Prognostic significance of thyroglobulin antibody epitopes in differentiated thyroid cancer

Radioactive iodine therapy for thyroid cancer coexisting with Hashimoto's thyroiditis: a systematic review and meta-analysis

OBJECTIVES

To investigate the clinical character of differentiated thyroid cancer (DTC) coexisting with Hashimoto's thyroiditis (HT) and provide state-of-art evidence for personalized radioactive iodine-131 therapy (RAIT) for patients coexisting with HT.

METHODS

From January 2000 to January 2023, PubMed, Embase, and Web of Science databases were searched for relevant original articles that published in English on the RAIT efficacy for DTC with HT. RevMan 5.4 and Stata 17.0 were used for data analysis.

RESULTS

Eleven studies involving 16 605 DTC patients (3321 with HT) were included. HT was more frequent in female (OR: 2.90, 95% confidence interval [CI]: 1.77-4.76, P < .00001). The size of tumour (MD: -0.20, 95% CI: -0.30 to -0.11), extrathyroidal extension rate (OR: 0.77, 95% CI: 0.67-0.90), and metastasis rate (OR: 0.18, 95% CI: 0.08-0.41) were less in HT, but tumour, node, metastasis (TNM) stage had no significant difference among HT and non-HT group. Disease-free survival (DFS) rate (OR: 1.96, 95% CI: 1.57-2.44, P < .00001), 5-year DFS (OR: 1.73, 95% CI: 1.04-2.89, P = .04), and 10-year DFS (OR: 1.56, 95% CI: 1.17-2.09, P = .003) were higher in HT group. The recurrent (OR: 0.62, 95% CI: 0.45-0.83, P = .002), RAIT dosage (MD = -38.71, 95% CI: -60.86 to -16.56, P = .0006), and treatment (MD: -0.13, 95% CI: -0.22 to -0.03, P = .008) were less in HT group.

CONCLUSIONS

DTC coexisting with HT was associated with less invasion. DFS of HT group was higher than non-HT group after RAIT. Low-dose treatment did not impair the efficacy of RAIT in DTC with HT.

ADVANCES IN KNOWLEDGE

Hashimoto's thyroiditis is a risk for DTC, but it minimalizes the progression of cancer and enhance the efficacy of RAIT, which should be considered in personalizing RAIT.

Thyroglobulin Antibodies and Tumor Epitope-Specific Cellular Immunity in Papillary Thyroid Cancer

Papillary thyroid carcinoma (PTC) is characterized by T cell infiltration and frequently by the presence of anti-thyroglobulin antibodies (TgAbs). The role of cellular immunity and of TbAbs in this context is a matter of debate. The aim of our study was to correlate the presence of TgAbs, tumor epitope-specific T cells and the clinical outcome of PTC patients. We studied n=183 consecutive patients with a diagnosis of PTC which were treated with total thyroidectomy plus 131I ablation. During a follow-up of in mean 97 months, most of the PTC patients had no signs of tumor relapse (n=157 patients). In contrast, one patient had serum Tg levels above the detection limit and<1 ng/ml, two patients Tg serum levels≥1 ng/ml and<2 ng/ml and n=23 patients had Tg serum levels≥2 ng/ml. Morphological signs of tumor recurrence were seen in 14 patients; all of these patients had serum Tg levels≥2 ng/ml. Importantly, with the exception of one patient, all TgAb positive PTC patients (n=27) had no signs of tumor recurrence as the serum Tg levels were below the assays functional sensitivities. Tetramer analyses revealed a higher number of tumor epitope-specific CD8+T cells in TgAb positive patients compared to TgAb negative PTC patients. In summary, we show that the occurrence of TgAbs may have an impact on the clinical outcome in PTC patients. This might be due to a tumor epitope-specific cellular immunity in PTC patients.

Prognostic value of preoperative thyroid autoantibodies for post-thyroidectomy patient pathology: A retrospective cohort study

OBJECTIVE

The aim of this study was to evaluate the clinical value of preoperative thyroid autoantibodies with reference to the post-thyroidectomy patient pathology.

DESIGN

A retrospective cohort study.

SETTING

Two tertiary care academic hospitals.

MATERIALS AND METHODS

A total of (n = 473) subjects who underwent thyroidectomy from 2009 to 2019 were included. Preoperative serum thyroid autoantibodies (anti-thyroglobulin [anti-Tg] and anti-thyroperoxidase [anti-TPO]) were measured, and the potential predictors of postoperative pathological diagnosis (age, gender, and thyroid autoantibodies) were assessed using multivariable regression models.

