivity (r = 0.519; P = 0.005). Logistic regression analysis showed an association between maximum standardized uptake and B-type Raf kinase mutation positivity even after adjustment for age and gender (P = 0.01). B-type Raf kinase mutation is closely related to ¹⁸F-fluorodeoxyglucose-positron emission tomography maximum standardized uptake levels in patients with incidentally detected papillary thyroid cancer.

Bilateral Renal Metastasis of Hürthle Cell Thyroid Cancer with Discordant Uptake Between I-131 Sodium Iodide and F-18 FDG

Renal metastasis of thyroid cancer is extremely rare. We report the case of a 62-year-old woman with Hürthle cell thyroid cancer (HCTC) with lungs, bones, and bilateral kidneys metastases. The renal metastatic lesions were clearly demonstrated by ¹³¹I whole body scan (WBS) with SPECT/CT. However, they exhibited false-negative results in ¹⁸F-FDG PET/CT, kidney ultrasonography, and contrast-enhanced CT scan. The findings imply that tumors have low glucose metabolism and are able to accumulate radioiodine, which is not commonly found in the relatively aggressive nature of HCTC. The patient received two sessions of 200 mCi ¹³¹I therapy within 6 months duration. There was complete treatment response as evaluated by the second post-therapeutic ¹³¹I SPECT/CT and serum thyroglobulin. To our knowledge, renal metastasis from HCTC with positive ¹³¹I but negative ¹⁸F-FDG uptake has not been reported in the literature. This case suggests that ¹³¹I SPECT/CT is useful for lesion localization and prediction of ¹³¹I therapy response.

Can the American Thyroid Association Risk of Recurrence Predict Radioiodine Refractory Disease in Differentiated Thyroid Cancer?

OBJECTIVE

The aim of this study was to compare the TNM staging system and the American Thyroid Association (ATA) recurrence risk classification in predicting radioiodine refractory disease (RRD) in differentiated thyroid cancer (DTC) and to analyze the correlation of stimulated thyroglobulin (Tg) levels and rate of Tg elevation with the standardized uptake value on ¹⁸F-fludeoxyglucose (FDG) PET/CT scan.

METHODS

RRD was indicated through the retrospective analysis of consecutive ¹⁸F-FDG PET/CT scans in DTC with stimulated Tg >10 ng/ml and negative ¹³¹I NaI whole-body scans (WBS). Tg elevation velocity was compared to the likelihood of a positive scan. The ATA recurrence risk and TNM staging system were compared to see which of them better predicted the subsequent development of RRD.

RESULTS

Fifty-eight of 636 subjects developed RRD: 52 papillary and 6 follicular thyroid cancer. The median time between diagnosis and a negative WBS was 24 months (range 12-240). RRD developed in 11 low-risk, 32 intermediate-risk and 15 high-risk patients. A better response to therapy was seen in the low-risk versus the intermediate- and high-risk groups. ¹⁸F-FDG PET/CT scans had a diagnostic accuracy of 94.8%, sensitivity of 97.7%, specificity of 85.7%, positive predictive value of 95.6% and negative predictive value of 92%. There was no correlation between the Tg level or rate of rise and a positive scan. Overall, PET-CT upstaged 18 (31%) cases, leading to a change in management in 20 (35%) cases.

CONCLUSION

The TNM and ATA staging systems show no significant difference in predicting the development of RRD. RRD is less likely in stage I, II and low-risk patients. There is no correlation between the level or rate of Tg rise and a positive ¹⁸F-FDG PET/CT scan.

F18-FDG-PET for recurrent differentiated thyroid cancer: a systematic meta-analysis

Background

Positron emission tomography (PET) with fluor-18-deoxy-glucose (FDG) is widely used for diagnosing recurrent or metastatic disease in patients with differentiated thyroid cancer (DTC).

Purpose

To assess the diagnostic accuracy of FDG-PET for DTC in patients after ablative therapy.

Material and Methods

A systematic search was conducted in Medline/PubMed, EMBASE, Cochrane Library, Web of Science, and Open Grey looking for all English-language original articles on the performance of FDG-PET in series of at least 20 patients with DTC having undergone ablative therapy including total thyroidectomy. Diagnostic performance measures were pooled using Reitsma’s bivariate model.

Results

Thirty-four publications between 1996 and 2014 met the inclusion criteria. Pooled sensitivity and specificity were 79.4% (95% confidence interval [CI], 73.9–84.1) and 79.4% (95% CI, 71.2–85.4), respectively, with an area under the curve of 0.858.

Conclusion

F18-FDG-PET is a useful method for detecting recurrent DTC in patients having undergone ablative therapy.

Both F-18 FDG-avidity and Malignant Shape of Cervical Lymph Nodes on PET/CT after Total Thyroidectomy Predict Resistance to High-dose I-131 Therapy in Patients with Papillary Thyroid Cancer

Objective:

Resistance of metastatic lymph nodes (LNs) to high dose I-131 therapy is associated with high morbidity in patients with differentiated thyroid cancer. We evaluated the role of F-18 FDG PET/CT in the prediction of resistance to high dose I-131 therapy in patients with papillary thyroid cancer.

