Prognostic Value of 18F-FDG PET/CT Metabolic Parameters in Metastatic Differentiated Thyroid Cancers

Lactate Dehydrogenase A is Associated with Elevated FDG Metabolism, Radioiodine Non-avidity, and Poor Prognosis in Differentiated Thyroid Cancer

RATIONALE AND OBJECTIVES

The role of lactate dehydrogenase A (LDHA) expression in differentiated thyroid cancer (DTC), especially in radioiodine-refractory DTC, remains unclear. The aim of this study was to analyse the relationships and the prognostic value of LDHA, glycolysis, and radioactive iodine (RAI) avidity in DTC.

METHODS

DTC patients who underwent 18F-FDG PET/CT and subsequent total thyroidectomy or metastasectomy were enroled. The expression levels of LDHA, glucose transporters (Glut) and Ki67 proteins in tumour tissue were measured using immunohistochemistry. The maximum standardised uptake value (SUVmax), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) of 18F-FDG PET/CT were measured. A radioiodine whole body scan was used to determine lesion radioiodine avidity.

RESULTS

69 patients with DTC were enroled in this study, including 37 women (53.6%) and 32 men (46.4%), with a median age of 52 years (11 to 77 years). Regarding the pathological category, papillary thyroid cancer was documented in 50 patients (72.5%), while follicular and poorly differentiated thyroid cancer were found in 12 patients (17.4%) and seven patients (10.1%), respectively. Distant metastases were observed in 27 (39.1%) patients; 34 (49.3%) were classified as stage I, 16 (23.2%) as stage II, and 3 (4.3%) and 16 (23.2%) patients in stages III and IV, respectively. LDHA expression levels were correlated with Glut3 expression levels (r = 0.395, P = 0.003) and SUVmax (r = 0.408, P = 0.002). The median LDHA expression and lesion SUVmax of the RAI avidity group were lower than those of the non-RAI avidity group (200 vs. 285, P = 0.036; 3.06 vs. 8.38, P = 0.038, respectively). Elevated SUVmax (P = 0.004), MTV (P = 0.014), TLG (P = 0.001) and LDHA expression (P = 0.048) led to shorter time to progression (TTP); Cox regression analysis revealed that TLG (HR: 4.773, P = 0.047) was an independent prognostic factor of TTP.

CONCLUSION

Elevated LDHA is correlated with increased glucose metabolism, decreased radioiodine avidity, and accelerated disease progression. Moreover, 18F-FDG PET/CT acting as "in vivo pathology" is an excellent predictor of DTC prognosis.

The role of 18 F-FDG-PET/CT in the management of differentiated thyroid cancer

INTRODUCTION

In previous literature, 18 F-FDG-PET/ CT imaging significantly impacted differentiated thyroid cancer (DTC) therapy. Low thyroglobulin (Tg) levels and negative Iodine-131 (131I) whole-body scan (WBS), along with negative 18 F-FDG-PET/ CT, suggested a lesser likelihood of active illness. Positive 18 F-FDG-PET/CT findings, however, were associated with a variety of signs of local recurrence and regional or distant metastases in patients with suspected WBS. We aim to evaluate the utility of 18 F-FDG-PET/CT in managing DTC patients with negative 131I post-therapy WBS and elevated Tg.

MATERIAL AND METHODS

We retrospectively reviewed 55 patients with DTC (76% papillary and 24% follicular). Patients underwent total thyroidectomy or several radioactive iodine (RAI) treatments or both. WBS was performed 5-7 days after RAI treatment. Inclusion criteria were elevated serum Tg, negative anti-Tg auto-antibodies (AbTg) during long-term follow-up, presence of 18F-FDG-PET/CT images, and negative or suspicious WBS.

RESULTS

54% of 18 F-FDG-PET/CTs detected at least one lesion, mainly, cervical lymph nodes (49.9%), mediastinal lymph nodes (40.4%), local recurrence (34%), and bone or tissue metastasis (36.2%). The three major sites of metastasis were lung, bone, and liver. 18 F-FDG-PET/CT identified recurrence or metastasis in 45% of patients with high serum Tg and negative WBS, modifying therapeutic management in half the patients for suitable treatment modality (surgery vs. tyrosine kinase inhibitor).

