Undetectable sensitive serum thyroglobulin (<0.1 ng/ml) in 163 patients with follicular cell-derived thyroid cancer: results of rhTSH stimulation and neck ultrasonography and long-term biochemical and clinical follow-up

Diagnostic, Theranostic and Prognostic Value of Thyroglobulin in Thyroid Cancer

Thyroglobulin (Tg) is an iodinated glycoprotein, which is normally stored in the follicular colloid of the thyroid, being a substrate for thyroid hormone production. Since it is produced by well-differentiated thyroid cells, it is considered a reliable tumor marker for patients with differentiated thyroid carcinoma (DTC) during their follow-up after total thyroidectomy and radioiodine ablation. It is used to monitor residual disease and to detect recurrent disease. After total thyroid ablation, unstimulated highly sensitive Tg measurements are sufficiently accurate to avoid exogenous or endogenous thyrotropin (TSH) stimulation and provide accurate diagnostic and prognostic information in the great majority of DTC patients. Adopting sophisticated statistical analysis, i.e., decision tree models, the use of Tg before radioiodine theranostic administration was demonstrated to be useful in refining conventional, pathology-based risk stratification and providing personalized adjuvant or therapeutic radioiodine administrations. The follow-up of DTC patients aims to promptly identify patients with residual or recurrent disease following primary treatment. Our review paper covers the diagnostic, theranostic and prognostic value of thyroglobulin in DTC patients.

Coexistence of Hashimoto's Thyroiditis in Differentiated Thyroid Cancer: Post-Operative Monitoring of Anti-Thyroglobulin Antibodies and Assessment of Treatment Response

INTRODUCTION

Differentiated thyroid carcinoma (DTC) is frequently found in conjunction with autoimmune thyroid disorders, particularly Hashimoto's thyroiditis (HT). This study investigates the impact of coexisting HT on the persistence of an indeterminate response to therapy due to positive anti-thyroglobulin antibodies (AbTg), measured via competitive immunoassay, in a consecutive patient series from Calabria, Southern Italy.

METHODS

This retrospective longitudinal study analyzed 259 consecutive DTC patients managed at the Endocrinology Unit of Renato Dulbecco Hospital (Catanzaro, Italy) up to 2023. Patients with medullary and undifferentiated thyroid carcinoma, partial thyroidectomy, less than six months of post-operative monitoring, or missing clinical data were excluded. Demographic information, histological findings, initial tumor stage, and ATA risk category were collected. The response to therapy was assessed based on ATA guidelines.

RESULTS

Among the 259 patients, 29% had coexisting HT. Patients with HT exhibited distinct characteristics: a higher proportion of females (87.0% vs. 74.7%), a shorter post-operative monitoring duration (median 3 vs. 5 years), and a higher prevalence of papillary thyroid carcinoma (PTC) (97.4% vs. 86.3%). The tumor size, lymph node involvement, and distant metastasis were similar between the groups, with patients without HT having a higher incidence of extrathyroidal tumor extension. However, the initial TNM stage and ATA risk category did not differ significantly. At the six-month follow-up, HT patients showed a higher rate of indeterminate responses, primarily due to positive AbTg. After 12 months, the response categories aligned, with decreasing AbTg levels in the HT group. After 24 months, most patients with long-term follow-up demonstrated an excellent response to DTC therapy, irrespective of HT coexistence.

CONCLUSIONS

While HT does not worsen DTC prognosis, it may result in indeterminate responses. AbTg measurements in the peri-operative period should be encouraged to facilitate post-operative monitoring, emphasizing the importance of using standardized assays. Further research in larger populations with extended follow-up is needed to comprehensively understand the HT-DTC relationship.

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.

Radioiodine remnant ablation in stage I adult papillary thyroid carcinoma: does it improve postoperative outcome?

Objective

To determine whether radioiodine remnant ablation (RRA) reduces cause-specific mortality (CSM) or tumor recurrence rates (TRR) after potentially curative bilateral thyroidectomy (BT) in low-risk adult papillary thyroid carcinoma (APTC) patients, we compared postoperative outcomes in 1836 pTNM stage I APTC patients having BT alone with 832 having BT+RRA during two consecutive 25-year periods.

Methods

The THEN cohort (consecutively managed during 1966-1990) comprised 809 patients (36% having BT+RRA) and the NOW cohort (1991-2015) comprised 1859 patients (29% BT+RRA). Analyses of differences in occurrence rates between BT alone and BT+RRA patients were performed with SAS software.

Results

During 1966-1990, when RRA rates rose ten-fold, 20-year CSM after BT alone was 0.6% and after BT+RRA was 1.2% (P = 0.66); during 1991-2015, when RRA rates progressively fell, no PTC deaths occurred in 1859 patients. In the THEN cohort, RRA did not significantly improve TRR at local, regional, or distant sites (P > 0.1), when compared to BT alone. RRA in NOW cohort was administered to 49% of node-positive (pN1) patients and 17% of node-negative (pN0/NX) patients (P < 0.0001); TRR therefore, were examined separately for pN0/NX and pN1 patients. In 1157 pN0/NX cases, 20-year locoregional TRR were 3.1% after BT and were higher (P = 0.049) at 8.6% after BT+RRA. In four pN1 groups, stratified by metastatic nodal burden, RRA did not significantly reduce the locoregional TRR observed after BT with curative intent (P > 0.5).

Conclusions

In a 5-decade experience, RRA administered postoperatively to stage I APTC patients did not reduce either CSM or TRR and should probably not be indicated when such patients undergo potentially curative BT.

