Ablation with low-dose radioiodine and thyrotropin alfa in thyroid cancer

Ablation Rates and Long-Term Outcome Following Low-Dose Radioiodine for Differentiated Thyroid Cancer in the West of Scotland: A Retrospective Analysis

OBJECTIVE

Low-dose radioiodine is an accepted means of remnant ablation in patients with low- to intermediate-risk differentiated thyroid cancer (DTC) based on the results of several phase III trials. We evaluated the rate of ablation success and long-term recurrence outcomes in the first 3 years of implementing this practice at our institution.

METHODS

Patients who received 1.1 to 1.2 gigabecquerel (30 millicurie) were identified retrospectively from the radionuclide database, January 1, 2012, to December 31, 2014, inclusive. Successful ablation was defined as Iodine-131uptake <0.1% on diagnostic scan and Tg level <2.0 ng/mL at 6 to 8 months after treatment. Follow-up was conducted annually for 10 years and relapse rates were determined based on the available clinical, radiological, and biochemical information.

RESULTS

We identified 114 patients, 109 of whom had dual response assessment. The median age was 43 years (range, 14 to 80 years). Almost 70% had T1 or T2 tumors, with T3 and T4 tumors recorded in 27% and 2.5% of patients, respectively. Nodal staging was performed in just over 30% and involved lymph nodes were detected in 21% (N1a 8% and N1b 13%). Ablation success based on diagnostic scan alone was 94.7% (108/114), Tg alone 94.7% (108/114), and on both modalities was 90.4% (103/114).

CONCLUSION

Remnant ablation was achieved in >90%, and the corresponding clinical recurrence rate was only 1.8% despite the inclusion of patients with locally advanced disease. Low-dose radioiodine is effective and may be suitable for a proportion of patients with higher-risk DTC.

Theranostics of Thyroid Cancer

Molecular imaging is pivotal in evaluating and managing patients with different thyroid cancer histotypes. The existing, pathology-based, risk stratification systems can be usefully refined, by incorporating tumor-specific molecular and molecular imaging biomarkers with theranostic value, allowing patient-specific treatment decisions. Molecular imaging with different radioactive iodine isotopes (ie, I131, I123, I124) is a central component of differentiated carcinoma (DTC)'s risk stratification while [18F]F-fluorodeoxyglucose ([18F]FDG) PET/CT is interrogated about disease aggressiveness and presence of distant metastases. Moreover, it is particularly useful to assess and risk-stratify patients with radioiodine-refractory DTC, poorly differentiated, and anaplastic thyroid cancers. [18F]F-dihydroxyphenylalanine (6-[18F]FDOPA) PET/CT is the most specific and accurate molecular imaging procedure for patients with medullary thyroid cancer (MTC), a neuroendocrine tumor derived from thyroid C-cells. In addition, [18F]FDG PET/CT can be used in patients with more aggressive clinical or biochemical (ie, serum markers levels and kinetics) MTC phenotypes. In addition to conventional radioiodine therapy for DTC, new redifferentiation strategies are now available to restore uptake in radioiodine-refractory DTC. Moreover, peptide receptor theranostics showed promising results in patients with advanced and metastatic radioiodine-refractory DTC and MTC, respectively. The current appropriate role and future perspectives of molecular imaging and theranostics in thyroid cancer are discussed in our present review.

Comparison of Recombinant Human Thyroid-Stimulating Hormone and Thyroid Hormone Withdrawal for 131 I Therapy in Patients With Intermediate- to High-Risk Thyroid Cancer : A Systematic Review and Meta-analysis

BACKGROUND

This meta-analysis and systematic review aimed to evaluate the therapeutic efficacy and advantages associated with the use of recombinant human thyroid-stimulating hormone (rhTSH) for radioactive iodine (RAI) therapy in patients with intermediate- to high-risk differentiated thyroid cancer.

PATIENTS AND METHODS

MEDLINE, EMBASE, and Cochrane databases were searched to identify relevant articles reporting clinical outcomes of rhTSH compared with thyroid hormone withdrawal (THW) in patients with intermediate- to high-risk differentiated thyroid cancer published between January 2012 and June 2023. Meta-analyses were performed (PROSPERO registration number: CRD42022340915) to assess the success rate of radioiodine remnant ablation (RRA) in patients with intermediate to high risk and determine the disease control rate among patients with distant metastases, evaluated using the RECIST criteria.

RESULTS

Thirteen studies involving 1858 patients were included in the meta-analysis. Pooled analyses revealed significantly higher overall RRA success rate in the rhTSH group compared with the THW group, with a risk ratio (RR) of 1.12 (95% confidence interval [CI], 1.01-1.25). However, in the subgroup analysis of high-risk patients, pooled analyses showed no significant differences in RRA success rate between the rhTSH group compared with the THW group with a pooled RR of 1.05 (95% CI, 0.88-1.24). In patients with distant metastases, there were no significant differences in the disease control rate between groups, with a pooled RR of 1.06 (95% CI, 0.78-1.44).

CONCLUSIONS

rhTSH for RAI therapy is a practical option for RAI therapy in patients with intermediate- to high-risk thyroid cancer, including those with distant metastases.

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.

Higher adjuvant radioactive iodine therapy dosage helps intermediate-risk papillary thyroid carcinoma patients achieve better therapeutic effect

Objective

This retrospective study aims to evaluate the therapeutic effect of varying dosages of adjuvant radioactive iodine (RAI) therapy on intermediate-risk papillary thyroid carcinoma (PTC) patients.

Methods

This retrospective study involved a total of 427 intermediate-risk PTC patients, out of which 202 received a 3.7GBq dosage of RAI, and 225 received a 5.55GBq dosage. The evaluation involved assessing the therapeutic outcomes, number of treatment cycles, and successful remnant ablation rates in both dose groups, six months post-adjuvant RAI therapy. Univariate and multivariate logistic regression analyses were employed to identify factors linked with excellent response (ER). Following this, prognostic nomograms were constructed to provide a visual representation of the prediction models. Calibration curves, the concordance index (C-index), and the receiver operating characteristic (ROC) curve were employed to evaluate the predictive performance of these nomograms. The Hosmer-Lemeshow test was applied to assess the models' goodness-of-fit. Additionally, the clinical utility of the prognostic nomograms was appraised through decision curve analysis (DCA).

Results

The high-dose (HD) group exhibited significantly higher proportions of ER, single treatment cycles, and successful remnant ablation rates (p<0.05). Being male, receiving a 3.7GBq dose, having an N1b stage, an sTg level ≥10ng/ml, or an sTg/TSH ratio ≥0.11 were independent risk factors for Non-ER. Two prognostic nomograms, "sTg Nomogram" and "sTg/TSH Nomogram", were established. The ranking of factors contributing to ER, in descending order, included the sTg or sTg/TSH ratio, N stage, therapy dosage, sex, and soft tissue invasion. The "sTg/TSH Nomogram" demonstrated a higher C-index compared to the "sTg Nomogram". The calibration curves indicated excellent calibration for both nomograms. DCA demonstrated that the net benefit of the "sTg/TSH Nomogram" was higher than that of the "sTg Nomogram".

Conclusion

Higher initial RAI therapy doses can improve therapeutic efficacy for intermediate-risk PTC patients. The developed nomograms, particularly the "sTg/TSH Nomogram", could assist clinicians in optimal therapeutic decision-making.

