Selected Controversies of Radioiodine Imaging and Therapy in Differentiated Thyroid Cancer

Therapeutic efficacies of remnant ablation and radioiodine adjuvant therapy in differentiated thyroid cancer

BACKGROUND

Successful ablation in 131I therapy for differentiated thyroid cancer (DTC) includes both remnant ablation (RA) and radioiodine adjuvant therapy (RAT). This study aimed to differentiate between the therapeutic efficacies of RA and RAT, investigate the factors associated with their effectiveness, and assess their impact on prognosis.

METHODS

This retrospective study included patients with DTC who underwent initial 131I therapy at our tertiary center. The successful RA (SRA) and successful RAT (SRAT) was determined based on the 131I-diagnostic whole-body scan (Dx-WBS), TSH-stimulated thyroglobulin (sTg) levels, and neck ultrasound at the 6th month after 131I therapy. The patients were divided into complete response and persistent/recurrent disease groups during the follow-up period.

RESULTS

A total of 232 patients were included, 91.8% (213/232) of patients achieved SRA, only 8.1% (19/232) failed RA (FRA). Among the 213 patients in the SRA group, 70.4% (150/213) achieved SRAT and 29.6% (63/213) failed RAT (FRAT). Only pre-ablation sTg >10 ng/mL (OR = 46.968, 95% CI 9.731-226.699, P < 0.001) was an independent risk factor predicting the failure of RAT. The prognostic analysis included 215 patients, and 6.1% (13/215) were classified as persistent/recurrent disease at the last follow-up. Both pre-ablation sTg >10 ng/mL (HR = 4.765, 95% CI 1.371-16.566, P = 0.014) and FRAT (HR = 10.104, 95% CI 1.071-95.304, P = 0.043) independently predicted persistent/recurrent disease.

CONCLUSIONS

RA is easy to achieve successfully, whereas RAT evaluation provides greater value than RA for prognosis prediction. For patients with low Tg levels and no imaging evidence of disease, routine Dx-WBS during follow-up has minimal significance.

Vitamin C in the Management of Thyroid Cancer: A Highway to New Treatment?

Thyroid cancer (TC) is the most common endocrine malignancy, with an increased global incidence in recent decades, despite a substantially unchanged survival. While TC has an excellent overall prognosis, some types of TC are associated with worse patient outcomes, depending on the genetic setting. Furthermore, oxidative stress is related to more aggressive features of TC. Vitamin C, an essential nutrient provided with food or as a dietary supplement, is a well-known antioxidant and a scavenger of reactive oxygen species; however, at high doses, it can induce pro-oxidant effects, acting through multiple biological mechanisms that play a crucial role in killing cancer cells. Although experimental data and, less consistently, clinical studies, suggest the possibility of antineoplastic effects of vitamin C at pharmacological doses, the antitumor efficacy of this nutrient in TC remains at least partly unexplored. Therefore, this review discusses the current state of knowledge on the role of vitamin C, alone or in combination with other conventional therapies, in the management of TC, the mechanisms underlying this association, and the perspectives that may emerge in TC treatment strategies, and, also, in light of the development of novel functional foods useful to this extent, by implementing novel sensory analysis strategies.

Predictors of response to Radioactive Iodine Therapy in Intermediate and high risk patients with papillary thyroid carcinoma

BACKGROUND

Radioactive iodine (RAI) therapy is the standard treatment approach after total thyroidectomy in patients with papillary thyroid carcinoma (PTC). We aimed to identify predictive factors of response to the treatment in intermediate and high-risk patients with PTC. In addition, the impact of multiple RAI treatments was explored.

METHODS

In a 3-year retrospective study, data from intermediate and high-risk patients with PTC who received RAI therapy following total thyroidectomy, were analyzed by the end of year-one and year-three. Demographic data, tumor size, capsular/vascular invasion, extrathyroidal extension, local or distant metastasis, initial dose and cumulative dose of RAI, serum thyroglobulin(Tg), antithyroglobulin antibody(TgAb), and imaging findings were investigated. Patients with an excellent response to a single dose of RAI treatment, after three years of follow-up were classified as the "Responder group". Excellent response was defined as stimulated serum Tg less than 1 ng/ml, or unstimulated serum Tg less than 0.2 ng/ml in TgAb-negative patients with negative imaging scans.