Comparison Between Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA) and Conventional Open Thyroidectomy for Patients Undergoing Total Thyroidectomy and Central Neck Dissection: A Propensity Score-Matching Analysis

Background

Use of the novel transoral endoscopic thyroidectomy vestibular approach (TOETVA) is increasing worldwide. Although several studies have compared safety and efficacy of TOETVA and other approaches, most focused on comparisons in the context of unilateral thyroidectomy. Therefore, the present study aimed to compare the safety and surgical completeness of TOETVA with conventional open thyroidectomy (COT) in patients with papillary thyroid carcinoma (PTC) undergoing total thyroidectomy and central neck dissection.

Methods

The medical records of patients who underwent TOETVA or COT by a single surgeon between June 2017 and October 2021 were retrospectively reviewed. All patients were diagnosed with PTC and underwent total thyroidectomy with central neck dissection. Propensity score-matching (PSM) was used to reduce potential selection bias and to adjust for differences in baseline clinicopathological characteristics.

Results

After PSM, 84 (TOETVA: 28; COT: 56) patients remained in the study population. There were no significant differences in sex, mean age, combined thyroiditis, tumor size, capsule invasion, tumor multifocality in the same lobe, or tumor location between the groups. Operative time was longer (190.54 ± 28.26 vs. 123.93 ± 29.78 min, P<0.001), while postoperative drainage volume (161.07 ± 225.30 vs. 71.16 ± 28.56 ml, P=0.045) was greater, in the TOETVA group than in the COT group. The groups exhibited no significant differences in the mean number of central lymph nodes retrieved (9.39 ± 4.01 vs. 10.71 ± 5.17, P=0.202), mean number of metastatic central lymph nodes (1.36 ± 1.93 vs. 1.77 ± 2.31, P=0.421), postoperative mean thyroglobulin levels (0.08 ± 0.24 vs. 0.10 ± 0.27, P=0.686), rate of transient hypoparathyroidism (TOETVA: 67.9% vs. COT: 66.1%, P=0.870), rate of transient vocal cord palsy (TOETVA: 0% vs. COT: 1.8%, P=1.000), or other complications (TOETVA: 3.6% vs. COT: 0%, P=0.333).

Conclusions

TOETVA is a safe approach in select patients with PTC and exhibits similar efficacy to COT in terms of surgical completeness.

The Role of Thyroglobulin in Preoperative and Postoperative Evaluation of Patients With Differentiated Thyroid Cancer

Thyroglobulin (Tg) is secreted by thyroid follicular cells and stored in the thyroid follicular lumen as a component of thyroid hormone. It is known that both benign and well-differentiated malignant thyroid tissue can secrete Tg. In recent years, growing lines of evidence have shown that Tg plays an important role in the diagnosis and metastasis of preoperative differentiated thyroid carcinoma (DTC). The levels of Tg, whether in the serum or in a fine-needle aspiration washout fluid, are usually viewed as an excellent indicator in the monitoring of postoperative DTC, including the guidance and evaluation of radioactive iodine ablation. Nevertheless, some factors limit the application of Tg, such as the method used to measure Tg and the presence of Tg antibodies. This review aimed to summarize the role of Tg in the preoperative and postoperative evaluation of patients with DTC, and the factors influencing Tg. This review could provide a reference for a more accurate application of Tg in patients with DTC.

A Novel Thyroglobulin Immunoassay Using the Specimen-Pretreatment Process Improves the Accuracy of Thyroglobulin Measurements in Anti-Thyroglobulin Positive Specimens

BACKGROUND

Recently, second-generation thyroglobulin (Tg) sandwich immunoassays have been used in clinical laboratories to measure the serum Tg levels, which is a tumor marker used to monitor postoperative patients with differentiated thyroid cancers. However, these immunoassays are often subject to Tg autoantibody (TgAb) interference. TgAb interference is inevitable for almost all Tg immunoassays, resulting in unreliable Tg measurement values of TgAb-positive samples.

METHODS

To address TgAb interference, we have developed a novel immunoassay based on a fully automated chemiluminescent enzyme immunoassay system using the effective specimen-pretreatment process to inactivate TgAb in blood and evaluated its assay performance.

RESULTS

The developed assay was traceable to BCR457 IRMM reference material with a limit of quantification of 0.03 ng/mL. The pretreatment process inactivated almost all TgAb in specimens and allowed accurate Tg measurements in TgAb-positive samples in which TgAb interference was observed using the immunoassays. Size-exclusion chromatography analysis of immunoreactive Tg molecule in a TgAb-positive serum verified disruption of the Tg-TgAb immune complex by the pretreatment process. Good correlation of Tg values in TgAb-negative specimens was observed between the new Tg immunoassay and the second-generation sandwich immunoassays. However, there were numerous discrepant samples on bias plots between the new Tg immunoassay and the second-generation sandwich immunoassays for TgAb-positive specimens.

CONCLUSIONS

This study indicates the new Tg immunoassay with the specimen-pretreatment process is both robust and free from interference by TgAb. Thus, this novel assay is superior to second-generation sandwich immunoassays and gives accurate Tg concentrations even for TgAb-positive cases.

[Follow-up of differentiated thyroid cancer]

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

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.

Surgical options for thyroid cancer and post-surgical management

INTRODUCTION

Differentiated thyroid cancer (DTC), which includes papillary and follicular, is the most common type of thyroid cancer and the incidence is rising. Survival rates of DTC are excellent, so the focus of management should be to optimize the initial oncological surgical resection, while providing follow up and adjunct therapies to improve long-term outcomes.