Radioactive Iodine in Differentiated Carcinoma of Thyroid: An Overview

Thyroid cancer is the fifth most prevalent cancer in women and the fastest-growing malignancy. Although surgery is still the basis of treatment, internal radiation therapy (Brachytherapy) with radioactive iodine-131, which functions by releasing beta particles with low tissue penetration and causing DNA damage, is also a potential option. The three basic aims of RAI therapy in well-differentiated thyroid tumors are ablation of the remnant, adjuvant therapy, and disease management. Radioactive iodine dose is selected in one of two ways, empiric and dosimetric, which relies on numerous criteria. The dosage for ablation is 30-100 mCi, 30-150 mCi for adjuvant therapy, and 100-200 mCi for treatment. The RAI treatment effectively aids in the treatment to achieve complete removal of the disease and increase survival. The present review intends to emphasize the significance of radioactive iodine in the management of differentiated thyroid cancer and put forward the current breakthroughs in therapy.

Early stimulated thyroglobulin after thyroidectomy for thyroid cancer predicts preradioiodine therapy thyroglobulin values

BACKGROUND

Follow-up of patients who undergo a total thyroidectomy is performed with thyroglobulin (Tg), and antithyroglobulin antibodies (AbTg). The objective of RAI adjuvant therapy is to negativize Tg to undetectable levels to ease the follow-up. The objective of this study was to evaluate the correlation of serum Tg values measured 2 weeks after surgery with the Tg value prior to RAI adjuvant therapy in order to define its utility as a reliable predictor of pretherapy Tg and as a potential predictor to avoid RAI adjuvant therapy.

METHODS

Retrospective analysis of a cohort recruited prospectively. Adult patients with thyroid carcinoma who underwent total thyroidectomy and classified as intermediate or high risk by ATA guidelines. All patients were left without levothyroxine support after surgery and for at least two weeks. We measured biochemical markers two-four weeks after thyroidectomy and before and after RAI.

RESULTS

We included 75 patients. Thirty-three (44.0%) patients were classified as ATA high risk. In the post-RAI scan, only 1 (1.3%) showed distant metastases. The comparison between early postoperative and pretherapy Tg values showed that Tg decreased or remained stable at postoperative levels in 75 patients (100%).

CONCLUSIONS

Postoperative Tg measurements are a reliable marker of pretherapy Tg levels in patients with intermediate- and high-risk thyroid carcinoma who are candidates for RAI adjuvant therapy. These results need correlation with outcomes and response to therapy in high-risk patients.

Outcomes of ATA Low-Risk Pediatric Thyroid Cancer Patients Not Treated With Radioactive Iodine Therapy

CONTEXT

The American Thyroid Association (ATA) Pediatric Guidelines recommend patients not receive radioactive iodine therapy (RAIT) for differentiated thyroid cancer (DTC) confined to the thyroid. Since publication, there is ongoing concern whether withholding RAIT will result in a lower rate of remission.

OBJECTIVE

This study explores whether ATA low-risk patients treated with and without RAIT achieved similar remission rates.

METHODS

Medical records of patients <19 years old diagnosed with DTC and treated with total thyroidectomy between 2010 and 2020 were reviewed. Multivariate logistic regression was performed to evaluate factors influencing RAIT administration and remission rate.

RESULTS

Ninety-five patients with ATA low-risk DTC were analyzed: 53% (50/95) and 47% (45/95) were treated with and without RAIT, respectively. RAIT was used to treat 82% of patients before 2015 compared with 33% of patients after 2015 (P < .01). No significant difference in 1-year remission rate was found between patients treated with and without RAIT, 70% (35/50) vs 69% (31/45), respectively. With longer surveillance, remission rates increased to 82% and 76% for patients treated with and without RAIT, respectively. Median follow-up was 5.8 years (IQR 4.3-7.9, range 0.9-10.9) and 3.6 years (IQR 2.7-6.6; range 0.9-9.3) for both cohorts. No risk factors for persistent or indeterminate disease status were found, including RAIT administration, N1a disease, and surgery after 2015.

CONCLUSION

Withholding RAIT for pediatric patients with ATA low-risk DTC avoids exposure to radiation and does not have a negative impact on remission rates. Dynamic risk stratification at 1-year after initial treatment is a suitable time point to assess the impact of withholding RAIT for these patients.

Effect of preparation method for radioactive iodine therapy on serum electrolytes

PURPOSE

Thyroid hormone withdrawal (THW) in preparation for radioactive iodine therapy (RIT) may lead to hyponatremia and hyperkalemia because hypothyroidism reduces the glomerular filtration rate. Using recombinant human thyrotropin (rhTSH) may avoid these changes; however, these two preparation methods have not been compared in the literature. The purpose of this study was to reveal whether THW and rhTSH as preparation methods for RIT affect serum electrolytes differently. We also evaluated clinical factors influencing the onset of hyponatremia and hyperkalemia during RIT.

MATERIALS AND METHODS

From April 2005 to December 2020, we analyzed 278 patients with thyroid cancer who received RIT. The patients were classified into two groups based on the preparation method, and renal function and serum electrolytes were compared between the groups. We also evaluated clinical factors that may affect overt hyponatremia (serum sodium level < 134 mmol/L) and hyperkalemia (serum potassium level ≥ 5.0 mmol/L).

RESULTS

Serum sodium and chloride levels in the THW group were significantly lower than those in the rhTSH group (p < 0.001 and p = 0.002, respectively). In contrast, the serum potassium level in the THW group was significantly higher than that in the rhTSH group (p = 0.008). As for clinical factors that may influence hyponatremia, age and estimated glomerular filtration rate (eGFR) were significantly associated with serum sodium level in the univariate analysis (p = 0.033 and p = 0.006, respectively). In the multivariate analysis, only age was significantly associated with serum sodium level (p = 0.030). Regarding hyperkalemia, distant metastases, the preparation method and eGFR were significantly associated with the serum potassium level in the univariate analysis (p = 0.005, p = 0.005 and p = 0.001, respectively). In the multivariate analysis, only eGFR was significantly associated with hyperkalemia (p = 0.019).

CONCLUSION

THW and rhTSH affect serum sodium and potassium levels differently. Renal function may be risk factors for hyperkalemia, whereas older age may be a risk factor for hyponatremia.

Factors Affecting Ablation Success After I-131 Radioactive Iodine Therapy in Low and Intermediate Risk Papillary Thyroid Cancer

The study was to evaluate the effect of radioactive iodine (RAI) treatment application time and clinical, histopathological factors on ablation success in patients with operated papillary thyroid cancer (PTC) in low and intermediate-risk. One hundred sixty-one patients with PTC in the low and intermediate-risk were evaluated. Most patients (89.4%) were in the low-risk, and 10.6% were in the intermediate-risk. When the patients were divided into two groups according to the date of receiving RAI treatment after surgery, those who received early treatment (≤3 months) constituted the majority of the patients (72.7%). Seventeen patients received 1.85 Gigabecquerel (GBq), 119 3.7 GBq, 25 5.55 GBq RAI. Most patients (82%) achieved ablation success after the first RAI treatment. The time interval between surgery and RAI treatment did not affect ablation success. Stimulated Tg level measured on the RAI treatment day was an independent predictive factor for successful ablation (p<0.001). The cut-off value of Tg found to predict ablation failure was 5.86 ng/ml. It was concluded that 5.55 GBq RAI treatment could predict ablation success compared to 1.85 GBq dose (p=0.017). It was concluded that having a T1 tumor may predict treatment success compared to a T2 or T3 tumor (p=0.001, p<0.001, retrospectively). The time interval does not affect ablation success in low and intermediate-risk PTC. The ablation success rate may decrease in patients who receive low-dose RAI and have high Tg levels before treatment. The most crucial factor in achieving ablation success is giving enough doses of RAI to ablate the residual tissue.

