Influence of the thyroid remnant in the elevation of the serum thyroglobulin after thyroidectomy in differentiated thyroid carcinoma. Importance of the diagnostic iodine total-body scanning

Serum Thyroglobulin Measurement Following Surgery Without Radioactive Iodine for Differentiated Thyroid Cancer: A Systematic Review

Background: The utility of serum thyroglobulin (Tg) measurement following partial thyroidectomy or total/near-total thyroidectomy without radioactive iodine (RAI) for differentiated thyroid cancer is unclear. This systematic review examines the diagnostic accuracy of serum Tg measurement for persistent, recurrent, and/or metastatic cancer in these situations. Methods: Ovid MEDLINE, Embase, and Cochrane Central were searched in October 2021 for studies on Tg measurement following partial thyroidectomy or total/near-total thyroidectomy without or before RAI. Quality assessment was performed, and evidence was synthesized qualitatively. Results: Thirty-seven studies met inclusion criteria. Four studies (N = 561) evaluated serum Tg measurement following partial thyroidectomy, five studies (N = 751) evaluated Tg measurement following total/near-total thyroidectomy without RAI, and 28 studies (N = 7618) evaluated Tg measurement following total or near-total thyroidectomy before RAI administration. Following partial thyroidectomy, Tg measurement was not accurate for diagnosing recurrence or metastasis, or estimates were imprecise. Following total/near-total thyroidectomy without RAI, evidence was limited due to few studies with very low rates of recurrence or metastasis, but indicated that Tg levels were usually stable and low. For Tg measurements before RAI administration, diagnostic accuracy for metastatic disease or persistence varied, although sensitivity appeared high (but specificity low) at a cutoff of >1 to 2.5 ng/mL. However, applicability to patients who do not undergo RAI is uncertain because patients selected for RAI are likely to represent a higher risk group. The evidence was very low quality for all scenarios. All studies had methodological limitations, and there was variability in the Tg thresholds evaluated, patient populations, outcomes assessed, and other factors. Conclusions: Very limited evidence suggests low utility of Tg measurement for identifying recurrent or metastatic disease following partial thyroidectomy. Following total/near-total thyroidectomy, Tg levels using a cutoff of 1-2.5 ng/mL might identify patients at low risk for persistent or metastatic disease. Additional research is needed to clarify the role of Tg measurement in these settings, determine optimal Tg thresholds, and determine appropriate measurement intervals.

Is there an added value for whole body scan combined with stimulated thyroglobulin testing for follow-up of differentiated thyroid cancer patients?

BACKGROUND

Whole-body scan (WBS) is indicated for selected patients in the follow-up of differentiated thyroid cancer (DTC).

AIM

The aim of this study was to evaluate the incidence of positive WBS in patients with negative stimulated thyroglobulin (sTg), to define the clinical characteristics of this group, and the association with disease outcome.

METHODS

DTC patients who underwent surveillance with simultaneous sTg and WBS were included.

RESULTS

Two hundred seventy-two patients were included. Age at diagnosis was 46.5 ± 15.2 years, 79% were female. Mean duration of follow-up was 11.6 ± 6.8 years. Patients were categorised according to stimulation test results: sTg(-)/WBS(-) in 192/272 (70.6%); sTg(+) regardless of WBS results in 33/272 (12.1%); and sTg(-)/WBS(+) in 47/272 (17.3%) subjects. sTg > 10 mg/dl was considered positive. The three groups had similar demographic and pathologic characteristics. During follow-up, additional treatment was given in 77 patients (28.3%). Twelve (4.4%) developed distant metastases; 16 patients (5.8%) died. No deaths were disease-related. There was no difference in mortality rate between categories (P = 0.182). On multivariate analysis, additional treatment was associated with male gender (P = 0.046) and positive stimulation test results, either sTg (P < 0.001) or WBS (P < 0.001). Of the 47 WBS(+)/sTg(-) patients, 7(15%) were treated due to positive WBS results, including two who underwent additional surgery.

CONCLUSION

A substantial proportion of stimulation test results were discordant. There was a significant association between WBS results and administration of additional treatment. Routine WBS had additional value for a small proportion of patients with no other evidence for disease and no indication for WBS.

Nuclear Molecular and Theranostic Imaging for Differentiated Thyroid Cancer

Traditional nuclear medicine is rapidly being transformed by the evolving concepts in molecular imaging and theranostics. The utility of new approaches in differentiated thyroid cancer (DTC) diagnostics and therapy has not been fully appreciated. The clinical information, relevant to disease management and patient care, obtained by scintigraphy is still being underestimated. There has been a trend towards moving away from the use of radioactive iodine (RAI) imaging in the management of the disease. This paradigm shift is supported by the 2015 American Thyroid Association Guidelines (1). A more systematic and comprehensive understanding of disease pathophysiology and imaging methodologies is needed for optimal utilization of different imaging modalities in the management of DTC. There have been significant developments in radiotracer and imaging technology, clinically proven to contribute to the understanding of tumor biology and the clinical assessment of patients with DTC. The research and development in the field continues to evolve, with expected emergence of many novel diagnostic and therapeutic techniques. The role for nuclear imaging applications will continue to evolve and be reconfigured in the changing paradigm. This article aims to review the clinical uses and controversies surrounding the use of scintigraphy, and the information it can provide in assisting in the management and treatment of DTC.

