Implications of thyroglobulin antibody positivity in patients with differentiated thyroid cancer: a clinical position statement

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.

Predicting clinical outcomes of patients with serum thyroglobulin antibodies after thyroidectomy for differentiated thyroid cancer: a retrospective study from a UK regional center

BACKGROUND

Twenty-twenty-five percent of patients with differentiated thyroid cancer (DTC) can have elevated thyroglobulin antibodies (TgAb). The study aimed to find any prognostic significance of elevated TgAb during follow-up.

METHODS

Ten-year retrospective study from a tertiary center including 79 patients with raised TgAb after total/staged thyroidectomy for DTC. We identified patients with stable (7.6%), increasing (15%) and decreasing levels of TgAb (77.2%); groups 1, 2 and 3 respectively. During follow-up we analyzed TgAb in subcategories by TgAb trend (>50% rise, <50% rise, >50% decline, <50% decline, positive to negative/normalization, negative to positive and stable levels), gender, age, surgery, autoimmune disease, histology, RAI uptake, distant metastases, and recurrence.

RESULTS

The incidence of raised TgAb levels was 33.2%, with female predominance. No connection was identified regarding other parameters. 11.4% had distant metastases. The highest mean maximum levels of TgAb was in group 2 (1918.75 IU/mL) and the lowest in group 3 (412.70 IU/mL). The recurrence rate changed significantly between the 3 groups: 50% in group 1, 75% in group 2, and 25% in group 3 (P=0.002). Recurrence rates decreased to 15% in the subcategory where TgAb became negative/normal from positive (P=0.0001). In patients with a negative to positive TgAb level trend or >50% rise, recurrence rates were 100% (P=0.041) and 70% (P=0.012) respectively.

CONCLUSIONS

Patients with increasing TgAb levels during follow-up have a higher rate of recurrence, distinctly for those with negative to positive trend and >50% rise in TgAb. These patients need closer follow-up, and TgAb may be used as a dynamic follow-up marker.

The effect of positive thyroglobulin antibodies on the prognosis and treatment response in patients with papillary thyroid carcinoma

Almost 15-30% of patients with papillary thyroid carcinoma (PTC) experience some degree of recurrence after treatment. Long-term follow-up and examination after thyroidectomy are very important in dealing with this issue. Serum thyroglobulin (Tg) level and neck ultrasound are the main part of follow-up for this purpose. The presence of thyroglobulin antibodies (TgAbs) leads to unreliable thyroglobulin (Tg) levels. The present study aims to evaluate the relationship between the simultaneous measurement of Tg and TgAb with long-term survival and response to treatment in these patients. This study was conducted by surveying available data from the medical records of 204 out of 600 patients over a 20-year period. In this research, 104 patients with positive TgAb were considered as the case group, and 100 patients with negative TgAb were selected as the control group. The relationship of TgAb titer was investigated with the staging, response to treatment (including the surgery number, number of radiotherapies, and dose of radioactive iodine), and recurrence in these patients. Also, the trend of TgAb changes was examined in the presence of high or low thyroglobulin levels during the follow-up period. Patients with high TgAb levels had more lymph node involvement, higher cumulative dose, a higher number of times received iodine, more surgical number, higher recurrence rate, and less excellent response (ER) to treatment during follow-ups. This effect of TgAb worsened in the presence of high Tg titer and remained up to 36 months. Overall, the baseline level of TgAb and its changes can be a suitable factor for predicting subsequent response to treatment and recurrence in patients with PTC. Accordingly, in cases with high TgAb and Tg levels, close follow-up should be considered up to Tg and TgAb normalization.

Lessons learned: establishing a CLIA-equivalent laboratory for targeted mass spectrometry assays - navigating the transition from research to clinical practice

Mass spectrometry (MS) assays offer exceptional capabilities in high multiplexity, specificity, and throughput. As proteomics technologies continue advancements to identify new disease biomarkers, transition of these innovations from research settings to clinical applications becomes imperative. To meet the rigorous regulatory standards of clinical laboratories, development of a clinical protein MS assay necessitates adherence to stringent criteria. To illustrate the process, this project focused on using thyroglobulin (Tg) as a biomarker and an immuno-multiple reaction monitoring (iMRM) MS-based assay as a model for establishing a Clinical Laboratory Improvement Amendments (CLIA) compliant laboratory within the Centers of Genomic and Precision Medicine, National Taiwan University. The chosen example also illustrates the clinical utility of MS assays to complement conventional immunoassay-based methods, particularly in cases where the presence of autoantibodies in 10-30% of patients hinders accuracy. The laboratory design entails a comprehensive coordination in spatial layout, workflow organization, equipment selection, ventilation systems, plumbing, electrical infrastructure, documentation procedures, and communication protocols. Practical aspects of the transformation process, including preparing laboratory facilities, testing environments, instrument validation, assay development and validation, quality management, sample testing, and personnel competency, are discussed. Finally, concordant results in proficiency testing demonstrate the harmonization with the University of Washington Medical Center and the quality assurance of the CLIA-equivalent Tg-iMRM MS assay established in Taiwan. The realization of this model protein MS assay in Taiwan highlights the feasibility of international joint development and provides a detailed reference map to expedite the implementation of more MS-based protein assays in clinical laboratories for patient care.

Thyroglobulin and thyroglobulin antibody: an updated clinical and laboratory expert consensus

OBJECTIVE

Thyroglobulin measurement is the cornerstone of modern management of differentiated thyroid cancer, with clinical decisions on treatment and follow-up based on the results of such measurements. However, numerous factors need to be considered regarding measurement with and interpretation of thyroglobulin assay results.

DESIGN

The present document provides an integrated update to the 2013 and 2014 separate clinical position papers of our group on these issues.

METHODS

Issues concerning analytical and clinical aspects of highly-sensitive thyroglobulin measurement will be reviewed and discussed based on an extensive analysis of the available literature.

RESULTS

Thyroglobulin measurement remains a highly complex process with many pitfalls and major sources of interference, especially anti-thyroglobulin antibodies, need to be assessed, considered and, when necessary, dealt with appropriately.

CONCLUSIONS

Our expert consensus group formulated 53 practical, graded recommendations for guidance on highly-sensitive thyroglobulin and TgAb in laboratory and clinical practice, especially valuable where current guidelines do not offer sufficient guidance.

Thyroglobulin immunoassay with a fully automated pretreatment process provides accurate thyroglobulin values in anti-thyroglobulin antibody positive specimens

OBJECTIVES

Human thyroglobulin (Tg) is widely used as a tumor marker for recurrence and metastasis of differentiated thyroid cancer (DTC). Currently, serum Tg values are measured using second-generation sandwich immunoassays (2^nd-IMA). However, interference by endogenous autoantibodies to thyroglobulin (TgAbs) can lead to false-negative results or falsely low Tg values. Here, we describe a new Tg assay using the immunoassay for total antigen including complex via pretreatment (iTACT) method to prevent TgAb interference and compare it with 2^nd-IMA.

METHODS

Tg values were evaluated by three assays: iTACT Tg, Elecsys Tg-II, which is a 2^nd-IMA, and LC-MS/MS (Liquid chromatography tandem-mass spectrometry). The ratio of Tg values between each assay was then compared to the Tg value by LC-MS/MS and TgAb titer. Tg immunoreactivity was analyzed by size-exclusion chromatography.

RESULTS

Correlation between iTACT Tg and LC-MS/MS using TgAb-positive specimens was good: Passing-Bablok regression with iTACT Tg = 1.084 x LC-MS/MS + 0.831. Correlation between 2^nd-IMA and LC-MS/MS showed a relatively lower slope: 2^nd-IMA = 0.747 x LC-MS/MS - 0.518. Thus, Tg values determined by iTACT Tg are equivalent to those of LC-MS/MS regardless of TgAb titer, whereas 2^nd-IMA gave lower Tg values due to TgAb interference. Tg-TgAb complexes of various molecular weights were verified by size-exclusion chromatography. Tg values measured by 2^nd-IMA fluctuated depending on the molecular weight of the Tg-TgAb complexes, whereas iTACT Tg accurately quantified Tg values regardless of the size of the Tg-TgAb complexes.

CONCLUSION

Tg values in TgAb-positive specimens were accurately determined by iTACT Tg. TgAb-positive specimens contain Tg-TgAb complexes of various molecular weights that interfere with Tg value determination by 2^nd-IMA, whereas iTACT Tg is unaffected by the presence of Tg-TgAb complexes.