RESULTS

Patients with positive thyroid autoantibodies were more likely to have malignant disease than benign disease; adjusted odds ratio (AOR) = 1.6 (1.3-2.7, p = 0.002) for anti-Tg, and AOR = 1.6 (1.1-2.5, p = 0.027) for anti-TPO. A subset analysis of the same predictors performed on patients with cancer (malignant vs. microcarcinoma) showed that patients with ages ≥40 were more likely to develop microcarcinoma as opposed to malignant disease; AOR = 1.8 (1.1-3.1, p = 0.03) for anti-TPO, and AOR = 1.7 (1.0-2.9, p = 0.04) for anti-Tg.

CONCLUSION

Preoperative thyroid autoantibodies could be used clinically to predict the risk of malignancy in thyroid nodules, thus helping guide treatment decisions in patients with thyroid nodules and speeding up the decision to undergo surgical intervention.

Ultrasound evolution of parenchymal changes in the thyroid gland with autoimmune thyroiditis in children prior to the development of papillary thyroid carcinoma - a follow-up study

Background

Follicular cell-derived thyroid carcinoma represents the vast majority of paediatric thyroid cancers (TCs). Papillary thyroid carcinoma (PTC) accounts for over 90% of all childhood TC cases, and its incidence in paediatric patients is increasing. The objective of this follow-up study was to present the outcome of ultrasound (US) and laboratory monitoring of paediatric patients with autoimmune thyroiditis (AIT) prior to the development of PTC.

Patients and methods

This prospective study included 180 children and adolescents (132 females; 73.3%) with a suspicion of thyroid disorder referred to the Outpatient Endocrine Department. The patients were divided into four groups: 1) 28 patients with a mean age of 10.7 [standard deviation (SD), 3.1] y, in whom PTC was detected during the active surveillance of AIT [AIT(+), PTC(+) follow up (F)]; 2) 18 patients with a mean age of 12.8 (SD, 3.4) y, in whom PTC and AIT were detected upon admission (A) [AIT(+), PTC(+) A]; 3) 45 patients with a mean age of 13.0 (SD, 3.4) y, in whom PTC was detected upon admission and AIT was excluded [AIT(-), PTC(+) A]; and 4) an age- and sex-matched control group of 89 patients with AIT and with a mean age of 9.4 (SD, 3.0) y. The analysis included clinical, US, and laboratory assessment results of children on admission (groups 1-4) and during follow-up (groups 1 and 4) in the Paediatric Endocrine Outpatient Department.

Results

Upon admission of those in group 1, the US evaluation revealed a hypoechogenic thyroid gland in 12 and an irregular normoechogenic gland in 16 patients. US monitoring revealed an increase in thyroid echogenicity and an increased irregularity of the thyroid structure during the follow-up period of all of the patients from group 1. Such changes were not noticed in group 4. PTC was diagnosed at the mean time of 3.6 y (3 mo-9 y) since AIT confirmation in group 1. The mean maximum PTC diameter as per the US was significantly smaller in group 1 than in groups 2 and 3 [13.2 (10.8) mm vs. 22.2 (12.8) and 22.05 (15.4) mm]. Fewer patients in group 1 were referred to 131I than in groups 2 and 3 (71.4% vs. 94.4 and 93.3%). Interestingly, significant differences were observed in the thyroglobulin antibody (TgAb)/thyroid peroxidase antibody (TPOAb) ratio between groups 2 and 3, as opposed to group 4, at the beginning of observation [15.3 (27.6) and 3.5 (8.8] vs. 0.77 (1.9)]. In group 1, after the follow-up, an increase in the TgAb/TPOAb ratio was observed [1.2 (9.8) to 5.2 (13.5)]. There were no significant differences between groups 1-3 in labeling index Ki67, lymph nodes metastasis, extrathyroidal extension, and angioinvasion. There were no associations between thyroid-stimulating hormone, TgAb, and the extent of the disease.

Conclusion

The use of thyroid US focused on the search for developing tumours in the routine follow-up of patients with AIT may not only help in the early detection of thyroid malignancies that are not clinically apparent but may also influence the invasiveness of oncological therapy and reduce the future side effects of 131I therapy. We propose that the repeat evaluation of TPOAb and TgAb warrants further exploration as a strategy to determine TC susceptibility in paediatric patients with AIT in larger multicentre studies.

