Early post-treatment risk stratification of differentiated thyroid cancer: comparison of three high-sensitive Tg assays

Long-term predictive value of highly sensitive thyroglobulin measurement

OBJECTIVE

To examine the predictive value of unremarkable nonstimulated highly sensitive thyroglobulin (hsTg) measurement with regard to the results of stimulated thyroglobulin (Tg) measurement, diagnostic whole-body scintigraphy, recurrence and differentiated thyroid cancer (DTC)-related death.

DESIGN, PATIENTS AND MEASUREMENTS

We retrospectively analysed the data of all 461 (410 without anti-Tg-antibodies [TgAbs], 51 with) DTC patients who were referred to our department for treatment and follow-up care of differentiated thyroid cancer from 2004 onwards, and in whom at least one posttreatment Tg value was measured in our hospital at least 3 months after I-131 ablation.

RESULTS

In the group of TgAb-negative patients, 2.0% of patients with an unstimulated Tg < 0.1 ng/ml showed a stimulated Tg ≥ 1.0 ng/ml, whereas this happened in 77.6% with an unstimulated Tg ≥ 0.1 but <1.0 ng/ml. An unstimulated hsTg ≥ 0.1 ng/ml had a sensitivity specificity positive and negative predictive value of 90.0%, 94.1%, 77.6% and 97.6%, respectively, for a stimulated Tg ≥ 1.0 ng/ml. In TgAb-positive patients, this was 75%, 97%, 75% and 97%, respectively. An unstimulated Tg ≥ 0.1 ng/ml did not significantly discriminate with regard to the risk of DTC-related death (p = .06), but ≥1.0 ng/ml did (p = .012), as did a stimulated Tg ≥ 1.0 ng/ml (p = .029). Excluding patients with distant metastases at diagnosis nullifies this significance.

CONCLUSION

Except for patients with distant metastases, both TgAb negative and TgAb positive patients with an undetectable nonstimulated hsTg measurement have a very good prognosis. The high net present value of unstimulated hsTg testing means that further diagnostic procedures can be omitted in such patients.

Multi-center evaluation of the highly sensitive Abbott ARCHITECT and Alinity thyroglobulin chemiluminescent microparticle immunoassay

Background

Thyroglobulin (Tg) is an essential part for the management of patients with differentiated thyroid carcinoma (DTC) after thyroidectomy. Highly sensitive Tg assays are now established in clinical practice as they facilitate follow‐up of DTC patients. In this study, we evaluated the recently launched highly sensitive Abbott Tg assay for Alinity and ARCHITECT.

Methods

In this three‐center study, Tg values of 447 routine patient samples, characterized for the presence of anti‐Tg, were measured with the ARCHITECT Tg assay and compared with the Roche Elecsys TgII assay. In addition, a subset of 154 samples was compared also with the Beckman Tg Access assay and another subset (n = 122) with Abbott Tg on the Alinity i analyzer.

Results

LoQ was verified to be less than or equal to 0.1 ng/ml confirming that the Tg assay on ARCHITECT and Alinity is highly sensitive. Correlation of ARCHITECT, Alinity, and Roche was excellent with a slope between 0.9 and 1.1 and a correlation coefficient >0.98. Correlation to Beckmann Tg was also very good, but the differences in absolute values were significant (slope: 1.477).

Conclusions

The Abbott Thyroglobulin assay, which is standardized to CRM‐457, demonstrated a high correlation to the Roche and Beckman Tg assays, though good agreement of absolute values was only observed between Abbott and Roche. Strength of correlation and slope were not affected by the presence of anti‐Tg indicating that all assays included in the study have a similar susceptibility to anti‐Tg.

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.

Prognostic Implications of Preablation Stimulated Tg: A Retrospective Analysis of 2500 Thyroid Cancer Patients

CONTEXT

The risk of persistent and recurrent disease in patients with differentiated thyroid cancer (DTC) is a continuum that ranges from very low to very high, even within the 3 primary risk categories. It is important to identify independent clinicopathological parameters to accurately predict clinical outcomes.

OBJECTIVE

To examine the association between pre-ablation stimulated thyroglobulin (ps-Tg) and persistent and recurrent disease in DTC patients and investigate whether incorporation of ps-Tg could provide a more individualized estimate of clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Medical records of 2524 DTC patients who underwent total thyroidectomy and radioiodine ablation between 2006 and 2018 were retrospectively reviewed.

MAIN OUTCOME MEASURE

Ps-Tg was measured under thyroid hormone withdrawal before remnant ablation. Association of ps-Tg and clinical outcomes.