Modified dynamic risk stratification system further predicts individual outcome in patients with intermediate-risk papillary thyroid cancer

OBJECTIVE

We assessed the contribution of initial treatment response to further refining prediction of individual outcomes in intermediate-risk papillary thyroid cancer (PTC) on the American Thyroid Association (ATA) risk stratification system. Dynamic risk stratification (DRS) as originally proposed by Tuttle et al. in 2010 was modified to also include serum antithyroglobulin antibodies (TgAb) as a surrogate marker of the likelihood of persistent disease, specifically in patients with thyroglobulin assay interference by TgAb.

METHODS

Three hundred and seventy-three patients with ATA intermediate-risk PTC were enrolled retrospectively upon reviewing medical records. Patients were followed at the National Cancer Institute in Bogota, Colombia after being treated with total thyroidectomy and I-131 therapy between 2009 and 2013. Best response to initial therapy was classified as excellent, indeterminate, biochemically incomplete or structurally incomplete. Final disease status after a median follow-up of 7.1 years was classified as no evidence of disease (NED), indeterminate, or persistent disease (either biochemically or structurally). The rate of recurrence was determined in excellent responders.

RESULTS

Excellent response was achieved by 164 patients (43.9%). At a median follow-up of 42 months, 19 (11.6%) had experienced recurrence. 87.4% of initially excellent responders available at the final checkpoint were NED, compared to 28% of those with biochemically or structurally incomplete response and to 60.2% of all ATA intermediate-risk PTC patients in our cohort.

CONCLUSIONS

Modified DRS further predicted individual outcomes in intermediate-risk PTC, potentially allowing ongoing management to be tailored accordingly.

Findings of I-131 SPECT/CT, 18F-FDG, and 68Ga-FAPI-04 PET/CT Imaging in a Patient Treated with Radioiodine Therapy for Metastatic Papillary Thyroid Carcinoma

A 50-year-old man undergone total thyroidectomy and histopathology revealed papillary thyroid carcinoma with a tumor size of 4.5 cm. The patient was referred to a nuclear medicine clinic for radioiodine therapy. Since the thyroglobulin level before the treatment was 495 ug/L, low-dose (185 MBq) I-131 scan was performed. In addition to multiple liver metastases, bone metastases were detected in the sacrum and right 7^th rib in I-131 whole body scanning and single photon emission computed tomography/computed tomography (CT) imaging at the time of initial staging. We present a case of multiple metastatic papillary thyroid carcinoma whose radioiodine treatment response and clinical outcome were evaluated with ¹⁸F-fluorodeoxyglucose and Gallium-68 FAPI-04 positron emission tomography/CT.

Quality of life in thyroid cancer

To explore the impact of differentiated thyroid cancer (DTC) on quality of life (QoL) a clinical analytical framework was developed. Based on the clinical analytical framework, a systematic literature search was performed to identify studies applying patient-reported outcomes (PRO) instruments among patients with DTC. Subsequently, the scope was narrowed down to studies comparing scores on the Medical Outcomes Study (MOS) Short form 36 (SF-36) to a reference population (clinical interpretability criterion). Further, the currently available thyroid cancer (TC) specific QoL PROs were review in accordance with the standards of the International Society of Quality of Life Research. In the initial search, 213 studies were included. The additional 'clinical interpretability'-criteria, limited the final study sample to 16 studies, 13 cross-sectional and 3 longitudinal. QoL was impacted across all SF-36 scales. The impact was generally modest and the impact was impeded by time since diagnosis and treatment. Four TC specific instruments were identified. Generally, the documentation of their measurement properties, particularly content validity and clinical validity, including substantial quantitative validation, was scarce. As was the cross-cultural applicability of the currently available instruments. This restricted, focused, clinically founded review showed an impact on a broad range of QoL issues. There is a need for large-scale measurement of QoL outcome longitudinally, using well-validated PRO instruments in order to identify with certainty the impact on subgroups.

Clinical irrelevance of lower titer thyroglobulin autoantibodies in patients with differentiated thyroid carcinoma

Objective

Thyroglobulin (Tg) is an established tumor marker for differentiated thyroid carcinoma (DTC) patients. However, Tg immunoassays can be subject to Tg autoantibody (TgAb) interference resulting in incorrect Tg values. Therefore, Tg measurement with liquid chromatography-tandem mass spectrometry (LC-MS/MS) could be promising in patients with TgAbs. In this study, we compared Tg IRMA and Tg-LC-MS/MS analytically in the presence of TgAbs. Furthermore, we compared the clinical interpretation of results obtained by both Tg assays in DTC patients with lower TgAbs titers (<10 U/mL) during 131I ablation therapy.

Methods

Totally 118 DTC patients diagnosed between 2006 and 2014 in a University Medical Center were followed with the Tg-IRMA (Thermo Fischer Scientific) and ARCHITECT anti-Tg (Abbott Laboratories) assays. We re-analyzed their samples with a sensitive Tg-LC-MS/MS method (Labcorp, limit of quantification of 0.02 ng/mL). Passing-Bablok regression analysis was performed on samples obtained during 131I ablation therapy and follow-up.

Results

In 304 samples with lower TgAb titers, a good analytical agreement was found between both Tg assays (slope of 1.09 (95% CI: 1.05-1.16)). Fifty-five samples with potentially interfering TgAbs showed higher Tg-LC-MS/MS values than Tg-IRMA (slope of 1.45 (95% CI: 1.12->>100)). In patients(n = 91) with lower TgAb titers at the time of 131I ablation therapy, the Tg assays showed a clinical concordance of 91.2, 87.9, and 98.9%, respectively, using a Tg cut-off value of 1.0, 2.0, and 5.0 ng/mL.

Conclusions

In DTC patients with lower titer TgAbs, Tg-IRMA is still a reliable and useful tumor marker. In DTC patients with potentially interfering TgAbs, Tg-IRMA values decreased due to TgAb interference.

High Thyroglobulin Antibody Following Intravenous Immunoglobulin Therapy in Athyreotic Differentiated Thyroid Cancer Patients

American Thyroid Association guidelines recommend to follow athyreotic differentiated thyroid cancer patients with measurement of serum thyroglobulin and thyroglobulin antibody as tumor markers. The guidelines recommend that rising thyroglobulin or thyroglobulin antibody should prompt additional investigations and potentially additional therapies. Two patients with differentiated thyroid cancer who also received intravenous immunoglobulin are presented. Their cancer history, serial thyroglobulin and thyroglobulin antibody measurements and imaging findings relative to the time course of intravenous immunoglobulin treatment are illustrated. Acute rise in thyroglobulin antibody led to further imaging which did not show cancer progression. Additional history documented an intravenous immunoglobulin treatment exposure had occurred within the past one to two months before the increased thyroglobulin antibody measurement. Follow-up serial thyroglobulin antibody levels declined over time after the intravenous immunoglobulin exposure. Intravenous immunoglobulin, which is a pooled human serum product, contains thyroglobulin antibody. Commercially available thyroglobulin antibody assays may detect the thyroglobulin antibody contained within the administered intravenous immunoglobulin, leading to alarm and further imaging to exclude progressive malignancy. Thyroglobulin antibody rise and fall can be demonstrated in relationship to intravenous immunoglobulin time of administration. Thyroglobulin antibody is higher at time-points sooner than at later time-points following intravenous immunoglobulin treatments. Intravenous immunoglobulin may be a benign source of transiently high thyroglobulin antibody measured in the follow-up of differentiated thyroid cancer patients. Repeat thyroglobulin and thyroglobulin antibody testing one to two months following a higher level in a patient treated with intravenous immunoglobulin may avoid unnecessary imaging to look for progressive malignancy.

Thyroid nodules in children and adolescents: Investigation and management

Clinically detectable thyroid nodules are less common in children than adults. However, they are associated with an increased risk of malignancy. Therefore, thorough evaluation of paediatric thyroid nodules is necessary, and an understanding of the features associated with a higher risk of malignancy is important to guide management and referral. Thyroid cancer in children differs significantly from that seen in adults in terms of genetics, presentation, response to treatment and prognosis. Children often present with more advanced disease, but the vast majority have excellent long-term prognosis. Evaluation and management of thyroid nodules and thyroid cancer require a multidisciplinary team approach and involvement of specialists with experience in this field. This review summarises investigative pathways for thyroid nodules in children and outlines current management strategies for paediatric thyroid nodules and cancer.