Laboratory Thyroid Tests: A Historical Perspective

Background: This review presents a timeline showing how technical advances made over the last seven decades have impacted the development of laboratory thyroid tests. Summary: Thyroid tests have evolved from time-consuming manual procedures using isotopically labeled iodine as signals (¹³¹I and later ¹²⁵I) performed in nuclear medicine laboratories, to automated nonisotopic tests performed on multianalyte instruments in routine clinical chemistry laboratories. The development of isotopic radioimmunoassay techniques around 1960, followed by the advent of monoclonal antibody technology in the mid-1970s, led to the development of a nonisotopic immunometric assay methodology that forms the backbone of present-day thyroid testing. This review discusses the development of methods for measuring total thyroxine and triiodothyronine, direct and indirect free thyroid hormone measurements and estimates (free thyroxine and free triiodothyronine), thyrotropin (TSH), thyroid autoantibodies (thyroperoxidase, thyroglobulin [Tg] and TSH receptor autoantibodies), and Tg protein. Despite progressive improvements made in sensitivity and specificity, current thyroid tests remain limited by between-method differences in the numeric values they report, as well as nonspecific interferences with test reagents and interferences from analyte autoantibodies. Conclusions: Thyroid disease affects ∼10% of the U.S. population and is mostly managed on an outpatient basis, generating 60% of endocrine laboratory tests. In future, it is hoped that interferences will be eliminated, and the standardization/harmonization of tests will facilitate the establishment of universal test reference ranges.

The Immune Landscape of Papillary Thyroid Cancer in the Context of Autoimmune Thyroiditis

Simple Summary

The association between papillary thyroid cancer and Hashimoto’s thyroiditis went through a long-standing human debate recently elucidated by the establishment of a novel mouse model. Papillary thyroid carcinoma is an excellent model for studying the tumor immune microenvironment because it is naturally accompanied by immune cells, making it a good candidate for the treatment with immune checkpoint inhibitors.

Abstract

Papillary thyroid cancer (PTC) often co-occurs with Hashimoto’s thyroiditis, an association that has long been reported in clinical studies, remaining controversial. Experimental evidence has recently shown that pre-existing thyroiditis has a beneficial effect on PTC growth and progression by a distinctive expansion of effector memory CD8 T cells. Although the link between inflammation and PTC might involve different components of the immune system, a deep characterization of them which includes T cells, B cells and tertiary lymphoid structures, Mye-loid cells, Neutrophils, NK cells and dendritic cells will be desirable. The present review article considers the role of the adaptive and innate immune response surrounding PTC in the context of Hashimoto’s thyroiditis. This review will focus on the current knowledge by in vivo and in vitro studies specifically performed on animals’ models; thyroid cancer cells and human samples including (i) the dual role of tumor-infiltrating lymphocytes; (ii) the emerging role of B cells and tertiary lymphoid structures; (iii) the role of myeloid cells, dendritic cells, and natural killer cells; (iv) the current knowledge of the molecular biomarkers implicated in the complex link between thyroiditis and PTC and the potential implication of cancer immunotherapy in PTC patients in the context of thyroiditis.

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 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.

Immunoglobulin Preparations Can Mislead Clinical Decision-Making in Follow-Up of Differentiated Thyroid Cancer

OBJECTIVE

Intravenous and subcutaneous immunoglobulins are commonly used for immune substitution or as immune modulators in a variety of inflammatory and autoimmune disorders. Exogenous thyroid-specific thyroglobulin (Tg) antibodies present in the donor plasma may interfere with the interpretation of measurements of Tg autoantibodies (Tg-Abs) in the recipient's plasma and potentially trigger an immune response in the recipient's immune cells. Levels of antibodies causing bioassay interferences or those leading to clinically relevant changes in patient outcomes are not known. Tg is used as a biomarker in the long-term surveillance of patients with differentiated thyroid cancer (DTC) following total thyroidectomy and radioactive iodine ablation. However, the presence of Tg-Abs in the circulation interferes with Tg measurements. Assessment of levels of Tg-Abs is thus recommended as a part of standard follow-up of DTC together with Tg testing.

METHODS

To understand the potential mechanisms and pathophysiologic significance of possible interferences associated with administration immunoglobulin preparations and Tg measurement, we overview the current knowledge on interactions between Tg autoimmunity and immunoglobulin preparations and illustrate diagnostic challenges and perspectives for follow-up of patients with DTC treated with exogenous immunoglobulins.

