Peripheral blood levels of thyroglobulin mRNA and serum thyroglobulin concentrations after radioiodine ablation of multinodular goiter with or without pre-treatment with recombinant human thyrotropin

Preradioactive Iodine Thyroglobulin Levels as Predictors of Metastasis in Well-Differentiated Thyroid Carcinoma Patients

Objective The aim of this study was to determine the cut-off value of thyroglobulin (Tg) levels as a predictor of metastases in post total thyroidectomy patients with well-differentiated thyroid carcinoma (DTC).

Materials and Methods A retrospective case-control study with an observational diagnostic approach was done. Subjects were 102 DTC patients divided into a case group with metastases and a control group without metastases. Tg and antithyroglobulin antibody (ATA) levels on thyroid-stimulating hormone (TSH)-stimulated preradioactive iodine were compared with each other. Diagnosis of metastases was based on postradioactive iodine whole-body scan. The cut-off value for Tg preradioactive iodine and the area under the curve (AUC) were obtained from the receiver operating characteristic curve.

Result The characteristics and histopathological type of DTC among these two groups were not significantly different (p = 0.47). The Tg levels in the case and control groups were 106 (2.2–6,000) ng/mL and 2.7 (0.3–10.10) ng/mL, respectively (p = 0.0001). TSH level in the case group was 50 (30–107) µIU/mL and in the control was 50 (20–100) µIU/mL (p = 0.224). ATA levels in the case and control groups were 0–3,000 and 0–629 ng/mL, respectively (p = 0.01). The AUC was 0.976 with a 95% confidence interval of 0.924 to 0.996 and a standard error of 0.016. The cut-off value of preradioactive iodine Tg was 10.1 ng/mL or higher with sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 96.1, 100, 98.0, 100, and 96.2%, respectively.

Conclusion Preradioactive iodine Tg level 10.1 ng/mL or higher can be used as a predictor of metastasis in patients with DTC.

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.

Relationship between circulating anti-thyroglobulin antibodies (TgAb) and tumor metabolism in patients with differentiated thyroid cancer (DTC): prognostic implications

PURPOSE

TgAb have been proposed as tumor markers in DTC. Recent evidence links TgAb levels with DTC aggressiveness. We aimed to evaluate the relationship between TgAb and tumor glucose metabolism in DTC patients.

METHODS

Seventy-one DTC patients who underwent ¹⁸F-FDG PET/CT were included. According to TgAb value and trends, patients were divided into TgAb positive (TgAb+) or negative (TgAb-) as well as in patients with increasing (Inc-TgAb) or decreasing (Dec-TgAb) trend. On the basis of the results of FDG-PET, post-therapy 131I and Tg levels, patients were divided into two groups according to the evidence (ED) or absence (NED) of disease. ED patients were further divided into three subgroups: 1. radioiodine avid with positive ¹⁸F-FDG PET/CT (PET+/131I+), 2. radioiodine refractory with positive ¹⁸F-FDG PET/CT (PET+/131I-) and 3. radioiodine avid with negative ¹⁸F-FDG PET/CT (PET-/131I+). MeanSUV of FDG-avid lesions was assessed and averaged for each patient (SUVmean-pt). T test was performed to assess the difference between SUVmean in TgAb-, TgAb+ and in Inc-TgAb and Dec-TgAb subgroups. Difference in TgAb between ED and NED patients as well as between ED patients and PET+/131I+, PET+/131I- and PET-/131I+ subgroups was compared.

RESULTS

SUVmean was significantly higher in Inc-TgAb with respect to Dec-TgAb subgroup (5.2 ± 1.5 vs. 2.9 ± 1.1, p < 0.05). TgAb were higher only in the ED PET+/131I+ subgroup with respect to NED patients (p < 0.01).

CONCLUSIONS

The relationship between higher tumor metabolism and trend of TgAb supports a prognostic relevance of TgAb in DTC patients. Significantly higher TgAb in radioiodine avid tumors with positive ¹⁸F-FDG PET/CT further testify the role of TgAb as surrogate tumor marker in DTC.

Sequential changes of serum antithyroglobulin antibody levels are a good predictor of disease activity in thyroglobulin-negative patients with papillary thyroid carcinoma

OBJECTIVE

To investigate whether elevated and sequential changes in serum antithyroglobulin antibody (TgAb) levels are indicators of recurrence or persistence of papillary thyroid cancer (PTC) in patients with undetectable thyroglobulin.

METHODS

In 56 patients followed for more than 7 years, we recorded all serum TgAb levels (except the ones determined within one year after (131)I therapy or diagnostic scans) and evaluated their disease status. All patients had undergone total thyroidectomy and remnant ablation by (131)I, and they were positive for TgAb and had undetectable thyroglobulin during follow-up. The sequential changes of TgAb were defined as persistently high, increasing, persistently medium, decreasing, and decreasing to negative. Recurrence or persistence of PTC was defined as active disease as assessed by (131)I scanning, (18)F-fluorodeoxyglucose positron emission tomography, ultrasonography, computed tomography, or surgical examination.

