Outcome after ablation in patients with low-risk thyroid cancer (ESTIMABL1): 5-year follow-up results of a randomised, phase 3, equivalence trial

Advances in Functional Imaging of Differentiated Thyroid Cancer

Simple Summary

Since the 1940s, radioactive iodine has been used for functional imaging and for treating patients with differentiated thyroid cancer (DTC). During this long-lasting experience, the use of iodine isotopes evolved, especially during the last years due to improved knowledge of thyroid cancer biology and improved performances of imaging tools. The present review summarizes recent advances in the field of functional imaging and theragnostic approach of DTC.

Abstract

The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with ¹⁸F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond ¹⁸F-FDG PET/CT, other tracers including ¹²⁴I, ¹⁸F-TFB and ⁶⁸Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments.

Radioiodine Remnant Ablation for Differentiated Thyroid Cancer: A Systematic Review and Meta-analysis

Importance

Postoperative radioactive iodine (RAI) remnant ablation for differentiated thyroid cancer (DTC) facilitates the early detection of recurrence and represents an adjuvant therapy that targets persistent microscopic disease. The optimal activity of RAI in low- and intermediate-risk DTC remains controversial.

Objective

To evaluate the long-term cure rate of different RAI activities in low- and intermediate-risk DTC. Secondary outcomes included successful remnant ablation, adverse effects, and hospital length of stay.

Data Source

A systematic search of the databases PubMed, Cochrane Collaboration, Embase, Scopus, and Web of Science was performed to identify randomized clinical trials (RCTs) and observational studies that compared long-term outcomes (>12 months) for American Thyroid Association-classified low- and intermediate-risk DTC based on receipt of either low-activity or high-activity RAI postoperatively.

Study Selection

All RCTs or observational studies evaluating patients with low- and intermediate-risk DTC who were treated initially with total/near-total thyroidectomy, followed by remnant RAI ablation with either low or high activities. Eligible studies had to present odds ratio, relative risk (RR), or hazard ratio estimates (with 95% CIs), standard errors, or the number of events necessary to calculate these for the outcome of interest rate.

Data Extraction

Two investigators reviewed the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Dichotomous variables were pooled as risk ratios and continuous data as weighted-mean differences. Quality assessment of the included studies was performed using the Newcastle-Ottawa and Jadad scales.

Main Outcomes and Measures

Disease recurrence was the primary outcome. Secondary outcomes included successful ablation, adverse effects, and length of stay.

Results

Ten studies that included 3821 patients met inclusion criteria, including 6 RCTs and 4 observational studies. There was no difference in long-term cure recurrence rates (RR, 0.88; 95% CI, 0.62-1.27, P = .50) or successful remnant ablation (RR, 0.95; 95% CI, 0.87-1.03; P = .20) between low-activity and high-activity RAI.

Conclusions and Relevance

In this systematic review and meta-analysis, low-activity RAI was comparable with high-activity RAI regarding successful ablation and recurrence rates. This suggests that low-activity RAI is preferable to high-activity in low- and intermediate-risk DTC because of its similar efficacy but reduced morbidity.

Trial Registration

PROSPERO Identifier: CRD42020166780.

Assessing potential impact of 2015 American Thyroid Association guidelines on community standard practice for I-131 treatment of low-risk differentiated thyroid cancer: case study of Jordan

OBJECTIVES

The 2015 American Thyroid Association (ATA) guidelines called for significantly more selective ¹³¹I therapy in patients with low-risk differentiated thyroid cancer (DTC). We hypothesized that application of these guidelines would significantly reduce the ¹³¹I activity utilized by an academic tertiary hospital in Jordan.

METHODS

All DTC patients managed at Jordan University Hospital (JUH) between 1/2009 and 6/2019 were classified according to the 2015 ATA risk category and ¹³¹I activity was assigned accordingly. The actual ¹³¹I activity administered was compared with that recommended by the 2015 ATA guidelines.

RESULTS

In total, 135/182 DTC patients (74.2%) managed at JUH underwent ¹³¹I therapy. Of those, 58 (43%) had ATA low-, 58 (43%) intermediate-, and 19 (14%) high-risk disease. The low-, intermediate-, and high-risk DTC patients received an average (±SD) initial ¹³¹I activity of 3.53 ± 0.95, 4.40 ± 1.49, and 5.06 ± 2.52 GBq, respectively. Withholding ¹³¹I therapy altogether in the 2015 ATA low-risk patients would result in decreasing the ¹³¹I activity in the overall patient population by 37%. Withholding ¹³¹I therapy only in low-risk papillary thyroid microcarcinomas while administering 1.11 GBq of ¹³¹I to other low-risk patients would result in 28% reduction of ¹³¹I.

CONCLUSION

This study demonstrates a significant reduction in ¹³¹I therapeutic activity that would be given to DTC patients in an academic tertiary setting in Jordan, following acceptance of the 2015 ATA recommendations. Institutions that adopted the 2015 ATA guidance should measure outcomes in comparison to their historical controls and report those findings, while long-term results of randomized controlled trials are forthcoming.

Change in Practice of Radioactive Iodine Administration in Differentiated Thyroid Cancer: A Single-Centre Experience

OBJECTIVE

Our study aimed to analyse temporal trends in radioactive iodine (RAI) treatment for thyroid cancer over the past decade; to analyse key factors associated with clinical decisions in RAI dosing; and to confirm lower activities of RAI for low-risk patients were not associated with an increased risk of recurrence.

METHODS

Retrospective analysis of 1,323 patients who received RAI at a quaternary centre in Australia between 2008 and 2018 was performed. Prospectively collected data included age, gender, histology, and American Joint Committee on Cancer stage (7th ed). American Thyroid Association risk was calculated retrospectively.