RESULTS

In patients with DTC treated with immunoglobulin preparations, monitoring of thyroid cancer using Tg and Tg-Abs is challenging due to possible analytical interferences through passive transfer of exogenous antibodies from immunoglobulin preparations.

CONCLUSION

Analytical interferences must be suspected when a discrepancy exists between clinical examination and diagnostic tests. Collaboration between endocrinologists, biologists, and pharmacologists is fundamental to avoid misdiagnosis and unnecessary medical or radiologic procedures.

ABBREVIATIONS

CT = computed tomography; DTC = differentiated thyroid cancer; FNAB = fine-needle aspiration biopsy; HAb = heterophile antibody; IMA = immunometric assay; IVIg = intravenous immunoglobulin; RAI = radioactive iodine; RIA = radioimmunoassay; SCIg = subcutaneous immunoglobulin; Tg = thyroglobulin; Tg-Ab = thyroglobulin autoantibody; Tg-MS = thyroglobulin mass spectrometry; TPO-Ab = thyroid peroxidase autoantibody; TSHR-Ab = thyrotropin receptor autoantibody.

Thyroid cancer and thyroid autoimmune disease: A review of molecular aspects and clinical outcomes

Thyroid cancer (TC) is the most prevalent malignant neoplasm that affects the endocrine system. Hashimoto's thyroiditis (HT), also known as chronic lymphocytic thyroiditis, is the most common autoimmune thyroid disease (AITD) that, together with Graves' disease (GD), represent the main autoimmune diseases that affect the thyroid gland. Some studies suggest a greater risk of AITD and the development of TC, while others, investigate its relationship with TC progression and patient prognosis. In this review, we have analyzed published data on the molecular aspects related to the association between AITD and TC, addressing their influence on TC progression, diagnosis, and prognosis of the patients. MEDLINE database (PubMed) platform was used as a search engine and the original articles related to the topic were selected using the keywords combination "thyroid cancer and Hashimoto thyroiditis" or "thyroid carcinoma and thyroid autoimmune disease". After the selection, we categorized the main findings of the papers into four topics: antitumor immunity, tumor progression, diagnosis, and prognosis. Although most of the studies have pointed out the presence of AITD as a factor that increases the risk of TC, few molecular mechanisms to support this conclusion have been described. Additionally, little information is available to explain, pathophysiologically, the effects of autoimmunity in TC diagnosis, progression, and prognosis.

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.

Clinical Analysis of Preoperative Anti-thyroglobulin Antibody in Papillary Thyroid Cancer Between 2011 and 2015 in Beijing, China: A Retrospective Study

The anti-thyroglobulin antibody (TgAb) has been suggested to be more common in patients with papillary thyroid cancer (PTC). Here, we performed a retrospective study investigated the correlation between TgAb level and PTC in Chinese patients between 2011 and 2015. Patients with goiter who underwent thyroidectomy and received a confirmed pathological diagnosis were enrolled into the study. Clinical characteristics and preoperative thyroglobulin antibody (TgAb) level data were collected from all enrolled patients. Based on the preoperative TgAb test results, patients were divided into a TgAb negative (TgAb-) group (<60 IU/mL) and a TgAb positive (TgAb+) group (≧60 IU/mL). Of the 4,046 patients, 671 patients were TgAb+ while 3,375 patients were TgAb-. There were 535 (79.7%) patients with PTC in the TgAb+ group, and 2,154 (63.8%) patients with PTC in the TgAb- group. The prevalance of PTC was significantly higher in TgAb+ patients than in TgAb- patients. TgAb+ patients were stratified into four groups based on the TgAb titer. The prevalence of PTC did not increase with TgAb titer. No significant difference in TgAb level was noted in patients with different clinicopathologies, including TNM stage, lymph node metastasis, and multifocal carcinoma. Regression analysis suggested a higher risk of PTC malignancy among TgAb+ patients. Preoperative TgAb level ≥60 IU/mL might be associated with a higher risk of PTC. However, there was no titer-dependent association between elevated TgAb titer and PTC malignancy.

Time trends of thyroglobulin antibody in ablated papillary thyroid carcinoma patients: Can we predict the rate of negative conversion?

OBJECTIVES

Persistence of thyroglobulin antibody (TgAb) in patients with papillary thyroid carcinoma (PTC) years after total thyroidectomy (TT) followed by ablation occurs even without any evidence of structural disease. Few studies have studied the natural course of TgAb positivity and factors that may influence this course. The present study evaluated the time trends of TgAb in ablated PTC patients and aimed to identify the predictive factors for the rate of negative conversion of TgAb.