Assessment of three different radioiodine doses for ablation therapy of thyroid remnants: Efficiency, complications and patient comfort

I-131 radioiodine (RAI) ablation removes postoperative residual tissue and facilitates follow-up in low- and intermediate-risk differentiated thyroid cancer (DTC). Although low doses have been reported to be as effective as higher doses for ablation, the doses administered still vary depending on the patient and the practitioner. We aimed to evaluate the ablation efficiency, complications, and length of stay (LOS) of patients with DTC treated with 3 different doses for ablation. Patients with DTC who received RAI therapy were retrospectively reviewed. One hundred thirty patients with low-intermediate-risk, according to American Thyroid Association classification, without known lymph nodes or distant metastases were included. Patients were divided into 3 groups as 30 to 50 mCi, 75 mCi, and 100 mCi. Residue thyroid and salivary glands were evaluated from 9 to 12 months post-RAI I-131 scans. No significant difference was found between groups regarding ablation success (P = .795). In multivariable analyses, pretreatment thyroglobulin (hazard ratio = 0.8, 95% confidence interval 0.601-0.952, P = .017) and anti- thyroglobulin antibody (hazard ratio = 1.0, 95% confidence interval 0.967-0.998, P = .024) were 2 independent predictors of ablation success. The mean LOS was 2.1 ± 0.3, 2.6 ± 0.6, and 2.9 ± 0.4 days, respectively, (P = .001). LOS rates of ≥ 3 days were 13.2%, 54.3%, and 84.8%, respectively. Mild decreases in hemoglobin, white blood cell (WBC), and platelet counts were observed in all groups after 6 weeks without any clinically significant findings. A lower rate of change in WBC counts was observed in the 30 to 50 mCi group compared to others. There was no dose-dependent difference regarding the early complaints questioned. Ablation with 30 to 50 mCi provides benefits such as shorter LOS, better patient comfort, less salivary gland dysfunction, and less WBC suppression, thus reducing costs without decreasing efficacy.

Update on iodine-refractory differentiated thyroid carcinoma

Radioiodine therapy represents a fundamental pillar in the routine adjuvant therapy of patients with high-risk differentiated thyroid carcinoma. However, a non-negligible percentage of these patients will develop iodine refractoriness, showing a worse prognosis, as well a lower survival, which demonstrates a clear need to explore different therapeutic approaches. Iodine refractory patient treatment continues to be a challenge, currently having different novel therapeutic options that should be known by the different specialties related to differentiated thyroid carcinoma (DTC). The aim of this work is to review iodine refractory thyroid carcinoma treatment, focusing especially on the definition of iodine refractoriness, highlighting its importance due to its high mortality, and introducing the different therapeutic options available for these patients.

Normal organ dosimetry for thyroid cancer patients treated with radioiodine as part of the multi-centre multi-national Horizon 2020 MEDIRAD project

PURPOSE

Dosimetry is rarely performed for the treatment of differentiated thyroid cancer patients with Na[131I]I (radioiodine), and information regarding absorbed doses delivered is limited. Collection of dosimetry data in a multi-centre setting requires standardised quantitative imaging and dosimetry. A multi-national, multi-centre clinical study was performed to assess absorbed doses delivered to normal organs for differentiated thyroid cancer patients treated with Na[131I]I.

METHODS

Patients were enrolled in four centres and administered fixed activities of 1.1 or 3.7 GBq of Na[131I]I using rhTSH stimulation or under thyroid hormone withdrawal according to local protocols. Patients were imaged using SPECT(/CT) at variable imaging time-points following standardised acquisition and reconstruction protocols. Whole-body retention data were collected. Dosimetry for normal organs was performed at two dosimetry centres and results collated.

RESULTS

One hundred and five patients were recruited. Median absorbed doses per unit administered activity of 0.44, 0.14, 0.05 and 0.16 mGy/MBq were determined for the salivary glands of patients treated at centre 1, 2, 3 and 4, respectively. Median whole-body absorbed doses for 1.1 and 3.7 GBq were 0.05 Gy and 0.16 Gy, respectively. Median whole-body absorbed doses per unit administered activity of 0.04, 0.05, 0.04 and 0.04 mGy/MBq were calculated for centre 1, 2, 3 and 4, respectively.

CONCLUSIONS

A wide range of normal organ doses were observed for differentiated thyroid cancer patients treated with Na[131I]I, highlighting the necessity for individualised dosimetry. The results show that data may be collated from multiple centres if minimum standards for the acquisition and dosimetry protocols can be achieved.

Recurrence-free survival and prognosis after adjuvant therapy with radioactive iodine-131 in patients with differentiated thyroid carcinoma

This study aimed to assess recurrence-free survival (RFS) rates and recurrence-related factors of patients who received adjuvant therapy (AT) with radioactive iodine (RAI) for differentiated thyroid cancer (DTC) following thyroidectomy. We evaluated 284 patients who underwent AT between January 2011 and July 2020 at our hospital. Recurrence was defined as visible recurrent lesions on image analysis or need for repeat surgery with pathologically confirmed recurrent lesions. RFS rate and prognostic factors were statistically evaluated. The median observation period was 30.2 months (range, 5.7-294 months). Overall, 192 patients were female and 92 were male, and the median age was 54 years (range, 9-85 years). Initial assessment revealed 39 recurrence cases. The 3-year RFS rate was 85.8% (95% confidence interval: 81.1-90.9%). Univariate analysis revealed that histology (except for papillary carcinoma), Tg level > 4 ng/dL before AT, and AT result significantly exacerbated the RFS rate. In multivariate analysis, histology and AT result were also important contributors to the worsening RFS rate. Results of AT can be determined relatively early and are important in predicting future recurrence in patients with DTC. Increasing the success rate of AT may lead to an improved prognosis.

Controversies in the Radioiodine Treatment of Patients With Differentiated Thyroid Cancer

The use of radioiodine (I-131) in the management of patients suffering differentiated thyroid cancer (DTC) has changed little in the past 40 years. The use of a standardized approach has served the majority of patients well over that time. However, there have been recent doubts concerning this approach in some low risk patients and if so, how can these patients recognized and which patients who may need more intensive treatment. A number of clinical trials have questioned the paradigms used in the treatment of DTC including what activity of I-131 should be used for ablation and which low risk patients should be treated with I-131 especially as there remains some doubts as to the long-term safety of I-131. Should a dosimetric approach be used to optimize the use of I-131 even though at present this approach has not been shown to improve outcomes in a formal clinical trial. The era of precision oncology represents a challenge and opportunity to nuclear medicine with a move away from a regime of standard care to one of highly individualized care based on the genetic profiling of the patient and their cancer. The treatment of DTC with I-131 is about to become very interesting.

Recurrent Differentiated Thyroid Cancer: The Current Treatment Options

Differentiated thyroid carcinomas (DTC) have an excellent prognosis, but this is sometimes overshadowed by tumor recurrences following initial treatment (approximately 15% of cases during follow-up), due to unrecognized disease extent at initial diagnosis or a more aggressive tumor biology, which are the usual risk factors. The possible sites of recurrence are local, regional, or distant. Local and regional recurrences can usually be successfully managed with surgery and radioiodine therapy, as are some isolated distant recurrences, such as bone metastases. If these treatments are not possible, other therapeutic options such as external beam radiation therapy or systemic treatments should be considered. Major advances in systemic treatments have led to improved progression-free survival in patients previously considered for palliative treatments; among these treatments, the most promising results have been achieved with tyrosine kinase inhibitors (TKI). This review attempts to give a comprehensive overview of the current treatment options suited for recurrences and the new treatments that are available in cases where salvage surgery is not possible or in cases resistant to radioiodine.