Serum glycomic profile as a predictive biomarker of recurrence in patients with differentiated thyroid cancer

PURPOSE

Thyroid cancer recurrence following curative thyroidectomy is associated with increased morbidity and mortality, but current surveillance strategies are inadequate for early detection. Prior studies indicate that tissue glycosylation is altered in thyroid cancer, but the utility of serum glycosylation in thyroid cancer surveillance remains unexplored. We therefore assessed the potential utility of altered serum glycomic profile as a tumor-specific target for disease surveillance in recurrent thyroid cancer.

EXPERIMENTAL DESIGN

We employed banked serum samples from patients with recurrent thyroid cancer post thyroidectomy and healthy controls. N-glycans were enzymatically released from serum glycoproteins, labeled via permethylation, and analyzed by MALDI-TOF mass spectrometry. Global level and specific subtypes of glycan structures were compared between patients and controls.

RESULTS

We evaluated 28 independent samples from 13 patients with cancer recurrence and 15 healthy controls. Global features of glycosylation, including N-glycan class and terminal glycan modifications were similar between groups, but three of 35 individual glycans showed significant differences. The three glycans were biosynthetically related biantennary core fucosylated N-glycans that only varied by the degree of galactosylation (G0F, G1F, and G2F; G: galactose, F: fucose). The ratio of G0F:G1F that captures reduced galactosylation was observed in patients samples but not in healthy controls (p = 0.004) and predicted thyroid cancer recurrence (AUC = 0.82, CI 95% = 0.64-0.99).

CONCLUSIONS

Altered N-glycomic profile was associated with thyroid cancer recurrence. This serum-based biomarker would be useful as an effective surveillance tool to improve the care and prognosis of thyroid cancer after prospective validation.

Thyroid Cancer Persistence in Patients with Unreliable Thyroglobulin Measurement: Circulating microRNA as Candidate Alternative Biomarkers

BACKGROUND

We aimed to evaluate the role of circulating miRNAs as a biomarker of the persistence of papillary thyroid cancer (PTC) in patients with an "uninformative" thyroglobulin (Tg) measurement.

METHODS

We prospectively enrolled 49 consecutive PTC patients with Tg-positive antibodies (TgAb) who had undergone a (near)-total thyroidectomy and ¹³¹I therapy (RIT). The serum thyroid stimulating hormone (TSH), Tg, and TgAb levels were measured before and at 6 and 12 months after RIT, respectively. The serum miRNA (221, 222, 375, 155, and 146b) levels were measured simultaneously.

RESULTS

The response to the initial therapy was assessed according to the 2015 ATA criteria. A decrease in 50% or more of serum miRNA over time was observed in 41/49 PTC patients, who showed an excellent response (ER), but six and two patients were classified to have an indeterminate/incomplete biochemical or incomplete structural response to initial therapy.

CONCLUSION

Serum miRNA kinetics emerge as a promising biomarker for the early detection of a persistent disease in PTC patients with uninformative Tg results.

Thyroglobulin antibodies: Trend over time and clinical impact in differentiated thyroid carcinoma with and without radioiodine ablation

INTRODUCTION

Thyroglobulin antibodies (TgAb) trend may be considered a surrogate marker for thyroglobulin in differentiated thyroid carcinoma. The aim of this study is to analyse, in cases with positive TgAb, trend over time and its relationship with response to treatment.

MATERIAL AND METHODS

Retrospective and descriptive study of 100 patients with differentiated thyroid carcinoma and positive TgAb (measured by electrochemoluminiscense) after thyroidectomy. Assessment of response to initial treatment was performed 6-24 months after surgery. Status at last follow-up was evaluated.

RESULTS

After the first year nearly half of the patients showed a reduction in TgAb levels ≥50%, in 91% of these patients, status at last follow up was excellent response (65%) or indeterminate response due to decreasing TgAb levels (26%). At first assessment, indeterminate responses were found in 49% of cases, without significant differences among initial risk of recurrence category or whether radioiodine ablation was performed. At last evaluation (median 53.5 months), 15% of ablated low-risk patients had an indeterminate response (due to declining TgAb), vs 62% in the non-ablated low-risk group (p 0.03). Median time to negativization for post-surgical TgAb levels<100UI/ml was 11 months [3-94] vs 31 months [8-119] for patients with TgAb≥100UI/ml (p 0.0003).

CONCLUSION

A reduction of ≥50% in TgAb levels during the first year correlated with favourable outcomes. Non-ablated patients and patients with higher levels of post-surgical TgAb may need a longer time to achieve negative conversion.

Radioactive iodine therapy: multiple faces of the same polyhedron

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

Thyroglobulin and thyroglobulin antibodies: assay-dependent management consequences in patients with differentiated thyroid carcinoma

OBJECTIVES

International guidelines recommend fixed cut-off values for thyroglobulin (Tg). These cut-offs do not take potential assay differences into account. This study aimed to evaluate if different assays for Tg and Tg antibodies (TgAb) affect management guidance for differentiated thyroid cancer (DTC) patients.

METHODS

In 793 samples derived from 413 patients with DTC, Tg and TgAb were simultaneously measured with two immunometric assays: Immulite 2000XPi and Kryptor compact plus. In addition, a qualitative measurement for TgAb interference (recovery test) was performed on the Kryptor compact plus platform. The extent to which different assays lead to different classifications of response to therapy was evaluated when applying the current cut-offs for Tg.

RESULTS

Mean Tg concentrations were 37.4% lower with Kryptor as compared with Immulite. Applying guideline based cut-off values for Tg, 33 (4.7%) samples had a Tg-on concentration ≥1.0 μg/L with Immulite and <1.0 μg/L with Kryptor. Of the samples tested as TgAb+ with at least one assay (n=125), 68 (54.4%) samples showed discrepancy in TgAb status. Differences between Immulite and Kryptor measurements resulted in a change in the response to therapy classification in 94 (12.0%) measurements derived from 67 (16.2%) individual patients.

CONCLUSIONS

A substantial portion of DTC patients were classified differently dependent on which Tg and TgAb assays are used, when applying the cut-off values as defined in clinical guidelines. Such differences can significantly affect clinical management. In the context of large between-method variation, the recommended Tg cut-offs in guidelines should be used with wisdom rather than as fixed cut-offs.

Change in Antithyroglobulin Antibody Levels is a Good Predictor of Responses to Therapy in Antithyroglobulin Antibody-Positive Pediatric Papillary Thyroid Carcinoma Patients

OBJECTIVE

Antithyroglobulin antibodies (TgAbs) could be used as a surrogate tumor marker of TgAb-positive-differentiated thyroid carcinoma. This study aims to determine whether the change in TgAb levels over time could be used as a predictor of responses to therapy in pediatric papillary thyroid carcinoma (PTC) patients.

METHODS

We retrospectively analyzed the records of 48 pediatric PTC patients with TgAb levels ≥50 IU/ml 6 months after initial ¹³¹I treatment. Suppressed thyroglobulin (Tg) levels 6 months after initial ¹³¹I treatment were used to divide the patients into positive Tg (P-Tg, Tg ≥ 0.2 ng/ml) and negative Tg (N-Tg, Tg < 0.2 ng/ml) groups. Responses to therapy were classified as the acceptable response (AR) group and the not acceptable response (NAR) group.

RESULTS

Of 48 enrolled patients with 58 months (range, 24-143 months) of follow-up, 28 patients had NAR and 20 patients had AR. TgAb levels were decreasing ≥50% in 28 patients, decreasing <50% in 8 patients, and increasing in 12 patients. Multivariate analysis showed that high initial risk stratification and TgAb levels decreasing <50% or increasing were significantly associated with NAR (p < 0.05). Changes in Tg levels were also associated with NAR in the P-Tg group (p < 0.05).

CONCLUSION

Changes in TgAb levels over time could be used as a predictor of responses to therapy in TgAb-positive pediatric PTC patients. Changes in Tg levels over time are also associated with NAR to therapy in both TgAb-positive and Tg-positive pediatric PTC patients.

Impact of Thyroglobulin and Thyroglobulin Antibody Assay Performance on the Differential Classification of DTC Patients

CONTEXT

Measurements of thyroglobulin (Tg) and Tg antibodies are crucial in the follow-up of treated differentiated thyroid cancer (DTC) patients. Interassay differences may significantly impact follow-up.

OBJECTIVE

The aim of this multicenter study was to explore the impact of Tg and Tg antibody assay performance on the differential classification of DTC patients, as described in national and international guidelines.