RESULTS

In multivariate analysis, age, American Thyroid Association (ATA) risk stratification, distant metastasis, ps-Tg, and cumulative administered activities were the independent predictive factors for persistent/recurrent disease. Receiver operating characteristic analysis identified ps-Tg cutoff (≤10.1 ng/mL) to predict disease-free status with a negative predictive value of 95%, and validated for all ATA categories. Integration of ps-Tg into ATA risk categories indicated that the presence of ps-Tg ≤ 10.1 ng/mL was associated with a significantly decreased chance of having persistent/recurrent disease in intermediate- and high-risk patients (9.9% to 4.1% in intermediate-risk patients, and 33.1% to 8.5% in high-risk patients).

CONCLUSION

The ps-Tg (≤10.1 ng/mL) was a key predictor of clinical outcomes in DTC patients. Its incorporation as a variable in the ATA risk stratification system could more accurately predict clinical outcomes.

Undetectable thyroglobulin makes 123I whole-body scan and stimulated thyroglobulin obsolete in follow-up care of differentiated thyroid cancer: a retrospective study

Background

Differentiated thyroid cancer (DTC) is a common malignancy with increasing incidence. Follow-up care for DTC includes thyroglobulin (Tg) measurement and ultrasound (US) of the neck, combined with ¹³¹I remnant ablation when indicated. Diagnostic precision has evolved with the introduction of the new high-sensitive Tg-assays (sensitivity ≤0.1 ng/mL). The aim of the study was to determine the prognostic utility of high-sensitive Tg and the need for other diagnostic tests in DTC.

Methods

This was a retrospective, observational study. Patients with pathologically confirmed DTC, treated with total thyroidectomy and ¹³¹I remnant ablation, who had their complete follow-up care in our institution were selected (October 2013–December 2018). Subjects with possible thyroglobulin autoantibody interference were excluded. Statistical analysis was performed using the IBM SPSS® Statistics 24 software package.

Results

Forty patients were eligible for analysis. A total of 24 out of the 40 patients (60%) had an undetectable high-sensitive Tg 6 months after total thyroidectomy. None of these patients had a stimulated Tg above 1 ng/mL, or remnant on the ¹²³I Whole-Body Scan (WBS) after 1 year of follow-up. Ultrasound of the neck, performed between 6 and 12 months postoperative, was negative in 21 out of the 24 patients.

Conclusions

This study shows that an undetectable high-sensitive Tg can change the management of patients with DTC and decrease the use and need of stimulated Tg and ¹²³I WBS.

Exosomal miR-130a-3p promotes the progression of differentiated thyroid cancer by targeting insulin-like growth factor 1

The aim of the present study was to determine the expression and diagnostic value of exosomal miR-130a-3p in the serum of patients with differentiated thyroid cancer (DTC). Exosomes were isolated from the serum of patients with DTC and were identified using transmission electron microscopy. A novel exosomal miRNA, miR-130a-3p, was found to be significantly decreased in the serum of patients with DTC compared with those with benign thyroid tumors and healthy controls. Further study revealed that exosomal miR-130a-3p was correlated with the malignant characteristics of DTC, including tumor diameter, lymph node metastasis (LNM) and higher TNM stage. Receiver operating characteristic curve analysis demonstrated that the area under the curve of exosomal miR-130a-3p was better compared with that of TgAb and Tg in patients with DTC. More importantly, the combined use of exosomal miR-130a-3p, TgAb and Tg significantly enhanced the sensitivity and specificity, indicating that exosomal miR-130a-3p is a sensitive biomarker for DTC. A dual luciferase reporter assay indicated that insulin-like growth factor (IGF)-1 was a target gene of miR-130a-3p. Pearson's correlation analysis revealed a negative correlation between serum IGF-1 and serum exosomal miR-130a-3p levels. More importantly, exosomes from patients with DTC increased the expression of IGF-1 and p-PI3K/p-AKT, but these effects were abolished by siRNA targeting IGF-1 in TPC-1 cells. Taken together, the findings of the present study indicated that reduced exosomal miR-130a-3p levels were associated with the risk of DTC and may be used as a biomarker for the diagnosis of DTC.

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.

Unstimulated high-sensitive thyroglobulin is a powerful prognostic predictor in patients with thyroid cancer