Post-Surgical Indications to Radioiodine Treatment and Potential Risk Factors for Post-Treatment Recurrence in Patients with Intermediate-Risk Differentiated Thyroid Carcinoma

In this multicentric retrospective observational study, we investigated the potential risk factors for radioiodine (RAI) indication and the post-treatment recurrence of intermediate-risk differentiated thyroid cancer (DTC) 1 and 3 years from diagnosis. We included 121 patients who underwent thyroidectomy for intermediate-risk DTC. The 92 patients (76.0%) who underwent RAI treatment had a higher prevalence of extra-thyroid micro-extension (mETE) (p = 0.03), pT3 staging (p = 0.03) and recourse to therapeutic central (p = 0.04) and lateral (p = 0.01) neck dissection, as well as higher numbers (p = 0.02) and greater dimensions (p = 0.01) of lymph node metastases, compared with untreated patients. Relapse was observed in 18.1% and 20.7% of cases 1 and 3 years from diagnosis, respectively, with no significant differences between groups. A lower age at diagnosis (p = 0.03) and higher levels of stimulated thyroglobulin (Tg) (p = 0.04) emerged as the only independent risk factors for tumour relapse at 1 year. Tumour relapse at 3 years was only independently predicted by the presence of tumour relapse at 1 year (p = 0.04). In conclusion, mETE, pT3 and the presence of large, multiple or clinically evident lymph node metastases represent the main indicators for referring patients to RAI treatment. Early recurrence may be considered the most relevant factor when planning further surveillance.

Comparison of 1.1 GBq and 2.2 GBq Activities in Patients with Low-Risk Differentiated Thyroid Cancer Requiring Postoperative 131I Administration: A Real Life Study

OBJECTIVES

To compare the efficacy of low and moderate ¹³¹I activities in low-risk differentiated thyroid carcinoma (DTC) patients requiring postoperative thyroid remnant ablation in a real-world clinical setting.

METHODS

We retrospectively reviewed the records of 299 low-risk DTC patients (pT1-T2, Nx(0) Mx) who had undergone (near)-total thyroidectomy followed by ¹³¹I therapy, using either low (1.1 GBq) or moderate (2.2 GBq) radioiodine activities. The response to initial treatments was evaluated after 8-12 months, and patient responses were classified according to the 2015 American Thyroid Association guidelines.

RESULTS

An excellent response was observed in 274/299 (91.6%) patients, specifically, in 119/139 (85.6%) and 155/160 (96.9%) patients treated with low and moderate ¹³¹I activities, respectively (p = 0.029). A biochemically indeterminate or incomplete response was observed in seventeen (22.2%) patients treated with low ¹³¹I activities and three (1.8%) patients treated with moderate ¹³¹I activities (p = 0.001). Finally, five patients showed an incomplete structural response, among which three and two received low and moderate ¹³¹I activities, respectively (p = 0.654).

CONCLUSIONS

When ¹³¹I ablation is indicated, we encourage the use of moderate instead of low activities, in order to reach an excellent response in a significantly larger proportion of patients, including patients with the unexpected persistence of the disease.

Is radioiodine ablation with 1.1 GBq (30 mCi) 131I necessary in low-risk thyroid cancer patients? Results from a long-term follow-up prospective study

BACKGROUND

In patients with low-risk differentiated thyroid cancer (DTC), remnant ablation with radioiodine (RA) after total thyroidectomy (TT) is controversial. No benefits have been demonstrated in terms of mortality or disease-free survival. Recent evidence found that RA did not improve mid-term outcomes.

PURPOSE

To evaluate initial response to treatment and long-term follow-up status in low-risk DTC patients after TT vs. TT + RA with ¹³¹I 1.11 GBq (30 mCi).

METHODS

Prospective multicenter non-randomized study; 174 low-risk DTC that underwent TT were recruited an divided in two groups according to RA (87 ablated and 87 non-ablated). Response to treatment was evaluated at 6-18 months after thyroidectomy and at the end of follow-up with measurements of thyroglobulin, and anti-thyroglobulin antibodies levels, and neck ultrasonography.

RESULTS

Baseline characteristics of both groups were similar. Ablated patients: median age 45.5 years, 84% females, 95.4% papillary thyroid carcinoma (PTC), mean tumor size 16 mm; non-ablated: median age 45 years, 88.5% females, 96.6% PTC, mean tumor size 14 mm. Response to initial treatment was similar between both groups, with < 2% of structural incomplete response. Final status was evaluated in 139 cases (median follow-up of 60 months). Among ablated patients, 82.8% had no evidence of disease (NED), 12% had an indeterminate response (IR) and 5% a biochemical incomplete response (BIR). Non-ablated patients had NED in 90%, IR in 8.7% and BIR in 1.2%. No statistical difference was found between groups (p = 0.29). No patient had evidence of structural disease at the end of follow-up.

CONCLUSIONS

Our findings support the recommendation against routine RA in low-risk DTC patients.

Recombinant or endogenous thyroid-stimulating hormone for radioactive iodine therapy in thyroid cancer: state of knowledge and current controversies

For patients undergoing radioiodine therapy (RIT) of differentiated thyroid carcinoma (DTC), thyroid-stimulating hormone (TSH) stimulation prior to RIT can be achieved using thyroid hormone withdrawal (THW) or administration of recombinant human TSH (rhTSH). As THW can lead to nausea, headaches, vomiting, fatigue, and dizziness secondary to transient acute hypothyroidism, rhTSH could be a good alternative. Recombinant human TSH has been administered in patients in order to stimulate TSH for RIT since 2005. According to the Martinique criteria formulated by the leading professional societies involved in care of patients with DTC, rhTSH can be applied in 3 settings: for remnant ablation, adjuvant treatment, and treatment of known disease. Numerous studies have investigated the effects of rhTSH as a method of TSH stimulation on the thyroid cell, the systemic effects, biokinetics, and clinical outcomes; however, no consensus has been reached about many aspects of its potential use. Recombinant human TSH is able to stimulate sufficient TSH levels (>30 mIU L-1) and is hypothesized to decrease risks of tumor cell proliferation. As rhTSH-use avoids the transiently impaired renal function associated with THW, radioiodine excretion is faster with the former, leading to a lower iodine-131 uptake and a difference in fractional remnant uptake, effective half-life, mean residence time, and dose to the blood. Differences between rhTSH and THW were observed in radioiodine genotoxic effects and endothelial-dependent vasodilation and inflammation. For thyroid remnant ablation, THW and rhTSH lead to similar remnant ablation rates. For adjuvant therapy and treatment of known disease, insufficient trials have been conducted and future prospective studies are recommended. The current review provides a state-of-the-science overview on the issues and debates surrounding TSH stimulation through either rhTSH adminsitration orendogenous TSH production after levothyroxin withdrawal.