RESULTS

The median activities of RAI administered to low-risk patients decreased from 3.85 GBq (104 mCi) in 2008-2016 to 2.0 GBq (54 mCi) in 2017-2018. The principal driver of this change was an increased use of 1 GBq (27 mCi) from 1.3% of prescriptions in 2008-2011 to 18.5% in 2017-2018. In patients assigned as low risk per ATA stratification, lower activities of 1 GBq or 2 GBq (27 mCi or 54 mCi) were not associated with an increased risk of recurrence. In patients assigned to intermediate- or high-risk categories who received RAI as adjuvant therapy, there was no difference in risk of recurrence between 4 GBq (108 mCi) and 6 GBq (162 mCi).

CONCLUSIONS

Our data demonstrate an evolution of RAI activities consistent with translation of ATA guidelines into clinical practice. Use of lower RAI activities was not associated with an increase in recurrence in low-risk thyroid cancer patients. Our data also suggest lower RAI activities may be as efficacious for adjuvant therapy in intermediate- and high-risk patients.

Thyroid cancer, recent advances in diagnosis and therapy

Over the past several decades, the approach to the diagnosis and management of patients with follicular cell-derived thyroid cancer has evolved based on improved classification of patients better matching clinical outcomes, as well as advances in imaging, laboratory, molecular technologies and knowledge. While thyroid surgery, radioactive iodine therapy and TSH suppression remain the mainstays of treatment, this expansion of knowledge has enabled de-escalation of therapy for individuals diagnosed with low-risk well-differentiated thyroid cancer; better definition of treatment choices for patients with more aggressive disease; and improved ability to optimize treatments for patients with persistent and/or progressive disease. Most recently, the advancement of knowledge regarding the molecular aspects of thyroid cancer has improved thyroid cancer diagnosis and has enabled individualized therapeutic options for selected patients with the most aggressive forms of the disease. Guidelines from multiple societies across the world reflect these changes, which focus on taking a more individualized approach to clinical management. In this review, we discuss the current more personalized approach to patients with follicular cell-derived thyroid cancer and point toward areas of future research still needed in the field.

Ablation therapy using a low dose of radioiodine may be sufficient in low- to intermediate-risk patients with follicular variant papillary thyroid carcinoma

OBJECTIVES

Follicular variant papillary thyroid carcinoma (FVPTC) is treated similarly to classical variant papillary thyroid carcinoma (cPTC). However, FVPTC has unique tumour features and behaviours. We investigated whether a low dose of radioiodine was as effective as a high dose for remnant ablation in patients with FVPTC and evaluated the recurrence of low-intermediate risk FVPTC.

METHODS

Data from cPTC and FVPTC patients treated with I-131 from 2004 to 2014 were reviewed. Demographics, tumour behaviour, lymph node metastasis, and local recurrence data were compared between FVPTC and cPTC patients. Then, low-intermediate risk FVPTC patients were divided into low, intermediate, and high I-131 dose groups, and postoperative I-131 activities were analysed to evaluate the effectiveness of I-131 therapy for thyroid remnant ablation.

RESULTS

In total, 799 cases of FVPTC (n = 168) and cPTC (n = 631) treated with I-131 were identified. Patients with FVPTC had a larger primary nodule size than cPTC, but lymph node metastases and local recurrence were more prevalent in cPTC than in FVPTC. For the low-, intermediate-, and high-dose groups, success rates of ablation did not differ (82.0%, 80%, and 81.3%, respectively).

CONCLUSION

FVPTC differs from cPTC in behaviour. Low-dose ablation may be sufficient in FVPTC patients with low-intermediate disease risk.

Current practice in patients with differentiated thyroid cancer

Considerable changes have occurred in the management of differentiated thyroid cancer (DTC) during the past four decades, based on improved knowledge of the biology of DTC and on advances in therapy, including surgery, the use of radioactive iodine (radioiodine), thyroid hormone treatment and availability of recombinant human TSH. Improved diagnostic tools are available, including determining serum levels of thyroglobulin, neck ultrasonography, imaging (CT, MRI, SPECT-CT and PET-CT), and prognostic classifications have been improved. Patients with low-risk DTC, in whom the risk of thyroid cancer death is <1% and most recurrences can be cured, currently represent the majority of patients. By contrast, patients with high-risk DTC represent 5-10% of all patients. Most thyroid cancer-related deaths occur in this group of patients and recurrences are frequent. Patients with high-risk DTC require more aggressive treatment and follow-up than patients with low-risk DTC. Finally, the strategy for treating patients with intermediate-risk DTC is frequently defined on a case-by-case basis. Prospective trials are needed in well-selected patients with DTC to demonstrate the extent to which treatment and follow-up can be limited without increasing the risk of recurrence and thyroid cancer-related death.

Risk of structural persistent disease in pediatric patients with low or intermediate risk differentiated thyroid cancer

PURPOSE

In pediatric patients with differentiated thyroid cancer (DTC), the risk of recurrence is high and the indication for postoperative ¹³¹I administration is still debated. The aim of this study was to assess the outcome in low and intermediate risk pediatric DTC patients.

METHODS

We retrospectively evaluated 45 pediatric patients with low or intermediate risk DTC, treated with surgery and ¹³¹I between 1992 and 2002 and with no detectable antithyroglobulin (Tg) antibodies. Follow-up was performed every 6-12 months with Tg blood level determination and imaging procedures.

RESULTS

During follow-up (64 ± 53 months), 15 events occurred (33% cumulative event rate, with an annual event rate of 5% person years). Five of these patients were submitted to additional surgery and all these 15 patients underwent a second ¹³¹I treatment course. All patients were alive at the end of the follow-up. Structural persistent disease occurred more frequently in patients at intermediate risk (p < 0.01) and in those with Tg values after thyroid hormone withdrawal >10 ng/ml before ¹³¹I therapy (p < 0.01). At multivariate analysis, only a postoperative thyroid stimulating hormone-stimulated Tg level >10 ng/ml was an independent predictor of persistent disease.