Methods:

The subjects were 307 patients who underwent total or near total thyroidectomy followed by high dose (5.55-6.66 GBq) I-131 therapy. We divided the patients into three subgroups by visual assessment of regional LNs: FDG-avid LNs with a malignant shape on CT (PET/CT-positive group), FDG-avid LNs with a benign shape on CT (PET/CT-intermediate group) and no FDG-avid lesion (PET/CT-negative group). We measured the maximum SUV (SUVmax) of FDG-avid LNs in each patient. The presence or absence of focal increased uptake of I-131 was evaluated by whole body scan (WBS), and was denoted as WBS-positive group or WBS-negative group, respectively. Resistance to therapy was defined as presence of thyroglobulin (Tg) in serum (Tg ≥1.0 ng/ml) 3-6 months after I-131 therapy. Univariate and multivariate analyses were performed to determine the relationship between resistance to I-131 therapy and various clinico-pathologic variables.

Results:

PET/CT-positive, intermediate, and negative groups included 20 (6.5%), 44 (14.3%) and 243 (79.2%) patients, respectively. The mean SUVmax was significantly higher in the PET/CT-positive group than that of the PET/CT-intermediate group (4.6 vs. 2.7, P <0.001). Univariate analysis revealed that the PET/CT-positive group (P <0.001), T2-4 stage (P <0.001), N1b stage (P = 0.001), lower dose (5.55 GBq) of I-131 (P <0.001), and the WBS-positive group (P = 0.029) were associated with resistance to therapy. In multivariate analysis, the PET/CT-positive group, lower dose of I-131, N1b stage, and T2-4 stage remained significant with odds ratios of 10.07 (P <0.001), 3.82 (P <0.001), 3.58 (P = 0.001), and 2.53 (P = 0.009), respectively.

Conclusion:

FDG-avidity and malignant shape of cervical LNs on pre-therapy FDG PET/CT were a strong risk factors predicting resistance to high dose I-131 therapy. A lower dose of administered I-131 (5.55 GBq) and more extensive tumors (T2-4 and N1b) were also associated with resistance to high dose I-131 therapy.

ARNT2 Regulates Tumoral Growth in Oral Squamous Cell Carcinoma

Aryl hydrocarbon receptor nuclear translocator (ARNT) 2 is a transcriptional factor related to adaptive responses against cellular stress from a xenobiotic substance. Recent evidence indicates ARNT is involved in carcinogenesis and cancer progression; however, little is known about the relevance of ARNT2 in the behavior of oral squamous cell carcinoma (OSCC). In the current study, we evaluated the ARNT2 mRNA and protein expression levels in OSCC in vitro and in vivo and the clinical relationship between ARNT2 expression levels in primary OSCCs and their clinicopathologic status by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemistry. Using ARNT2 overexpression models, we performed functional analyses to investigate the critical roles of ARNT2 in OSCC. ARNT2 mRNA and protein were down-regulated significantly (P < 0.05 for both comparisons) in nine OSCC-derived cells and primary OSCC (n=100 patients) compared with normal counterparts. In addition to the data from exogenous experiments that ARNT2-overexpressed cells showed decreased cellular proliferation, ARNT2-positive OSCC cases were correlated significantly (P < 0.05) with tumoral size. Since von Hippel-Lindau tumor suppressor, E3 ubiquitin protein ligase, a negative regulator of hypoxia-inducible factor (HIF1)-α, is a downstream molecule of ARNT2, we speculated that HIF1-α and its downstream molecules would have key functions in cellular growth. Consistent with our hypothesis, overexpressed ARNT2 cells showed down-regulation of HIF1-α, which causes hypofunctioning of glucose transporter 1, leading to decreased cellular growth. Our results proposed for the first time that the ARNT2 level is an indicator of cellular proliferation in OSCCs. Therefore, ARNT2 may be a potential therapeutic target against progression of OSCCs.

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.

Post-PET ultrasound improves specificity of 18F-FDG-PET for recurrent differentiated thyroid cancer while maintaining sensitivity

Background

Positron emission tomography (PET) using fluor-18-deoxyglucose (18F-FDG) with or without computed tomography (CT) is generally accepted as the most sensitive imaging modality for diagnosing recurrent differentiated thyroid cancer (DTC) in patients with negative whole body scintigraphy with iodine-131 (I-131).

Purpose

To assess the potential incremental value of ultrasound (US) over 18F-FDG-PET-CT.

Material and Methods

Fifty-one consecutive patients with suspected recurrent DTC were prospectively evaluated using the following multimodal imaging protocol: (i) US before PET (pre-US) with or without fine needle biopsy (FNB) of suspicious lesions; (ii) single photon emission computed tomography (≥3 GBq I-131) with co-registered CT (SPECT-CT); (iii) 18F-FDG-PET with co-registered contrast-enhanced CT of the neck; (iv) US in correlation with the other imaging modalities (post-US). Postoperative histology, FNB, and long-term follow-up (median, 2.8 years) were taken as composite gold standard.

Results

Fifty-eight malignant lesions were identified in 34 patients. Forty lesions were located in the neck or upper mediastinum. On receiver operating characteristics (ROC) analysis, 18F-FDG-PET had a limited lesion-based specificity of 59% at a set sensitivity of 90%. Pre-US had poor sensitivity and specificity of 52% and 53%, respectively, increasing to 85% and 94% on post-US, with knowledge of the PET/CT findings (P < 0.05 vs. PET and pre-US). Multimodal imaging changed therapy in 15 out of 51 patients (30%).

Conclusion

In patients with suspected recurrent DTC, supplemental targeted US in addition to 18F-FDG-PET-CT increases specificity while maintainin sensitivity, as non-malignant FDG uptake in cervical lesions can be confirmed.

Risk Stratification of Thyroid Incidentalomas Found on PET/CT: The Value of Iodine Content on Noncontrast Computed Tomography

BACKGROUND

The Hounsfield unit (HU) ratio of thyroid nodules was assessed compared to the contralateral thyroid lobe on noncontrast computed tomography (CT) to stratify further the risk of malignancy in thyroid incidentalomas found on 18F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/CT (PET/CT).