CONCLUSION

The findings redemonstrate that elevated Tg with negative or suspicious WBS necessitates 18 F-FDG-PET/CT for localization of recurrence. 18 F-FDG-PET/CT is useful in managing locally recurrent or metastatic DTC with high Tg levels. It influences treatment and accurately assesses disease severity.

I-PET score: Combining whole body iodine and 18 F-FDG PET/CT imaging to predict progression in structurally or biochemically incomplete thyroid cancer

OBJECTIVE

We propose a new scoring system (I-PET) combining whole body scan (WBS) and FDG findings to identify patients who have or are likely to become refractory to radioactive iodine.

DESIGN

Retrospective analysis of 142 patients age >18 with differentiated thyroid cancer who had a F-18 labelled fluoro-2-deoxyglucose (¹⁸ F-FDG) positron emission tomography (PET) and WBS within a 6-month period between 2010 and 2020. Pairs of ¹⁸ F-FDG PET and WBS were reviewed by three independent nuclear medicine physicians and an I-PET score was assigned: I-PET [0]: Iodine -ve/FDG -ve, I-PET [1]: Iodine +ve/FDG -ve, I-PET [2]: Iodine +ve/FDG +ve and I-PET [3]: Iodine -ve/FDG +ve. Patients with FDG +ve lesions (I-PET [2] and I-PET [3]) were further classified into groups A and B if SUVmax was ≤5 or >5, respectively. Follow-up data were obtained by chart review. Progression was defined as structural progression as per RECIST 1.1 or further surgical intervention; or biochemical progression as unstimulated thyroglobulin increasing >20% from baseline.

RESULTS

Of 142 patients included in the study 121 patients had follow-up data available for review. At baseline, 49 patients were classified as I-PET [0], 10 as I-PET [1], 16 as I-PET [2] and 46 as I-PET [3]. Progression was seen in 11/49 (22%) of I-PET [0], 4/10 (40%) of I-PET [1], 10/16 (63%) of I-PET [2] and 34/46 (74%) of I-PET [3] (p < 0.001). I-PET [2B] and I-PET [3B] had a progression rate of 88% (7/8) and 78% (25/32), respectively. I-PET [3B] were 9.6 times more likely to commence multikinase inhibitor therapy (p = 0.001) and had 8 times greater mortality (p = 0.003) than patients in other I-PET groups combined.

CONCLUSION

I-PET is a simple readily acquired imaging biomarker that potentially enhances the dynamic risk stratification and guide treatment in thyroid cancer.

Using 18F-FDG-PET/CT Metrics to Predict Survival in Ra-Dio-Iodine Refractory Thyroid Cancers

Radio-iodine refractory (RAI-R) differentiated thyroid cancer (DTC) is a rare disease with a poor prognosis and limited therapeutic resources. Therefore, identifying prognostic factors is essential in order to select patients who could benefit from an early start of treatment. The aim of this study is to identify positron emission tomography with 18F-fluorodeoxyglucose with integrated computed tomography (18F-FDG-PET/CT) parameters to predict overall survival (OS) in patients with RAI-R DTC. In this single-center retrospective study, we analyze the 18F-FDG-PET/CT parameters of 34 patients with RAI-R DTC between April 2007 and December 2019. The parameters collected are MTV, SUVmax and progression for each site of metastasis (neck, mediastinum, lungs, liver, bone) and total sites. ROC curves, Kaplan–Meier survival analysis curves, univariate and multivariate Cox analyses determine prognostic factors for 1-year and 5-year OS. The parameters for mediastinum, liver and total sites are significantly associated with worse 1-year and 5-year OS by both ROC curve analysis and Kaplan–Meier survival analysis. Univariate Cox analysis confirms significance of mediastinum SUVmax (HR 1.08; 95% CI [1.02–1.15]; p = 0.014) and total SUVmax (HR 1.06; 95% CI [1–1.12]; p = 0.042) for worse 1-year OS; of mediastinum SUVmax (HR 1.06; 95% CI [1.02–1.10]; p = 0.003), liver SUVmax (HR 1.04; 95% CI [1.01–1.08]; p = 0.02), liver MTV (HR 2.56; 95% CI [1.13–5.82]; p = 0.025), overall SUVmax (HR 1.05; 95% CI [1.02–1.08]; p = 0.001) and total MTV (HR 1.41; 95% CI [1.07–1.86]; p = 0.016) for worse 5-year OS. Multivariate Cox analysis confirms a significant association between liver MTV (HR 1.02; 95% CI [1–1.04]; p = 0.042) and decrease 1-year OS. In this study, we demonstrate that in RAI-R DTC, 18F-FDG-PET/CT parameters of the mediastinum, liver and overall tumor burden were prognostic factors of poor 1-year and 5-year OS. Identifying these criteria could allow early therapeutic intervention in order to improve patients’ survival.