CONCLUSIONS

In pediatric patients with DTC, postoperative high stimulated Tg values (>10 ng/ml) should be taken into account for deciding the extent of both initial treatment and follow-up.

The Optimal Activity of Radioactive Iodine for Remnant Ablation in Low/Intermediate Risk Differentiated Thyroid Carcinoma: A Continuous Controversy and Meta-Analysis

Radioactive iodine (RAI) is widely used for remnant ablation in low/intermediate differentiated thyroid carcinoma (DTC). However, the optimal effective dose that overweighs the benefits over unwanted side effects is a matter of controversy. This meta-analysis aimed to assess low versus high doses of RAI activity for DTC remnant ablation. Two authors independently searched PubMed and Cochrane Library using the keywords low dose radioactive iodine, high dose radioactive iodine, low-risk/intermediate risk, differentiated thyroid carcinoma, and remnant ablation. Two hundred and twenty references were identified when limiting the engine to controlled trials in English and during the period from January 2010 to December 2020. Nine trials (five from Europe and four from Asia) including 3137 patients fulfilled the inclusion and exclusion criteria. The data were then entered in an extraction sheet detailing the trial information including the author's name, year of publication, country, and type of surgery, preparation for RAI, the patients and control number in the low and high-dose groups, follow-up period, and the results. Out of 220 articles retrieved, nine controlled trials were included (follow-up period range, six months to 12 years, 3137 patients, and low risk of bias). The analysis favored the high dose for remnants ablation, odd ratio, 0.73, 95% CI, 0.50-1.07; P-value for the overall effect was 0.10. However, the results were limited due to the significant heterogeneity observed (56%, P-value 0.03). High-dose RAI was better for DTC remnants ablation. Further studies focusing on intermediate-risk DTC and adjusting for preoperative and postoperative factors are recommended.

Advancements in the treatment of differentiated thyroid cancer

Derived from follicular epithelial cells, differentiated thyroid cancer (DTC) accounts for the majority of thyroid malignancies. The threefold increase in DTC incidence over the last three decades has been largely attributed to advancements in detection of papillary thyroid microcarcinomas. Efforts to address the issue of overtreatment have notably included the reclassification of encapsulated follicular variant papillary thyroid cancers (EFVPTC) to non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). In the last 5 years, the overall management approach for this relatively indolent cancer has become less aggressive. Although surgery and radioiodine ablation remain the mainstay of DTC therapy, the role of active surveillance is being explored. Furthermore, the most recent American Thyroid Association (ATA) guidelines offer flexibility between lobectomy and total thyroidectomy for thyroid nodules between 1 cm and 4 cm in the absence of extrathyroidal extension or nodal disease. As our understanding of the natural history and molecular underpinnings of DTC evolves, so might our approach to managing low-risk patients, obviating the need for invasive intervention. Simultaneously, advances in interventional and systemic therapies have greatly expanded treatment options for high-risk surgical candidates and patients with widespread disease, and continue to be areas of active investigation. Continued research efforts are essential to improve our ability to offer effective individualized therapy to patients at all disease stages and to reduce the incidence of recurrent and progressive disease.

Multimodal imaging of thyroid cancer

PURPOSE OF REVIEW

Thyroid cancer is the most common endocrine cancer in adults with rising incidence. Challenges in imaging thyroid cancer are twofold: distinguishing thyroid cancer from benign thyroid nodules, which occur in 50% of the population over 50 years; and correct staging of thyroid cancer to facilitate appropriate radical surgery in a single session. The clinical management of thyroid cancer patients has been covered in detail by the 2015 guidelines of the American Thyroid Association (ATA). The purpose of this review is to state the principles underlying optimal multimodal imaging of thyroid cancer and aid clinicians in avoiding important pitfalls.

RECENT FINDINGS

Recent additions to the literature include assessment of ultrasound-based scoring systems to improve selection of nodules for fine needle biopsy (FNB) and the evaluation of new radioactive tracers for imaging thyroid cancer.

SUMMARY

The mainstay of diagnosing thyroid cancer is thyroid ultrasound with ultrasound-guided FNB. Contrast-enhanced computed tomography and PET with [F]-fluorodeoxyglucose (FDG) and MRI are reserved for advanced and/or recurrent cases of differentiated thyroid cancer and anaplastic thyroid cancer, while [F]FDOPA and [Ga]DOTATOC are the preferred tracers for medullary thyroid cancer.

Can we safely reduce the administration of 131-iodine in patients with differentiated thyroid cancer? - experience of the Brugmann hospital in Brussels

Background

131-iodine (¹³¹I) administration after surgery remains a standard practice in differentiated thyroid cancer (DTC). In 2014, the American Thyroid Association presented new guidelines for the staging and management of DTC, including no systematic ¹³¹I in patients at low-risk of recurrence and a reduced ¹³¹I activity in intermediate risk.The present study aims at evaluating the rate of response to treatment following this new therapeutic management compared to our previous treatment strategy in patients with DTC of different risks of recurrence.

Methods

Patients treated and followed up for DTC according to the 2014-ATA guidelines (Group 2) were compared to those treated between 2007 and 2014 (Group 1) in terms of general characteristics, risk of recurrence (based on the 2015-ATA recommendations), preparation to ¹³¹I administration, cumulative administered ¹³¹I activity and response to treatment.