METHODS

This retrospective analysis included 82 patients who had thyroid incidentalomas on PET/CT in 2011. On PET/CT, the maximal standardized uptake value ratios of the thyroid nodule compared to liver (T/BSUV) and the HU ratios of the thyroid nodule compared to contralateral thyroid lobe (T/BHU) were calculated. Diagnostic performances of the T/BSUV and T/BHU were compared.

RESULTS

The area under the curve of T/BHU was higher than that of T/BSUV (0.941 vs. 0.689, p < 0.0001). The sensitivity, specificity, and accuracy of T/BHU were significantly higher than those of T/BSUV (100% vs. 77.8%, p = 0.0313; 80.0% vs. 60.0%, p = 0.0433; 86.6% vs. 65.9%, p = 0.0041, respectively). The risk of malignancy was much higher (71.1%) in nodules with a T/BHU cutoff value ≤0.68, whereas it was 0% in nodules with a T/BHU of >0.68. In this study, there were 18 nodules with nondiagnostic (n = 7) or atypia of undetermined significance or follicular lesion of undetermined significance cytologies (n = 11) after fine-needle aspiration biopsy (FNAB). When the T/BHU cutoff value was applied, three (60%) of the five nodules with a T/BHU of ≤0.68 were found to be papillary carcinomas. The remaining 13 nodules with a T/BHU of >0.68 were all benign with a risk of malignancy of 0%.

CONCLUSIONS

T/BHU is a simple and effective parameter to stratify the risk of malignancy in thyroid incidentalomas found on PET/CT. This may be of clinical relevance in those nodules with nondiagnostic or undetermined significance cytologies upon FNAB in the scheme of current clinical practice.

Simultaneous occurrence of distant metastases to the small intestine and the thoracic esophagus from anaplastic thyroid carcinoma: a case report

Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy and characterized by spreading to regional lymph nodes and distant metastases, but we were unable to find a previous report of simultaneous metastases of transformed ATC to either the small intestine or thoracic esophagus in the English language literature. A 60-year-old man suffered from well-differentiated thyroid carcinoma and underwent total thyroidectomy. Eight years later, local recurrence of thyroid cancer showed intense fluorodeoxyglucose/positron emission tomography (FDG-PET) uptake at the paratracheal region, which was suspected as a remnant tumor of the thyroid that transformed from differentiated to ATC. At that time, the patient underwent resection of the small intestine to remove an abdominal mass and consequently developed stenosis of the thoracic esophagus caused by the esophageal tumor. Histological scrutiny of specimens from both tumors in the small intestine and thoracic esophagus demonstrated the same pattern as that of undifferentiated carcinoma. Regarding histological verification and a change in the FDP-PET uptake level, it is strongly possible that our case demonstrated coincident metastases of ATC to both the small intestine and esophagus. In conclusion and to the best of our knowledge, this report is the first to present evidence suggesting that ATC has the potential to metastasize to any organs, including the digestive tract.

Postoperative fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography: an important imaging modality in patients with aggressive histology of differentiated thyroid cancer

BACKGROUND

Aggressive histopathologic subtypes of differentiated thyroid cancer (DTC) are fluorodeoxyglucose (FDG)-avid tumors and are at high risk for persistent/recurrent disease. In these patients, fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is performed in cases of suspicion of recurrence based on thyroglobulin (Tg) levels or thyroglobulin antibodies (TgAb). The goals of this study were to evaluate the sensitivity of systematic postoperative FDG-PET/CT and to identify risk factors for abnormal FDG-PET/CT.

METHODS

Single-center retrospective study of 38 consecutive patients (16 males, 22 females; mean age, 57 years) with aggressive histology DTC, without known persistent disease at the time of postoperative radioactive iodine (RAI) ablation. The most frequent aggressive histologic subtypes were tall cell papillary carcinoma (45%) and poorly differentiated carcinoma (42%).

RESULTS

A total of 86 lesions were found in 20 (53%) patients, distributed in 33 organs. FDG-PET/CT and the postablation whole-body scan (RAI WBS) showed persistent disease in 15 and 12 patients, respectively. FDG-PET/CT was more sensitive than WBS for the detection of individual lesions (69% vs. 59%). Both imaging techniques were complementary with 41% of the lesions detected only by FDG-PET/CT and 31% only by RAI WBS. The only risk factor of abnormal FDG-PET/CT was a stimulated Tg level (Tg/TSH) measured at ablation >10 ng/mL with persistent disease showing FDG uptake in 72% of the patients with a Tg/TSH >10 ng/mL and in 10% of the patients with Tg/TSH ≤10 ng/mL.

CONCLUSION

Postoperative FDG-PET/CT should be performed routinely in patients with aggressive histology DTC.

Correlation of BRAFV600E Mutation and Glucose Metabolism in Thyroid Cancer Patients: An ¹⁸F-FDG PET Study

There is significant interest in a better understanding of the genetic underpinnings of the increased glucose metabolic rates of cancer cells. Thyroid cancer demonstrates a broad variability of (18)F-FDG uptake as well as several well-characterized oncogenic mutations. In this study, we evaluated the differences in glucose metabolism of the BRAF(V600E) mutation versus BRAF wild-type (BRAF-WT) in patients with metastatic differentiated thyroid cancer (DTC) and poorly differentiated thyroid cancer (PDTC).