Assessment of Treatment Response to Lenvatinib in Thyroid Cancer Monitored by F-18 FDG PET/CT Using PERCIST 1.0, Modified PERCIST and EORTC Criteria-Which One Is Most Suitable?

Background: We aimed to compare the established metabolic response criteria PERCIST and EORTC for their applicability and predictive value in terms of clinical response assessment early after the initiation of lenvatinib therapy in patients with metastatic radioiodine-refractory (RAI) thyroid cancer (TC). Methods: In 25 patients treated with lenvatinib, baseline and 4-month follow-up F-18 FDG PET/CT images were analyzed using PERCIST 1.0, modified PERCIST (using SUVpeak or SUVmax) and EORTC criteria. Two groups were defined: disease control (DC) and progressive disease (PD), which were correlated with PFS and OS. Results: PERCIST, mPERCIST, PERCISTmax and EORTC could be applied in 80%, 80%, 88% and 100% of the patients based on the requirements of lesion assessment criteria, respectively. With PERCIST, mPERCIST, PERCISTmax and EORTC, the patients classified as DC and PD ranged from 65 to 68% and from 32 to 35%, respectively. Patients with DC exhibited a longer median PFS than patients with PD for EORTC (p < 0.014) and for PERCIST and mPERCIST (p = 0.037), respectively. Conclusion: EORTC and the different PERCIST criteria performed equally regarding the identification of patients with PD requiring treatment changes. However, the applicability of PERCIST 1.0 using SULpeak seems restricted due to the significant proportion of small tumor lesions.

Prognostic Role of 2-[18F]FDG PET/CT Metabolic Volume Parameters in Patients Affected by Differentiated Thyroid Carcinoma with High Thyroglobulin Level, Negative 131I WBS and Positive 2-[18F]-FDG PET/CT

The clinical and prognostic role of 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) in the study of patients affected by differentiated thyroid carcinoma (DTC) with positive serum thyroglobulin (Tg) level and negative [¹³¹I] whole-body scan ([¹³¹I]WBS) has already been demonstrated. However, the potential prognostic role of semi-quantitative PET metabolic volume features, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), has not yet been clearly investigated. The aim of this retrospective study was to investigate whether the main metabolic PET/CT parameters may predict the prognosis. We retrospectively included 122 patients with a positive 2-[¹⁸F]FDG PET/CT for DTC disease after a negative [¹³¹I]WBS with Tg > 10 ng/mL. The maximum and mean standardized uptake value (SUVmax and SUVmean), MTV and TLG of the hypermetabolic lesion, total MTV (tMTV) and total TLG (tTLG) were measured for each scan. Progression-free survival (PFS) and overall survival (OS) curves were plotted according to the Kaplan-Meier analysis. After a median follow up of 53 months, relapse/progression of disease occurred in 87 patients and death in 42. The median PFS and OS were 19 months (range 1-132 months) and 46 months (range 1-145 months). tMTV and tTLG were the only independent prognostic factors for OS. No variables were significantly correlated with PFS. The best thresholds derived in our sample were 6.6 cm³ for MTV and 119.4 for TLG. In patients with negative WBS and Tg > 10 ng/mL, 2-[¹⁸F]FDG PET/CT metabolic volume parameters (tMTV and tTLG) may help to predict OS.

Development and validation of a prediction model based on the organ-based metabolic tumor volume on FDG-PET in patients with differentiated thyroid carcinoma

BACKGROUND

Although patients with differentiated thyroid cancer (DTC) generally have a good prognosis, patients with a large metabolic tumor volume (MTV) on FDG-PET may experience poor clinical courses. We measured organ-based MTVs and tested its prognostic performance in comparison to conventional MTV (cMTV).

METHODS

We retrospectively analyzed the cases of 280 patients who received their first I-131 therapy in 2003-2014 at our hospital and showed an FDG-avid metastatic lesion. We randomly divided the patients into training (n = 190) and validation (n = 90) datasets. We classified the MTVs as MTV_neck-node, MTV_distant-node, MTV_lung, MTV_bone, and MTV_other-organs and tested with/without dichotomization vis-à-vis overall survival (OS). Based on the estimated weighting coefficients of the organ-based MTVs, we propose a new index: the adjusted whole-body MTV (aMTV). Using the validation dataset, we compared the aMTV with cMTV for predicting OS.