Results

In total, 136 patients were included: 78 in Group 1 and 58 in Group 2. The two groups were not statistically different in terms of clinical characteristics nor risk stratification: 42.3% in Group 1 and 31% in Group 2 were classified as low risk, 38.5 and 48.3% as intermediate risk and 19.2 and 20.7% as high risk (P = 0.38). Two patients (one in each group) with distant metastases were excluded from the analysis.Preparation to ¹³¹I administration consisted in rhTSH stimulation in 23.4% of the patients in Group 1 and 100% in Group 2 (p < 0.001).¹³¹I was administered to 46/77 patients (59.7%) in Group 1 (5 at low risk of recurrence) and 38/57 patients (66.7%) in Group 2 (0 with a low risk). Among the patients treated by ¹³¹I, median cumulative activity was significantly higher in Group 1 (3.70GBq [100 mCi] range 1.11-11.1 GBq [30-300 mCi]) than in Group 2 (1.11 GBq [30 mCi], range 1.11-7.4 GBq [30-200 mCi], P < 0.001). Complete response was found in 90.9% in Group 1 vs. 96.5% in Group 2 (P = 0.20).

Conclusions

Using the 2015-ATA evidence-based guidelines for the management of DTC, meaning no ¹³¹I administration in low-risk patients, a low activity in intermediate and even high risk patients, and a systematic use of rhTSH stimulation before ¹³¹I therapy allowed us to reduce significantly the median administered ¹³¹I activity, with a similar rate of complete therapeutic response.

Ultrasonography surveillance in papillary thyroid carcinoma patients after total thyroidectomy according to dynamic risk stratification

PURPOSE

To investigate the role of neck US surveillance in patients with papillary thyroid carcinoma (PTC) after total thyroidectomy according to dynamic risk stratification (DRS) based on response to initial therapy.

METHODS

This retrospective study included 812 patients with PTC who underwent total thyroidectomy with prophylactic central neck dissection from January 2003 through February 2007. The relative risk of recurrence/persistence according to DRS was evaluated with the multivariable Cox regression proportional hazard model.

RESULTS

There were 132 men and 680 women. The mean age at surgery was 45.2 years. Postoperative US was used for DRS. According to DRS, 676 patients had excellent response, 78 indeterminate response, 40 biochemical incomplete response, and 18 structural incomplete response to initial therapy. Neck US was performed during follow-up and detected locoregional recurrences in 21 patients (2.6%): 12 with excellent response, 2 with biochemical incomplete response, and 7 with structural incomplete response according to DRS. Only 1 patient (0.1%) with excellent response had a locoregional recurrence that exceeded 8 mm in its shortest diameter, which is the size cut-off for diagnostic US fine-needle aspiration in suspicious lymph nodes. This patient did not develop biochemical abnormalities during follow-up.

CONCLUSIONS

Postoperative neck US surveillance after total thyroidectomy with prophylactic central neck dissection is not essential in PTC patients who show excellent response to initial therapy. Future studies are needed to verify the role of US surveillance in patients who receive variable degrees of treatments.

Longer-term recurrence rate after low versus high dose radioiodine ablation for differentiated thyroid Cancer in low and intermediate risk patients: a meta-analysis

Background

Regarding the longer-term recurrence rate the optimal activity for the remnant thyroid ablation in patients with differentiated thyroid cancer (DTC) is discussed controversially. For the short-term ablation success rate up to 12 months there are already several meta-analyses. In this study we performed the first meta-analysis regarding the longer-term recurrence rate after radioactive 131-I administration.

Methods

We conducted an electronic search using PubMed/MEDLINE, EMBASE and the Cochrane Library. All randomized controlled trials (RCTs) assessed the recurrence rate after radioactive iodine ablation in patients with DTC, with a follow-up of at least two years were selected. Statistics were performed by using Review Manager version 5.3 and Stata software.

Results

Four RCTs were included in the study, involving 1501 patients. There was no indication for heterogeneity (I² = 0%) and publication bias. The recurrence rate among patients who had a low dose 131-iodine ablation was not higher than for a high dose activity (odds ratio (OR) 0.93 [95% confidence interval (CI) 0.53–1.63]; P = 0.79). The mean follow-up time was between 4.25 and 10 years. The subgroup analysis regarding the TSH stimulated thyroglobulin values (< 10 ng/mL versus < 2 ng/mL versus ≤1 ng/mL) showed no influence on recurrence rate.

Conclusions

For the first time we showed that the longer-term, at least 2-year follow-up, recurrence rate among patients who had 131-iodine ablation with 1.1 GBq was not higher than with 3.7 GBq.

Contemporary considerations in adjuvant radioiodine treatment of adults with differentiated thyroid cancer

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy with a growing incidence worldwide. The initial conventional management is surgery, followed by consideration of ¹³¹ I treatment that includes three options. These are termed remnant ablation (targeting benign thyroid remnant), adjuvant (targeting presumed microscopic DTC) and known disease (targeting macroscopic DTC) treatments. Some experts mostly rely on clinicopathologic assessment for recurrence risk to select patients for the ¹³¹ I treatment. Others, in addition, apply radioiodine imaging to guide their treatment planning, termed theranostics (aka theragnostics or radiotheragnostics). In patients with low-risk DTC, remnant ablation rather than adjuvant treatment is generally recommended and, in this setting, the ATA recommends a low ¹³¹ I activity. ¹³¹ I adjuvant treatment is universally recommended in patients with high-risk DTC (a primary tumor of any size with gross extrathyroidal extension) and is generally recommended in intermediate-risk DTC (primary tumor >4 cm in diameter, locoregional metastases, microscopic extrathyroidal extension, aggressive histology or vascular invasion). The optimal amount of ¹³¹ I activity for adjuvant treatment is controversial, but experts reached a consensus that the ¹³¹ I activity should be greater than that for remnant ablation. The main obstacles to establishing timely evidence through randomized clinical trials for ¹³¹ I therapy include years-to-decades delay in recurrence and low disease-specific mortality. This mini-review is intended to update oncologists on the most recent clinical, pathologic, laboratory and imaging variables, as well as on the current ¹³¹ I therapy-related definitions and management paradigms, which should optimally equip them for individualized patient guidance and treatment.