METHODS

Forty-eight DTC and 34 PDTC patients who underwent (18)F-FDG PET/CT for tumor staging were identified from a database search. All patients were tested for the BRAF(V600E) mutation and assigned to 1 of 2 groups: BRAF(V600E) mutated and BRAF-WT. (18)F-FDG uptake of tumor tissue was quantified by maximum standardized uptake value (SUVmax) of the hottest malignant lesion in 6 prespecified body regions (thyroid bed, lymph nodes, lung, bone, soft tissue, and other). When there were multiple lesions in 1 of the prespecified body regions, only the 1 with the highest (18)F-FDG uptake was analyzed.

RESULTS

In the DTC cohort, 24 tumors harbored a BRAF(V600E) mutation, whereas 24 tumors were BRAF-WT. (18)F-FDG uptake of BRAF(V600E)-positive lesions (median SUVmax, 6.3; n = 53) was significantly higher than that of BRAF-WT lesions (n = 39; median SUVmax, 4.7; P = 0.019). In the PDTC group, only 5 tumors were BRAF(V600E)-positive, and their (18)F-FDG uptake was not significantly different from the BRAF-WT tumors. There was also no significant difference between the SUVmax of all DTCs and PDTCs, regardless of BRAF mutational status (P = 0.90).

CONCLUSION

These data suggest that BRAF(V600E)-mutated DTCs are significantly more (18)F-FDG-avid than BRAF-WT tumors. The effect of BRAF(V600E) on tumor glucose metabolism in PDTC needs further study in larger groups of patients.

(18)F-fluorodeoxyglucose positron emission tomography to assess response after radiation therapy in anaplastic thyroid cancer

AIM

To assess the interest of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET/CT) to evaluate the tumor response after radiotherapy (RT) in anaplastic thyroid cancer (ATC) patients.

METHODS AND MATERIALS

92 patients were treated for ATC at our institution from 1987 to 2012, out of which 64 (70%) received an aggressive multimodal treatment and 28 (30%) a palliative treatment. In the multimodal treatment group, curative-intended surgery, chemotherapy, and RT were delivered in 35 (55%), 59 (92%), and 56 (88%) patients. The maximum standardized uptake value (SUVmax) was determined in tumor (T), nodes (N) and metastases (M) in each available (18)F-FDG PET/CT.

RESULTS

The median follow-up was 3.2years. The 1-year actuarial overall survival (OS) was 18% (median: 5.2months) in the entire population and 27% (median: 7months) in the multimodal treatment group. In the multivariate analysis, RT, surgery, and pre-RT chemotherapy independently predicted for OS, with HRs respectively of 0.1, 0.3, and 0.5. Quantification of FDG uptake with SUVmax was assessable in 26 (40%), 19 (30%), and 25 (39%) of (18)F-FDG PET/CT performed initially (prior to any treatment), prior to RT, and after RT, respectively. Mean SUVmax significantly decreased in T (p<0.001), but not in N (p=0.1) and M (p=0.3) during the assessment period, which might be related to the local effect of RT. Comparing pre- and post-RT (18)F-FDG PET/CT, the T mean relative SUVmax decrease was lower (23±54%) in the 4 patients that had a local relapse (LR) as compared with others in the 12 others patients (62±33%; p=0.3). A relative SUVmax decrease inferior to 20% significantly predicted for LR (p=0.02).

CONCLUSION

The prognosis of ATC patients remains dismal despite an aggressive multimodal treatment. Although our results were not significant, (18)F-FDG PET/CT could potentially serve as a surrogate marker of treatment response in ATC.

Tumor-Associated Inflammatory Cells in Thyroid Carcinomas

The complex interactions between immune cells and tumor cells in cancer play a major role in tumor development and subsequent patient outcomes. Different types of tumor-associated inflammatory cells (TAICs), such as dendritic cells, macrophages, lymphocytes, and mast cells, have been recognized for many years in several tumors; however, the role of TAICs in cancer is still not completely understood. This review article focuses on the major types of TAICs, including their general role in cancer and, more specifically, their role and distribution in thyrocyte-derived carcinomas.

PTEN regulates plasma membrane expression of glucose transporter 1 and glucose uptake in thyroid cancer cells

Glucose represents an important source of energy for the cells. Proliferating cancer cells consume elevated quantity of glucose, which is converted into lactate regardless of the presence of oxygen. This phenomenon, known as the Warburg effect, has been proven to be useful for imaging metabolically active tumours in cancer patients by (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). Glucose is internalised in the cells by glucose transporters (GLUTs) belonging to the GLUT family. GLUT1 (SLC2A1) is the most prevalent isoform in more aggressive and less differentiated thyroid cancer histotypes. In a previous work, we found that loss of expression of PTEN was associated with increased expression of GLUT1 on the plasma membrane (PM) and probability of detecting thyroid incidentalomas by FDG-PET. Herein, we investigated the molecular pathways that govern the expression of GLUT1 on the PM and the glucose uptake in WRO (expressing WT PTEN) and FTC133 (PTEN null) follicular thyroid cancer cells cultured under glucose-depleted conditions. The membrane expression of GLUT1 was enhanced in glucose-deprived cells. Through genetic manipulations of PTEN expression, we could demonstrate that the lack of this oncosuppressor has a dominant effect on the membrane expression of GLUT1 and glucose uptake. We conclude that loss of function of PTEN increases the probability of cancer detection by FDG-PET or other glucose-based imaging diagnosis.