RESULTS

In a univariate analysis, MTV_distant-node and MTV_other-organs were more strongly correlated with the OS than the dichotomized forms, whereas the dichotomized forms of MTV_neck-node, MTV_lung, and MTV_bone were more strongly correlated with OS than the continuous variables. The aMTV was thus expressed as 0.69 × dic(MTV_neck-node) + 0.02 × MTV_distant-node + 1.05 × dic(MTV_lung) + 1.58 × dic(MTV_bone) + 0.01 × MTV_other-organs, where dic(x) represents 0 or 1 based on the optimized cut-off. In the model evaluation using the validation group, aMTV was a significant predictor of OS with a higher c-index (0.7676) than cMTV (0.7218).

CONCLUSION

In DTC patients with FDG-avid metastasis before I-131 therapy, all organ-based MTVs were significant predictors of prognosis. As the aMTV outperformed the cMTV for predicting prognoses, we recommend measuring the MTV on an organ basis.

Impact of 18F-FDG PET/CT on Clinical Management of Suspected Radio-Iodine Refractory Differentiated Thyroid Cancer (RAI-R-DTC)

Background: As reported in the literature, [18F]-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]-FDG PET/CT) provides useful qualitative and semi-quantitative data for the prognosis of advanced differentiated thyroid cancer. Instead, there is a lack of data about the real clinical impact of 18F-FDG PET/CT on the choice of the more effective therapeutic approach for advanced differentiated thyroid cancer (DTC) that starts to lose iodine avidity. The primary aim of this retrospective study was to assess how 18F-FDG PET/CT can guide the choice of the best therapeutic approach to RAI-refractory DTC (RAI-R-DTC) in patients with a doubtful iodine uptake/negative 18F-FDG PET/CT I whole-body scan after several radioactive iodine therapies (RAIT). The secondary aim was to assess the prognostic role of clinical and semi-quantitative metabolic 18F-FDG PET/CT parameters in comparison to published data. Materials and methods: A monocentric retrospective observational study was performed, reviewing the medical records of 53 patients recruited from a database of 208 patients treated at our Institution between 2011 and 2019, with advanced DTC that underwent FDG PET/CT scan for a suspected RAI-R-DTC. Selected patients had to perform a 18F-FDG PET/CT scan after the second RAIT based on a doubtful iodine uptake/negative 131 I whole-body scan and/or persistent elevated thyroglobulin levels. Metabolic response was defined according to positron emission tomography response criteria in solid tumors (PERCIST) guidelines. Standardized uptake value (SUV)max, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated. The association between metabolic features, clinical parameters and progression free survival (PFS) was assessed applying Kruskal–Wallis, chi-square-Pearson correlation tests, and Cox regression analyses when appropriate. Results: Among our sample of 53 patients (mean age 52.0 ± 19.9 years; 31 women and 22 men), 27 (51.0%) presented a positive 18F-FDG PET/CT scan: 16 (59.0%) underwent watchful waiting, 4 (15.0%) received external-beam radiation therapy (EBRT), 4 (15.0%) underwent surgery, 2 (7.4%) received another course of RAI therapy, and 1 underwent surgery + EBRT. PERCIST response was evaluated in 14/27 patients. Median follow-up was 5.8 ± 3.9 years and median PFS was 38.0 ± 21.8 months. At the last follow-up assessment, 14/53 (26.4%) demonstrated disease progression, 13/53 (24.5) persistence of structural disease, 25/53 (47%) persistence of biochemical disease, and 15/53 (28%) had an excellent response. A significant association was found between therapeutic approach, metabolic response, and final disease response evaluation, as well as a linear correlation between MTV and TLG with thyroglobulin level. Conclusions: Our Institutional experience confirmed the role of 18F-FDG PET/CT as a useful guide in the clinical management of RAI-R-DTC and obviated further unnecessary RAIT.

Investigating 18F-FDG PET/CT Parameters as Prognostic Markers for Differentiated Thyroid Cancer: A Systematic Review

Aims: The aim of this study was to determine whether ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) parameters might be prognostic markers for patients with differentiated thyroid carcinoma (DTC).