Recombinant human thyrotropin versus thyroid hormone withdrawal preparation for radioiodine ablation in differentiated thyroid cancer: Experience in a South Taiwanese medical center

This retrospective study was designed to compare the treatment response of patients with differentiated thyroid cancer (DTC) prepared for radioiodine ablation (RIA) with thyroid hormone withdrawal (THW) or recombinant human thyrotropin (rhTSH) stimulation. Patients with DTC were followed-up retrospectively between 2013 and 2018 in Kaohsiung Chang Gung Memorial Hospital, Taiwan. We compared the excellent response ratios between THW (49.9%) and rhTSH (50.1%) stimulation. Patients were then divided into subgroups, on the basis of age, sex, extrathyroidal extension, lymph node metastasis, and tumor-node-metastasis stage, for analysis. In all, 647 patients were followed-up after RIA. The ratios of THW or rhTSH use in the different subgroups were not statistically significant. In all the patients, the excellent response rate with THW and rhTSH was 80% and 76.5%, respectively, which was not statistically significant. The subgroup analysis, including age, sex, extrathyroidal extension, lymph node metastasis, and tumor-node-metastasis stage (low and high risk), showed similar results. Furthermore, the logistic regression analysis revealed no statistically significant differences among the subgroups. The multivariate analysis showed extrathyroidal extension, lymph node metastasis, and high I¹³¹ dose were the prognostic factors affecting the excellent response rate. In conclusion, the THW and rhTSH preparations for RIA were similar in terms of the excellent response rates and subgroup clinical outcomes.

Overexpression of Both Human Sodium Iodide Symporter (NIS) and BRG1-Bromodomain Synergistically Enhances Radioiodine Sensitivity by Stabilizing p53 through NPM1 Expression

Improved therapeutic strategies are required to minimize side effects associated with radioiodine gene therapy to avoid unnecessary damage to normal cells and radiation-induced secondary malignancies. We previously reported that codon-optimized sodium iodide symporter (oNIS) enhances absorption of I-131 and that the brahma-associated gene 1 bromodomain (BRG1-BRD) causes inefficient DNA damage repair after high-energy X-ray therapy. To increase the therapeutic effect without applying excessive radiation, we considered the combination of oNIS and BRG1-BRD as gene therapy for the most effective radioiodine treatment. The antitumor effect of I-131 with oNIS or oNIS+BRD expression was examined by tumor xenograft models along with functional assays at the cellular level. The synergistic effect of both BRG1-BRD and oNIS gene overexpression resulted in more DNA double-strand breaks and led to reduced cell proliferation/survival rates after I-131 treatment, which was mediated by the p53/p21 pathway. We found increased p53, p21, and nucleophosmin 1 (NPM1) in oNIS- and BRD-expressing cells following I-131 treatment, even though the remaining levels of citrulline and protein arginine deiminase 4 (PAD4) were unchanged at the protein level.

The effect of thyroid hormone withdrawal performed to evaluate the success of I-131 ablation on quality of life and psychological symptoms in female patients with low-risk differentiated thyroid cancer

Aim: There is a need to evaluate the treatment response in patients who have undergone radioiodine treatment (RIT) for differentiated thyroid cancer. Diagnostic tests that are used for this purpose include radioiodine whole-body scan (WBS) and serum thyroglobulin (Tg) measurement, which are most accurate during thyroid-stimulating hormone (TSH) stimulation. However, temporary discontinuation of thyroid hormone therapy to increase TSH (withdrawal) may be associated with the morbidity of hypothyroidism. The study aimed to show the effects of thyroid hormone withdrawal (THW) on quality of life and psychological symptoms in female patients with low-risk, well-differentiated papillary thyroid cancer. Methods: We applied the short form-36 (SF-36) and Symptom Checklist-90-R (SCL-90-R) questionnaires to the patients in the euthyroid state who have referred a median of 9 months (6-13 months) after RIT to perform a dWBS and to evaluate stimulated Tg. We applied the same questionnaire again when thyroid-stimulating hormone (TSH) was > 30 μIU/mL 4 weeks after THW (hypothyroid state). Results: 52 patients were evaluated (median age 48 years, range 23-65 years). There was a statistically significant worsening in anxiety, psychosis, additional items, and general symptoms of the SCL-90-R questionnaire, physical functioning, role limitation due to physical health, energy/fatigue, emotional well-being, social function, and general health change in the SF-36 questionnaire. Conclusions: THW worsened the patients’ psychological symptoms and quality of life. To reduce the side effects of hypothyroidism, treatment response assessment with TSH stimulation should be used only in a selected group of patients with a higher risk of recurrence.

Radioiodine therapy in the different stages of differentiated thyroid cancer

Differentiated thyroid cancer is the most frequent type of thyroid cancer with an increasing incidence in the last decades. The initial management is represented by surgical treatment followed by radioactive iodine therapy that includes remnant ablation, adjuvant treatment or treatment of metastatic disease. Radioactive iodine treatment is performed only in selected cases based on the risk of recurrence and mortality during follow up, according to American Joint Committee on Cancer Union for international Cancer Control Tumor, Node, Metastasis (AJCC/TNM) staging system and the 2015 American Thyroid Association (ATA) risk stratification system. This article will review the key factors to consider when planning radioactive iodine therapy in differentiated thyroid cancer patients after surgery and during follow up.

Patient Preparation and Radiation Protection Guidance for Adult Patients Undergoing Radioiodine Treatment for Thyroid Cancer in the UK

Radioactive iodine is a highly effective treatment for thyroid cancer and has now been used in clinical practice for more than 80 years. In general, the treatment is well tolerated. However, it can be logistically quite complex for patients due to the need to reduce iodine intake and achieve high levels of thyroid-stimulating hormone prior to treatment. Radiation protection precautions must also be taken to protect others from unnecessary radiation exposure following treatment. It has been well documented by thyroid cancer patient support groups that there is significant variation in practice across the UK. It is clear that some patients are being asked to observe unnecessarily burdensome restrictions that make it more difficult for them to tolerate the treatment. At the instigation of these support groups, a multidisciplinary group was assembled to examine the evidence and generate guidance on best practice for the preparation of patients for this treatment and the management of subsequent radiation protection precautions, with a focus on personalising the advice given to individual patients. The guidance includes advice about managing particularly challenging situations, for example treating patients who require haemodialysis. We have also worked together to produce a patient information leaflet covering these issues. We hope that the guidance document and patient information leaflet will assist centres in improving our patients' experience of receiving radioactive iodine. The patient information sheet is available as Supplementary Material to this article.

The outcome of treatment in differentiated thyroid cancer according to recommendations in current Dutch and American guidelines

OBJECTIVE

Assessment of treatment outcome in current de-escalation for differentiated thyroid cancer (DTC) according to the 2015 Dutch thyroid cancer guidelines (NL-15) and American Thyroid Association guidelines (ATA-15).

DESIGN

Retrospectively, the recommendations of the NL-15 and ATA-15 guidelines were evaluated to estimate potentially adequate, under- and overtreatment of DTC in patients treated in the University Medical Center Groningen between 2007 and 2017.

PATIENTS

A total of 240 patients with a cT1-T3aN0-1aM0 DTC fulfilled the inclusion criteria.

MEASUREMENTS

After actual treatment was given, patients were again categorized according to both guidelines into low, intermediate, or high-risk based on tumour status. Next, they were categorized into a congruent low-risk (n = 60), congruent high-risk (n = 73), or incongruent risk group (n = 107). Follow-up data were used to estimate the proportion of potentially adequate, under-, and overtreatment according to both guidelines.

RESULTS

Comparing treatment recommended by NL-15 and ATA-15 showed significantly more over- and adequate treatment when following NL-15 recommendations, and more undertreatment following ATA-15 (all: p < .001). Subanalysis of the congruent low-risk group showed overtreatment in 64% when following NL-15 guidelines (p < .001). No treatment differences were found in the congruent high-risk group. Undertreatment was most often seen in the incongruent risk group when following ATA-15 (p < .001).