Immunocytochemical analysis of glucose transporter protein-1 (GLUT-1) in typical, brain invasive, atypical and anaplastic meningioma

Glucose transporter-1 (GLUT-1) is one of the major isoforms of the family of glucose transporter proteins that facilitates the import of glucose in human cells to fuel anaerobic metabolism. The present study was meant to determine the extent of the anaerobic/hypoxic state of the intratumoral microenvironment by staining for GLUT-1 in intracranial non-embolized typical (WHO grade I; n = 40), brain invasive and atypical (each WHO grade II; n = 38) and anaplastic meningiomas (WHO grade III, n = 6). In addition, GLUT-1 staining levels were compared with the various histological criteria used for diagnosing WHO grade II and III meningiomas, namely, brain invasion, increased mitotic activity and atypical cytoarchitectural change, defined by the presence of at least three out of hypercellularity, sheet-like growth, prominent nucleoli, small cell change and "spontaneous" necrosis. The level of tumor hypoxia was assessed by converting the extent and intensity of the stainings by multiplication in an immunoreactive score (IRS) and statistically evaluated. The results were as follows. (1) While GLUT-1 expression was found to be mainly weak in WHO grade I meningiomas (IRS = 1-4) and to be consistently strong in WHO grade III meningiomas (IRS = 6-12), in WHO grade II meningiomas GLUT-1 expression was variable (IRS = 1-9). (2) Histologically typical, but brain invasive meningiomas (WHO grade II) showed no or similarly low levels of GLUT-1 expression as observed in WHO grade I meningiomas (IRS = 0-4). (3) GLUT-1 expression was observed in the form of a patchy, multifocal staining reaction in 76% of stained WHO grade I-III meningiomas, while diffuse staining (in 11%) and combined multifocal and areas of diffuse staining (in 13%) were only detected in WHO grades II and III meningiomas, except for uniform staining in angiomatous WHO grade I meningioma. (4) "Spontaneous" necrosis and small cell change typically occurred away from the intratumoral capillary network embedded within the pattern of GLUT-1 staining. Taken together, GLUT-1 staining cannot be applied as a substitute for histologic grading in order to predict tumor behavior. However, assessment of tumor hypoxia in association with "spontaneous" necrosis and foci of small cell change may substantially contribute to the neuropathologic diagnosis of WHO grades II and III meningioma.

Role of isotope scan, including positron emission tomography/computed tomography, in nodular goitre

Nuclear medicine techniques were first used in clinical practice for diagnosing and treating thyroid diseases in the 1950s, and are still an integral part of thyroid nodules work-up. Thyroid imaging with iodine or iodine-analogue isotopes is the only examination able to prove the presence of autonomously functioning thyroid tissue, which excludes malignancy with a high probability. In addition, a thyroid scan with technetium-99m-methoxyisobutylisonitrile is able to avoid unnecessary surgical procedures for cytologically inconclusive thyroid nodules, as confirmed by meta-analysis and cost-effectiveness studies. Finally, positron emission tomography alone, and positron emission tomography combined with computed tomography scans with (18)F-fluoro-2-deoxy-d-glucose are also promising for diagnosing thyroid diseases, but further studies are needed before introducing them to clinical practice.

The difference in relationship between 18F-FDG uptake and clinicopathological factors on thyroid, esophageal, and lung cancers

OBJECTIVES

The aim of this study was to reveal the differences in clinicopathological factors affecting maximum standardized uptake value (SUVmax) between esophageal squamous cell carcinoma (ESCC), non-small-cell lung cancer (NSCLC), and papillary thyroid cancer (PTC).

METHODS

This study consisted of 119 patients with ESCC (n=43), PTC (n=40), or NSCLC (n=36). We investigated the correlations between SUVmax and clinicopathological factors by using Spearman's correlation coefficient and the Kruskal-Wallis test. Multiple regression analysis was used to investigate which clinicopathological factors significantly affected SUVmax in each cancer type.

RESULTS

The SUVmax correlated with glucose transporter-1 (GLUT-1) expression in NSCLC (r=0.536, P=0.007) and ESCC (r=0.597, P<0.001) but not in PTC. The SUVmax correlated with Ki-67 expression in NSCLC (r=0.381, P=0.022) and PTC (r=0.374, P=0.017) but not in ESCC. A high SUVmax was correlated with a higher pathological T stage (p-T stage) in NSCLC (r=0.536) and ESCC (r=0.597, both P<0.001) but not in PTC. An elevated SUVmax was significantly associated with pathological lymph node status (p-N) in NSCLC, but not in ESCC and PTC. In multiple regression analysis, p-T stage and GLUT-1 expression were statistically significant factors in ESCC, and p-T stage was a statistically significant factor in NSCLC. In PTC, Ki-67 showed a statistically significant association with SUVmax.

CONCLUSION

SUVmax in NSCLC depended on the tumor invasion area; SUVmax in ESCC depended on tumor depth and GLUT-1 expression; and SUVmax in PTC might be associated with cell proliferation. The biological factors affecting SUVmax differ according to tumor type.

Thyroid Carcinoma Detected by 18F-Fluorodeoxyglucose Positron Emission Tomography Among Individuals Without Prior Evidence of Thyroid Disease: Relevance and Clinicopathologic Features

OBJECTIVE

The expanding use of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) has contributed to an increasing number of thyroid incidentalomas. The present study aimed to estimate the prevalence of 18F-FDG-PET thyroid incidentalomas and evaluate the clinicopathologic features of thyroid malignancies detected by 18F-FDG-PET.

METHODS

We reviewed all 18F-FDG-PET exams performed at the Portuguese Institute of Oncology, Lisbon, between 2007 and 2012 (n = 9,374). The inclusion criteria were focal thyroid uptake and absence of known thyroid disease.