DESIGN

Four commonly used Tg and Tg antibody assays were technically compared to reflect possible effects on patients with DTC follow-up. Storage stability at different storage temperatures was also investigated for LIAISON® and Kryptor assays, as this is an underexposed topic in current literature.

RESULTS

B.R.A.H.M.S. assays yield approximately 50% lower Tg values over the whole range compared to the DiaSorin and Roche assays investigated. These differences between assays may result in potential misclassification in up to 7% of patients if fixed cutoffs (eg, 1 ng/mL) are applied. Poor correlation was also observed between the Tg antibody assays when the method-specific upper limits of normal are used as cutoffs. Storage of Tg and Tg antibodies was possible for 3 to 4 weeks at -20°C and -80°C. Calibration of the assays, however, was found to be crucial for stable results over time.

CONCLUSIONS

Technical aspects of Tg and Tg antibody assays, including interassay differences, calibration and standardization, and cutoff values, may have a significant clinical impact on the follow-up of DTC patients.

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 New Dynamic Response to Therapy Assessment in Postoperative Patients With Low-Risk Differentiated Thyroid Cancer Treated Without Radioactive Iodine

Background

Total thyroidectomy (TT) or lobectomy without radioactive iodine (RAI) is becoming a common management for patients with low-risk differentiated thyroid cancer (DTC). However, the assessment of response to therapy for these patients remains controversial. The aim of this study was to propose and validate a new dynamic evaluation strategy to assess the response to therapy in patients with low-risk DTC treated with TT or lobectomy but without RAI.

Methods

We performed a retrospective analysis of 543 adult patients with low-risk DTC who underwent TT or lobectomy without RAI therapy. Follow-up consisted of trends of serum thyroglobulin (Tg), anti-thyroglobulin antibody (TgAb) levels and neck ultrasonography (US) were conducted every 6-24 months. Response to therapy assessments were defined as excellent response, biochemical incomplete response, structural incomplete response, and indeterminate response according to the follow-up findings.

Results

At a median follow-up of 51 months (range 33-66 months), 517 (95%) had excellent response, while the other 26 had either biochemical incomplete response (an increasing trend of suppressed serum Tg levels, n=9; an increasing trend of TgAb levels, n=3) or indeterminate response (a stable or decreasing trend of suppressed serum Tg levels, but a stable positive trend of TgAb levels, n=14). No patients had structural incomplete response or no deaths related to thyroid cancer. The risk of incomplete response was significantly higher in lobectomy than in TT (p<0.001).

Conclusion

Our study proposed and validated a new dynamic response to therapy assessment depending on trends of suppressed serum Tg, TgAb levels, and neck US findings which could be an appropriate tool for postoperative follow-up in low-risk DTC patients without RAI therapy. Our findings provided further evidence to support no routine recommendation of RAI after surgery in low-risk DTC.

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients

INTRODUCTION

The determination of thyroglobulin levels by immunoassay and imaging studies is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients.

OBJECTIVES

Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer.

METHODS

This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (69) and with structural incomplete response to treatment (23). Results were analysed using the Unity Real-Time program and expressed as fg/μg RNA. A Receiver Operating Characteristic curve was constructed to assess Tg-mRNA cut-off values.

RESULTS

Tg-mRNA levels were not significantly different between the group with excellent response [0.10 fg/μg RNA (0.08-0.17)] and the group with incomplete structural response [0.133 fg/μg RNA (0.07-0.33)] (P < .06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value 36.4% CONCLUSIONS: Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.

Life after thyroid cancer: the role of thyroglobulin and thyroglobulin antibodies for postoperative follow-up

INTRODUCTION

Differentiated thyroid carcinomas (DTCs) are treated with (near-)total thyroidectomy and radioiodine therapy. Recently, the use of highly sensitive thyroglobulin (hsTg) assays has simplified DTC follow-up and improved patients' quality of life. More limited approaches are currently applied in low-risk patients requiring interpretations of Tg results in different clinical scenarios. Finally, Tg assays are hampered by interference from thyroglobulin autoantibodies (TgAb).

AREAS COVERED

The role of Tg measurement in DTC patients treated with complete thyroid ablation, thyroidectomy alone, or lobectomy is summarized. The management of patients carrying positive TgAb is also addressed.

EXPERT OPINION

Patients with undetectable hsTg after total thyroid ablation are safely managed by periodic hsTg measurement, combined with selective use of imaging procedures in few cases. Serum hsTg trend remains informative in patients treated without radioiodine ablation. However, reliable reference values are urgently needed in this setting. The role of hsTg is debated in patients who have undergone lobectomy due to the amount of Tg released by a functioning thyroid lobe. The evaluation of TgAb trend over time (i.e. surrogate tumor marker) is recommended in patients with positive TgAb and potentially interfering Tg results.

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.

Are psychiatric disorders associated with thyroid hormone therapy in adolescents and young adults with type 1 diabetes?

BACKGROUND

To evaluate the association between thyroid autoimmunity and psychiatric disorders (depression, anxiety, eating disorder, schizophrenia or attention-deficit/hyperactivity disorder) among adolescents and young adults with type 1 diabetes (11-25 years).

METHODS

We compared 9368 type 1 diabetes patients with thyroid autoimmunity (3789 of them treated with levothyroxine) with 62 438 type 1 diabetes patients without any thyroid disease from a multicentre diabetes patient follow-up registry (DPV) in terms of psychiatric disorders. Thyroid autoimmunity was defined as documented diagnosis of Hashimoto thyroiditis or positive antibodies against thyroid peroxidase or thyroglobulin. Multivariable logistic regression models were used to calculate odds ratios for the respective psychiatric disorders in type 1 diabetes patients with thyroid autoimmunity (overall and stratified by levothyroxine therapy) compared to type 1 diabetes patients without thyroid diseases (reference).

RESULTS

Of the 9368 patients with thyroid autoimmunity, 62% were female with a median (Q1-Q3) age of 16.3 (14.2-17.6) years. Thyroid autoimmunity (with or without levothyroxine therapy) revealed a slight, but significant higher chance for depression (odds ratio [OR], 1.35, 95% confidence interval [CI], 1.19, 1.52), eating disorder (OR, 1.25, CI, 1.03, 1.51), attention-deficit/hyperactivity disorder (OR, 1.22, CI, 1.07, 1.39) and schizophrenia (OR, 1.63, CI, 1.04, 2.56). In individuals with prescribed levothyroxine therapy because of thyroid dysfunction significantly higher odds for depression (OR, 1.63, CI, 1.34, 1.99), anxiety (OR, 1.60, CI, 1.18, 2.18), and attention-deficit/hyperactivity disorder (OR, 1.71, CI, 1.38, 2.12) were observed compared to reference. Thyroid autoimmunity without required levothyroxine therapy revealed no differences to the reference group.

CONCLUSIONS

Patients on levothyroxine had significantly higher odds for psychiatric disorders, but thyroid autoimmunity in terms of high antibody levels only did not show higher odds for any psychiatric disorder.

A Joint Statement from the American Thyroid Association, the European Association of Nuclear Medicine, the European Thyroid Association, the Society of Nuclear Medicine and Molecular Imaging on Current Diagnostic and Theranostic Approaches in the Management of Thyroid Cancer

Background: The American Thyroid Association (ATA), the European Association of Nuclear Medicine, the European Thyroid Association, and the Society of Nuclear Medicine and Molecular Imaging have established an intersocietal working group to address the current controversies and evolving concepts in thyroid cancer management and therapy. The working group annually identifies topics that may significantly impact clinical practice and publishes expert opinion articles reflecting intersocietal collaboration, consensus, and suggestions for further research to address these important management issues. Summary: In 2019, the intersocietal working group identified the following topics for review and interdisciplinary discussion: (i) perioperative risk stratification, (ii) the role of diagnostic radioactive iodine (RAI) imaging in initial staging, and (iii) indicators of response to RAI therapy. Conclusions: The intersocietal working group agreed that (i) initial patient management decisions should be guided by perioperative risk stratification that should include the eighth edition American Joint Committee on Cancer staging system to predict disease specific mortality, the modified 2009 ATA risk stratification system to estimate structural disease recurrence, with judicious incorporation of molecular theranostics to further refine management recommendations; (ii) diagnostic RAI scanning in ATA intermediate risk patients should be utilized selectively rather than being considered mandatory or not necessary for all patients in this category; and (iii) a consistent semiquantitative reporting system should be used for response evaluations after RAI therapy until a reproducible and clinically practical quantitative system is validated.