The impact of radioactive iodine treatment on survival among papillary thyroid cancer patients according to the 7th and 8th editions of the AJCC/TNM staging system: a SEER-based study

Papillary thyroid cancer is a very common endocrine malignancy. The 8th American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system introduced major changes. We conducted this retrospective cohort analysis to assess the benefits of radioactive iodine (RAI) according to different stratification of patients. The source of the data was the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. From 2006 to 2015, patients with papillary thyroid cancer were included in our study. The interactions between different variables and RAI treatment were tested by multivariate Cox regression models to compare the survival differences according to RAI treatment between the patients assessed with the 7th and 8th edition of the AJCC/TNM staging system. The results of the interaction analysis and group comparisons indicated that the effects of RAI treatment on patients staged with the 7th and 8th editions were similar. Patients with early Stage, early T stage, N0 and subtotal or near total thyroidectomy benefited greatly from RAI treatment. Patients with Stage III according to the 8th edition benefited less from RAI than patients with Stage III according to the 7th edition. Patients with T1a benefited from RAI but benefited less than patients with other T stages. Patients with T3a benefited more from RAI than those with T3b. According to the 8th edition, Stage III/IV more accurately differentiates patients with advanced stage disease. These patients benefitted less from RAI treatment, which may be due to the relatively weaker iodine uptake by tumor cells. T1a patients benefitted less than patients with other T stages. The difference in RAI benefit between patients with T3a and T3b is a novel finding in our study.

Efficacy of Low-Dose Radioiodine Ablation in Low- and Intermediate-Risk Differentiated Thyroid Cancer: A Retrospective Comparative Analysis

(1) Background-low-dose radioiodine ablation is an accepted strategy for the treatment of low- and intermediate-risk thyroid carcinomas, although there is no international consensus. The aim of this study is to describe the clinical experience with low-dose radioiodine ablation in patients with low- and intermediate-risk thyroid cancer compared to high-dose ablation. (2) Methods-174 patients with low- and intermediate-risk thyroid cancer, 90 treated with low-dose ablation and 84 treated with high-dose ablation, were included. The primary endpoint was response to treatment one year after ablation, defined by stimulated thyroglobulin, whole body scan and ultrasound imaging. (3) Results-an excellent response rate of 79.8% in the low-dose group and 85.7% in the high-dose group was observed (p = 0.049). Stimulated thyroglobulin at the moment of ablation (p = 0.032) and positive antithyroglobulin antibodies (p < 0.001) were independent predictive factors for nonexcellent response. Young age (p = 0.023), intermediate initial recurrence risk (p < 0.001) and low-dose ablation (p = 0.004) were independent predictive factors for recurrence. (4) Conclusion-low-dose ablation seemed to be less effective than high-dose ablation, especially in those patients with positive antithyroglobulin antibodies or higher stimulated thyroglobulin levels at the moment of ablation. Low dose was associated with higher recurrence rates, and lower age and intermediate initial recurrence risk were independent risk factors for recurrence in our sample.

Clinicopathologic risk factors of radioactive iodine therapy based on response assessment in patients with differentiated thyroid cancer: a multicenter retrospective cohort study

PURPOSE

We investigated whether predictive clinicopathologic factors can be affected by different response criteria and how the clinical usefulness of radioactive iodine (RAI) therapy should be evaluated considering variable factors in patients with differentiated thyroid carcinoma (DTC).

METHODS

A total of 1563 patients with DTC who underwent first RAI therapy after total or near total thyroidectomy were retrospectively enrolled from 25 hospitals. Response to therapy was evaluated with two different protocols based on combination of biochemical and imaging studies: (1) serum thyroglobulin (Tg) and neck ultrasonography (US) and (2) serum Tg, neck US, and radioiodine scan. The responses to therapy were classified into excellent and non-excellent or acceptable and non-acceptable to minimize the effect of non-specific imaging findings. We investigated which factors were associated with response to therapy depending on the follow-up protocols as well as response classifications. Multivariate logistic regression analysis was performed to identify factors significantly predicting response to therapy.

RESULTS

The proportion of patients in the excellent response group significantly decreased from 76.5 to 59.6% when radioiodine scan was added to the follow-up protocol (P < 0.001). Preparation method (recombinant human TSH vs. thyroid hormone withdrawal) was a significant factor for excellent response prediction evaluated with radioiodine scan (OR 2.129; 95% CI 1.687-2.685; P < 0.001) but was not for other types of response classifications. Administered RAI activity, which was classified as low (1.11 GBq) or high (3.7 GBq or higher), significantly predicted both excellent and acceptable responses regardless of the follow-up protocol.

CONCLUSIONS

The clinical impact of factors related to response prediction differed depending on the follow-up protocol or classification of response criteria. A high administered activity of RAI was a significant factor predicting a favorable response to therapy regardless of the follow-up protocol or classification of response criteria.

Treatment of Differentiated Thyroid Carcinomas

Differentiated thyroid cancer (DTC) is the most common thyroid cancer and is frequently encountered in clinical practice. The incidence of DTC has increased significantly over the past three decades. Surgical resection, radioactive iodine (RAI), and levothyroxine suppression therapy remain the primary modalities for DTC treatment. Active surveillance for low-risk thyroid cancer may be an alternative to immediate surgery for appropriately selected patients. Patient characteristics influence treatment selection and intensity. In the subset of patients with progressive distant metastatic disease, not amenable to treatment with surgery or RAI, novel agents, including targeted therapies and immunotherapy, should be considered.