RESULTS

Focal thyroid uptake was observed in 60 out of 9,374 18F-FDG-PET exams (prevalence of 0.64%). Fine-needle aspiration cytology (FNAC) was performed in 23 patients and reported as malignant in 14 cases (56.5% primary thyroid carcinoma; 4.3% secondary malignancy), as benign in 7 cases (30.5%) and as follicular lesion of undetermined significance in 2 cases (8.7%). Fourteen patients had surgery. A final histologic diagnosis of papillary thyroid carcinoma was established in 12 cases (52.2%). Three were multifocal (25.0%); 8 had extrathyroidal extension (66.7%); 5 had angioinvasion (41.7%); 3 had lymph nodes metastases (25.0%) and 2 showed lung metastases (16.7%). Overall, 91.7% were classified as intermediate or high risk. All patients had radioiodine therapy. At the last observation (mean follow-up was 29.9 months), persistent or recurrent disease was identified in 4 patients (33.3%) and none died from thyroid malignancy.

CONCLUSIONS

Thyroid carcinomas disclosed by 18F-FDG-PET are associated with aggressive histological criteria likely to carry a worse prognosis.

Distant metastatic lesions in patients with differentiated thyroid carcinoma. Clinical implications of radioiodine and FDG uptake

AIM

Many investigators have reported an inverse relationship between iodine and glucose utilization of differentiated thyroid carcinoma (DTC) according to its degree of differentiation; however, not every DTC is compatible with this phenomenon. This study was conducted to evaluate the clinical implication of iodine and glucose uptake at distant metastatic lesions in DTC patients.

PATIENTS, METHODS

64 DTC patients (women 47; mean age 49.9 ± 16.4 years) with distant metastasis who underwent post (131)I treatment whole-body scan (RxWBS) and FDG PET/CT were included in the study. Radioiodine (RAI) and FDG uptake of metastatic lesions were evaluated. TSH stimulated serum thyroglobulin (s-Tg) were obtained.

RESULTS

53 of 64 patients (82.8%) were RAI(+) group, and 37 patients (57.8%) were FDG(+) group. Patients in the RAI(-) group showed a higher rate of FDG uptake than RAI(+) group (100.0% vs. 49.1%, p = 0.002). Patients in the FDG(-) group showed a higher rate of RAI uptake than FDG(+) group (100.0% vs. 70.3%, p = 0.002). Patients with s-Tg < 100 ng/ml were frequently observed in the FDG(-)/RAI(+) group and the FDG(+)/RAI(-) group (p = 0.023). And patients with s-Tg ≥ 500 ng/ml were more frequently observed in the FDG(+)/RAI(+) group, compared with the FDG(+)/RAI(-) group (p = 0.036). Reduced disease-specific survival (DSS) was observed in patients with RAI(-) (p = 0.003), FDG(+) (p = 0.006), SUVmax > 3.6 (p<0.001), and s-Tg > 75.8 ng/ml (p = 0.009). In multivariate analysis, only a SUVmax > 3.6 was significantly predictive of DSS (p = 0.006).

CONCLUSION

An inverse relationship between RAI and FDG uptake, flip-flop phenomenon, was observed in patients with metastatic lesions of DTC. Reduced disease-specific survival was observed in patients with FDG(+), RAI(-) in metastatic lesions, or high s-Tg value.

Incidental thyroid cancer detected by (18)F-FDG PET: does it have different clinicopathological features?

OBJECTIVES

The prevalence and risk of malignancy in thyroid incidentalomas has been investigated in previous studies; however, these studies have not looked at the characteristics of incidental thyroid cancer (ITC) detected by fluorine-18 fluorodeoxyglucose PET. Therefore, we aimed to assess the clinicopathologic features of ITC.

METHODS

From March 2008 to December 2011, a total of 2892 patients underwent total thyroidectomy for papillary thyroid cancer. Among them, patients belonging to the ITC group were defined as those in whom focal thyroid uptake was reported as an incidental finding on PET imaging and further evaluation revealed the presence of malignancy. In addition, two control groups with non-PET incidental thyroid cancer (NITC) were selected: NITC-A patients (n=48) who underwent a total thyroidectomy in March 2008 and NITC-B patients (n=48) who underwent a total thyroidectomy for papillary thyroid cancer and were matched for the confounding effects of age and sex.

RESULTS

There were no significant differences in clinicopathologic features, except for age and tumour node metastasis (TNM) staging, between ITC and NITC-A patients. More ITC than NITC-A patients were aged 45 years or older. Although T, N, or M staging was not different between ITC and NITC-A, there were more ITC patients with stage III/IV tumours. After matching for age and sex, none of the clinicopathologic features showed significant differences between ITC and NITC-B patients.

CONCLUSION

No significant differences were observed between ITC and NITC patients except for age and TNM staging. More ITC patients had advanced TNM stage most likely due to patient age.

Detectable thyroglobulin with negative imaging in differentiated thyroid cancer patients

In the absence of autoantibodies against thyroglobulin (Tg), Tg measurement nowadays is the cornerstone of clinical management of differentiated thyroid cancer patients. DTC patients presenting with a positive Tg measurement without an anatomical correlate on anatomic imaging provide a management challenge to the attending physician.

Based on the literature we will provide an overview of the most important steps to undertake in such patients and their potential clinical consequences.

Clinicopathologic characteristics of synchronous primary thyroid cancer detected by initial staging 18F-FDG PET-CT examination in patients with underlying malignancy

BACKGROUND

The objective of this study was to define clinicopathologic characteristics in concurrent primary thyroid cancer detected by initial (18)fluorine-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG PET-CT) scanning in patients with underlying malignancy.