RESULTS

Of the 56 patients enrolled, 10 patients had persistent PTC and 12 patients had recurrent PTC at more than 1 year after total thyroidectomy and (131)I therapy. TgAb was persistently high in 4 patients (3 with active PTC), increasing in 6 patients (4 with active PTC), persistently medium in 16 patients (12 with active PTC), decreasing in 5 patients (none with active PTC), and decreased to negative in 25 patients (3 with active PTC). According to the trend, the patients with persistently high TgAb, increasing TgAb, and persistently medium TgAb had active disease more often (p<0.001). In the multivariable regression analyses, the trend of TgAb change was a strong predictor of PTC activity (p<0.001, R(2)=-0.501). The most common diagnostic procedures performed for active disease were neck ultrasonography (21 patients) followed by (18)F-fluorodeoxyglucose positron emission tomography (11 patients). The patients with autoimmune thyroid disease had better prognoses than did the patients without autoimmune thyroid disease (18% active PTC vs. 53% active PTC, p=0.02).

CONCLUSION

The presence of TgAb is indicative of an active tumor. Sequential TgAb change is a good predictor of disease prognosis and is helpful for clinical decision making.

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

BACKGROUND

Even though the presence of antithyroglobulin antibodies (TgAbs) represents a significant problem in the follow-up of patients with differentiated thyroid cancer (DTC), the current guidelines on the management of DTC that have been published in recent years contain no text concerning the methods to be used for detecting such antibody-related interference in thyroglobulin (Tg) measurement or how to manage TgAb-positive patients in whom Tg cannot be used reliably as a tumor marker.

AIM

An international group of experts from the European Thyroid Association Cancer Research Network who are involved in the care of DTC patients met twice to form a consensus opinion on how to proceed with treatment and follow-up in TgAb-positive DTC patients based on the available evidence in the literature. Here we will report on the consensus opinions that were reached regarding technical and clinical issues.

RESULTS

This clinical opinion article provides an overview of the available evidence and the resulting consensus recommendations. The current literature does not provide sufficient data for giving evidence-based answers to many questions arising in the care of TgAb-positive DTC patients. Where insufficient evidence was available, a thorough discussion by a group of physician-scientists, all of whom have a distinguished track record in thyroid cancer care, was held to arrive at a consensus expert opinion. The questions and answers discussed were then summarized into an algorithm for the management of TgAb-positive patients.

CONCLUSION

We were able to define 26 consensus expert recommendations and a resulting algorithm for the care of TgAb-positive DTC patients.

Undetectable pre-ablation thyroglobulin levels in patients with differentiated thyroid cancer: it is not always what it seems

OBJECTIVE

To establish the frequency of U Tg (undetectable pre-ablation thyroglobulin) in TgAb- negative patients and to evaluate the outcome in the follow-up.

SUBJECTS AND METHODS

We retrospectively reviewed 335 patients' records. Twenty eight patients (9%) had U Tg. Mean follow-up was 42 ± 38 months. All subjects had undergone total thyroidectomy, and lymph nodes were positive in 13 (46%) patients. Tg and TgAb levels were measured 4 weeks after surgery by IMA technology in hypothyroid state. No evidence of disease (NED) status was defined as undetectable (< 1 ng/mL) stimulated Tg and negative Tg-Ab and/or negative WBS, together with normal imaging studies.

RESULTS

Seventeen patients (61%) were considered with NED. Four patients (14%) had persistent disease (mediastinum, n = 1, lung n = 2, unknown n = 1), and 7 (25%) had detectable TgAb by other method during their follow-up.

CONCLUSIONS

U Tg levels usually is associated to a complete surgery. However, in a low percentage of patients, this may be related to false negative Tg or TgAb measurement.

Evaluation of T cell stimulation by thyrotropin-receptor epitopes in Graves' disease

In Graves' disease (GD) immunized T cells reactive to TSH-receptor epitopes contribute to pathogenesis through B cell help, and cytotoxicity. We evaluated T cell responses to synthetic TSH-receptor epitopes in hyperthyroid patients with GD prior to therapy, at 6-8 weeks after radioactive iodine (RAI) administration, or 6-8 months later when euthyroid, and in control subjects. All T cell responses were relatively low as generally found in human autoimmune diseases. Responses in hyperthyroid GD patients were significantly greater than among controls, were augmented 6-8 weeks after RAI treatment, were still present after patients became euthyroid, and did not differ between DR3+ and non-DR3+ patients. Patient's T cells reacted to multiple different epitopes, and reactivity differed depending on the course of the disease and treatment.While certain epitopes most commonly cause T cell reactivity, we did not find evidence for a single or few "dominant" epitopes.