AREAS COVERED

It is important for providers to be aware of the most recent guidelines for DTC management, as practices have changed in recent years. In this review, we will highlight some of the updates in the American Thyroid Association (ATA) guidelines and the American Joint Committee on Cancer (AJCC) edition changes in order to better guide practitioners in the management of the evolving treatment strategies. Management of DTC includes diagnosis of thyroid nodules, defining the best operative or non-operative treatment for patients using a multidisciplinary approach, and surveillance of DTC to optimize patients in terms of both clinical and quality of life outcomes.

EXPERT COMMENTARY

As the rate of DTC rises yet the mortality remains stable, management focuses on disease-free follow up and optimal long-term outcomes. Current controversies in management of DTC include proper oncological surgery depending on the nature and size of the DTC, the cytopathology nomenclature, management of lymph node disease, and appropriate surveillance strategies. Preoperative risk stratification is key. We have many modalities to aid in that stratification, such as identifying known concerning features of nodules with expert-performed ultrasound, thyroglobulin (Tg) levels, molecular testing, and evidence based outcomes data for recurrence rates. However, many individual cases still present with multiple management options, thus highlighting the importance of patient discussion and a multidisciplinary approach. It is important for providers to recognize that the short and long-term follow up must be guided by surveillance studies, and patients need to be re-risk stratified in order to optimize detection of recurrence yet sustain quality of life.

Serum thyroglobulin or thyroglobulin in fine-needle aspiration washout of metastatic lymph nodes: which one should we have confidence in for the surveillance of thyroid carcinoma?

BACKGROUND

The objective of this study was to evaluate the diagnostic performance of serum thyroglobulin (S-Tg), thyroglobulin in fine-needle aspiration washout (FNA-Tg) and fine-needle aspiration cytology (FNAC) in the detection of lateral metastatic lymph nodes (LNs) in patients with thyroid carcinoma.

METHODS

The study included 19 lateral metastatic LNs from 19 patients with thyroid carcinoma who underwent FNAC for the suspicion of metastatic disease on ultrasonogrphy (US). The S-Tg, FNA-Tg, FNAC, and histopathological results were correlated.

RESULTS

Compared with S-Tg, both FNAC and FNA-Tg showed higher sensitivity (89.5%, 89.5% versus 68.4%, respectively) and accuracy (89.5%, 89.5% versus 68.4%, respectively). The combined use of FNAC and FNA-Tg or FNAC and S-Tg showed superior diagnostic power.

CONCLUSIONS

S-Tg measurement is a less reliable method for follow-up in patients with thyroid carcinoma in comparison with FNA-Tg. For patients with negative S-Tg but suspicious features in US, FNAC combined with FNA-Tg is strongly recommended to confirm the diagnosis.

Is a second recombinant human thyrotropin stimulation test useful? The value of postsurgical undetectable stimulated thyroglobulin level at the time of remnant ablation on clinical outcome

OBJECTIVE

The management of patients with differentiated thyroid cancer (DTC) has changed in recent years, and monitoring depends on the risk of persistent/recurrent disease. The objective was to assess the prognostic value of a single stimulated thyroglobulin (Tg) measured at the time of the first radioiodine therapy (Stim-Tg1), and the utility of a second stimulated Tg measurement performed 6-12 months later (Stim-Tg2). We also examined the role of neck ultrasound (US) in the early diagnosis of recurrence.

DESIGN

This was a retrospective observational cohort study conducted in a tertiary referral hospital. Of 213 evaluated patients with DTC, 169 were finally included.

METHODS

Measurement of Stim-Tg1, Stim-Tg2 and neck US.

RESULTS

Stim-Tg1 was undetectable in 71 of 169 patients (42%). All of them (71/71) continued to have negative Stim-Tg2. Seventy of 71 had an excellent response to the first treatment. Sixty-eight of 71 had no evidence of disease after an average follow-up of 7·2 years. In patients with detectable Stim-Tg1 (98/169; 58%), Stim-Tg2 became negative in 40. The negative predictive value (NPV) of Stim-Tg1 was 0·96. The optimal Stim-Tg1 cut-off level for identifying persistence was 3·65 ng/ml. Recurrence was detected in 14 patients. Neck US was useful for identifying local recurrence (13/14; 92·85%).

CONCLUSIONS

Stim-Tg1 is a reliable marker with a high NPV. A second stimulation test should be avoided in patients with negative Stim-Tg1. In patients with biochemical persistence, Stim-Tg2 is useful for confirming/ruling out final status. Neck US plays a valuable role in the early diagnosis of recurrence.

Papillary thyroid carcinomas with biochemical incomplete or indeterminate responses to initial treatment: repeat stimulated thyroglobulin assay to identify disease-free patients

Papillary thyroid cancer (PTC) patients treated with thyroidectomy and radioiodine remnant ablation (RRA) often have detectable TSH-stimulated thyroglobulin (Tg) levels without localizable disease after primary treatment. To assess the value of repeat stimulated Tg assays in these patients' follow-up, we retrospectively analyzed 86 cases followed in 5 Italian thyroid-cancer referral centers. We enrolled 86 patients with PTCs treated with total/near-total thyroidectomy plus RRA between January 1,1990 and January 31, 2006. In all cases, the initial postoperative visit revealed stimulated serum Tg ≥1 ng/mL, negative Tg antibodies, and no structural evidence of disease. None received empiric radioiodine therapy. Follow-up (median: 9.6 years) included neck ultrasound and basal Tg assays (yearly) and at least 1 repeat stimulated Tg assay. Of the 86 patients analyzed (initial risk: low 63 %, intermediate 35 %, high 2 %), one (1 %) had ultrasound-detected lymph node disease and persistently elevated stimulated Tg levels at 3 years. In 17 (20 %), imaging findings were consistently negative, but the final stimulated Tg levels was still >1 ng/mL (median 2.07 ng/mL, range 1.02-4.7). The other 68 (80 %) appeared disease-free (persistently negative imaging findings with stimulated Tg levels ≤1 ng/mL). Mean intervals between first and final stimulated Tg assays were similar (5.2 and 4.8 years) in subgroups with versus without Tg normalization. Reclassification as disease-free was significantly more common when initial stimulated Tg levels were indeterminate (<10 ng/mL). In unselected PTC cohorts with incomplete/indeterminate biochemical responses to thyroidectomy and RRA, periodic remeasurement of stimulated Tg allows most patients to be classified as disease-free.