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients

INTRODUCTION

The determination of thyroglobulin (Tg) levels by immunoassay is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients.

OBJECTIVES

Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA (Tg-mRNA) levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer.

METHODS

This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (n=69) and with structural incomplete response to treatment (n=23). Results were analysed using the Unity Real-Time program and expressed as fg/μg RNA. A Receiver Operating Characteristic curve was constructed to establish Tg-mRNA cut-off values.

RESULTS

Tg-mRNA levels were not significantly different between the group with excellent response [0.10fg/μg RNA (0.08-0.17)] and the group with incomplete structural response [0.133fg/μg RNA (0.07-0.33)] (p<0.06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value was 36.4%.

CONCLUSIONS

Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.

The role of a new polyclonal competitive thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer with structural disease but low levels of serum thyroglobulin by immunometric and LC-MS/MS methods

PURPOSE

The aims of this study were to assess the role of an in-house competitive thyroglobulin assay (Tg-c) in the follow-up of metastatic differentiated thyroid carcinoma (DTC) patients who presented underestimated Tg measurements by immunometric assays (Tg-IMA) and to compare the results with IMA and LC-MS/MS Tg methods.

METHODS

This prospective study included 40 patients. Twenty-one with metastatic disease: 14 had Tg-IMA levels inappropriately low or undetectable (eight patients with positive and six with borderline TgAb) and seven had high Tg-IMA levels. Nineteen had an excellent response to therapy. The competitive assay employs a polyclonal antibody produced in rabbits immunized with human Tg, Tg labeled with biotin, and for the solid phase separation, a monoclonal anti-rabbit IgG antibody adsorbed to microtiter plates.

RESULTS

All 14 patients with structural disease and underestimated levels of Tg-IMA presented detectable Tg-c levels. The median Tg-c level in the group with positive TgAb was 183 µg/L (range: 22-710 µg/L), and 58 µg/L (range 23-148 µg/L) in the borderline TgAb group. The levels of Tg-LC-MS/MS were detectable in some patients (range < 0.5-18 µg/L). All seven patients with high Tg-IMA presented also high levels of Tg-c. Only 2/19 patients with excellent response had Tg-c levels above the functional sensitivity.

CONCLUSIONS

The competitive assay was able to detect Tg in all patients, even in the presence of serum TgAb, and may be an option in patients with underestimated Tg-IMA and relevant structural disease.

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.

Clinical outcome of patients with differentiated thyroid cancer and raised antithyroglobulin antibody levels: a retrospective study

BACKGROUND

Thyroglobulin (Tg) is a specific tumor marker for differentiated thyroid cancer (DTC). However, in the presence of an antithyroglobulin antibody (TgAb), it becomes unreliable. The purpose of the study was to assess the long-term outcome of DTC patients with raised TgAb.

METHOD

In a retrospective study, we included patients with DTC who had raised TgAb following total thyroidectomy. We excluded patients with persistently raised Tg (≥ 1 ng/ml) or radioiodine avid disease. Serial TgAb levels, excellent response (ER), incomplete response (IR), and anatomical recurrence were evaluated.

RESULTS

A total of seventy-six patients were included in the study. Patients with IR had higher baseline TgAb (1071.27 ± 1216.17 vs. 99.61 ± 91.29 IU/ml, p < 0.001) and central compartment lymph node metastases (70.8% vs. 46.4%, p = 0.035) in comparison to those in the ER group. In the first follow-up, 64 (84.2%) patients had a stable or fall in the TgAb (0 to - 98.3%). Sixty-eight patients received high-dose radioiodine therapy (RIT). Out of these, 59 (86.5%) had transient, and 51 (75%) had a long-term fall in TgAb. After a follow-up period of 58.74 ± 26.26 months, 63.2% (48 out of 76) patients had IR. Nine (11.8%) patients had a rising TgAb level (3.7-170.9%) from baseline. Eleven patients underwent 18F-FDG PET/CT, and five of them demonstrated metabolically active recurrent disease. Three patients underwent cervical lymph nodes dissection. None of the patients died during the follow-up period.

CONCLUSION

High post-operative TgAb levels and central compartment lymph nodal metastases are risk factors for IR. RIT leads to a significant fall in the TgAb in these patients. The low level of raised TgAb is associated with an excellent outcome. Patients with recurrences had very high baseline TgAb > 1000 IU/ml. Raised TgAb was associated with good clinical outcomes and not associated with increased mortality.

Antithyroglobulin Antibody Variation During Follow-Up Has a Good Prognostic Value for Preoperative Antithyroglobulin Antibody-Positive Differentiated Thyroid Cancer Patients: A Retrospective Study in Southwest China

OBJECTIVE

Antithyroglobulin antibody (TgAb) is a potential tumour marker for detecting differentiated thyroid cancer (DTC) recurrence, but insufficient data have supported its clinical applications. Our study aimed to describe the changing trend of TgAb after surgery and identify the relationship between this trend and clinical outcomes.

PATIENTS AND METHODS

We reviewed the electronic records of 1,686 DTC patients who had undergone total thyroidectomy (TT) and radioactive iodine (¹³¹I) therapy at West China Hospital of Sichuan University from January 2015 to December 2017. Finally, 289 preoperative TgAb-positive DTC patients were included and divided into four subgroups depending on the clinical outcome: Group A (tumour free), Group B (uncertain), Group C (incomplete biochemical response), and Group D (structural disease). The patient demographics, tumour characteristics, operations, pathology reports, and all serological biomarkers were reviewed and compared, and the prognostic efficacy of TgAb was evaluated.

RESULTS

Among all 1,686 patients, 393 (23.65%) were TgAb positive (>40 IU/ml) preoperatively. The TgAb level in Group A decreased significantly after surgery and ¹³¹I therapy and stabilised at a low level after 1-2 years of ¹³¹I therapy. However, in the other three groups, the decrease in TgAb was not significant after treatment. Conversely, TgAb declined slowly and remained stable or increased. The variations in TgAb relative to the preoperative level of Group A were significantly larger than those of Groups B, C, and D at most time points of follow-up (p < 0.001). By receiver operating characteristic (ROC) analyses, the variations of TgAb > -77.9% at 6 months after ¹³¹I therapy (area under the curve (AUC) = 0.862; p < 0.001) and TgAb > -88.6% at 2 years after ¹³¹I therapy (AUC = 0.901; p < 0.001) had good prognostic efficacy in tumour-free survival. When the variation in TgAb > -88.6% at 2 years after ¹³¹I therapy was incorporated as a variable in the American Thyroid Association (ATA) categories, both intermediate- and high-risk patients also had a significantly increased chance of being tumour free (from 75.68% to 93.88% and 42.0% to 82.61%, respectively).

CONCLUSIONS

For preoperative TgAb-positive DTC patients, variations in TgAb > -77.9% at 6 months after ¹³¹I therapy and TgAb > -88.6% at 2 years after ¹³¹I therapy had good prognostic efficacy. Their incorporation as variables in the ATA risk stratification system could more accurately predict disease-free survival.

Positive Thyroid Peroxidase Antibody and Thyroglobulin Antibody are Associated With Better Clinicopathologic Features of Papillary Thyroid Cancer

OBJECTIVE

To compare the thyroid autoantibody status of patients with papillary thyroid cancer (PTC) and benign nodular goiter as well as possible associations between thyroid autoantibodies and clinicopathologic features of PTC.

METHODS

A total of 3934 participants who underwent thyroidectomy were enrolled in this retrospective study. Patients were divided into PTC and benign nodule groups according to pathological diagnosis. Based on the preoperative serum antibody results, PTC patients were divided into thyroid peroxidase antibody (TPOAb)-positive, thyroglobulin antibody (TgAb)-positive, dual TPOAb- and TgAb-positive, or antibody-negative groups.

RESULTS

Of the 3934 enrolled patients, 2926 (74.4%) were diagnosed with PTC. Multivariate regression analyses suggested that high thyroid-stimulating hormone levels (adjusted odds ratio [OR] = 1.732, 95% CI [1.485-2.021], P < .001), positive TgAb (adjusted OR = 1.768, 95% CI [1.436-2.178], P < .001), and positive TPOAb (adjusted OR = 1.452, 95% CI [1.148-1.836], P = .002) were independent risk factors for predicting malignancy of thyroid nodules. Multinomial multiple logistic regression analyses indicated that positive TPOAb alone was an independent predictor of less central lymph node metastasis in PTC patients (adjusted OR = 0.643, 95% CI [0.448-0.923], P = .017), whereas positive TgAb alone was significantly associated with less extrathyroidal extension (adjusted OR = 0.778, 95% CI [0.622-0.974], P = .028). PTC patients with dual-positive TPOAb and TgAb displayed a decreased incidence of extrathyroidal extension (adjusted OR = 0.767, 95% CI [0.623-0.944], P = .012) and central lymph node metastasis (adjusted OR = 0.784, 95% CI [0.624-0.986], P = .037).