MATERIALS AND METHODS

Overall, 1279 patients who underwent TT and subsequent ablation for PTC, with available data on thyroid peroxidase Ab (TPOAb) and TgAb prior to surgery (preop-) and ablation (abl-) were enrolled. Patients with initial distant metastasis or recurrence during follow-up were excluded.

RESULTS AND CONCLUSION

Preop-TgAb was positive in 24.9% of patients (n = 319), whereas abl-TgAb positivity decreased to 12.8% (n = 164). In 164 patients positive for abl-TgAb, TgAb in patients with higher abl-TgAb levels decreased more gradually than those observed in patients with lower abl-TgAb levels (p < 0.001). Furthermore, in patients within the same range of abl-TgAb levels, patients positive for abl-TPOAb had a higher rate of negative conversion of TgAb compared with negative patients for abl-TPOAb (log rank p < 0.001). TPOAb significantly increased the rate of negative conversion in multivariate analysis adjusted for abl-TgAb (odds ratio 1.59, 95% confidence interval 1.11-2.28, p = 0.011). This study clearly showed that abl-TgAb titers and abl-TPOAb status can predict the rate of negative conversion. These findings can guide the optimal timing for additional examination in patients positive for TgAb during follow-up.

Circulating BRAFV600E Levels Correlate with Treatment in Patients with Thyroid Carcinoma

BACKGROUND

BRAF^V600E is the most common mutation in papillary thyroid carcinoma (PTC) and can be associated with aggressive disease. Previously, a highly sensitive blood RNA-based BRAF^V600E assay was reported. The objective of this study was to assess the correlation of BRAF^V600E circulating tumor RNA levels with surgical and medical treatment.

METHODS

Circulating BRAF^V600E levels were assessed in (i) a murine model of undifferentiated (anaplastic) thyroid carcinoma with known BRAF^V600E mutation undergoing BRAF^V600E-inhibitor (BRAFi) treatment, and (ii) in 111 patients enrolled prior to thyroidectomy (n = 86) or treatment of advanced recurrent or metastatic PTC (n = 25). Blood samples were drawn for BRAF^V600E analysis before and after treatment. Testing characteristics were assessed and positivity criteria optimized. Changes in blood BRAF^V600E values were assessed and compared to clinical characteristics and response to therapy.

RESULTS

In a murine model of anaplastic thyroid carcinoma with BRAF^V600E mutation, blood BRAF^V600E RNA correlated with tumor volume in animals treated with BRAFi. In tissue BRAF^V600E-positive (n = 36) patients undergoing initial surgery for PTC, blood BRAF^V600E levels declined postoperatively (median 370.0-178.5 fg/ng; p = 0.002). In four patients with metastatic or poorly differentiated thyroid carcinoma receiving targeted therapies, blood BRAF^V600E declined following therapy and corresponded with radiographic evidence of partial response or stable disease.

CONCLUSIONS

This study shows the correlation of blood BRAF^V600E levels in response to treatment in both an established animal model of thyroid cancer and in patients with BRAF^V600E-positive tumors with all stages of disease. This assay represents an alternative biomarker in patients with positive thyroglobulin antibodies, and tumors, which do not express thyroglobulin.

Thyroglobulin levels before radioactive iodine therapy and dynamic risk stratification after 1 year in patients with differentiated thyroid cancer

OBJECTIVES

We sought to assess the relationship between stimulated thyroglobulin (sTg) before radioactive iodine therapy (RIT), and the dynamic risk stratification 1 year after treatment, and to establish the utility of the sTg as a predictor of response to therapy in these patients. A retrospective chart review of patients with differentiated thyroid cancer (DTC) who underwent RIT after surgery and were followed for at least 1 year, was carried out.

SUBJECTS AND METHODS

Patients were classified according to the dynamic risk stratification 1 year after initial treatment. The sTg values before RIT were compared among the groups. ROC curve analysis was performed.

RESULTS

Fifty-six patients were enrolled (mean age 44.7 ± 14.4 years, 80.7% had papillary carcinoma). Patients with excellent response had sTg = 2.1 ± 3.3 ng/mL, those with indeterminate response had sTg = 8.2 ± 9.2 ng/mL and those with incomplete response had sTg = 22.4 ± 28.3 ng/mL before RIT (p = 0.01). There was a difference in sTg between excellent and incomplete response groups (p = 0.009) while no difference was found between indeterminate and either excellent or incomplete groups. The ROC curve showed an area under the curve of 0.779 assuming a sTg value of 3.75 ng/mL.