CONCLUSIONS

Low-risk patients were treated too aggressively when following NL-15 recommendations, where the less aggressive ATA-15 approach seemed more adequate. Treatment of intermediate risk DTC patients varies greatly, with a relative higher rate of undertreatment according to the recommendations of the ATA-15, advocating further refining of the risk classification in this patient group.

Effect of recombinant human thyroid stimulating hormone on long-term salivary gland dysfunction in thyroid cancer patients treated with radioactive iodine. A systematic review

Adjuvant radioactive iodine (RAI) is administered to thyroid cancer patients following thyroidectomy for remnant tissue ablation and metastatic disease management. Patients are prepared with thyroid hormone withdrawal (THW) or recombinant human thyroid stimulating hormone (rhTSH). Long-term salivary gland dysfunction (LT-SGD) is a common, dosage-dependent, RAI adverse effect. Although rhTSH preparation seems to reduce LT-SGD, this effect could be due to lower RAI activity generally used in rhTSH-prepared patients. Therefore, this meta-analysis investigated the effect of preparation type on LT-SGD development. Literature search (PubMed, Medline, EmBase, Cochrane, Web of Science, LILACS, Google Scholar) was performed four times (January-November 2022) and studies reporting LT-SGD incidence ≥1 year after RAI in patients prepared with rhTSH/THW were identified. The LT-SGD risk ratio (RR) was estimated with various models considered for sensitivity analysis (fixed-effect, random-effects, study-quality adjusted, publication-bias adjusted, individual-patient-data meta-analysis adjusted for RAI). Subgroup analysis according to RAI activity (<3.7/≥3.7 GBq) also was performed. Literature search resulted in five studies (321 rhTSH, 632 THW patients). The pooled RRs according to various models were 0.65 (95% confidence interval -95CI, 0.49-0.86; fixed-effect); 0.62 (95CI, 0.38-1.02; random-effects); 0.72 (95CI, 0.54-0.96; quality adjusted); 0.76 (95CI, 0.58-0.99; publication-bias adjusted); 0.0.80 (95CI, 0.55-1.14; individual-patient-data meta-analysis). The pooled RRs stratified for RAI activity were 0.26 (95CI, 0.05-1.30) for <3.7 GBq; 0.75 (95CI, 0.57-0.98) for ≥3.7 GBq. The number of patients needed to be prepared with rhTSH to prevent one case of LT-SGD ranged between seven and thirty-seven. There is moderate-quality scientific evidence that rhTSH preparation may consistently protect salivary gland function.

Role of 131I in low-risk differentiated thyroid cancer

Differentiated thyroid cancer (DTC) is the most frequent endocrine neoplasm, with an increase in recent decades. Papillary carcinoma is the most frequent histological subtype and a large number of cases are related to tumors of small size and with little clinical repercussion, detected incidentally or as a consequence of the availability of diagnostic techniques. The "good prognosis" of the majority of cases has maintained for years the controversy in the approach to these patients, especially in two basic aspects of the therapeutic protocol: surgery and the administration of radioiodine. While in metastatic and high-risk patients, the administration of ¹³¹I therapy is widely accepted, in intermediate-low risk patients its use is highly questioned. In this paper we review the available evidence on radioiodine therapy in low-risk patients.

The Patient Experience of Thyroid Cancer

The 3 phases of thyroid cancer care are discussed: diagnosis, management, and survivorship. Drivers of quality of life (QOL) in each phase are described, and suggestions are made for mitigating the risk of poor QOL. Active surveillance is another emerging management strategy that has the potential to improve QOL by eliminating upfront surgical morbidity but will need to be studied prospectively.

Paediatric differentiated thyroid carcinoma: a UK National Clinical Practice Consensus Guideline

This guideline is written as a reference document for clinicians presented with the challenge of managing paediatric patients with differentiated thyroid carcinoma up to the age of 19 years. Care of paediatric patients with differentiated thyroid carcinoma differs in key aspects from that of adults, and there have been several recent developments in the care pathways for this condition; this guideline has sought to identify and attend to these areas. It addresses the presentation, clinical assessment, diagnosis, management (both surgical and medical), genetic counselling, follow-up and prognosis of affected patients. The guideline development group formed of a multi-disciplinary panel of sub-speciality experts carried out a systematic primary literature review and Delphi Consensus exercise. The guideline was developed in accordance with The Appraisal of Guidelines Research and Evaluation Instrument II criteria, with input from stakeholders including charities and patient groups. Based on scientific evidence and expert opinion, 58 recommendations have been collected to produce a clear, pragmatic set of management guidelines. It is intended as an evidence base for future optimal management and to improve the quality of clinical care of paediatric patients with differentiated thyroid carcinoma.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

Treatment strategies for low-risk papillary thyroid carcinoma: a position statement from the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism (SBEM)

Increasingly sensitive diagnostic methods, better understanding of molecular pathophysiology, and well-conducted prospective studies have changed the current approach to patients with thyroid cancer, requiring the implementation of individualized management. Most patients with papillary thyroid carcinoma (PTC) are currently considered to have a low risk of mortality and disease persistence/recurrence. Consequently, current treatment recommendations for these patients include less invasive or intensive therapies. We used the most recent evidence to prepare a position statement providing guidance for decisions regarding the management of patients with low-risk PTC (LRPTC). This document summarizes the criteria defining LRPTC (including considerations regarding changes in the TNM staging system), indications and contraindications for active surveillance, and recommendations for follow-up and surgery. Active surveillance may be an appropriate initial choice in selected patients, and the criteria to recommend this approach are detailed. A section is dedicated to the current evidence regarding lobectomy versus total thyroidectomy and the potential pitfalls of each approach, considering the challenges during long-term follow-up. Indications for radioiodine (RAI) therapy are also addressed, along with the benefits and risks associated with this treatment, patient preparation, and dosage. Finally, this statement presents the best follow-up strategies for LRPTC after lobectomy and total thyroidectomy with or without RAI.

Strategies for Radioiodine Treatment: What’s New

Radioiodine treatment (RAI) represents the most widespread and effective therapy for differentiated thyroid cancer (DTC). RAI goals encompass ablative (destruction of thyroid remnants, to enhance thyroglobulin predictive value), adjuvant (destruction of microscopic disease to reduce recurrences), and therapeutic (in case of macroscopic iodine avid lesions) purposes, but its use has evolved over time. Randomized trial results have enabled the refinement of RAI indications, moving from a standardized practice to a tailored approach. In most cases, low-risk patients may safely avoid RAI, but where necessary, a simplified protocol, based on lower iodine activities and human recombinant TSH preparation, proved to be just as effective, reducing overtreatment or useless impairment of quality of life. In pediatric DTC, RAI treatments may allow tumor healing even at the advanced stages. Finally, new challenges have arisen with the advancement in redifferentiation protocols, through which RAI still represents a leading therapy, even in former iodine refractory cases. RAI therapy is usually well-tolerated at low activities rates, but some concerns exist concerning higher cumulative doses and long-term outcomes. Despite these achievements, several issues still need to be addressed in terms of RAI indications and protocols, heading toward the RAI strategy of the future.

Thyroid Carcinoma, Version 2.2022, NCCN Clinical Practice Guidelines in Oncology

Differentiated thyroid carcinomas is associated with an excellent prognosis. The treatment of choice for differentiated thyroid carcinoma is surgery, followed by radioactive iodine ablation (iodine-131) in select patients and thyroxine therapy in most patients. Surgery is also the main treatment for medullary thyroid carcinoma, and kinase inhibitors may be appropriate for select patients with recurrent or persistent disease that is not resectable. Anaplastic thyroid carcinoma is almost uniformly lethal, and iodine-131 imaging and radioactive iodine cannot be used. When systemic therapy is indicated, targeted therapy options are preferred. This article describes NCCN recommendations regarding management of medullary thyroid carcinoma and anaplastic thyroid carcinoma, and surgical management of differentiated thyroid carcinoma (papillary, follicular, Hürthle cell carcinoma).