Contemporary Debates in Adult Papillary Thyroid Cancer Management

An ever-increasing population of patients with papillary thyroid cancer is engaging with health care systems around the world. Numerous questions about optimal management have arisen that challenge conventional paradigms. This is particularly the case for patients with low-risk disease, who comprise most new patients. At the same time, new therapies for patients with advanced disease are also being introduced, which may have the potential to prolong life. This review discusses selected controversial issues in adult papillary thyroid cancer management at both ends of the disease spectrum. These topics include: (i) the role of active surveillance for small papillary cancers; (ii) the extent of surgery in low-risk disease (lobectomy vs total thyroidectomy); (iii) the role of postoperative remnant ablation with radioiodine; (iv) optimal follow-up strategies in patients, especially those who have only undergone lobectomy; and (v) new therapies for advanced disease. Although our current management is hampered by the lack of large randomized controlled trials, we are fortunate that data from ongoing trials will be available within the next few years. This information should provide additional evidence that will decrease morbidity in low-risk patients and improve outcomes in those with distant metastatic disease.

Thyroid Cancer Patients With No Evidence of Disease: The Need for Repeat Neck Ultrasound

CONTEXT

Ultrasonography (US) is considered the most sensitive tool for imaging persistent or recurrent papillary thyroid cancer (PTC) in the neck.

OBJECTIVE

To clarify the usefulness of routine neck US in low- and intermediate-risk patients with PTC with no evidence of disease 1 year after thyroidectomy.

DESIGN

Retrospective analysis of prospectively recorded data.

SETTING

Academic center.

PATIENTS

Two hundred twenty-six patients with PTC with sonographically normal neck lymph nodes and unstimulated serum thyroglobulin (Tg) levels that were either undetectable (<0.20 ng/mL) or low (0.21 to 0.99 ng/mL) at the 1-year evaluation.

INTERVENTIONS

Yearly assessment: unstimulated serum Tg level, anti-Tg-antibody (TgAb) titer, TSH levels, and ultrasound examination of neck lymph nodes.

MAIN OUTCOME MEASURES

Rates of ultrasonographic lymph node abnormalities at the 3-year and last follow-up visits.

RESULTS

In patients with an undetectable Tg level at the 1-year evaluation, sonographically suspicious neck lymph nodes were found in 1.2% of patients at 3 years and in 1.8% at the last visit [negative predictive values (NPVs) of 1-year Tg < 0.2 ng/mL: 98.8% (95% CI 95.8% to 99.9%) and 98.2% (95% to 99.6%), respectively]. Similar NPVs emerged for low detectable 1-year Tg levels [98.2% (90.3% to 99.9%) and 94.5% (84.9% to 98.9%) at the 3-year and last visits, respectively]. Seventy-five percent of the nodal lesions were likely false positive; none required treatment.

CONCLUSIONS

Low- and intermediate-risk patients with PTC with negative ultrasound findings and unstimulated Tg levels <1 ng/mL at the 1-year evaluation can be safely followed with clinical assessments and unstimulated serum Tg determinations. Neck US might be repeated if TgAb titers rise, or unstimulated Tg levels exceed 1 ng/mL.

Unexpected high-risk pathologic features following thyroidectomy in the chinese immigrant population

OBJECTIVE

To compare rates of unexpected high-risk pathologic features between Chinese and non-Asian patients who underwent thyroidectomy for papillary thyroid cancer.

METHODS

This was a retrospective cohort study at a tertiary academic urban medical center. Patients who underwent thyroidectomy for papillary carcinoma from 2015 to 2017 were included. Patient demographics, tumor characteristics, and tumor histopathology were analyzed. Primary outcome was the presence of adverse histopathologic features such as lymphovascular invasion (LVI) or microscopic/minimal extrathyroidal extension (mETE). Differences between the groups were analyzed using multivariate logistical regression analysis and propensity score-weighted analysis.

RESULTS

One hundred seventy-nine patients were included: 58 Chinese-born and 121 non-Asian. The median age of the cohort was 47 years old (36-58). Twenty-nine percent of patients were male, and 71% were female. There was no statistically significant difference between the two cohorts in rates of LVI, multifocality, extent of surgery, or presence of thyroiditis. Patients with mETE were more likely to have larger tumors (P = 0.00247). Both the multivariate and propensity-weighted models demonstrated that Chinese ancestry was independently associated with an increased rate of unexpected mETE (adjusted prevalence ratio, 2.52; 95% confidence interval, 1.82-3.48).

CONCLUSION

mETE is significantly higher in the immigrant Chinese compared to the non-Asian population. Given the high prevalence of unexpected mETE in the Chinese population, the added risk of this finding should be brought into the discussion during initial surgical planning.

LEVEL OF EVIDENCE

3 Laryngoscope, 130:1844-1849, 2020.

Clinical Significance of Gross Invasion of Strap Muscles in Patients With 1- to 4-cm-Sized Papillary Thyroid Carcinoma Undergoing Lobectomy

BACKGROUND

Given the emerging evidence supporting the lack of prognostic significance of gross extrathyroidal extension invading only strap muscles (strap-gETE), this study investigated whether lobectomy is feasible for patients with strap-gETE.

METHODS

A retrospective cohort study was conducted with 636 patients who had 1- to 4-cm-sized papillary thyroid carcinoma (PTC) treated with thyroid lobectomy. Patients with gross invasion of perithyroidal organs other than strap muscles or synchronous distant metastasis were excluded from the study. Disease-free survival (DFS) was compared according to the presence of strap-gETE.