CONCLUSION

Although preoperative positive TPOAb and TgAb are independent predictive markers for PTC, they are also associated with better clinicopathologic features of PTC.

Hashimoto's thyroiditis as a risk factor for thyroid cancer

PURPOSE OF REVIEW

To summarize the recent developments in considering Hashimoto's thyroiditis as a risk factor for thyroid cancer.

RECENT FINDINGS

Modern approaches to understanding the co-occurrence of Hashimoto's thyroiditis and thyroid cancer have consistently found increased prevalence of both conditions, separately as well as of their coexistence. The inflammatory process in Hashimoto's thyroiditis is understood as a potential risk factor for thyroid cancer development. This has also provided a better understanding of the limitations in the current diagnostic and follow-up armamentarium for both conditions, resulting in international guidelines from the clinical and scientific societies. Other recent developments call for a paradigm shift in guidelines on thyroid carcinomas when lymphocytic infiltration is present, which potentially should always be considered the case at least in areas of sufficient iodine intake.

SUMMARY

The literature of Hashimoto's thyroiditis as a risk factor for thyroid cancer is reviewed over the last year to highlight new developments in the understanding of their association and future clinical implications.

The De Novo Detection of Anti-Thyroglobulin Antibodies and Differentiated Thyroid Cancer Recurrence

Background: The prevalence and clinical significance of de novo detection of anti-thyroglobulin antibodies (TgAbs) during the follow-up of patients with differentiated thyroid cancer (DTC) is unknown. Methods: We utilized the National Thyroid Cancer Treatment Cooperative Study registry (1987-2012). Patients registered after 1996 (n = 3318) were analyzed. We identified 1545 subjects who had available TgAb status (TgAb cohort) between years 1996 and 2012, of whom 1325 were TgAb negative at first postoperative follow-up testing. From this initial TgAb-negative group, we excluded 513 patients: 423 patients who had less than 3 years of follow-up and/or fewer than three follow-up visits, 86 patients with persistent disease after initial treatment, and 4 patients with data entry errors. The remaining 812 patients were included for analysis, comprising the TgAb persistently negative group (defined as TgAb negative for at least 3 consecutive follow-up visits and at least 3 years of follow-up) (n = 772) and the de novo TgAb-positive group in whom TgAbs became detectable (n = 40). We then assessed whether de novo appearance of TgAb was associated with DTC structural recurrence by using the Kaplan-Meier method. Results: The de novo detection of TgAb occurred in 5% of DTC patients. Recurrence of DTC in the TgAb persistently negative group compared with the de novo TgAb-positive group did not differ significantly (9.6% vs. 15.0%, p = 0.23). Baseline characteristics, histology, history of radiation exposure, staging, and median duration of follow-up were similar between the two groups. Interestingly, in all six patients who suffered a recurrence in the de novo TgAb-positive group, the TgAbs were negative at the time of recurrence detection and became positive at a median of 2.1 (0.7-8.7) years after the structural recurrence. Conclusions: Utilizing a large North American DTC registry, we found the prevalence of de novo TgAb detection to be 5% among initially TgAb-negative patients. We did not find a statistically significant association between de novo TgAb development and DTC structural recurrence. Larger prospective studies are required to confirm these findings and further assess the significance of de novo TgAb detection in the follow-up of DTC.

Comparison between a new thyroglobulin assay with the well-established Beckman Access immunoassay: A preliminary report

OBJECTIVES

Measurement of serum thyroglobulin (Tg) plays a key role in the post-thyroidectomy management of differentiated thyroid carcinoma (DTC). In this context, the performance of new-generation thyroglobulin assay has clinical implications in the follow-up of DTC patients. Aim of this study was to compare the new highly sensitive Liaison Tg II (Tg-L) with the well-established Tg Access assay (Tg-A).

MATERIALS AND METHODS

A total of 91 residual serum samples (23 positive and 68 negatives for Tg auto-antibodies) were tested by the Beckman Access and Diasorin Liaison assays. Study samples were from 21 patients with pathologically proven DTC and control samples from 70 (16 patients with benign thyroid disease and 54 apparently healthy subjects).

RESULTS

Our results showed that Tg-L was highly correlated with Tg-A for both values ranging between 0.2 and 50 ng/mL (Pearson's r = 0.933 [95%CI 0.894-0.958], P < .001) and higher than 50 ng/mL (Pearson's r = 0.849 [95%CI 0.609-0.946], P < .001). For Tg values lower than 0.2 ng/mL, the overall concordance rate was 92%. Moreover, we tested 7 fine-needle aspiration washout fluids (FNA), showing an overall concordance rate in discriminating negative and positive of 100%. Finally, we found no interference by Tg auto-antibodies (TgAbs) for both Tg-L and Tg-A. Conversely, rheumatoid factor (RF) interferes with Tg-A, but not with Tg-L in one patient with no relapsing thyroid carcinoma.

CONCLUSIONS

Liaison Tg II demonstrated a good correlation with Access Tg assay both for sera and FNAs. Further studies on larger population are needed to evaluate Tg-L clinical impact on DTC patient's follow-up.

Circulating biomarkers for the detection of tumor recurrence in the postsurgical follow-up of differentiated thyroid carcinoma

PURPOSE OF REVIEW

To discuss advances and challenges in thyroglobulin and Tg-antibody (TgAb) measurement and their impact on clinical management of differentiated thyroid carcinoma (DTC).

RECENT FINDINGS

Basal high-sensitive Tg (hsTg) measurement avoids the need for stimulation and greatly simplifies DTC patients' management. In addition, patients with undetectable hsTg after thyroid ablation are at a very low risk of recurrence and can be safely managed by periodic hsTg measurement alone. When TgAb is present, its trend over time serves as primary (surrogate) tumor marker. However, an undetectable hsTg measurement appears to indicate a complete remission of DTC even in the presence of TgAb. Finally, reliable reference values are not yet available for low-risk DTC who are treated with less than total thyroid ablation, and caution is needed before well-designed studies addressing these issues have been published.

SUMMARY

The use of hsTg assays has changed paradigms for DTC monitoring even in the presence of TgAb, and greatly reduced patients' discomfort and overall case-management costs. Reliable Tg interpretation criteria are urgently needed for patients treated with less than total thyroid ablation.

Significance of "de novo" appearance of thyroglobulin antibodies in patients with differentiated thyroid cancer

OBJECTIVE

Clinical and laboratory guidelines recommend thyroglobulin antibodies (TgAbs) measurement with every thyroglobulin (Tg) measurement for the follow-up of differentiated thyroid cancer (DTC) patients. However, no evidence exists on the need for perpetual TgAbs testing in patients who are TgAb-negative at baseline. Our study was carried out to evaluate the prevalence, the dynamic changes, and the clinical significance of TgAbs that appeared de novo during the follow-up of DTC patients who were TgAb-negative at baseline.

METHODS

The data of DTC patients with negative pre-ablation TgAbs were reviewed retrospectively. The main characteristics of patients with both transient and sustained de novo TgAbs appearance were analyzed. DTC patients with persistently negative TgAbs served as controls.

RESULTS

Among 119 patients with pre-ablation negative TgAbs, 14 cases (11.7%) with de novo TgAbs appearance (10 and 4 patients with a transient and sustained de novo TgAbs appearance, respectively) were detected. No differences in disease-free survival were observed in patients with de novo TgAbs appearance compared to controls. The TgAbs peak value was higher in patients with sustained de novo appearance compared to patients with transient de novo. Two of 14 patients with de novo TgAbs developed structural disease with concurrently detectable Tg in both cases.

CONCLUSIONS

Transient de novo TgAbs appearance is not infrequent during DTC patients' follow-up, and it has no apparent clinical impact. Sustained de novo TgAbs appearance is rare and may predict structural recurrences; however, similar disease-free survival was observed in patients with sustained de novo TgAbs and TgAb-negative DTC patients.