RESULTS

333 patient records with a complete data set were analyzed in this study. After three years of initial treatment, 271 patients were non-responders (NR) and 62 were responders (R). At baseline, the median pre-ablation serum Tg level was 5.7 ng/ml in the NR group, and 1.25 ng/ml in the R group (P < 0.001). TSH-Stimulated serum Tg greater than 15.7 ng/ml, was associated with response failure even after multiple RAI therapy, AUC: 0.717(0.660-0.774), sensitivity: 52.5%, specificity: 89.47%, P < 0.001. On the other hand, multiple RAI therapy was associated with excellent response in 16.2% of the patients. The chance of ER was decreased by 74% if initial post-operation ultrasound imaging confirmed the presence of locoregional involvement, OR 0.26, (95% CI: 0.12-0.55), P < 0.001.

CONCLUSION

Stimulated serum Tg and locoregional involvement after total thyroidectomy are predictive factors of non-response to RAI therapy in intermediate and high-risk patients with PTC. In addition, a minority of patients achieve excellent response after multiple RAI therapy.

Current Advances in Radioactive Iodine-Refractory Differentiated Thyroid Cancer

BACKGROUND

Differentiated thyroid cancer (DTC) patients have an outstanding overall long-term survival rate, and certain subsets of DTC patients have a very high likelihood of disease recurrence. Radioactive iodine (RAI) therapy is a cornerstone in DTC management, but cancer cells can eventually develop resistance to RAI. Radioactive iodine-refractory DTC (RAIR-DTC) is a condition defined by ATA 2015 guidelines when DTC cannot concentrate RAI ab initio or loses RAI uptake ability after the initial therapy. The RAIR condition implies that RAI cannot reveal new met-astatic foci, so RAIR-DTC metabolic imaging needs new tracers. 18F-FDG PET/CT has been widely used and has demonstrated prognostic value, but 18F-FDG DTC avidity may remain low. Fibroblast activation protein inhibitors (FA-Pi)s, prostatic-specific membrane antigen (PSMA), and somatostatin receptor (SSTR) tracers have been proposed as theragnostic agents in experimental settings and Arg-Gly-Asp (RGD) peptides in the diagnostic trial field. Multi-targeted tyrosine kinase inhibitors are relatively new drugs approved in RAIR-DTC therapy. Despite the promising targeted setting, they relate to frequent adverse-event onset. Sorafenib and trametinib have been included in re-differentiation protocols aimed at re-inducing RAI accumulation in DTC cells. Results appear promising, but not excellent.

CONCLUSIONS

RAIR-DTC remains a challenging nosological entity. There are still controversies on RAIR-DTC definition and post-RAI therapy evaluation, with post-therapy whole-body scan (PT-WBS) the only validated criterion of response. The recent introduction of multiple diagnostic and therapeutic agents obliges physicians to pursue a multidisciplinary approach aiming to correct drug introduction and timing choice.

Current practice in intermediate risk differentiated thyroid cancer - a review

Although the overall prognosis for differentiated thyroid cancer (DTC) is excellent, a subset of patients will experience disease recurrence or may not respond to standard treatments. In recent years, DTC management has become more personalized in order to enhance treatment efficacy and avoid unnecessary interventions.In this context, major guidelines recommend post-surgery staging to assess the risk of disease persistence, recurrence, and mortality. Consequently, risk stratification becomes pivotal in determining the necessity of postoperative adjuvant therapy, which may include radioiodine therapy (RIT), the degree of TSH suppression, additional imaging studies, and the frequency of follow-up.However, the intermediate risk of recurrence is a highly heterogeneous category that encompasses various risk criteria, often combined, resulting in varying degrees of aggressiveness and a recurrence risk ranging from 5 to 20%. Furthermore, there is not enough long-term prognosis data for these patients. Unlike low- and high-risk DTC, the available literature is contradictory, and there is no consensus regarding adjuvant therapy.We aim to provide an overview of intermediate-risk differentiated thyroid cancer, focusing on criteria to consider when deciding on adjuvant therapy in the current context of personalized approach, including molecular analysis to enhance the accuracy of patient management.