Methods: We searched for eligible articles in PubMed, EMBASE (Ovid), Cochrane Library, and ClinicalTrials.gov from inception to February 2021. We included studies addressing the association between ¹⁸F-FDG PET/CT parameters and clinical outcomes among patients with DTC. Quality assessment was performed using the Quality in Prognosis Studies (QUIPS) tool.

Results: A total of 25 studies including 2,954 patients (1,994 females, 67.5%) were included; 2,416 patients (81.8%) had papillary thyroid carcinoma (PTC), and the mean or median follow-up time ranged from 19.1 months to 17.1 years. Thirteen (52.0%) studies were assessed as “unclear” for the domain of study participation. The most common timing of PET/CT scans was after thyroidectomy (in 20 of 25 studies, 80%), especially in patients with an elevated thyroglobulin (Tg) and a negative radioiodine whole-body scan (WBS). The most common PET parameter was FDG uptake. Twelve of 17 (70.6%) and 12 of 12 (100%) studies showed an association between PET/CT parameters and disease progression and survival in patients with DTC, respectively.

Conclusion:¹⁸F-FDG PET/CT parameters alone or combined with other variables can serve as prognostic markers to identify DTC patients with poor outcomes, especially in the setting of an elevated Tg and a negative WBS. Future research is needed to confirm these findings and to examine the prognostic value of PET/CT parameters for DTC patients, considering the heterogeneity in PET/CT parameters, unclear information of patients, and PET/CT-adapted treatment modifications.

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.

Identification of Radioactive Iodine Refractory Differentiated Thyroid Cancer

Most differentiated thyroid cancer (DTC) patients have an excellent prognosis. However, about one-third of DTC patients with recurrent or metastatic disease lose the hallmark of specific iodine uptake initially or gradually and acquire radioactive iodine-refractory DTC (RAIR-DTC) with poor prognosis. Due to the potentially severe complications from unnecessarily repeated RAI therapy and encouraging progress of multiple targeted drugs for advanced RAIR-DTC patients, it has become crucial to identify RAIR-DTC early. In this review, we focus on the progress and controversies regarding the defining of RAIR-DTC, further with subsistent approaches and promising molecular nuclear medicine imaging in identifying RAIR-DTC, which may shed light on the proper management methodsof such patients.

The Prognosis of Papillary Thyroid Cancer with Initial Distant Metastasis is Strongly Associated with Extensive Extrathyroidal Extension: A Retrospective Cohort Study

BACKGROUND

Extensive extrathyroidal extension (ETE) has a significant role in the prognosis of papillary thyroid cancer (PTC) without distant metastasis, but its role in PTC with initial distant metastasis has never been studied. This study aimed to evaluate the prognostic significance of extensive ETE regarding disease progression, survival, and remission in PTC patients with initial distant metastasis.

METHODS

This retrospective cohort study included PTC patients with initial distant metastasis who underwent total thyroidectomy with a median follow-up period of 6.7 years. The prognostic significance of extensive ETE was assessed in terms of time to tumor progression (TTP), cancer-specific survival (CSS), and cumulative incidence of remission with all-cause death as the competing event.

RESULTS

The study enrolled 64 patients. Of these patients, 21 (32.8%) had extensive ETE, which was associated with a shorter TTP (adjusted hazard ratio [HR], 4.10; p = 0.015) and a lower CSS rate (p = 0.002, log-rank), particularly for patients 55 years of age or older with stage 4b disease (10-year CSS rate: 33.3% in those with and 92.3% in those without extensive ETE; p = 0.017). Additionally, remission was observed only in patients without extensive ETE (10-year cumulative incidence of remission: 0.0% in those with and 29.3% in those without extensive ETE; p = 0.013).

CONCLUSIONS

Extensive ETE of the primary lesion results in poorer prognoses for PTC patients with initial distant metastasis. The high CSS rate for patients with stage 4b PTC but no extensive ETE indicates that the prognosis of this patient population should be distinguished from that of other stage 4 cases.

Prognostic Value of FDG-PET/CT Metabolic Parameters in Metastatic Radioiodine-Refractory Differentiated Thyroid Cancer

PURPOSE

There are no standardized prognostication algorithms for metastatic radioiodine-refractory (RAI-R) differentiated thyroid cancer (DTC). We hypothesize that [F]-FDG PET/CT may predict progression versus stability of disease based on quantitative analysis of metabolic tumor volume (MTV) and total lesion glycolysis (TLG).