Dynamic Risk Stratification for Predicting Treatment Response in Differentiated Thyroid Cancer

Prognosis in Differentiated Thyroid Cancer (DTC) patients is excellent, but a significant degree of overtreatment still exists because of the inability to accurately identify small patient cohorts who experience a more aggressive form of the disease, often associated with certain poor prognostic factors. Identifying these cohorts at an early stage would allow patients at high risk to receive more aggressive treatment while avoiding unnecessary and invasive treatments in those at low risk. Most risk stratification systems include age, tumor size, grade, presence of local invasion, and regional or distant metastases. Here we discuss these common factors as well as their association with treatment response, but also other upcoming markers including histology and multifocality of primary tumor, dose administered and preparation method for Radioiodine Therapy (RAI), Thyroglobulin (Tg), Anti-thyroglobulin Antibodies (Tg-Ab) levels both at initial management and during follow-up, and the presence of previously existing benign thyroid disease. In addition, we examine the role of remnant size and avidity as well as surgeons' experience in performing thyroidectomies with recurrence rate, discussing its impact on disease prognosis. Our results reveal that treatment response has a statistically significant association with histology, T and M stages, surgeons' experience, Tg levels and remnant score both during RAI and follow up and Tg-Ab levels during follow-up whole body scan (WBS).

Serum biomarkers for thyroid cancer

The high prevalence of thyroid cancer requires a reliable serum biomarker for diagnosis and prognostic monitoring. Serum thyroglobulin has been established as the primary postoperative and postablative monitoring biomarker for this malignancy. However, the presence of thyroglobulin antibody imposes a significant interference on its overall management, which cannot be diminished by currently available assays. Trends on the level of the thyroglobulin antibody during follow-up is considered as a surrogate biomarker, but controversy exists. A variety of alternative biomarkers are being proposed and investigated, nevertheless, clinical trials and prospective validations are needed before they can be regarded as clinically viable serum parameters for thyroid cancer.

Data on characterization of glass biochips and validation of the label-free biosensor for detection of autoantibodies in human serum

The data represent in-depth characterization of a novel method for highly sensitive simultaneous measuring in human serum of both critical parameters of autoantibodies: concentration and native kinetics. The latter refers to autoantibody interaction with free, not immobilized, antigen. The method and related biosensors are based on the spectral-correlation and spectral-phase interferometry. The data cover: multi-factor optimization and quantitative characterization of the developed affordable single-used biochips, including X-ray photoelectron spectroscopy (XPS) control of chemical modifications of the surface during fabrication; antibody screening; optimization and verification of protocols for label-free biosensing in human serum; mathematical model for fitting experimental data and calculation of kinetic constants of interaction of autoantibodies with free antigen; comprehensive verification of the method specificity; correlation between the data obtained with the developed biosensor and with enzyme linked immunosorbent assay (ELISA); comparison of analytical characteristics of the developed biosensor with the most advanced label-based methods. The data importance is confirmed by a companion paper (DOI 10.1016/j.bios.2020.112187), which shows that the combination of mentioned autoantibody parameters is promising for more accurate criteria for early diagnostics and efficient therapy of autoimmune disorders. The obtained data can be used in development of a wide range of biosensors, both label-free and based on various labels.

Prognostic Significance of Thyroglobulin Antibodies in Differentiated Thyroid Cancer

Objective

To investigate whether variations in thyroglobulin autoantibodies (TgAb) are related to the recurrence or persistence of differentiated thyroid carcinoma (DTC) and may therefore be useful as surrogate tumor markers. Design and Methods. We retrospectively studied 98 subjects (83 women, 47 ± 15 years old) from an initial cohort of 1017 patients treated for DTC in five hospitals, with positive TgAb at any time during the follow-up. Patients presented five different patterns of evolution of serum TgAb concentrations: (1) stable positive TgAb, (2) de novo appearance, (3) an increase of more than 50%, (4) TgAb levels from positive to negative, and (5) a decrease of more than 50%.

Results

In the group of 11 patients with stable TgAb, four cases presented persistence of the disease with structural incomplete response. In the group of 22 patients with sustained increasing trend rising more than 50% or de novo detectable TgAb levels, three patients were diagnosed with structural incomplete response. There was no evidence of recurrence or persistence of the disease in any of the 65 patients who showed a significant decrease in (n = 35) or disappearance of (n = 30) TgAb.

Conclusions

Our results suggest that not only the appearance of a significant increase in TgAb but also stable concentrations of TgAb should be regarded as a sufficient risk condition for an active search for recurrent or persistent disease. Conversely, a significant decrease in TgAb levels can represent a good prognostic sign.

Dynamics of serum antithyroglobulin antibodies in patients with differentiated thyroid cancer

PURPOSE

Serum antithyroglobulin antibodies (sTgAb) affect the reliability of Tg measurement in patients with thyroid cancer. We compared the outcome of patients with detectable and undetectable sTgAb, stratified according to the initial risk of recurrence (RR); also the response to treatment in patients with detectable sTgAb treated with total thyroidectomy (TT) with and without radioiodine remnant ablation (RA) and the sTgAb trend in the long-term follow-up according to the initial response.

METHODS

We included 432 patients submitted to TT, with or without RA; 106 patients had detectable sTgAb levels. Median follow-up was 53 months.

RESULTS

There were no statistically significant differences considering presentation between negative or positive sTgAb subjects. The frequency of structural incomplete response (SIR) in low, intermediate, and high RR was similar. Undetectable sTgAb in patients was achieved in a median of 16 months in ablated patients compared with 11 months in those without RA (p = 0.0232). Patients without RA had a higher rate of undetectable sTgAb during the first 12 months. A SIR was observed in 3% of patients with declining sTgAb, in 19% of those with stable levels, and in 43% with increasing sTgAb (p = 0.004). The status of no evidence of disease was achieved more frequently in patients with initial sTgAb levels < 200 mUI/l, independently of the initial RR.

CONCLUSIONS

There was no impact of sTgAb on the initial clinical presentation and the response to therapy in low-risk patients treated with or without RA. sTgAb trend is more useful than an absolute value to predict a SIR.

Measuring thyroglobulin in patients with thyroglobulin autoantibodies: evaluation of the clinical impact of BRAHMS Kryptor® Tg-minirecovery test in a large series of patients with differentiated thyroid carcinoma

Background

The present study was undertaken to evaluate the clinical impact of a thyroglobulin (Tg) minirecovery test (Tg-mRec) in a large series of differentiated thyroid carcinoma (DTC) patients treated and monitored homogeneously in a tertiary referral center.

Methods

Included were 1120 serum samples from 798 DTC patients. Tg, Tg autoantibodies (TgAb) and Tg-mrec measurements were performed on the automated Kryptor® platform and results compared to the corresponding clinical status.

Results

Among included samples 228 (20%) were TgAb-positive (TgAb+) and 892 (80%) TgAb-negative (TgAb−), respectively. Tg cutoff points were settled at 0.31 μg/L and 0.15 μg/L for TgAb− and TgAb+ patients, respectively, by ROC curve analysis. The diagnostic performance of serum Tg was reduced in TgAb+ compared to TgAb− patients, however, 87% of TgAb+ patients with recurrent disease and, particularly, all patients with distant metastases were correctly detected by adopting an optimized Tg cutoff for TgAb+ patients. A disturbed recovery was found in only 1% of TgAb− patients and in these cases no clinically relevant information was added by the Tg-mRec. Among TgAb+ patients with undetectable Tg and undisturbed Tg-mRec, no one had recurrent disease. However, a falsely undetectable Tg was demonstrated in two patients with recurrent disease who next to increased TgAb also had a disturbed Tg-mRec test.

Conclusions

There is no additional clinical benefit from performing Tg-mRec in most patients. It can however be considered in TgAb+ patients with undetectable Tg levels as it may help differentiate between patients with true negative and false negative Tg levels in the presence of such antibodies.

In properly selected patients with differentiated thyroid cancer, antithyroglobulin antibodies decline after thyroidectomy and their sole presence should not be an indication for radioiodine ablation

OBJECTIVE

Our objective was to evaluate the trend of antithyroglobulin antibodies (TgAb) during follow-up of patients with differentiated thyroid cancer (DTC) treated without RAI, as well as their role in the risk of recurrence.

SUBJECTS AND METHODS

This was a prospective, descriptive study. A total of 152 consecutive patients with DTC treated in a single institution undergoing total thyroidectomy without RAI and followed for a median of 2.3 years (0.5-10.3) were divided in two groups: TgAb(-) (n = 111) and TgAb(+) (n = 41). Patients were classified according to AJCC 7th and 8th editions, as well as to their risk of recurrence and response to treatment categories.