[Therapy concepts for thyroid carcinoma]

Theranostics via the sodium iodide symporter (NIS) offer a unique option in differentiated thyroid carcinoma. The diagnostic and therapeutic nuclides have similar uptake and kinetics, making the NIS the most important theranostic target in this disease. Radioiodine refractory thyroid carcinomas (RRTC) are characterised by reduced/absent NIS expression, thus eliminating this structure as a theranostic target. Also due to limited therapeutic options, there are approaches to generate new theranostic targets in RRTC, via the expression of somatostatin receptors (SSTR) or the prostate-specific membrane antigen (PSMA), but the current evidence does not yet allow a final evaluation of the prospects of success.

Novel recombinant human thyroid-stimulating hormone in aiding postoperative assessment of patients with differentiated thyroid cancer-phase I/II study

PURPOSE

Thyroid hormone withdrawal (THW) inevitably induced hypothyroidism in patients with differentiated thyroid cancer (DTC), and we aimed to evaluate the safety and efficacy of a novel recombinant human thyroid-stimulating hormone (rhTSH, ZGrhTSH) as an alternative of THW in China.

METHODS

Totally, 64 DTC patients were enrolled with 24 in the dose-escalation cohort equally grouped into 0.9 mg × 1 day, 0.9 mg × 2 day, 1.8 mg × 1 day, and 1.8 mg × 2 day dosage, and 40 further enrolled into 0.9 mg × 2 day dose-expansion cohort. All patients underwent both ZGrhTSH phase and levothyroxine (L-T₄) withdrawal phase for self-comparison in terms of TSH levels, the radioactive iodine (RAI) uptake, stimulated thyroglobulin level, and the quality of life (QoL).

RESULTS

In ZGrhTSH phase, no major serious adverse events were observed, and mild symptoms of headache were observed in 6.3%, lethargy in 4.7%, and asthenia in 3.1% of the patients, and mostly resolved spontaneously within 2 days. Concordant RAI uptake was noticed in 89.1% (57/64) of the patients between ZGrhTSH and L-T₄ withdrawal phases. The concordant thyroglobulin level with a cut-off of 1 μg/L was noticed in 84.7% (50/59) of the patients without the interference of anti-thyroglobulin antibody. The QoL was far better during ZGrhTSH phase than L-T₄ withdrawal phase, with lower Billewicz (- 51.30 ± 4.70 vs. - 39.10 ± 16.61, P < 0.001) and POMS (91.70 ± 16.70 vs. 100.40 ± 22.11, P = 0.011) scores which indicate the lower the better. Serum TSH level rose from basal 0.11 ± 0.12 mU/L to a peak of 122.11 ± 42.44 mU/L 24 h after the last dose of ZGrhTSH. In L-T₄ withdrawal phase, a median of 23 days after L-T₄ withdrawal was needed, with the mean TSH level of 82.20 ± 31.37 mU/L. The half-life for ZGrhTSH clearance was about 20 h.

CONCLUSION

The ZGrhTSH held the promise to be a safe and effective modality in facilitating RAI uptake and serum thyroglobulin stimulation, with better QoL of patients with DTC compared with L-T₄ withdrawal.

[Therapy concepts for thyroid carcinoma]

Theranostics via the sodium iodide symporter (NIS) offer a unique option in differentiated thyroid carcinoma. The diagnostic and therapeutic nuclides have similar uptake and kinetics, making the NIS the most important theranostic target in this disease. Radioiodine refractory thyroid carcinomas (RRTC) are characterised by reduced/absent NIS expression, thus eliminating this structure as a theranostic target. Also due to limited therapeutic options, there are approaches to generate new theranostic targets in RRTC, via the expression of somatostatin receptors (SSTR) or the prostate-specific membrane antigen (PSMA), but the current evidence does not yet allow a final evaluation of the prospects of success.

Relationship of PPARG overexpression with prognostic parameters in papillary thyroid carcinoma

Objectives

PAX8/PPARG chromosomal rearrangement is frequently seen in thyroid cancer, and PPARG overexpression has been shown in the follicular variant of papillary thyroid carcinoma, but not in papillary thyroid carcinoma other than the follicular variant. The main aim of this study was to investigate the frequency of PPARG overexpression among papillary thyroid carcinoma and if there were any variants of papillary thyroid carcinoma with PPARG overexpression other than the follicular variant.