RESULTS

Strap-gETE was present in 50 patients (7.9%), with the remaining 586 patients (92.1%) showing no evidence of gETE. During the median follow-up period of 7.4 years, 6% of the patients with strap-gETE and 5.1% of the patients without gETE experienced structural persistent/recurrent disease (p = 0.99). No differences in DFS were observed between the two groups (hazard ratio [HR], 1.24; 95% confidence interval [CI], 0.38-4.08; p = 0.720). After adjustment for five major risk factors (age, gender, tumor size, multifocality, and cervical lymph node metastasis status) in the multivariate analysis, the presence of strap-gETE did not exhibit an independent role in the development of structural persistent/recurrent disease (HR 1.05; 95% CI 0.24-4.53, p = 0.950).

CONCLUSIONS

Strap-gETE did not increase the risk of structural persistent/recurrent disease for the patients who underwent lobectomy for 1- to 4-cm-sized PTC. The study data support the limited role of strap-gETE in clinical outcomes and may broaden the indications for lobectomy for patients with PTCs.

Risk-oriented concept of treatment for intrathyroid papillary thyroid cancer

Adapting treatment and follow-up according to the risk of recurrence and/or death from thyroid cancer is a relatively recent concept of "personnalized" medicine, developed particularly to avoid overtreatment of low-risk thyroid cancer which represents the majority of thyroid cancers diagnosed in the world today. For low-risk thyroid cancer, this decrease in extent of treatment involves the extent of surgery-total thyroidectomy, lobectomy or no surgery with active surveillance-but also the indications, doses and methods of stimulation when or if administering radioactive iodine (RAI), the indication for suppressive thyroxin therapy and the extent and modalities for follow-up that should be adapted to the risk of recurrence. The aim is to optimize medical resources and quality of life, particularly for low-risk patients whose life expectancy is that of the general population.

Is TSH suppression still necessary in intermediate- and high-risk papillary thyroid cancer patients with pre-ablation stimulated thyroglobulin <1 ng/mL before the first disease assessment?

OBJECTIVE

Since papillary thyroid cancer (PTC) patients with pre-ablation stimulated thyroglobulin (s-Tg) < 1 ng/mL generally have a favorable prognosis, is TSH suppression still necessary in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL after initial therapy? The aim of this study was to assess the rate of disease recurrence in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL according to TSH levels measured 1 year after initial therapy.

METHODS

A retrospective series of intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL was analyzed. Disease status was defined as the presence or absence of structural disease during late follow-up. Patients were grouped according to TSH level at 1 year: group 1, TSH < 0.1 mIU/L; group 2, TSH 0.1‒0.5 mIU/L; group 3, 0.5‒2 mIU/L; group 4, >2 mIU/L.

RESULTS

This study included 166 patients (78.3% females, median age 44 years) of whom the risk of recurrence was intermediate in 97 (58.4%) and high in 69 (41.6%). The response to initial therapy at 1 year was excellent in 163 patients (98.2%) and indeterminate in 3 (1.8%). Group 1 consisted of 63 patients (38%), group 2 of 47 (28%), group 3 of 28 (17%), and group 4 of 28 (17%). During a median follow-up duration of 5.8 years, disease recurrence was observed in only 4 patients (2.4%). The rate of disease recurrence was not significantly different between the TSH groups.

CONCLUSION

TSH suppression before the first response to treatment assessment does not seem to influence the rate of disease recurrence after initial therapy in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL.

Loss of nuclear localization of thyroid transcription factor 1 and adverse outcomes in papillary thyroid cancer

Function of the thyroid follicular cell depends on nuclear expression of thyroid transcription factor 1 (TTF1). Regulation of this key protein regulating iodide transport is not well known, but its loss is linked to the most lethal of thyroid malignancies. We examined TTF1 nuclear expression in the context of adverse pathological features, disease recurrence, and BRAF status in papillary thyroid carcinomas with (n = 182) and without (n = 303) nodal metastases. Overall nuclear expression level of TTF1 was strong and diffuse in approximately 73%, whereas 27% exhibited lower levels or a paucity of nuclear staining. In the same cohort, approximately 59% exhibited the BRAF mutation. On univariate analysis, low levels of TTF1 nuclear expression was linked to vascular invasion, extrathyroidal extension, and nodal metastases. Multivariate analysis indicated that low levels of TTF1 were most strongly linked to nodal metastases and vascular invasion. Interestingly, TTF1 levels were not linked to the BRAF mutation. TTF1 staining alone predicted disease recurrence, but when combined with BRAF status, the 2 markers exhibited a more marked influence. Patients lacking the BRAF mutation and exhibiting normal levels of TTF1 exhibited very low levels of disease recurrence (11% at 10 years). Conversely, patient tumors with low levels of TTF1 and the BRAF mutation recurred in 31% of cases in the same time frame. The mixed expression of BRAF under varying levels of differentiation may explain, in part, the contradictory studies regarding the impact of BRAF mutations on patient prognosis and also indicates a complex genomic signature for dedifferentiated thyroid cancer.

Conventional Radioiodine Therapy for Differentiated Thyroid Cancer

This article presents an overview of the use of radioactive iodine (131-I) in the treatment of patients with differentiated thyroid cancer. Topics reviewed include definitions; staging; the 2 principal methods for selection of 131-I dosage; the indications for ablation, adjuvant treatment, and treatment; the recommendations for the use of 131-I contained in the guidelines of the American Thyroid Association and the Society of Nuclear Medicine and Molecular Imaging; the dosage recommendations and selection of dosage approach for 131-I by these organizations; the use of recombinant human thyrotropin for radioiodine ablation, adjuvant therapy, or treatment; and the MedStar Washington Hospital Center approach.