PATIENTS AND METHODS

Among 155 patients with known underlying malignancy and with focal FDG uptake in the thyroid, 25 patients (22 females; mean age ± SD 54.4 ± 11.2 years; age range 27-70 years) who were confirmed as having papillary thyroid cancer (PTC; synchronous thyroid cancer) by cytological examination were included. Another 25 patients (24 females; mean age ± SD, 48.8 ± 12.7 years) with focal uptake in preoperative (18)F-FDG PET-CT due to PTC and no history of other malignancy (primary thyroid cancer) were also included. Immunohistochemical studies were performed for glucose transporter-1 (GLUT-1) and vascular endothelial growth factor (VEGF).

RESULTS

GLUT-1 expression was significantly lower in synchronous thyroid cancer (7 of 25 patients, 28%) compared with primary thyroid carcinoma (15 of 25 patients, 60%; p = 0.045). However, age and tumor size of synchronous thyroid cancer were not significantly different from the patients with primary thyroid carcinomas. There was no significant difference in VEGF expression, maximal standardized uptake values, extrathyroidal extension, lymph node metastasis, advanced stage, and multifocality between both thyroid cancer groups.

CONCLUSION

Clinicopathologic characteristics of synchronous thyroid cancer in patients with underlying malignancy were not different from those of patients with primary thyroid cancers except for GLUT-1 expression.

PET and PET/CT imaging in thyroid and adrenal diseases: an update

Positron emission tomography (PET) and PET/computed tomography (PET/CT) with different tracers are imaging methods increasingly used in patients with thyroid and adrenal diseases. The aim of this article is to provide an overview based on literature data about the usefulness of PET imaging in this setting. PET and PET/CT with different tracers have been used in patients with thyroid diseases including differentiated thyroid carcinoma, medullary thyroid carcinoma, and poorly differentiated and anaplastic thyroid carcinoma. The usefulness of 18F-FDG-PET and PET/CT in assessing indeterminate thyroid nodules at fine needle aspiration biopsy and the clinical relevance of thyroid incidental 18F-FDG uptake has also been evaluated. Currently, great interest is being shown in a variety of PET tracers that target specific characteristics of adrenal gland function, allowing a more accurate characterization of adrenal masses and staging of adrenal tumors. Since PET/CT using different tracers is an expensive diagnostic tool which necessitates ionizing radiation exposure, cost-effectiveness studies are needed in order to define the appropriate use of this diagnostic method in various endocrine disorders.

F18-FDG-PET/CT thyroid incidentalomas: a wide retrospective analysis in three Italian centres on the significance of focal uptake and SUV value

Thyroid incidental uptake is defined as a thyroid uptake incidentally and newly detected by imaging techniques performed for an unrelated purpose and especially for non-thyroid diseases. Aim of the study was to establish the prevalence and pathological nature of focal thyroid incidentalomas detected at F18-FDG-PET/CT in patients studied for oncological purposes and not for thyroid disease. Secondary end point was to establish a possible maximum standardised uptake value cut-off over which a malignant lesion should be suspected. We have retrospectively evaluated 49519 patients who underwent F18-FDG-PET/CT for oncologic purposes in three Nuclear Medicine Centres (N.1 = 11278, N.2 = 31076, N.3 = 7165). A focal incidental thyroid uptake was diagnosed in 729 (1.5 %) patients (287-39.4 % male and 442-60.6 % female; average age: 65.26). Of 729 thyroid incidentalomas 211 (28.9 %) underwent further investigation to determine the nature of the nodule; 124/211 (58.8 %) incidentalomas were benign, 72/211 (34.1 %) malignant, 4/211 (1.9 %) non-diagnostic at cytological examination in the absence of surgery and histological evaluation and 11/211 (5.2 %) were indeterminate at cytological examination. A centre-based receiver operating curve (ROC) analysis of the patients with a definitive diagnosis was performed to identify a SUVmax cut-off useful in differentiating benign from malignant incidentalomas. In the centre N.1 it was 4.8 (sensitivity = 95.7 %, specificity = 46.4 %, area under the curve = 0.758); 5.3 in the centre N.2 (sensitivity = 76.3 %, specificity = 72.5 %, area under the curve = 0.815); 7 in the centre N.3 (sensitivity = 57.1 %, specificity = 79.3 %, area under the curve = 0.627). F18-FDG-PET/CT thyroid incidentalomas are a relevant diagnostic reality which requires further investigations and clinical management especially considering that, despite mainly benign, approximately one third of focal thyroid uptakes are malignant.

Genotyping analysis and ¹⁸FDG uptake in breast cancer patients: a preliminary research

Background

Diagnostic imaging plays a relevant role in the care of patients with breast cancer (BC). Positron Emission Tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG) has been widely proven to be a clinical tool suitable for BC detection and staging in which the glucose analog supplies metabolic information about the tumor. A limited number of studies, sometimes controversial, describe possible associations between FDG uptake and single nucleotide polymorphisms (SNPs). For this reason this field has to be explored and clarified. We investigated the association of SNPs in GLUT1, HIF-1a, EPAS1, APEX1, VEGFA and MTHFR genes with the FDG uptake in BC.

Methods

In 26 caucasian individuals with primary BC, whole-body PET-CT scans were obtained and quantitative analysis was performed by calculating the maximum Standardized Uptake Value normalized to body-weight (SUVmax) and the mean SUV normalized to body-weight corrected for partial volume effect (SUVpvc). Human Gene Mutation Database and dbSNP Short Genetic Variations database were used to analyze gene regions containing the selected SNPs. Patient genotypes were obtained using Sanger DNA sequencing analysis performed by Capillary Electrophoresis.