Background Differentiated thyroid carcinoma (DTC) has an excellent prognosis and the role of high-sensitive thyroglobulin measured during levothyroxine (ON-T4 hs-Tg) testing to discriminate patients with structural from not-evidence of disease (SED and NED, respectively) has been investigated. We conducted a systematic review and meta-analysis evaluating the performance of ON-T4 hs-Tg in two clinical scenarios considering its negative predictive value (NPV) as primary outcome: (1) diagnostic performance of Tg when undetectable value and NED status are simultaneously demonstrated; (2) prognostic performance of undetectable Tg in predicting NED in the subsequent follow-up. Methods This systematic review and meta-analysis were registered on PROSPERO (CRD42019125092). PubMed, Scopus, CENTRAL and Web of Science were searched until February 12, 2019. Original articles reporting data on SED/NED in patients with detectable/undetectable ON-T4 hs-Tg were selected. Summary operating points were estimated using a random-effects model. Results Out of 1413 retrieved papers, 10 studies evaluating 1796 patients were included. Participants were outpatients diagnosed with DTC, treated with near-total (NTx) or total thyroidectomy (TTx) with or without radioactive iodine (RAI). The NPV of ON-T4 hs-Tg for diagnostic and prognostic performance was 99.4% (95% CI 98.9-99.9; I2 = 13%) and 99.4% (95% CI 98.8-100; I2 = 0%), respectively. Conclusions Our findings show that ON-T4 hs-Tg is an excellent diagnostic tool and prognostic factor to rule-out SED. A high level of evidence is provided to decrease the intensity and frequency of follow-up in those DTC patients having undetectable high-sensitive Tg.

Utility of recombinant human TSH stimulation test in the follow-up of patients with differentiated thyroid cancer depending on basal thyroglobulin results

Background

Thyroglobulin (Tg) is fundamental for differentiated thyroid cancer (DTC) monitoring. Tg detection can be enhanced using recombinant human thyroid-stimulating hormone (TSH) (rhTSH). This study is aimed to evaluate the use of the rhTSH stimulation test when using a high-sensitivity Tg assay.

Methods

We retrospectively studied 181 rhTSH tests from 114 patients with DTC and negative for antithyroglobulin antibodies (anti-TgAb). Image studies were performed in all cases. Serum Tg and anti-TgAb were measured using specific immunoassays.

Results

rhTSH stimulation in patients with basal serum Tg (b-Tg) concentrations lower than 0.2 ng/mL always resulted in rhTSH-stimulated serum Tg (s-Tg) concentrations lower than 1.0 ng/mL and negative structural disease. In patients with b-Tg concentration between 0.2 and 1.0 ng/mL, s-Tg detected one patient (1/30) who showed biochemical incomplete response. Patients with negative images had lower s-Tg than those with nonspecific or abnormal findings (p<0.05). Receiver operating characteristic curve analysis of the s-Tg to detect altered images showed an area under the curve of 0.763 (p<0.05). With an s-Tg cutoff of 0.85 ng/mL, the sensitivity was 100%, decreasing to 96.15% with an s-Tg cutoff of 2 ng/mL.

Conclusions

Patients with DTC with b-Tg concentrations equal or higher than 0.2 ng/mL can benefit from the rhTSH stimulation test.

Contemporary Debates in Adult Papillary Thyroid Cancer Management

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

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.

Differentiated thyroid cancer theranostics: radioiodine and beyond

The term theranostics is the combination of a diagnostic tool that helps to define the right therapeutic tool for specific disease. It signifies the "we know which sites require treatment (diagnostic scan) and confirm that those sites have been treated (post-therapy scan)" demonstrating the achievable tumor dose concept. This term was first used by John Funkhouser at the beginning of the 90s, at the same time the concept of personalized medicine appeared. In nuclear medicine, theranostics is easy to apply and understand because of an easy switch from diagnosis to therapy with the same vector. It helps in maximizing tumor dose and sparing normal tissue with high specific and rapid uptake in metastasis. The oldest application of this concept is radioactive iodine I-131 (RAI). The first treatment based on the theranostic concept was performed on thyroid cancer patients with RAI in 1946. From then on management of differentiated thyroid cancer (DTC) has evolved on the multimodality concept. We now use the term "our" patient instead of "my" patient to signify this. However, the initial surgical management followed by RAI as per the theranostics has remained the mainstay in achieving a cure in most of DTC patients. The normal thyroid cells metabolise iodine, the principle of which is utilized in imaging of the thyroid gland with isotopes of iodine. RAI treatment of DTC is based on the principle of sodium iodide symporter (NIS) expressing thyroid cells with DTC cells having the ability of trapping circulating RAI successfully helping in treatment of residual and metastatic disease. NIS is usually negative in poorly differentiated cells and is inversely proportional to Glucose transporter receptor Type 1 expression. Both positive and negative NIS are the key components of the theranostic approach in treatment of DTC. Presence or absence of NIS is documented by either whole body iodine scintigraphy (WBS) or 2-deoxy-2(18F) fludeoxyglucose (FDG) positron emission tomography computed tomography (PET-CT). Currently, single photon emission CT and CT (SPECT-CT) has significantly improved the precision and sensitivity of whole body iodine scintigraphy with its capability of accurate localization of disease foci whether iodine avid or non-avid. This has helped in a more personalized approach in treatment. This review will give an overview of the role of NIS in the theranostic approach to management with RAI, its current status and also the molecular approach to treatment in RAI refractory disease.