CONCLUSION

Our study results suggest that the higher the sTg before RIT, the greater the likelihood of an incomplete response to initial treatment. A sTg cut-off of 3.75 ng/mL was found to be a good predictor of response to initial treatment in patients with DTC.

Thyroid autoimmune antibodies in patients with papillary thyroid carcinoma: a double-edged sword?

PURPOSE

The relationship between thyroid autoimmunity and thyroid cancer remains controversial. The objective of this study is to comprehensively analyze the association between thyroid autoimmune antibodies and disease statuses of papillary thyroid carcinoma (PTC).

METHODS

Patients were divided into different groups according to their final diagnoses after radioiodine therapy as well as their serum anti-thyroglobulin antibody (TgAb) and anti-thyroidperoxidase antibody (TPOAb) titers. Clinicopathologic characteristics were then compared between groups.

RESULTS

In all, 1126 PTC patients met the inclusion criteria. When compared with thyroid autoimmune antibody negative group, patients in positive group were young female predominant. After age and gender adjusted, patients in thyroid autoimmune antibody positive group had much more cervical metastatic node count and this effect was limited to the central compartment but not to the lateral compartment. Antibody positivity rate was much lower in patients with distant metastasis and multivariable logistic regression analysis showed positive status of antibody was a protective factor of distant metastasis of PTC with an OR value of 0.403 (95% CI 0.216-0.622, p < 0.001). Additionally, subgroup analysis demonstrated single TgAb positivity and combined positivity of TgAb and TPOAb were shown to be related to less distant metastatic disease.

CONCLUSIONS

Positive thyroid auto-antibody status could be a risk factor of more metastatic cervical lymph nodes while a protective factor of distant metastatic disease in PTC patients. The association between thyroid autoimmunity and thyroid cancer can be patient and antibody specific. A systemic immunosupression status may exist in PTC patients with distant metastasis.

Prognostic value of preoperative anti-thyroglobulin antibody in differentiated thyroid cancer

CONTEXT

The coexistence of differentiated thyroid cancer (DTC) and thyroid autoimmune disease could represent a better or worse prognosis. This study investigated the prognostic importance of preoperative anti-thyroglobulin antibody (TgAb) in DTC patients.

DESIGN AND PATIENTS

This retrospective hospital-cohort study enrolled 1171 consecutive DTC patients with preoperative TgAb data, who underwent total thyroidectomy between January 2006 and December 2011. Clinical parameters studied included demographics, primary tumour characteristics, radioiodine therapy, thyroid function tests, preoperative thyroglobulin (Tg) and TgAb levels, and cancer persistence/recurrence.

RESULTS

A total of 254 (21.7%) patients were preoperatively TgAb positive. The percentage positive for thyroid peroxidase (TPO) antibody and lymphocytic thyroiditis was significantly higher in the TgAb-positive group. The TgAb-positive group had a significantly higher rate of lymphatic invasion and lymph node metastasis both overall and in patients without TPOAb and lymphocytic thyroiditis (non-HT group). The mean number of total and central lymph nodes dissected and rate of lateral lymph node dissection were significantly higher in the TgAb-positive group, both overall and in non-HT patients. In regression analysis, preoperative TgAb was an independent risk factor for lateral lymph node metastasis. Over 50.2±14.5 months of follow-up, disease persistence/recurrence was not significantly different between patients with and without TgAb, both overall and in non-HT patients. Preoperative TgAb showed no significant correlation with final disease status.

CONCLUSION

Positive preoperative serum TgAb is associated with worse primary tumour characteristics but rarely showed poor prognosis, probably due to more aggressive treatment of these subjects.

Epitope-Specific Antitumor Immunity Suppresses Tumor Spread in Papillary Thyroid Cancer

CONTEXT

Papillary thyroid cancer (PTC) is characterized by a lymphocytic infiltration. PTC patients with lymphocytic infiltration may have a better clinical outcome.

OBJECTIVE

Characterization of tumor epitope-specific immunity and correlation analyses with the clinical outcome.

PATIENTS

150 PTC patients; 40 Hashimoto thyroiditis (HT) patients; 21 healthy controls; 27,239 healthy whites (for HLA typing).

MAIN OUTCOME MEASURES

HLA class I restricted thyroperoxidase (TPO) and thyroglobulin (Tg) epitope-specific T cells (tetramer analyses), correlation analyses between HLA class II phenotypes, T cell immunity, and the clinical course.