Methods

Immunohistochemical analysis of PPARG overexpression was performed using a PPARG monoclonal antibody in a series of 111 paraffin-embedded blocks of thyroid tumours. Of the patients in our study, 100 were diagnosed with papillary thyroid carcinoma, 9 with follicular adenoma and 2 with follicular carcinoma.

Results

PPARG staining was detected in 19 of the 111 cases. Sixteen patients with PPARG overexpression had papillary thyroid carcinoma and 3 had follicular adenoma.

Conclusion

PPARG overexpression was detected mainly in follicular-variant papillary thyroid carcinoma. Vascular invasion, lymphatic invasion, thyroid capsule invasion and lymph node positivity were lower in patients with PPARG overexpression.

2022 ETA Consensus Statement: What are the indications for post-surgical radioiodine therapy in differentiated thyroid cancer?

Modern use of post-operative radioactive iodine (RAI) treatment for differentiated thyroid cancer (DTC) should be implemented in line with patients' risk stratification. Although beneficial effects of radioiodine are undisputed in high-risk patients, controversy remains in intermediate-risk and some low-risk patients. Since the last consensus on post-surgical use of RAI in DTC patients, new retrospective data and results of prospective randomized trials have been published, which have allowed the development of a new European Thyroid Association (ETA) statement for the indications of post-surgical RAI therapy in DTC. Questions about which patients are candidates for RAI therapy, which activities of RAI can be used, and which modalities of pre-treatment patient preparation should be used are addressed in the present guidelines.

Theranostics in Thyroid Cancer

The main targeting structure for theranostics in thyroid cancer is the sodium-iodine symporter (NIS), which has been used in clinical routine for the diagnosis and treatment of thyroid diseases for more than 70 years. Because the different iodine (I) nuclides (¹²³I, ¹²⁴I, ¹³¹I) have the same kinetics, uniquely congruent theranostics are possible in differentiated thyroid cancer. Besides the NIS, there are further possibilities by using expression of somatostatin receptors or the expression of the prostate-specific membrane antigen, for example, in radioiodine-refractory differentiated thyroid cancer, medullary thyroid cancer, or anaplastic thyroid cancer.

[Follow-up of differentiated thyroid cancer]

The management of differentiated thyroid carcinoma has shown considerable changes in recent years, moving away from a fixed therapy regimen towards individual treatment strategies. The aim of our work (literature research) is to present current developments in the follow-up of differentiated thyroid cancer.For the management of individual follow-up, an initial evaluation and, at later time points, the re-evaluation of the risk of recurrence is crucial. The performance of I-131-diagnostics after radioiodine therapy can provide essential information and can be seen as a survey of a new baseline situation, in order to be able to draw a comparison in case of a rising Thyreoglobulin (Tg).The measurement of Tg with a highly sensitive assays shows a high negative predictive value. Negative Tg measurements with these assays seem to indicate complete remission even with Tg antibodies being present. An increasing Tg value in follow-up implies further diagnostic work-up, primarily neck ultrasonography. Sonographically suspicious findings should be subjected to fine needle biopsy, whereby in addition to cytological processing, determination of Tg from the sample can be recommended. If the suspicious lesion cannot be displayed sonographically and Tg values keep rising, computed tomography (CT) and magnetic resonance imaging (MRI) of the neck region can provide further information. FDG-PET/CT has also shown an excellent performance in this setting.The previously fixed therapy regimen has been realigned towards an individual treatment management. Current studies and guidelines lead to a repetitive recurrence risk evaluation and the adjustment of the aftercare planning to the individual risks with appropriately selected examination methods and personalized intervals of assessment.

Radioactive Iodine Therapy in Differentiated Thyroid Cancer: 2020 Update

OBJECTIVE. The paradigm of theranostics is based on tailoring therapy for the purpose of optimizing outcomes. This principle is being applied to radioactive iodine therapy. Consequently, thyroid cancer therapy protocols are evolving. The purpose of this article is to promote a modern approach to radioiodine therapy. CONCLUSION. This article highlights guidelines and position statements, summarizes the prognostication systems of thyroid cancer, and reviews which prescribed activities of ¹³¹I.