Thyroid Cancer in Pediatrics

Well differentiated thyroid cancer (DTC) in children is characterized by a high rate of response to treatment and low disease-specific mortality. Treatment of children with DTC has evolved toward a greater reliance on evaluation and monitoring with serial serum thyroglobulin measurements and ultrasound examinations. Radioiodine therapy is recommended for thyroid remnant ablation in high-risk patients, treatment of demonstrated radioiodine-avid local-regional disease not amenable to surgical resection, or distant radioiodine-avid metastatic disease. Sufficient time should be given for benefits of radioiodine therapy to be realized, with follow-up monitoring. Re-treatment with radioiodine can be deferred until progression of significant disease manifests.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Low postoperative nonstimulated thyroglobulin as a criterion to spare radioiodine ablation

This study evaluated the recurrence rate in patients with papillary thyroid carcinoma (PTC) who had low nonstimulated thyroglobulin (Tg), measured with a second-generation assay, after total thyroidectomy and who were not submitted to ablation with (131)I. The objective was to define whether low postoperative nonstimulated Tg can be used as a criterion to spare patients with PTC from therapy with (131)I. This was a prospective study including 222 patients with PTC (except for microcarcinoma restricted to the thyroid and tumor with extensive extrathyroid invasion (pT4), aggressive histology, extensive lymph node (LN) involvement, or known residual disease). After thyroidectomy, all patients had nonstimulated Tg<0.3 ng/ml, negative antithyroglobulin antibodies (TgAb) and neck ultrasonography (US) showing no anomalies. Because of this finding, the patients were not submitted to ablation with (131)I. The time of follow-up ranged from 15 to 102 months (median 62 months). Of the 222 patients, 217 (97.7%) continued to have nonstimulated Tg <0.3 ng/ml and negative US. Tg was undetectable in the last assessment in 185 of these patients and detectable in 32. Five patients (2.2%) exhibited an increase in Tg, and LN metastases were detected in 4 (structural recurrence). One patient progressed to an increase in Tg, but disease was not detected by the imaging methods (biochemical recurrence). The results obtained here suggest that patients with PTC who have low nonstimulated Tg (measured with a second-generation assay and in the absence of TgAb) and negative neck US after thyroidectomy do not require ablation with (131)I.

Characterization of a new highly sensitive immunometric assay for thyroglobulin with reduced interference from autoantibodies

Measurements of serum thyroglobulin (Tg) with sensitive immunoassays are of great importance for the management of patients with differentiated thyroid carcinomas. However, interference of circulating autoantibodies to Tg (hTgAb) hampers the usefulness of most assays. We have produced a panel of monoclonal antibodies (mAbs) selected to bind Tg in the presence of Tg autoantibodies and developed a sensitive immunoassay for Tg with minor interference by hTgAbs. The antibodies were characterized by cross-inhibition and immunoassay combination studies, as well as affinity estimation. The within-run and total imprecision of the assay were determined with 2664 samples in 60 separate runs. The most sensitive assay combination with superior protection against autoantibodies consisted of two solid phase mAbs and two tracer mAbs with distinct binding sites. The assay was linear and displayed a wide dynamic range up to 1342 μg/l with a functional sensitivity of 0.1 μg/l and a total imprecision of less than 10 %. There was good agreement between the new high sensitive immunofluorometric assay (IFMA) and two well-established Tg assays from Brahms Kryptor and Roche Diagnostics. Mean difference between the new IFMA and the Kryptor assay was 0.059 μg/l with a 95 % confidence interval of −0.032 to 0.151 μg/l, whereas the mean difference between the new IFMA and the Roche assay was −0.80 μg/l with a 95 % confidence interval of −1.24 to −0.35 μg/l.

The value of combined application of ultrasound-guided fine needle aspiration cytology and thyroglobulin measurement for the diagnosis of cervical lymph node metastases from thyroid cancer

Objective:

The aim of this study was to explore the diagnostic value of ultrasound-guided (US-guided) fine-needle aspiration cytology (FNAC), thyroglobulin measurement on fine-needle aspiration (FNA-Tg), combined US-guided FNAC, and the ratio between FNA-Tg and serum Tg (FNA-Tg/serum Tg) for patients with cervical lymph node (CLN) metastases from thyroid carcinoma.

Methods:

We selected 148 patients with thyroid cancer with suspicious CLN metastases who met the inclusion criteria. FNAC findings, FNA-Tg levels, and serum Tg levels were evaluated before surgical treatment. The results of FNAC and FNA-Tg from CLNs were analyzed retrospectively.

Results:

Ninety-four of 148 cases were metastatic and 54 were benign. The sensitivity, specificity, and accuracy of FNAC were 68.1%, 100.0%, and 79.7%, respectively. The sensitivity, specificity, and accuracy of FNA-Tg/serum Tg were 91.5%, 88.9%, and 90.5%, respectively. The sensitivity, specificity, and accuracy of FNA-Tg [10 ng/mL] were 98.9%, 68.5%, and 87.8%, respectively. The sensitivity, specificity, and accuracy of combined US-guided FNAC and FNA-Tg/serum Tg were 95.7%, 96.3%, and 95.9%, respectively. There was a statistically significant difference between FNAC and combined US-guided FNAC and FNA-Tg/serum Tg for sensitivity, specificity, and accuracy (P < 0.05).