RESULTS

The frequency of TPO- and Tg-specific CD8+ T cells in PTC patients was largely increased compared with healthy controls (TPO and Tg, P < 0.005 and P < 0.005) and was similar to those in HT patients. HLA-DQB1*03-positive PTC patients had a significantly lower risk [risk ratio (RR), 0.170; 95% confidence interval (CI), 0.037 to 0.755; P < 0.05] and HLA-DRB1*03-positive and HLA-DQB1*02-positive PTC patients a significantly higher risk (HLA-DRB1*03: RR, 4.400; 95% CI, 1.378 to 14.05; P < 0.05; HLA-DQB1*02: RR, 3.692; 95% CI, 1.102 to 12.38; P < 0.05) for distant metastases, compared with patients with other haplotypes. HLA-DQB1*03-positive PTC patients revealed an increased responsiveness of tumor epitopes in vitro. These tumor epitope-specific CD8+ T cells were also found in lymph node metastases of HLA-DQB1*03-positive PTC patients.

CONCLUSION

We demonstrate a tumor epitope-specific immunity in PTC patients and the protective role of HLA-DQB1*03 against metastatic spread. These results have direct implications for new treatment options with immune checkpoint inhibitors.

Influence of chronic lymphocytic thyroiditis on the risk of persistent and recurrent disease in patients with papillary thyroid carcinoma and elevated antithyroglobulin antibodies after initial therapy

INTRODUCTION

In patients with papillary thyroid carcinoma who have negative serum thyroglobulin after initial therapy, the risk of structural disease is higher among those with elevated antithyroglobulin antibodies compared to patients without antithyroglobulin antibodies. Other studies suggest that the presence of chronic lymphocytic thyroiditis is associated with a lower risk of persistence/recurrence of papillary thyroid carcinoma.

OBJECTIVE

This prospective study evaluated the influence of chronic lymphocytic thyroiditis on the risk of persistence and recurrence of papillary thyroid carcinoma in patients with negative thyroglobulin but elevated antithyroglobulin antibodies after initial therapy.

METHODS

This was a prospective study. Patients with clinical examination showing no anomalies, basal Tg<1ng/mL, and elevated antithyroglobulin antibodies 8-12 months after ablation were selected. The patients were divided into two groups: Group A, with chronic lymphocytic thyroiditis on histology; Group B, without histological chronic lymphocytic thyroiditis.

RESULTS

The time of follow-up ranged from 60 to 140 months. Persistent disease was detected in 3 patients of Group A (6.6%) and in 6 of Group B (8.8%) (p=1.0). During follow-up, recurrences were diagnosed in 2 patients of Group A (4.7%) and in 5 of Group B (8%) (p=0.7). Considering both persistent and recurrent disease, structural disease was detected in 5 patients of Group A (11.1%) and in 11 of Group B (16.1%) (p=0.58). There was no case of death related to the disease.

CONCLUSION

Our results do not support the hypothesis that chronic lymphocytic thyroiditis is associated with a lower risk of persistent or recurrent disease, at least in patients with persistently elevated antithyroglobulin antibodies after initial therapy for papillary thyroid carcinoma.

Thyroglobulin Antibody Screen Prior to Mass Spectrometry Provides Measurable Cost Savings and Optimal Laboratory Utilization

OBJECTIVES

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods that allow accurate quantitation of thyroglobulin (Tg) in the presence of Tg antibodies (TgAbs) have recently become available. Due to cost differences between LC-MS/MS and immunoassay, some laboratories now offer a reflex test strategy that uses LC-MS/MS only for TgAb-positive samples. The goal of this study was to examine utilization of Tg testing strategies and cost savings.

METHODS

Test ordering patterns were examined for over 150,000 orders for TgAb and Tg in our laboratory. The average list price was determined from three separate commercial laboratories offering this testing.

RESULTS

Data showed that 89% of orders for Tg used the reflex test option, resulting in a savings of over $3 million compared with testing all samples by LC-MS/MS. Of the Tg by LC-MS/MS orders not using the reflex option, 1,663 also included a separate order for TgAb on the same patient sample, representing approximately $170,000 in potentially unnecessary costs from TgAb-negative samples.

CONCLUSIONS

Identifying situations to use more expensive testing methods (eg, LC-MS/MS) only when necessary, such as for TgAb-positive patients, leads to considerable cost savings and a more economical use of valuable health care resources.