Implication of different clinical and pathological variables in patients with differentiated thyroid cancer on successful ablation for 3700 MBq (131)I: a single Egyptian institutional experience over 14 years

OBJECTIVE

Is to investigate possible factors predicting success of ablation for 3700 MBq radioactive iodine 131 in patients with differentiated thyroid cancer (DTC) following near total thyroidectomy.

METHODS

This retrospective study enrolled 272 patients between 2000 and 2014. The success or failure of ablation was assessed 6 months after given the dose and our criteria for complete successful remnant ablation defined as: Negative (131)I whole body scan with no residual functioning thyroid tissue or distant functioning metastases and stimulated thyroglobulin (Tg) level less than 2 ng/ml. Different clinical and pathological factors, such as age, gender, tumor histology, grade and variants, size of primary malignant lesion, stage, and risk assessment according to the American (ATA) and European Thyroid Association (ETA) guidelines, associated pathology, tumor mutifocality, lymph node (LN) metastases and their number, invasiveness of the tumor (capsular invasion of the nodule, extra-thyroidal extension, and vascular invasion), baseline stimulated Tg level, and pre-ablative diagnostic scan were assessed.

RESULTS

There were 185 successful ablations (68 %). The baseline-stimulated Tg measured before the ablation was the only independent predictor of ablation success in multivariate analysis (P < 0.0001) with odds ratio (OR) of 2.64 (95 % CI: 1.54-4.54) and the optimal cutoff for this was 3.8 ng/mL. On the univariate analysis, LN metastases was predictor of ablation failure (P value = 0.03).

CONCLUSION

Baseline-stimulated Tg level is clinically important and had a significant predictive value for successful ablation; therefore, higher pre-ablation Tg should potentially be incorporated in the decision making for (131)I dosage or other treatment. In accordance with other studies, this is also applicable to cervical lymph nodal involvement and thyroid capsule invasion.

[Outcome of differentiated thyroid cancer after initial treatment]

Incidence of differentiated thyroid cancer has increased in the last two decades. This type of cancer is now being diagnosed at an earlier stage. Treatment strategy has been modified.

AIMS

The goals of this study were to analyze the outcome of differentiated thyroid cancer after initial treatment (surgery and radioiodine ablation) in patients evaluated and followed up in a single centre between l999 and 2009, to compare these results with others as well as to monitor the adoption of international recommendation. 107 patients having T1-T2 differentiated thyroid cancer were studied. Mean follow-up time was 63 months.

RESULTS

After surgery patients were prepared using thyroid hormone withdrawal or recombinant human thyrotropin, then 1.1-3.7 GBq 131-iodine was administered. First year evaluation consisted of ultrasound as well as serum thyrotropin and thyroglobulin (plus thyroglobulin antibody) determinations. Ablation success rate was 83% and the five year survival was 100%. There was not any cancer specific death.

CONCLUSION

In the future somewhat more radical surgery and less remnant ablation is needed with unified follow-up protocol.

Clinical significance of observation without repeated radioiodine therapy in differentiated thyroid carcinoma patients with positive surveillance whole-body scans and negative thyroglobulin

BACKGROUND/AIMS

Currently, there is no consensus on the necessity of repeated radioiodine therapy (RAI) in patients who show iodine uptake in the thyroid bed on a diagnostic whole-body scan (DxWBS) despite undetectable thyroglobulin (Tg) levels after remnant ablation. The present study investigated the clinical outcomes of scan-positive, Tg-negative patients (WBS+Tg-) who did or did not receive additional RAI.

METHODS

We retrospectively reviewed 389 differentiated thyroid carcinoma patients who underwent a total thyroidectomy and received high-dose RAI from January 2003 through December 2005. The patients were classified according to surveillance DxWBS findings and TSH-stimulated Tg levels 6 to 12 months after the initial RAI.

RESULTS

Forty-four of the 389 patients (11.3%) showed thyroid bed uptake on a DxWBS despite negative Tg levels (WBS+Tg-). There was no difference in clinical and pathological parameters between WBS+Tg- and WBS-Tg- patients, except for an increased frequency of thyroiditis in the WBS+Tg- group. Among the 44 WBS+Tg- patients, 27 subjects were treated with additional RAI; 25 subjects showed no uptake in subsequent DxWBS. Two patients were evaluated only by ultrasonography (US) and displayed no persistent/recurrent disease. The other 17 patients received no further RAI; Eight patients and two patients showed no uptake and persistent uptake, respectively, on subsequent DxWBS. Six patients presented negative subsequent US findings, and one was lost to follow-up. Over the course of 53.2 ± 10.1 months, recurrence/persistence was suspicious in two patients in the treatment group.

CONCLUSIONS

There were no remarkable differences in clinical outcomes between observation and treatment groups of WBS+Tg- patients. Observation without repeated RAI may be an alternative management option for WBS+Tg- patients.