Conclusion:

The method of FNA-Tg/serum Tg is sensitive enough for diagnosing CLN metastases from thyroid cancer. The combined application of US-guided FNAC and FNA-Tg/serum Tg contributes to improving the accuracy of diagnosing CLN metastases in patients with thyroid cancer.

Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Previous guidelines for the management of thyroid nodules and cancers were geared toward adults. Compared with thyroid neoplasms in adults, however, those in the pediatric population exhibit differences in pathophysiology, clinical presentation, and long-term outcomes. Furthermore, therapy that may be recommended for an adult may not be appropriate for a child who is at low risk for death but at higher risk for long-term harm from overly aggressive treatment. For these reasons, unique guidelines for children and adolescents with thyroid tumors are needed.

METHODS

A task force commissioned by the American Thyroid Association (ATA) developed a series of clinically relevant questions pertaining to the management of children with thyroid nodules and differentiated thyroid cancer (DTC). Using an extensive literature search, primarily focused on studies that included subjects ≤18 years of age, the task force identified and reviewed relevant articles through April 2014. Recommendations were made based upon scientific evidence and expert opinion and were graded using a modified schema from the United States Preventive Services Task Force.

RESULTS

These inaugural guidelines provide recommendations for the evaluation and management of thyroid nodules in children and adolescents, including the role and interpretation of ultrasound, fine-needle aspiration cytology, and the management of benign nodules. Recommendations for the evaluation, treatment, and follow-up of children and adolescents with DTC are outlined and include preoperative staging, surgical management, postoperative staging, the role of radioactive iodine therapy, and goals for thyrotropin suppression. Management algorithms are proposed and separate recommendations for papillary and follicular thyroid cancers are provided.

CONCLUSIONS

In response to our charge as an independent task force appointed by the ATA, we developed recommendations based on scientific evidence and expert opinion for the management of thyroid nodules and DTC in children and adolescents. In our opinion, these represent the current optimal care for children and adolescents with these conditions.

Serum Thyroglobulin Measured With a Second-Generation Assay in Patients Undergoing Total Thyroidectomy Without Radioiodine Remnant Ablation: A Prospective Study

BACKGROUND

Follow-up consisting of the measurement of nonstimulated serum thyroglobulin (Tg) combined with neck ultrasonography is recommended for patients with papillary thyroid carcinoma without indication for radioiodine ablation. There is no recommendation of thyrotropin suppression during this follow-up. New-generation Tg assays have been increasingly used, but few studies involve patients submitted only to thyroidectomy and they have several limitations. The objective of this prospective study was to define expected concentrations of nonstimulated Tg measured with a second-generation assay after total thyroidectomy in the absence of tumor.

METHODS

Serum Tg was measured using a second-generation assay in 69 patients without tumor and serum thyrotropin between 0.5 and 2 mIU/L, 3, 6, 12, and 24 months after total thyroidectomy. All patients had undetectable anti-Tg antibodies.

RESULTS

Serum Tg was undetectable in 44.4%, 57%, 62.5%, and 62.1% of the patients 3, 6, 12, and 24 months after thyroidectomy, respectively, and was ≤0.5 ng/mL in 60.3%, 80%, 90.6%, and 90.9% of patients. All patients had a Tg≤2 ng/mL 6 months after thyroidectomy, and 97% had a Tg≤1 ng/mL 24 months after surgery. There was no case of Tg conversion from undetectable to detectable and none of the patients presented an increase in Tg.

CONCLUSIONS

An important decline in serum Tg occurred between 3 and 6 months after total thyroidectomy. One year after surgery, Tg was undetectable in approximately 60% of the patients and was ≤2 ng/mL in all of them.

Is Stimulated Thyroglobulin Necessary after Ablation in All Patients with Papillary Thyroid Carcinoma and Basal Thyroglobulin Detectable by a Second-Generation Assay?

Objective. To evaluate the percentage of elevated stimulated thyroglobulin (sTg) and persistent or recurrent disease (PRD) in patients with detectable basal Tg < 0.3 ng/mL. Methods. The sample consisted of 130 patients with papillary thyroid carcinoma (PTC) who were at low risk of PRD and who had neck ultrasound (US) without abnormalities, negative anti-Tg antibodies (TgAb), and detectable basal Tg < 0.3 ng/mL about 6 months after ablation. Results. sTg was <1 ng/mL in 88 patients (67.7%), between 1 and 2 ng/mL in 26 (20%), and ≥2 ng/mL in 16 (12.3%). Imaging methods revealed the absence of tumors in 16 patients with elevated sTg. During follow-up, Tg increased to 0.58 ng/mL in one patient and lymph node metastases were detected. Sixty-nine patients continued to have detectable Tg < 0.3 ng/mL and US revealed recurrence in only one patient. Sixty patients progressed to persistently undetectable Tg without apparent disease on US. Conclusions. In low-risk patients with PTC who have detectable basal Tg < 0.3 ng/mL after ablation, negative TgAb, and US, persistent disease is rare and eventual recurrences can be detected by basal Tg elevation and/or subsequent US assessments, with follow-up without sTg being an "alternative" to Tg stimulation.

Serum thyroglobulin (Tg) monitoring of patients with differentiated thyroid cancer using sensitive (second-generation) immunometric assays can be disrupted by false-negative and false-positive serum thyroglobulin autoantibody misclassifications

CONTEXT

Reliable thyroglobulin (Tg) autoantibody (TgAb) detection before Tg testing for differentiated thyroid cancer (DTC) is critical when TgAb status (positive/negative) is used to authenticate sensitive second-generation immunometric assay ((2G)IMA) measurements as free from TgAb interference and when reflexing "TgAb-positive" sera to TgAb-resistant, but less sensitive, Tg methodologies (radioimmunoassay [RIA] or liquid chromatography-tandem mass spectrometry [LC-MS/MS]).