Radioiodine treatment of differentiated thyroid cancer related to guidelines and scientific literature

In differentiated thyroid cancer (DTC), radioiodine is administered to eliminate residual normal thyroid tissue after thyroidectomy (ablative treatment), to treat residual microscopic disease (adjuvant treatment), and to treat macroscopic or metastatic disease. Currently, treatment of DTC with ¹³¹I is still a matter of controversy due to the absence of prospective clinical trials assessing its benefit in terms of overall survival and recurrence-free interval. The current recommendations of the experts are based on observational retrospective data and on their interpretation of the literature. Pending the results of the prospective trials that are currently underway, the use of ¹³¹I seems to be justified not only in high-risk patients, but also in intermediate-risk and low-risk patients. The guidelines of The American and British Thyroid Association, European and American Societies of Nuclear Medicine, The European Consensus Group and the latest edition of National Comprehensive Cancer Network (NCCN) were considered in drawing up this continuing education document, we also undertook a review of the related scientific literature.

Recurrence after low-dose radioiodine ablation and recombinant human thyroid-stimulating hormone for differentiated thyroid cancer (HiLo): long-term results of an open-label, non-inferiority randomised controlled trial

BACKGROUND

Two large randomised trials of patients with well-differentiated thyroid cancer reported in 2012 (HiLo and ESTIMABL1) found similar post-ablation success rates at 6-9 months between a low administered radioactive iodine (¹³¹I) dose (1·1 GBq) and the standard high dose (3·7 GBq). However, recurrence rates following radioactive iodine ablation have previously only been reported in observational studies, and recently in ESTIMABL1. We aimed to compare recurrence rates between radioactive iodine doses in HiLo.

METHODS

HiLo was a non-inferiority, parallel, open-label, randomised controlled factorial trial done at 29 centres in the UK. Eligible patients were aged 16-80 years with histological confirmation of differentiated thyroid cancer requiring radioactive iodine ablation (performance status 0-2, tumour stage T1-T3 with the possibility of lymph-node involvement but no distant metastasis and no microscopic residual disease, and one-stage or two-stage total thyroidectomy). Patients were randomly assigned (1:1:1:1) to 1·1 GBq or 3·7 GBq ablation, each prepared with either recombinant human thyroid-stimulating hormone (rhTSH) or thyroid hormone withdrawal. Patients were followed up at annual clinic visits. Recurrences were diagnosed at each hospital with a combination of established methods according to national standards. We used Kaplan-Meier curves and hazard ratios (HRs) for time to first recurrence, which was a pre-planned secondary outcome. This trial is registered with ClinicalTrials.gov, number NCT00415233.

RESULTS

Between Jan 16, 2007, and July 1, 2010, 438 patients were randomly assigned. At the end of the follow-up period in Dec 31, 2017, median follow-up was 6·5 years (IQR 4·5-7·6) in 434 patients (217 in the low-dose group and 217 in the high-dose group). Confirmed recurrences were seen in 21 patients: 11 who had 1·1 GBq ablation and ten who had 3·7 GBq ablation. Four of these (two in each group) were considered to be persistent disease. Cumulative recurrence rates were similar between low-dose and high-dose radioactive iodine groups (3 years, 1·5% vs 2·1%; 5 years, 2·1% vs 2·7%; and 7 years, 5·9% vs 7·3%; HR 1·10 [95% CI 0·47-2·59]; p=0·83). No material difference in risk was seen for T3 or N1 disease. Recurrence rates were also similar among patients who were prepared for ablation with rhTSH and those prepared with thyroid hormone withdrawal (3 years, 1·5% vs 2·1%; 5 years, 2·1% vs 2·7%; and 7 years, 8·3% vs 5·0%; HR 1·62 [95% CI 0·67-3·91]; p=0·28). Data on adverse events were not collected during follow-up.

INTERPRETATION

The recurrence rate among patients who had 1·1 GBq radioactive iodine ablation was not higher than that for 3·7 GBq, consistent with data from large, recent observational studies. These findings provide further evidence in favour of using low-dose radioactive iodine for treatment of patients with low-risk differentiated thyroid cancer. Our data also indicate that recurrence risk was not affected by use of rhTSH.

FUNDING

Cancer Research UK.

Follow-up of differentiated thyroid cancer - what should (and what should not) be done

The treatment paradigm for thyroid cancer has shifted from a one-size-fits-all approach to more personalized protocols that range from active surveillance to total thyroidectomy followed by radioiodine remnant ablation. Accurate surveillance tools are available, but follow-up protocols vary widely between centres and clinicians, owing to the lack of clear, straightforward recommendations on the instruments and assessment schedule that health-care professionals should adopt. For most patients (that is, those who have had an excellent response to the initial treatment and have a low or intermediate risk of tumour recurrence), an infrequent assessment schedule is sufficient (such as a yearly determination of serum levels of TSH and thyroglobulin). Select patients will benefit from second-line imaging and more frequent assessments. This Review discusses the strengths and weaknesses of the surveillance tools and follow-up strategies that clinicians use as a function of the initial treatment and each patient's risk of recurrence.

The New TNM Staging System for Thyroid Cancer and the Risk of Disease Downstaging

In October 2016 the American Joint Committee on Cancer (AJCC) published the 8th edition of the AJCC/TNM cancer staging system and it has been introduced in clinical practice since 1st January 2018. The effect of most of the changes in the new edition was the downstaging of a significant number of patients into lower stages, reflecting their low risk of thyroid cancer-related death. One of the most relevant modification refers to the role of the microscopic extra-thyroidal tumor invasion, which is no longer considered as criterion for the classification of T3 tumors. With the present study we want to assess the impact of the changes of the new staging system and therefore we analyzed or casistic of 84 T1-T3 thyroid-cancer patients. The results of our analysis show that he downstaging of patients according to the 8th TNM edition does not necessarily reflect less aggressive disease: we actually reported 2 lymph-nodal recurrences (40%) in the five patients that were downstaged from pT3 to pT2 and the lypmh-nodal recurrence rate for stage I rises from 0% with the 7th TNM edition to 5.3% with the 8th edition.