METHODS

Retrospective study of 62 patients with metastatic RAI-R DTC to determine clinical outcomes with median follow-up from initial diagnosis of 11.1 years (8.38, 14.1) (range, 1.2-20 years). Baseline [F]-FDG PET/CT scans were evaluated qualitatively for regional and distant metastases and quantitatively for tumor burden based on MTV and TLG obtained using gradient segmentation method.

RESULTS

After diagnosis of metastatic RAI-R disease was established, the 5-year overall survival (OS) probability was 34%, and median OS was 3.56 years (2.87, infinity). The 5-year progression-free survival (PFS) probability was 19%, and median PFS was 1.31 years (1.03, 2.38). TSH-suppressed thyroglobulin (Tg) levels greater than 100 ng/mL and Tg doubling time (Tg-DT) less than 6 months were significantly associated with worse OS and PFS. Higher than median values of MTV and TLG were associated with worse OS (P = 0.06) and PFS (P = 0.007). Higher hazard of death was noted for higher values of log-MTV and log-TLG (HR, 1.17 [95% confidence interval, 0.99-1.39], P = 0.05, and HR, 1.14 [95% confidence interval, 1.00-1.31], P = 0.05, respectively).

CONCLUSIONS

[F]-FDG PET/CT metabolic parameters can help define the volume and biologic variations of metastatic tumor burden. Metabolic tumor volume and TLG can be used for dynamic risk stratification of patients with metastatic RAI-R DTC regarding PFS and complement Tg-DT for prognosis of clinical disease course.

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.

Lung adenocarcinoma and pulmonary metastases coexist in a patient with papillary thyroid carcinoma: A case report

RATIONALE

Multiple primary malignant tumors (MPMTs) are defined as 2 or more independent primary malignancies of different histologies/origins in the same individual. Although the incidence of MPMTs is being increasing, second primary cancer (SPC) is still rare and difficult to distinguish from metastasis. Here, we present a case of thyroid carcinoma with lung metastasis and primary lung cancer.

PATIENTS CONCERNS

The patient was a 66-year-old man diagnosed of papillary thyroid carcinoma (PTC) with lymph nodes, lung, and skeletons metastases. One of the pulmonary nodules had contrary manifestations, such as, noniodine avid, high uptake of F-fluorodexyglucose (F-FDG) and progress after iodine-131 radioiodine therapy.

INTERVENTIONS

CT guided biopsy and I-125 seed brachytherapy of nodule in right upper lobe were performed.

DIAGNOSIS

The patient was diagnosed of PTC with lymph nodes, lung, and skeletons metastases, accompanied by primary lung adenocarcinoma.

OUTCOMES

After 2 years of follow-up, nodules of inferior lobes almost disappeared and the nodule of right upper lobe shrank to only 0.7 cm.

LESSONS

Physicians should be aware of SPC in clinical work, and improve the early diagnosis rate with a variety of examination methods and select the best treatment to improve the prognosis of patients.

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.

Metformin reduces glycometabolism of papillary thyroid carcinoma in vitro and in vivo

More aggressive thyroid cancer cells show a higher activity of glycometabolism. Targeting cancer cell metabolism has emerged as a novel approach to prevent or treat malignant tumors. Glucose metabolism regulation effect of metformin in papillary thyroid cancer was investigated in the current study. Human papillary thyroid carcinoma (PTC) cell lines BCPAP and KTC1 were used. Cell viability was detected by CCK8 assay. Glucose uptake and relative gene expression were measured in metformin (0-10 mM for 48 h)-treated cells by ¹⁸F-FDG uptake assay and western blotting analysis, respectively. MicroPET/CT imaging was performed to detect ¹⁸F-FDG uptake in vivo After treatment with metformin at 0, 2.5, 5 and 10 mM for 48 h, the ratio of p-AMPK to total AMPK showed significant rising in a dose-dependent manner in both BCPAP and KTC1, whereas p-AKT and p-mTOR expression level were downregulated. ¹⁸F-FDG uptake reduced after metformin treatment in a dose-dependent manner, corresponding to the reduced expression level of HK2 and GLUT1 in vitro Xenograft model of PTC using BCPAP cells was achieved successfully. MicroPET/CT imaging showed that in vivo ¹⁸F-FDG uptake decreased after treatment with metformin. Immunohistochemistry staining further confirmed the reduction of HK2 and GLUT1 expression in the tumor tissue of metformin-treated PTC xenograft model. In conclusion, metformin could reduce glucose metabolism of PTC in vitro and in vivo Metformin, by targeting glycometabolism of cancer cells, could be a promising adjuvant therapy alternative in the treatment modality of advanced thyroid carcinoma.