OBJECTIVE

The purpose of this study was to assess how different Kronus (K) vs Roche (R) TgAb method cutoffs for "positivity" influence false-negative vs false-positive serum TgAb misclassifications that may reduce the clinical utility of reflex Tg testing.

METHODS

Serum Tg(2G)IMA, TgRIA, and TgLC-MS/MS measurements for 52 TgAb-positive and 37 TgAb-negative patients with persistent/recurrent DTC were compared. A total of 1426 DTC sera with TgRIA of ≥ 1.0 μg/L had false-negative and false-positive TgAb frequencies determined using low Tg(2G)IMA/TgRIA ratios (<75%) to indicate TgAb interference.

RESULTS

TgAb-negative patients with disease displayed Tg(2G)IMA, TgRIA, and TgLC-MS/MS serum discordances (% coefficient of variation = 24 ± 20%, range, 0%-100%). Of the TgAb-positive patients with disease, 98% had undetectable/lower Tg(2G)IMA vs either TgRIA or TgLC-MS/MS (P < .01), whereas 8 of 52 (15%) had undetectable Tg(2G)IMA + TgLC-MS/MS associated with TgRIA of ≥ 1.0 μg/L. Receiver operating characteristic curve analysis reported more sensitivity for TgAb method K vs R (81.9% vs 69.1%, P < .001), but receiver operating characteristic curve cutoffs (>0.6 kIU/L [K] vs >40 kIU/L [R]) had unacceptably high false-negative frequencies (22%-32%), whereas false positives approximated 12%. Functional sensitivity cutoffs minimized false negatives (13.5% [K] vs 21.3% [R], P < .01) and severe interferences (Tg(2G)IMA, <0.10 μg/L) (0.7% [K] vs 2.4% [R], P < .05) but false positives approximated 23%.

CONCLUSIONS

Reliable detection of interfering TgAbs is method and cutoff dependent. No cutoff eliminated both false-negative and false-positive TgAb misclassifications. Functional sensitivity cutoffs were optimal for minimizing false negatives but have inherent imprecision (20% coefficient of variation) that, exacerbated by TgAb biologic variability during DTC monitoring, could cause TgAb status to fluctuate for patients with low TgAb concentrations, prompting unnecessary Tg method changes and disrupting Tg monitoring. Laboratories using reflexing should limit Tg method changes by considering a patient's Tg + TgAb testing history in addition to current TgAb status before Tg method selection.

How sensitive (second-generation) thyroglobulin measurement is changing paradigms for monitoring patients with differentiated thyroid cancer, in the absence or presence of thyroglobulin autoantibodies

PURPOSE OF REVIEW

To discuss new insights regarding how sensitive (second-generation) thyroglobulin immunometric assays (TgIMAs), (functional sensitivities ≤0.10 μg/L) necessitate different approaches for postoperative thyroglobulin monitoring of patients with differentiated thyroid cancer (DTC), depending on the presence of thyroglobulin autoantibodies (TgAbs).

RECENT FINDINGS

Reliable low-range serum thyroglobulin measurement has both enhanced clinical utility and economic advantages, provided TgAb is absent (∼75% DTC patients). Basal [nonthyroid-stimulating hormone (TSH) stimulated] TgIMA measurement obviates the need for recombinant human TSH stimulation because basal TgIMA below 0.20 μg/L has comparable negative predictive value (>95%) to recombinant human TSH-stimulated thyroglobulin values below the cutoff of 2 μg/L. Now that radioiodine remnant ablation is no longer considered necessary to treat low-risk DTC, the trend and doubling time of low basal thyroglobulin values arising from postsurgical thyroid remnants have recognized prognostic significance. The major limitation of TgIMA testing is interference by TgAb (∼25% DTC patients), causing TgIMA underestimation that can mask disease. When TgAb is present, the trend in TgAb concentrations (measured by the same method) can serve as the primary (surrogate) tumor-marker and be augmented by thyroglobulin measured by a TgAb-resistant class of method (radioimmunoassay or liquid chromatography-tandem mass spectrometry).

SUMMARY

The growing use of TgIMA measurement is changing paradigms for postoperative DTC monitoring. When TgAb is absent, it is optimal to monitor the basal TgIMA trend and doubling time (using the same method) in preference to recombinant human TSH-stimulated thyroglobulin testing. When TgAb is present, interference renders TgIMA testing unreliable and the trend in serum TgAb concentrations per se (same method) can serve as a (surrogate) tumor-marker.

New-generation thyroglobulin assay: performance and implications for follow-up of differentiated thyroid carcinoma

OBJECTIVES

Differentiated thyroid cancer (DTC) requires long-term follow-up by serum thyroglobulin assay and cervical ultrasound, due to the risk of recurrence. Guidelines recommend basal assay under hormone therapy at 3 months, repeated at 6-12 months post-surgery, with or without associated isotopic ablation, after stimulation by recombinant human TSH to improve assay sensitivity. It was hypothesized that a new-generation assay kit with lower limits of detection and quantification would improve the sensitivity of the basal assay, enhance detection of premature recurrence and decrease the rate of false-negatives, thereby avoiding the need for the complementary stimulation test.

MATERIAL AND METHODS

A validation study of the second-generation thyroglobulin serum assay was performed in the laboratory of the Lyon Sud Hospital Centre (Lyon, France), with comparison to stimulation test results. Low-concentration serum pools were constituted, including patients followed for stage I to III DTC for whom basal and post-stimulation samples were available in the serum bank.