Personalized Dosimetry in the Context of Radioiodine Therapy for Differentiated Thyroid Cancer

The most frequent thyroid cancer is Differentiated Thyroid Cancer (DTC) representing more than 95% of cases. A suitable choice for the treatment of DTC is the systemic administration of 131-sodium or potassium iodide. It is an effective tool used for the irradiation of thyroid remnants, microscopic DTC, other nonresectable or incompletely resectable DTC, or all the cited purposes. Dosimetry represents a valid tool that permits a tailored therapy to be obtained, sparing healthy tissue and so minimizing potential damages to at-risk organs. Absorbed dose represents a reliable indicator of biological response due to its correlation to tissue irradiation effects. The present paper aims to focus attention on iodine therapy for DTC treatment and has developed due to the urgent need for standardization in procedures, since no unique approaches are available. This review aims to summarize new proposals for a dosimetry-based therapy and so explore new alternatives that could provide the possibility to achieve more tailored therapies, minimizing the possible side effects of radioiodine therapy for Differentiated Thyroid Cancer.

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.

Thyroglobulin-Based Risk Factor Repositioning for Determining Radioactive Iodine Activity in Patients with Papillary Thyroid Carcinoma: a Multicenter Retrospective Cohort Study

Purpose

We aimed to investigate the impact of various factors including radioactive iodine (RAI) activity on the therapeutic response according to the range of serum thyroglobulin (Tg) in patients with papillary thyroid carcinoma (PTC).

Methods

A total of 2809 patients were retrospectively enrolled from 24 hospitals. They were divided into four subgroups according to their serum Tg (stimulated Tg, sTg) or anti-Tg antibody (TgAb) levels, measured just before RAI therapy: sTg < 2 ng/mL, 2 ≤ sTg < 10 ng/mL, sTg ≥ 10 ng/mL, and TgAb > 100 IU/mL. The clinicopathologic factors for therapeutic responses, which were classified as acceptable response (AR) or non-AR, were compared in each subgroup.

Results

Clinical impact of the pN category on therapeutic response was different among subgroups based on sTg levels (subgroups with sTg < 2 ng/mL (P = 0.057), 2 ≤ sTg < 10 ng/mL (P = 0.032), and sTg ≥ 10 ng/mL (P = 0.001)). The pN category was also a significant factor in the subgroup with TgAb > 100 IU/mL (P = 0.006). The pT category was not associated with therapeutic response regardless of the sTg level. High activities of RAI (≥ 3.70 GBq) were associated with favorable therapeutic responses in only the subgroup with sTg ≥ 10 ng/mL (P = 0.044).

Conclusion

Risk factors for response prediction could be repositioned based on the serum Tg before RAI therapy. RAI activity should be determined while considering the serum Tg-aided remnant thyroid or malignant tissues as well as conventional factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-022-00756-4.

Functional imaging in thyroid cancer patients with metastases and therapeutic implications

Functional imaging plays a central role in the management of thyroid cancer patients. In patients with a differentiated thyroid cancer (DTC), radioactive iodine (RAI) is used mostly with a therapeutic intent, either post-operatively or as the first line systemic treatment in patients with known structural disease. A whole body scan is performed a few days after the RAI administration, and this procedure is very sensitive to detect all tumor foci with RAI uptake. PET/CT with ¹⁸F-FDG complements the use of RAI at the initial evaluation of patients with high-risk DTC, during follow-up in those with rising serum thyroglobulin levels over time, for the work-up of patients with documented structural disease and for assessing the efficacy of focal or systemic treatment modalities. ¹⁸F-FDG uptake is a prognostic indicator in all these clinical conditions. A dosimetric approach with ¹²⁴I PET/CT showed encouraging results. Several functional imaging modalities are currently available for medullary thyroid carcinoma (MTC) patients. ¹⁸F-FDG-PET/CT may be sensitive in MTC patients with high FDG uptake that signals aggressive disease. ¹⁸F-DOPA is the most sensitive imaging technique to visualize small tumor foci, and is also highly specific in patients with a known MTC, but should be complemented by a CT scan of the chest and by a MRI of the liver to detect small metastases.

Assessment of Different Radioiodine Doses for Post-ablation Therapy of Thyroid Remnants: A Systematic Review

The determination of radioiodine remnant ablation (RRA) dosage in post-operation thyroid residual tissues resection has been largely subject of discussion, yet no concise conclusion is released through systematic review studies. In this study, we conducted a systematic review of comparative experiments to evaluate and compare the efficacy of different prescribed dosages of radioiodine in post-op thyroid residual tissues resection among low, intermediate, and high-risk patients to approve the common method. Using automated searches, studies were collected from PubMed, Google Scholar, Elsevier, Scopus, and UpToDate, all until April 2021. Alongside the aforementioned sources, comparative experiments were added in for further investigation. Overall, 4000 patients with papillary thyroid cancer, differentiated thyroid carcinoma (DTC), metastasized and non-metastasized thyroid cancer took part in twenty-one trials are assessed. We discovered no significant difference in successful thyroid residual tissues excision between low-activity and high-activity radioiodine treatment in people with low and intermediate risk. In these individuals, there was no significant difference between the high therapeutic dose of 3700 MBq and the lesser dose of 1850 MBq for RRA. However, high-dose treatment usually yielded superior results. Low activity RRA causes fewer adverse effects in metastasis-free patients than high-activity 3.7 GBq. There was no significant therapeutic difference regarding treatment efficacy in patients with low and moderate risks. However, in patients with high-risk status, applying a high-dose regimen of RRA produced a significantly better response.

Radioactive iodine therapy: multiple faces of the same polyhedron

The incidence of differentiated thyroid carcinoma (DTC) has increased in recent decades with early stage, low risk papillary thyroid cancer (PTC) being detected and diagnosed. As a result, the psychological, financial, and clinical ramifications of overdiagnosis and excessively aggressive therapy are being increasingly recognized with many authorities calling for a re-evaluation of the traditional "one size fits all" management approaches. To address these critical issues, most thyroid cancer guidelines endorse a more risk adapted management strategy where the intensity of therapy and follow up is matched to the anticipated risk of recurrence and death from DTC for each patient. This "less is more" strategy provides for a minimalistic management approach for properly selected patients with low-risk DTC. This has re-kindled the long-standing debate regarding the routine use of radioactive iodine therapy (RIT) in DTC. Although recent guidelines have moved toward a more selective use of RIT, particular in patients with low-intermediate risk DTC, the proper selection of patients, the expected benefit, and the potential risks continue to be a source of ongoing controversy and debate. In this manuscript, we will review the wide range of clinical, imaging, medical team, and patient factors that must be considered when evaluating individual patients for RIT. Through a review of the current literature evaluating the potential benefits and risks of RIT, we will present a risk adapted approach to proper patient selection for RIT which emphasizes peri-operative risk stratification as the primary tool that clinicians should use to guide initial RIT management recommendations.