RESULTS

Both groups, TgAb(-) and TgAb(+), were similar regarding patient and tumor characteristics. At the end of follow-up, 90 (59.2%), 57 (37.5%), 3 (2%) and 2 (1.3%) patients achieved excellent, indeterminate, biochemically incomplete and structurally incomplete response, respectively. The risk of structural recurrence was similar in both groups (TgAb[-] 0.9% vs. TgAb[+] 2.4%, p = 0.46). In the TgAb(+) group, TgAb became negative in 10 (24.4%), decreased ≥ 50% without negativization in 25 (60.9%), decreased < 50% in 4 (9.8%) and remained stable or increased in 2 (4.9%) cases. The only incomplete structural response had increasing TgAb during follow-up.

CONCLUSIONS

In properly selected patients with DTC, TgAb concentration immediately after total thyroidectomy should not mandate RAI ablation, and their trend during follow-up may impact the risk of recurrence.

99mTc-Pertechnetate Scintigraphy Predicts Successful Postoperative Ablation in Differentiated Thyroid Carcinoma Patients Treated with Low Radioiodine Activities

BACKGROUND

Postoperative routine radioiodine (RAI) treatment is currently debated for patients with low-risk differentiated thyroid carcinoma (DTC) patients. If performed, a low ¹³¹I activity (i.e., 1 to 2 GBq) is recommended with the aim to ablate thyroid remnant and facilitate subsequent follow-up by thyroglobulin measurement. The purpose of this study was to evaluate the relationship between postsurgical technetium-99m (^99mTc)-pertechnetate scintigraphy and the rate of successful remnant ablation after low activity radioiodine ablation in patients with DTC.

METHODS

Enrolled were 193 patients with low risk DTC who underwent total thyroidectomy and RAI ablation with a fixed 1.1 GBq activity of ¹³¹I. ^99mTc-pertechnetate scans were done and thyrotropin stimulated thyroglobulin (sTg) levels measured just before ablation. Ablation effectiveness was assessed 6 to 12 months later by sTg measurement, neck ultrasound and diagnostic whole body scan.

RESULTS

A negative ^99mTc-perthecnetate scans was the best predictor of successful ablation (P<0.001) followed by preablative sTg levels <0.8 ng/mL (P=0.008) and ^99mTc-pertechnetate uptake rate values <0.9% (P=0.065). Neither sex nor age of the patient at the time of ablation or tumor histology and size showed a significant association with the rate of successful ablation.

CONCLUSION

The ^99mTc-pertechnetate scintigraphy is a simple and feasible tool to predict effectiveness of low activity ¹³¹I thyroid to ablate thyroid remnants in patients with DTC.

Clinical Applicability of Low Levels of Thyroglobulin Autoantibodies as Cutoff Point for Thyroglobulin Autoantibody Positivity

BACKGROUND

Thyroglobulin (Tg) is an established tumor marker in differentiated thyroid carcinoma (DTC). However, Tg assays can be subject to interference by autoantibodies against Tg (TgAbs). No clinical consensus exists on the cutoff value of TgAb positivity and its relationship to Tg assay interference. The aims of this study were to investigate the most applicable cutoff value for TgAb positivity in clinical practice and to evaluate whether tumor characteristics differ between TgAb+ and TgAb- patients during ablation therapy using the manufacturer's cutoff (MCO) and institutional cutoff (ICO).

METHODS

This single-center cohort study included 230 DTC patients diagnosed between January 2006 and December 2014. Serum Tg and TgAbs were measured with the Tg-IRMA (Thermo Fisher Scientific) and ARCHITECT Anti-Tg (Abbott Laboratories) assays. Patients were divided into TgAb- and TgAb+ based on the limit of detection (LoD; ≥0.07 IU/mL), functional sensitivity (FS; ≥0.31 IU/mL), MCO (≥4.11 IU/mL), and ICO (≥10 IU/mL).

RESULTS

All patients were TgAb+ based on the LoD; one patient was negative on FS. Fifty-five (23.9%) and 34 (14.8%) patients had TgAbs above the MCO and ICO, respectively. Histology, presence of multifocality, tumor-node-metastasis, and American Thyroid Assocation risk stratification did not differ between TgAb- and TgAb+ patients using MCO and ICO during ablation.

CONCLUSIONS

This study supports the use of a higher cutoff value than that of the FS for TgAb positivity in clinical settings. The LoD and FS are too sensitive to discriminate TgAb positivity and negativity in DTC patients during ablation therapy. The presence of TgAbs during ablation is not related to tumor characteristics and risk profile. This implies that TgAb positivity should not be considered a separate risk factor.

Changing Trend of Thyroglobulin Antibodies in Patients With Differentiated Thyroid Cancer Treated With Total Thyroidectomy Without 131I Ablation

BACKGROUND

Thyroglobulin (Tg) antibodies (TgAb) can interfere with Tg measurement and can be used as "Tg surrogate" in patients with differentiated thyroid cancer (DTC) treated with total thyroidectomy (TTx) and radioiodine remnant ablation (RRA). In contrast, few data, and in patients usually followed for a short-term follow-up, have been reported about the changes of TgAb levels in patients treated with TTx but without RRA. The aims of this study were to evaluate the changes of TgAb levels in DTC patients treated with TTx but not RRA and to identify the factors that influence these changes.

METHODS

The change in TgAb levels in 107 DTC (<1 cm) patients submitted to TTx but not RRA was evaluated. Patients were followed for a median of 6.3 years, and all had at least three determinations of TgAb and neck ultrasound (nUS).

RESULTS

TgAb levels showed a progressive decrease during follow-up. Initial TgAb levels and degree of lymphocytic infiltration influenced the time but not the rate of TgAb disappearance. No influence on time and rate of the decrease in TgAb was observed when the association with thyroperoxidase antibodies (TPOAb) levels were considered. A TgAb cutoff value of 61.9 IU/mL at first postoperative evaluation was a good indicator for disappearance of the TgAb within six years. No tumor recurrence was observed in the series. In one case, the progressive increase in TgAb anticipated the reappearance of benign thyroid tissue with lymphocytic infiltration.

CONCLUSIONS

TgAb levels decline in the majority of DTC patients treated with TTx but not ablated with radioiodine. The levels decrease rapidly after the surgical treatment and continue to decrease over time. The time of disappearance is influenced by the initial TgAb levels and the degree of lymphocytic infiltration. No influence of the actual TPOAb levels has been observed. An increase in TgAb levels should not be overlooked, since it can indicate the presence or reappearance of either normal thyroid tissue or tumor recurrence.

Low or Undetectable Basal Thyroglobulin Levels Obviate the Need for Neck Ultrasound in Differentiated Thyroid Cancer Patients After Total Thyroidectomy and 131I Ablation

BACKGROUND

Neck ultrasound (NUS) is currently seen as a main component of follow-up of differentiated thyroid cancer (DTC) and is usually performed regardless of non-stimulated thyroglobulin (Tg) levels. The aim of this study was to determine whether there is a clinical benefit from such a routine NUS in DTC patients.

METHODS

A retrospective database study was conducted of 3176 cervical ultrasound exams performed in 773 patients between June 15, 1996, and July 1, 2012. The accuracy of ultrasound results was assessed based on the results of further diagnostic and/or therapeutic procedures within six months of a particular ultrasound.

RESULTS

A total of 2199 NUS exams were classified as true negative, 216 as true positive, 692 as false positive in 339 (43.9%) individual patients, 170 of whom were low risk, and 69 as false negative. Thus, overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy [confidence interval] were 75.8% [70.1-81.5%], 76.1% [74.3-77.8%], 23.8% [18.1-29.5%], 97.0 [96.2-97.7%], and 76.0% [74.3-77.7%], respectively. No significant differences were found between low- and high-risk patients. There were no significant differences between patients with an undetectable and a low detectable (<1 μg/L) Tg level. However, these two groups both showed significantly lower positive predictive value and higher negative predictive value than patients with a Tg ≥1 μg/L. From January 2007 onwards, true-positive and false-negative neck ultrasounds were no longer observed in patients with Tg <1 μg/L.

CONCLUSION

After total thyroidectomy and ¹³¹I ablation, neck ultrasound should be reserved only for anti-Tg antibody negative patients with a Tg level of ≥1 μg/L.