RESULTS

The new assay proved robust and reliable, with good correlation with the technique presently used in the Lyon hospitals. None of the 54 patients showed false-negative results, which was the objective of our choice of threshold, and 5 were false-positive, for thyroglobulin thresholds of 0.1μg/L at baseline and 1.0μg/L post-stimulation. Positive and negative predictive values were 100% and 87.8% respectively.

CONCLUSION

These results allow an improvement in the follow-up algorithm for DTC, replacing the stimulation test by the new-generation thyroglobulin assay in post-therapeutic assessment.

Thyroglobulin measurement using highly sensitive assays in patients with differentiated thyroid cancer: a clinical position paper

Differentiated thyroid cancer (DTC) is the most common endocrine cancer and its incidence has increased in recent decades. Initial treatment usually consists of total thyroidectomy followed by ablation of thyroid remnants by iodine-131. As thyroid cells are assumed to be the only source of thyroglobulin (Tg) in the human body, circulating Tg serves as a biochemical marker of persistent or recurrent disease in DTC follow-up. Currently, standard follow-up for DTC comprises Tg measurement and neck ultrasound combined, when indicated, with an additional radioiodine scan. Measurement of Tg after stimulation by endogenous or exogenous TSH is recommended by current clinical guidelines to detect occult disease with a maximum sensitivity due to the suboptimal sensitivity of older Tg assays. However, the development of new highly sensitive Tg assays with improved analytical sensitivity and precision at low concentrations now allows detection of very low Tg concentrations reflecting minimal amounts of thyroid tissue without the need for TSH stimulation. Use of these highly sensitive Tg assays has not yet been incorporated into clinical guidelines but they will, we believe, be used by physicians caring for patients with DTC. The aim of this clinical position paper is, therefore, to offer advice on the various aspects and implications of using these highly sensitive Tg assays in the clinical care of patients with DTC.

In search of an unstimulated thyroglobulin baseline value in low-risk papillary thyroid carcinoma patients not receiving radioactive iodine ablation

BACKGROUND

The clinical use of serum thyroglobulin (Tg) as a tumor marker in papillary thyroid cancer (PTC) patients following total thyroidectomy continues to evolve, due in part to the introduction of more sensitive (second generation) Tg immunometric assays (Tg(2G)IMA, functional sensitivity ≤ 0.10 ng/mL), and the implementation of new recommendations against radioactive iodine ablation (RAIA) for patients at the lowest risk of recurrence. As a result, there is a need to establish the optimal timing and interpretation of serum Tg values while on levothyroxine-induced suppression of thyrotropin (TSH) in thyroidectomized PTC patients with a thyroid remnant. This study examines the pattern of decline and eventual baseline value of unstimulated Tg (uTg) concentrations following total thyroidectomy in patients with low-risk PTC who did not receive RAIA.

METHODS

The medical records of consecutive patients with thyroid cancer seen at the Los Angeles County + USC Medical Center were retrospectively reviewed. Serial uTg and TSH values from Tg-antibody negative low-risk PTC patients treated with total thyroidectomy and no RAIA were analyzed. Patients were stratified by degree of TSH suppression to assess the effect on uTg. Serial postoperative uTg values were evaluated for the temporal pattern of decline and ultimate baseline. Patients with medullary thyroid cancer (MTC) were studied as a surgical reference group.

RESULTS

Records from 577 consecutive thyroid cancer patients were reviewed, of which 36 met all criteria for inclusion. By 6 months, uTg fell to <0.5 ng/mL in 61% of patients and all patients demonstrated uTg < 0.5 ng/mL 2 years after surgery. During a median follow up of 5.7 years, uTg values remained below this level. The median uTg values in patients with papillary microcarcinoma, PTC, and MTC were similar at 0.11, 0.12, and 0.09 ng/mL, respectively. Further decline in uTg was not observed once the TSH was <0.5 mIU/L.

CONCLUSIONS

The uTg values during TSH suppression in Tg antibody-negative, low-risk PTC patients who did not receive RAIA were below 0.5 ng/mL by 6 months postoperatively in most cases and remained stable over the duration of patient follow-up.

Update on differentiated thyroid cancer staging

In this review, we demonstrate how initial estimates of the risk of disease-specific mortality and recurrent/persistent disease should be used to guide initial treatment recommendations and early management decisions and to set appropriate patient expectations with regard to likely outcomes after initial therapy of thyroid cancer. The use of ongoing risk stratification to modify these initial risk estimates is also discussed. Novel response to therapy definitions are proposed that can be used for ongoing risk stratification in thyroid cancer patients treated with lobectomy or total thyroidectomy without radioactive iodine remnant ablation.

Basal serum thyroglobulin measured by a second-generation assay is equivalent to stimulated thyroglobulin in identifying metastases in patients with differentiated thyroid cancer with low or intermediate risk of recurrence

BACKGROUND

Guidelines for the follow-up of differentiated thyroid cancer (DTC) recommend the measurement of TSH-stimulated thyroglobulin (s-Tg) instead of basal Tg on T4 therapy (b-Tg). However, these guidelines were established using first-generation Tg assays with a functional sensitivity (FS) of 0.5-1.0 ng/ml. Current more sensitive second-generation Tg assays (Tg2G; FS 0.05-0.10 ng/ml) have shown that low-risk DTC patients with undetectable b-Tg rarely have recurrences.

OBJECTIVES

This study was undertaken to compare b-Tg using a chemiluminescent Tg2G assay (Tg2GICMA; FS 0.1 ng/ml) with s-Tg in DTC patients with an intermediate risk of recurrence.