Designing and Developing PET-Based Precision Model in Thyroid Carcinoma: The Potential Avenues for a Personalized Clinical Care

This communication enumerates the current uses and potential areas where PET could be clinically utilized for developing "precision medicine" type model in thyroid carcinoma. (1) In routine clinics, PET imaging (with fluorodeoxyglucose [FDG]) is utilized to investigate patients of differentiated thyroid carcinoma (DTC) with high thyroglobulin and negative iodine scintigraphy (TENIS) and in medullary carcinoma thyroid (MCT) when the tumor markers (eg, calcitonin and carcino embryonic antigen [CEA]) are raised postoperatively (PET with FDG, ⁶⁸Ga-DOTA-NOC/TATE, FDOPA). Both are examples of management personalization, where PET-computed tomography (CT) has been found substantially useful in detecting sites of metastatic disease and making decision with regard to feasibility and planning of surgery on an individual patient basis. (2) The next important area of management personalization is in patients of TENIS with metastatic disease not amenable to surgery through examining FDG-PET findings in tandem with radio iodine scan and ⁶⁸Ga-DOTA-TATE/NOC PET/CT. Heterogeneous behavior of the metastatic lesions is frequently observed clinically: analyzing the findings of three studies aids in sub-segmenting patients into subgroups and thereby deciding upon the best approach (observation with LT4 suppression vs PRRT vs tyrosine kinase inhibitors) that could be individualized in a given case. (3) In metastatic/inoperable MCT, ⁶⁸Ga-DOTA-TATE/NOC PET-CT helps in deciding upon feasibility of targeted PRRT in an individual patient and helps in follow-up and response evaluation. (4) Disease prognostification with FDG-PET is evolving both in DTC and MCT, where FDG avidity would indicate an aggressive biology, though the implication of this from treatment viewpoint is unclear at this point. Conversely, a negative FDG-PET in DTC and TENIS would suggest a favorable prognosis in an individual. (5) Iodine-124 PET/CT has the added potential of obtaining lesional dosimetry compared to the SPECT approach, and could help in selecting appropriate doses on an individual basis.

Prognostic value of (18)F-fluorodeoxyglucose positron emission tomography in patients with gastric neuroendocrine carcinoma and mixed adenoneuroendocrine carcinoma

OBJECTIVE

Gastric neuroendocrine carcinomas (NEC) and mixed adenoneuroendocrine carcinoma (MANEC) are very rare, aggressive tumors of the stomach. We aimed to examine predictive role of pretreatment (18)F-FDG PET/CT-assessed metabolic parameter of primary tumors and metastases in patients with gastric NEC and MANEC.

METHODS

We conducted a review of the 27 patients with histopathologically confirmed NECs (n = 10) and MANEC (n = 17) of the stomach at our institution between January 2005 and December 2012. All patients underwent (18)F-FDG-PET examination at diagnosis. Metabolic parameters [SUVmax, SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG)] of the primary tumor and metastases on baseline PET/CT were analyzed.

RESULTS

The median follow-up duration was 39.4 months (95 % CI 20.0-58.1 months) and the median overall survival (OS) was 25.7 months (95 % CI 14.1-37.2 months). All gastric lesions were well visualized (average SUVmax = 12.0, range 3.0-41.8). When subjects were divided into two groups by ROC cut-off value of 210.9 and 612, patients with high TLG in primary lesion and metastases showed poorer prognosis compared to low TLG patients (P = 0.09, P = 0.002, respectively). In the sub-analysis of patients with metastasis (n = 12), patients with high TLG in whole body tumor showed significantly shorter OS compared to those with low TLG (31.7 ± 11.4 vs. 7.2 ± 2.1 months, P = 0.006).

CONCLUSION

(18)F-FDG PET/CT is useful in evaluating prognosis of advanced gastric cancer with neuroendocrine carcinoma components. Baseline MTV of primary gastric cancer with metastatic disease, and MTV, TLG of metastases may be prognostic markers in patients with gastric NEC and MANEC.