Insights into the posttranslational structural heterogeneity of thyroglobulin and its role in the development, diagnosis, and management of benign and malignant thyroid diseases

Thyroglobulin (Tg) is the major glycoprotein produced by the thyroid gland, where it serves as a template for thyroid hormone synthesis and as an intraglandular store of iodine. Measurement of Tg levels in serum is of great practical importance in the follow-up of differentiated thyroid carcinoma (DTC), a setting in which elevated levels after total thyroidectomy are indicative of residual or recurrent disease. The most recent methods for serum Tg measurement are monoclonal antibody-based and are highly sensitive. However, major challenges remain regarding the interpretation of the results obtained with these immunometric methods, particularly in patients with endogenous antithyroglobulin antibodies or in the presence of heterophile antibodies, which may produce falsely low or high Tg values, respectively. The increased prevalence of antithyroglobulin antibodies in patients with DTC, as compared with the general population, raises the very pertinent possibility that tumor Tg may be more immunogenic. This inference makes sense, as the tumor microenvironment (tumor cells plus normal host cells) is characterized by several changes that could induce posttranslational modification of many proteins, including Tg. Attempts to understand the structure of Tg have been made for several decades, but findings have generally been incomplete due to technical hindrances to analysis of such a large protein (660 kDa). This review article will explore the complex structure of Tg and the potential role of its marked heterogeneity in our understanding of normal thyroid biology and neoplastic processes.

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.

Detection of Circulating BRAF(V600E) in Patients with Papillary Thyroid Carcinoma

BRAF(V600E) is a common mutation in papillary thyroid carcinoma (PTC) correlated with aggressive features. Our objective was to assess the feasibility and accuracy of a novel RNA-based blood assay to identify individuals with a high-risk tumor mutation in patients with PTC. Patients with benign or malignant thyroid disorders were included between September 2013 and July 2014 before either thyroidectomy (n = 62) or treatment of recurrent or metastatic PTC (n = 8). RNA was isolated from peripheral blood lymphocytes and reverse transcribed and followed by two rounds of nested PCR amplification with a restriction digest specific for wild-type BRAF. BRAF(V600E) levels were quantified with standardization curves. Circulating BRAF(V600E) levels were compared with BRAF mutation status from surgical pathologic DNA-based tissue assays. Testing characteristics and receiving-operator curve using tissue results as the gold standard were assessed. Matched blood and tissue assays for BRAF(V600E) were performed on 70 patients with PTC (stages I to IV, n = 48) or other (n = 22) thyroid tumors. Sixty-three percent of PTC patients tested positive for BRAF(V600E) with conventional tissue assays on surgical specimens. The correlation between the RNA-based blood assay and tissue BRAF status was 0.71. PTC patients harbor detectable BRAF(V600E) circulating tumor cells. This blood assay is feasible and has potential as a biomarker for prognosis, surveillance, clinical decision making, and assessment of treatment response to BRAF-targeted therapies.

High Thyroglobulin Antibody Levels Increase the Risk of Differentiated Thyroid Carcinoma

BACKGROUND

Despite the many studies examining thyroid cancers, the effect of thyroid autoantibodies on differentiated thyroid carcinoma (DTC) remains unclear.

OBJECTIVE

To investigate the association between serologic thyroid autoantibodies (ATAs) and DTC, we retrospectively evaluated data of thyroid nodules obtained from patients who underwent thyroid surgery.

METHODS

Data of thyroid nodules obtained from 1,638 patients who underwent thyroid surgery were evaluated. Thyroid autoimmunity was assessed by the presence of thyroglobulin (TgAb) or thyroid peroxidase antibodies (TPOAb).

RESULTS

Among our study cohort, the prevalence of elevated TgAb (≥40 IU/mL) and TPOAb (≥50 IU/mL) was higher in patients with DTC than those with benign nodules. Patients with DTC and elevated TgAb had a higher prevalence of extrathyroidal invasion. In the multivariate analysis, TgAb ≥ 40 IU/mL was significantly associated with DTC (odds ratio [OR] = 2.10, 95% confidence interval [CI] 1.40-3.15) compared with TgAb < 40 IU/mL group, independent of other confounding factors such as decreased age, single nodule, and elevated TSH level. In conclusion, elevated TgAb was associated with DTC.

CONCLUSIONS

This study revealed that high levels of TgAb may act as an independent prediction factor for DTC, and suggests that patients with high TgAb concentrations may be predisposed to DTC.