Two decades of SPECT/CT - the coming of age of a technology: An updated review of literature evidence

PURPOSE

Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was introduced as a hybrid SPECT/CT imaging modality two decades ago. The main advantage of SPECT/CT is the increased specificity achieved through a more precise localization and characterization of functional findings. The improved diagnostic accuracy is also associated with greater diagnostic confidence and better inter-specialty communication.

METHODS

This review presents a critical assessment of the relevant literature published so far on the role of SPECT/CT in a variety of clinical conditions. It also includes an update on the established evidence demonstrating both the advantages and limitations of this modality.

CONCLUSIONS

For the majority of applications, SPECT/CT should be a routine imaging technique, fully integrated into the clinical decision-making process, including oncology, endocrinology, orthopaedics, paediatrics, and cardiology. Large-scale prospective studies are lacking, however, on the use of SPECT/CT in certain clinical domains such as neurology and lung disorders. The review also presents data on the complementary role of SPECT/CT with other imaging modalities and a comparative analysis, where available.

Improved Survival After Multimodal Approach with 131I Treatment in Patients with Bone Metastases Secondary to Differentiated Thyroid Cancer

Background: The objective of this study was to evaluate the overall survival (OS) of radioiodine (¹³¹I) treatments alone or combined with non-¹³¹I treatments in patients with bone metastases (BM) of differentiated thyroid cancer (DTC). Methods: This was a retrospective study of patients who were evaluated between 2001 and 2018 at MedStar Washington Hospital Center and who had DTC, BM, and at least one ¹³¹I treatment after the diagnosis of BM. The OS was analyzed by Kaplan-Meier survival curves and was compared by log-rank test between two groups: patients who received ¹³¹I treatments alone and those who received treatments combining ¹³¹I with non-¹³¹I treatments (CombTx). Non-¹³¹I treatments include surgery, radiofrequency ablation, cryotherapy, arterial embolization, external beam radiation, Cyberknife, systemic targeted therapy, and anti-resorptive medication. Results: A total of 77 patients met the above criteria and were followed up to 41 years. Thirty percent (23/77) of patients received ¹³¹I treatment alone, and 70% (54/77) received CombTx. For ¹³¹I treatment alone, the median survival was 3.9 years, and the 1-, 2-, 3-, 5-, and 10-year OS rates were 86%, 81%, 61%, 35%, and 23%, respectively. For CombTx, the median survival was 7.7 years, and the 1-, 2-, 3-, 5-, and 10-year OS rates were 96%, 92%, 86%, 69%, and 30%, respectively. Patients who had undergone initial ¹³¹I therapy within six months post thyroidectomy demonstrated a better median survival after BM diagnosis than those whose initial ¹³¹I therapy was six months or more after thyroidectomy (6.5 vs. 0.5 years; p < 0.001). Patients who received external beam radiation therapy demonstrated a better median survival than those who did not (7.8 vs. 4.4 years; p = 0.016). Patients who received denosumab demonstrated a better median survival than those who did not (7.7 vs. 5.2 years; p = 0.03). Patients who were <55 years of age at the initial diagnosis of DTC or at the initial diagnosis of BM had a better median OS than those diagnosed at ≥55 years of age (both p = 0.01). In the multivariate analysis, only age at initial diagnosis of DTC and initial ¹³¹I therapy within six months post thyroidectomy, and multiple ¹³¹I treatments were independent prognostic factors. Conclusions: In patients with DTC with BM, ¹³¹I treatment in combination with one or more non-¹³¹I direct and systemic treatments was associated with a significant increase in OS compared with those patients who were treated by ¹³¹I treatment alone.

Less than 2% of the Low- and Intermediate-Risk Differentiated Thyroid Cancers Show Distant Metastases at Post-Ablation Whole-Body Scan

BACKGROUND

Recently, there has been a trend to reduce the use of radioiodine remnant ablation (RRA) in patients with low-risk (LR) and intermediate-risk (IR) differentiated thyroid cancer (DTC).