METHODS

We evaluated 168 DTC patients with a low (n = 101) and intermediate (n = 67) risk of recurrence treated by total thyroidectomy (147 also treated with radioiodine), with a mean follow-up of 5 years.

RESULTS

b-Tg was undetectable with the Tg2GICMA in 142 of 168 patients. s-Tg was <2 ng/ml in 138 of these 142 patients, and only 3 of these 138 (2%) presented metastases on cervical ultrasound (US). Of the 4 of 142 patients with s-Tg >2 ng/ml, 1 had cervical metastases seen after radioiodine. Furthermore, 26 of 168 patients presented detectable b-Tg with the Tg2GICMA; 17 of these 26 patients also presented s-Tg >2 ng/ml. In 10 of these 17 patients, metastases were detected. Cervical US or b-Tg were positive in 14 of 15 patients with recurrent disease. Globally, the sensitivity and negative predictive value of the Tg2GICMA plus US were 93 and 99%, respectively.

CONCLUSION

b-Tg measured with a Tg2GICMA and cervical US, used together, are equivalent to s-Tg in identifying metastases in patients with DTC with a low or intermediate risk of recurrence.

Unstimulated highly sensitive thyroglobulin in follow-up of differentiated thyroid cancer patients: a meta-analysis

CONTEXT

Serum thyroglobulin (Tg) is an indicator of differentiated thyroid cancer (DTC) relapse.

OBJECTIVE

Our objective was to conduct a meta-analysis of published data about the diagnostic performance of highly sensitive serum Tg (hsTg) during levothyroxine therapy in DTC follow-up.

DATA SOURCES

We performed a comprehensive literature search of PubMed/MEDLINE and Scopus for studies published until July 2013.

STUDY SELECTION

Studies investigating the diagnostic performance of basal hsTg in monitoring DTC were eligible. Exclusion criteria were 1) articles not within the field of interest; 2) reviews, letters, or conference proceedings; 3) articles evaluating serum Tg measurement with a functional sensitivity >0.1 ng/mL; 4) overlap in patient data; and 5) insufficient data to reassess diagnostic performance of basal serum hsTg.

DATA EXTRACTION

Information was collected concerning basic study data, patient characteristics, and technical aspects. For each study, the number of true-positive, false-positive, true-negative, and false-negative findings for basal hsTg, considering stimulated Tg measurement as a reference standard, were recorded.

DATA SYNTHESIS

Pooled data demonstrated that the negative predictive value of hsTg was 97% and 99% considering a stimulated Tg measurement >1 ng/mL and >2 ng/mL as cutoffs for positivity, respectively. Despite the high pooled sensitivity of basal hsTg, the pooled specificity, accuracy, and positive predictive value were insufficient to completely substitute for a stimulated Tg measurement.

CONCLUSIONS

Basal hsTg measurement has a very high negative predictive value but an insufficient positive predictive value for monitoring DTC patients. Therefore, a Tg stimulation test can be avoided in patients with an undetectable basal hsTg, whereas a stimulated Tg measurement should be considered when hsTg levels are detectable.

Thyroglobulin antibody (TgAb) methods - Strengths, pitfalls and clinical utility for monitoring TgAb-positive patients with differentiated thyroid cancer

Thyroglobulin autoantibodies (TgAb) are detected at diagnosis or during treatment in approximately 25% of patients with differentiated thyroid cancer (DTC). When present, TgAb interferes with thyroglobulin (Tg) measurement causing falsely low or undetectable Tg immunometric assay (IMA) values that can mask disease. Guidelines mandate that every Tg test have TgAb measured simultaneously and quantitatively by immunoassay and not a recovery test. The propensity and magnitude of TgAb-Tg interference relates to both Tg and TgAb concentrations and the class of Tg method used. Because the TgAb trend reflects changes in thyroid tissue mass, TgAb concentrations serve as a surrogate post-operative DTC tumor marker. A rising, or de novo appearance of TgAb may indicate recurrence, whereas a progressive decline suggests successful treatment. This review focuses on the technical limitations of current TgAb methods, characteristics of TgAb interference with different classes of Tg method, and the clinical value of monitoring TgAb trends as a surrogate DTC tumor marker.

Clinical review: improving the measurement of serum thyroglobulin with mass spectrometry

CONTEXT

Serum thyroglobulin (Tg) measurements are central to the management of patients treated for differentiated thyroid carcinoma. For decades, Tg measurements have relied on methods that are subject to interference by commonly found substances in human serum and plasma, such as Tg autoantibodies. As a result, many patients need additional imaging studies to rule out cancer persistence or recurrence that could be avoided with more sensitive and specific testing methods.

OBJECTIVES

The aims of this review are to: 1) briefly review the interferences common to Tg immunoassays; 2) introduce readers to liquid chromatography-tandem mass spectrometry as a method for quantifying proteins in human serum/plasma; and 3) discuss the potential benefits and limitations of the method in the quantification of serum Tg.

RESULTS

Mass spectrometric methods have traditionally lacked the sensitivity, robustness, and throughput to be useful clinical assays. These methods failed to meet the necessary clinical benchmarks due to the nature of the mass spectrometry workflow and instrumentation. Over the past few years, there have been major advances in reagents, automation, and instrumentation for the quantification of proteins using mass spectrometry. More recently, methods using mass spectrometry to detect and quantify Tg have been developed and are of sufficient quality to be used in the management of patients.

CONCLUSIONS

Novel serum Tg assays that use mass spectrometry may avoid the issue of autoantibody interference and other problems with currently available immunoassays for Tg. Prospective studies are needed to fully understand the potential benefits of novel Tg assays to patients and care providers.