Individualized treatment of differentiated thyroid cancer: The value of surgery in combination with radioiodine imaging and therapy - A German position paper from Surgery and Nuclear Medicine

A consensus statement about indications for post-surgical radioiodine therapy (RIT) in differentiated thyroid cancer patients (DTC) was recently published by the European Thyroid Association (ETA) 1. This publication discusses indications for RIT on the basis of an individual risk assessment. Many of the conclusions of this consensus statement are well founded and accepted across the disciplines involved. However, especially from the perspective of nuclear medicine, as the discipline responsible for indicating and executing RIT, some of the recommendations may require further clarification with regard to their compatibility with established best practice and national standards of care. Assessment of the indications for RIT is strongly dependent on the weighing up of benefits and risks. On the basis of longstanding clinical experience in nuclear medicine, RIT represents a highly specific precision medicine procedure of proven efficacy with a favorable side-effect profile. This distinguishes RIT significantly from other adjuvant oncological therapies and has resulted in the establishment of this procedure as a usually well-tolerated, standard safety measure. With regard to its favorable risk/benefit ratio, this procedure should not be unnecessarily restricted, in the interest of offering reassurance to the patients. Both patients' interests and regional/national differences need to be taken into account. We would therefore like to comment on the recent consensus from the perspective of authors and to provide recommendations based on the respective published data.

State of the Art in the Current Management and Future Directions of Targeted Therapy for Differentiated Thyroid Cancer

Two-thirds of differentiated thyroid cancer (DTC) patients with distant metastases would be classified as radioactive iodine-refractory (RAIR-DTC), evolving into a poor outcome. Recent advances underlying DTC molecular mechanisms have shifted the therapy focus from the standard approach to targeting specific genetic dysregulations. Lenvatinib and sorafenib are first-line, multitargeted tyrosine kinase inhibitors (TKIs) approved to treat advanced, progressive RAIR-DTC. However, other anti-angiogenic drugs, including single targeted TKIs, are currently being evaluated as alternative or salvage therapy after the failure of first-line TKIs. Combinatorial therapy of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signalling cascade inhibitors has become a highly advocated strategy to improve the low efficiency of the single agent treatment. Recent studies pointed out targetable alternative pathways to overcome the resistance to MAPK and PI3K pathways’ inhibitors. Because radioiodine resistance originates in DTC loss of differentiation, redifferentiation therapies are currently being explored for efficacy. The present review will summarize the conventional management of DTC, the first-line and alternative TKIs in RAIR-DTC, and the approaches that seek to overcome the resistance to MAPK and PI3K pathways’ inhibitors. We also aim to emphasize the latest achievements in the research of redifferentiation therapy, immunotherapy, and agents targeting gene rearrangements in advanced DTC.

Thyroidectomy without Radioiodine in Patients with Low-Risk Thyroid Cancer

BACKGROUND

In patients with low-risk differentiated thyroid cancer undergoing thyroidectomy, the postoperative administration of radioiodine (iodine-131) is controversial in the absence of demonstrated benefits.

METHODS

In this prospective, randomized, phase 3 trial, we assigned patients with low-risk differentiated thyroid cancer who were undergoing thyroidectomy to receive ablation with postoperative administration of radioiodine (1.1 GBq) after injections of recombinant human thyrotropin (radioiodine group) or to receive no postoperative radioiodine (no-radioiodine group). The primary objective was to assess whether no radioiodine therapy was noninferior to radioiodine therapy with respect to the absence of a composite end point that included functional, structural, and biologic abnormalities at 3 years. Noninferiority was defined as a between-group difference of less than 5 percentage points in the percentage of patients who did not have events that included the presence of abnormal foci of radioiodine uptake on whole-body scanning that required subsequent treatment (in the radioiodine group only), abnormal findings on neck ultrasonography, or elevated levels of thyroglobulin or thyroglobulin antibodies. Secondary end points included prognostic factors for events and molecular characterization.

RESULTS

Among 730 patients who could be evaluated 3 years after randomization, the percentage of patients without an event was 95.6% (95% confidence interval [CI], 93.0 to 97.5) in the no-radioiodine group and 95.9% (95% CI, 93.3 to 97.7) in the radioiodine group, a difference of -0.3 percentage points (two-sided 90% CI, -2.7 to 2.2), a result that met the noninferiority criteria. Events consisted of structural or functional abnormalities in 8 patients and biologic abnormalities in 23 patients with 25 events. Events were more frequent in patients with a postoperative serum thyroglobulin level of more than 1 ng per milliliter during thyroid hormone treatment. Molecular alterations were similar in patients with or without an event. No treatment-related adverse events were reported.

CONCLUSIONS

In patients with low-risk thyroid cancer undergoing thyroidectomy, a follow-up strategy that did not involve the use of radioiodine was noninferior to an ablation strategy with radioiodine regarding the occurrence of functional, structural, and biologic events at 3 years. (Funded by the French National Cancer Institute; ESTIMABL2 ClinicalTrials.gov number, NCT01837745.).

Initial Evaluation of Therapy Response after Adjuvant Radioiodine Therapy in Patients with Early-Stage Papillary Thyroid Cancer-Does Time Matter?

BACKGROUND

The aim was to assess ablation success after initial radioiodine (RAI) therapy in early-stage PTC patients and compare outcomes of first diagnostic control after 6 and 9 months (6m/9m-DC) to examine whether time could possibly avoid unnecessary overtreatment.

METHODS

There were 353 patients who were matched regarding age, sex, and tumor stage and divided in two groups depending on time of first DC (6m- and 9m-DC). Therapy response was defined as thyroglobulin level <0.5 ng/mL, no pathological uptake in the diagnostic I-131 whole-body scintigraphy (WBS), and no further RAI therapy courses. The 6m-DC group was further divided into endogenously and exogenously stimulated TSH before RAI therapy and compared regarding outcome.

RESULTS

No significant differences were found between 6m-DC vs. 9m-DC regarding I-131 uptake in WBS (p = n.s.), Tg levels (p = n.s.), re-therapy rates (p = n.s.), and responder rates (p = n.s.). Significantly less relevant pathological I-131 uptake was found in WBS (p = 0.006) in endogenously compared to exogenously stimulated 6m-DC patients, resulting in lower re-therapy (p = 0.028) and higher responder rates (p = 0.001).

CONCLUSION

DC at 6 months after RAI therapy and stimulation with recombinant human thyroid-stimulating hormone (rhTSH) represent the most balanced solution. Particularly regarding quality of life and mental relief of patients, early DC with rhTSH represents sufficient and convenient assessment of ablation success.

Comparing High and Low-Dose Radio-Iodine Therapy in Thyroid Remnant Ablation Among Intermediate and Low-Risk Papillary Thyroid Carcinoma Patients-Single Centre Experience

The role of Iodine-131 therapy is well established as an adjuvant therapy and for thyroid remnant ablation in differentiated thyroid cancer (DTC); however controversy still exists regarding its appropriate dose. Purpose of this study was to compare the effectiveness of low-dose and high-dose Iodine-131 ablation therapies in low- and intermediate-risk PTC patients. Eighty-four patients were divided equally into Group I: Ablated with high dose of Iodine-131 and Group II: Ablated with low dose of Iodine-131. Iodine-131 WBS, serum TG levels and USG neck of all patients were performed at first presentation, 6 months, 1 year, and 2 years follow up. Results are as follows: Group I: 64%, 72%, and 76% intermediate-risk patients were disease free at the follow up intervals of 6 months, 1 year, and 2 years, respectively. Similarly 70%, 82%, and 82% low-risk patients were disease free at above mentioned intervals. Group II: 56%, 60%, and 64% were disease free among intermediate-risk patients while percentage of disease free low-risk patients was 70%, 76%, and 76% at follow up intervals. Low dose of radioactive Iodine-131 was found as effective as high dose in thyroid remnant ablation of PTC patients.