OBJECTIVES

The aim of this paper was to evaluate the diagnostic role of whole-body scan (ptWBS) performed after RRA in LR and IR DTC patients.

METHODS

We analyzed 545 DTC patients treated with total thyroidectomy and RRA in hypothyroidism followed by a ptWBS. Neck ultrasound (US) and serum thyroglobulin measurement were performed. According to the American Thyroid Association guidelines, patients were classified as LR (n = 345) and IR (n = 200).

RESULTS

In addition to the thyroid remnant, the ptWBS showed the presence of further areas of ¹³¹I uptake in 16/545 (2.9%) cases. ptWBS showed laterocervical lymph node metastases in 11/16 patients (10/11 were also detected by US), mediastinal uptake in 1/16, lung metastases in 3/16, and bone metastases in 1/16. Only 6/545 (1.1%) metastases were detected by ptWBS alone. After 7.8 years, 8/16 patients were free of disease, and 8 had persistent disease: 4 "biochemical" and 4 "structural." Remission was achieved in 3 cases after one single ¹³¹I course, in 1 case after surgery, and in the last 4 cases after several ¹³¹I courses.

CONCLUSIONS

The ptWBS diagnostic role was clinically relevant for the therapeutic strategies of our patients only in 1.1% of the cases. The cost-effectiveness of performing RRA and ptWBS in all LR and IR patients to find 1-2% of the cases with distant metastases remains controversial.

Controversies, Consensus, and Collaboration in the Use of 131I Therapy in Differentiated Thyroid Cancer: A Joint Statement from the American Thyroid Association, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association

BACKGROUND

Publication of the 2015 American Thyroid Association (ATA) management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer was met with disagreement by the extended nuclear medicine community with regard to some of the recommendations related to the diagnostic and therapeutic use of radioiodine (131I). Because of these concerns, the European Association of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging declined to endorse the ATA guidelines. As a result of these differences in opinion, patients and clinicians risk receiving conflicting advice with regard to several key thyroid cancer management issues.

SUMMARY

To address some of the differences in opinion and controversies associated with the therapeutic uses of 131I in differentiated thyroid cancer constructively, the ATA, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association each sent senior leadership and subject-matter experts to a two-day interactive meeting. The goals of this first meeting were to (i) formalize the dialogue and activities between the four societies; (ii) discuss indications for 131I adjuvant treatment; (iii) define the optimal prescribed activity of 131I for adjuvant treatment; and (iv) clarify the definition and classification of 131I-refractory thyroid cancer.

CONCLUSION

By fostering an open, productive, and evidence-based discussion, the Martinique meeting restored trust, confidence, and a sense of collegiality between individuals and organizations that are committed to optimal thyroid disease management. The result of this first meeting is a set of nine principles (The Martinique Principles) that (i) describe a commitment to proactive, purposeful, and inclusive interdisciplinary cooperation; (ii) define the goals of 131I therapy as remnant ablation, adjuvant treatment, or treatment of known disease; (iii) describe the importance of evaluating postoperative disease status and multiple other factors beyond clinicopathologic staging in 131I therapy decision making; (iv) recognize that the optimal administered activity of 131I adjuvant treatment cannot be definitely determined from the published literature; and (v) acknowledge that current definitions of 131I-refractory disease are suboptimal and do not represent definitive criteria to mandate whether 131I therapy should be recommended.

Controversial Issues in Thyroid Cancer Management

The lack of prospective randomized clinical trials for most management topics in differentiated thyroid cancer forces us to make management recommendations based on retrospective observational data, which are often incomplete, subject to selection bias, and conflicting. Therefore, it is not surprising that many aspects of thyroid cancer management remain controversial and not well defined. This review will examine the controversies surrounding 3 important topics in thyroid cancer management: the option of thyroid lobectomy as initial therapy, the use of preoperative neck imaging to optimize the completeness of the initial surgery, and the selective use of radioactive iodine for remnant ablation, adjuvant treatment, or treatment for known persistent or recurrent disease. As thyroid cancer management moves toward a much more risk-adapted approach to personalized recommendations, clinicians and patients must balance the risks and benefits of the potential options to arrive at a plan that is optimized regarding both patient preferences/values and the philosophy/experience of the local disease management team.