Results

BC patients were genotyped for the following nine SNPs: GLUT1: rs841853 and rs710218; HIF-1a: rs11549465 and rs11549467; EPAS1: rs137853037 and rs137853036; APEX1: rs1130409; VEGFA: rs3025039 and MTHFR: rs1801133. In this work correlations between the nine potentially useful polymorphisms selected and previously suggested with tracer uptake (using both SUVmax and SUVpvc) were not found.

Conclusions

The possible functional influence of specific SNPs on FDG uptake needs further studies in human cancer. In summary, this is the first pilot study, to our knowledge, which investigates the association between a large panel of SNPs and FDG uptake specifically in BC patients. This work represents a multidisciplinary and translational medicine approach to study BC where, the possible correlation between SNPs and tracer uptake, may be considered to improve personalized cancer treatment and care.

The role of fluorine-18-fluorodeoxyglucose positron emission tomography in aggressive histological subtypes of thyroid cancer: an overview

Aggressive histological subtypes of thyroid cancer are rare and have a poor prognosis. The most important aggressive subtypes of thyroid cancer are Hürthle cell carcinoma (HCTC) and anaplastic and poorly differentiated carcinoma (ATC and PDTC). The American Thyroid Association recently published guidelines for the management of patients with ATC, but no specific guidelines have been done about HCTC. We performed an overview of the literature about the role of Fluorine-18-Fluorodeoxyglucose positron emission tomography or positron emission tomography/computed tomography (FDG-PET or PET/CT) in aggressive histological subtypes of thyroid cancer. Only few original studies about the role of FDG-PET or PET/CT in HCTC, PDTC, and ATC have been published in the literature. FDG-PET or PET/CT seems to be useful in staging or followup of invasive and metastatic HCTC. FDG-PET or PET/CT should be used in patients with ATC in initial staging and in the followup after surgery to evaluate metastatic disease. Some authors suggest the use of FDG-PET/CT in staging of PDTC, but more studies are needed to define the diagnostic use of FDG-PET/CT in this setting. Limited experience suggests the usefulness of FDG-PET or PET/CT in patients with more aggressive histological subtypes of DTC. However, DTC presenting as radioiodine refractory and FDG-PET positive should be considered aggressive tumours with poor prognosis.

Glucose transporters in cancer metabolism

PURPOSE OF REVIEW

Transformed cells exhibit a high rate of glucose consumption beyond that necessary for ATP synthesis. Glucose aids in the generation of biomass and regulates cellular signaling critical for oncogenic progression. A key rate-limiting step in glucose utilization is the transport of glucose across the plasma membrane. This review will highlight key glucose transporters (GLUTs) and current therapies targeting this class of proteins.

RECENT FINDINGS

GLUTs, enabling the facilitative entry of glucose into a cell, are increasingly found to be deregulated in cancer. Although cancer-specific expression patterns for GLUTs are being identified, comprehensive analyses substantiating a role for individual GLUTs are still required. Studies defining GLUTs as being rate-limiting in specific tumor contexts, the identification of GLUT1 inhibitors via synthetic lethality screens, novel engagement of the insulin-responsive GLUT4 in myeloma and identification of GLUT9 being a urate transporter, are key advances underscoring the need for continued investigation of this large and enigmatic class of proteins.

SUMMARY

Tumor cells exhibit elevated levels of glucose uptake, a phenomenon that has been capitalized upon for the prognostic and diagnostic imaging of a wide range of cancers using radio-labeled glucose analogs. We have, however, not yet been able to target glucose entry in a tumor cell-specific manner for therapy. GLUTs have been identified as rate-limiting in specific tumor contexts. The identification and targeting of tumor-specific GLUTs provide a promising approach to block glucose-regulated metabolism and signaling more comprehensively.

CD133-expressing thyroid cancer cells are undifferentiated, radioresistant and survive radioiodide therapy

Purpose

¹³¹I therapy is regularly used following surgery as a part of thyroid cancer management. Despite an overall relatively good prognosis, recurrent or metastatic thyroid cancer is not rare. CD133-expressing cells have been shown to mark thyroid cancer stem cells that possess the characteristics of stem cells and have the ability to initiate tumours. However, no studies have addressed the influence of CD133-expressing cells on radioiodide therapy of the thyroid cancer. The aim of this study was to investigate whether CD133⁺ cells contribute to the radioresistance of thyroid cancer and thus potentiate future recurrence and metastasis.

Methods

Thyroid cancer cell lines were analysed for CD133 expression, radiosensitivity and gene expression.

Results

The anaplastic thyroid cancer cell line ARO showed a higher percentage of CD133⁺ cells and higher radioresistance. After γ-irradiation of the cells, the CD133⁺ population was enriched due to the higher apoptotic rate of CD133⁻ cells. In vivo ¹³¹I treatment of ARO tumour resulted in an elevated expression of CD133, Oct4, Nanog, Lin28 and Glut1 genes. After isolation, CD133⁺ cells exhibited higher radioresistance and higher expression of Oct4, Nanog, Sox2, Lin28 and Glut1 in the cell line or primarily cultured papillary thyroid cancer cells, and lower expression of various thyroid-specific genes, namely NIS, Tg, TPO, TSHR, TTF1 and Pax8.

Conclusion

This study demonstrates the existence of CD133-expressing thyroid cancer cells which show a higher radioresistance and are in an undifferentiated status. These cells possess a greater potential to survive radiotherapy and may contribute to the recurrence of thyroid cancer. A future therapeutic approach for radioresistant thyroid cancer may focus on the selective eradication of CD133⁺ cells.