High thyroglobulin and negative whole-body scan: no long-term benefit of empiric radioiodine therapy

Efficacy of Empirical 131 I Radioiodine Therapy in Well-Differentiated Thyroid Carcinoma Patients With Thyroglobulin-Elevated Negative Iodine Scintigraphy Syndrome : A Systematic Review and Meta-analysis

OBJECTIVES

This study aimed to perform a systematic review and meta-analysis on the efficacy of empirical high-dose radioiodine therapy in treating differentiated thyroid cancer patients with thyroglobulin (Tg)-elevated negative iodine scintigraphy (TENIS) syndrome.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library to identify relevant studies published until April 2022. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist and registered in an international prospective register of systematic reviews (PROSPERO). Meta-analyses of proportions and odds ratios were performed to assess the beneficial effect of empirical high-dose radioiodine therapy in patients with TENIS syndrome. Subgroup analysis was also performed according to the presence of micrometastasis or macrometastasis.

RESULTS

We identified 14 studies including 690 patients who received empirical high-dose radioiodine therapy for TENIS syndrome. Those who had micrometastasis exhibited additional lesions not previously observed on diagnostic whole-body scan (prop = 0.64, 95% confidence interval [CI], 0.51-0.77) and had reduced serum Tg levels (prop = 0.69; 95% CI, 0.52-0.84) after empirical radioiodine treatment. No such findings were observed among patients with macrometastasis. Moreover, we found that the empirical radioiodine treatment group had lower serum Tg levels than did controls (odds ratio = 0.27; 95% CI, 0.09-0.87), which suggests a lower risk of disease progression.

CONCLUSIONS

Our findings indicate that empirical high-dose radioiodine therapy promoted beneficial effects and could be recommended for patients with TENIS syndrome, especially those with micrometastasis.

Current Advances in Radioactive Iodine-Refractory Differentiated Thyroid Cancer

BACKGROUND

Differentiated thyroid cancer (DTC) patients have an outstanding overall long-term survival rate, and certain subsets of DTC patients have a very high likelihood of disease recurrence. Radioactive iodine (RAI) therapy is a cornerstone in DTC management, but cancer cells can eventually develop resistance to RAI. Radioactive iodine-refractory DTC (RAIR-DTC) is a condition defined by ATA 2015 guidelines when DTC cannot concentrate RAI ab initio or loses RAI uptake ability after the initial therapy. The RAIR condition implies that RAI cannot reveal new met-astatic foci, so RAIR-DTC metabolic imaging needs new tracers. 18F-FDG PET/CT has been widely used and has demonstrated prognostic value, but 18F-FDG DTC avidity may remain low. Fibroblast activation protein inhibitors (FA-Pi)s, prostatic-specific membrane antigen (PSMA), and somatostatin receptor (SSTR) tracers have been proposed as theragnostic agents in experimental settings and Arg-Gly-Asp (RGD) peptides in the diagnostic trial field. Multi-targeted tyrosine kinase inhibitors are relatively new drugs approved in RAIR-DTC therapy. Despite the promising targeted setting, they relate to frequent adverse-event onset. Sorafenib and trametinib have been included in re-differentiation protocols aimed at re-inducing RAI accumulation in DTC cells. Results appear promising, but not excellent.

CONCLUSIONS

RAIR-DTC remains a challenging nosological entity. There are still controversies on RAIR-DTC definition and post-RAI therapy evaluation, with post-therapy whole-body scan (PT-WBS) the only validated criterion of response. The recent introduction of multiple diagnostic and therapeutic agents obliges physicians to pursue a multidisciplinary approach aiming to correct drug introduction and timing choice.

Efficacy of Empirical Radioiodine Therapy in Patients with Differentiated Thyroid Cancer and Elevated Serum Thyroglobulin without Evidence of Structural Disease: A Propensity Score Analysis

We assessed the outcome of administration of empiric radioactive iodine (RAI) therapy to patients with differentiated thyroid cancer (DTC), in a propensity-score-matched cohort of patients with biochemical incomplete response (BIR) and without evidence of structural disease. We retrospectively evaluated 820 DTC patients without distant metastases, who underwent total thyroidectomy followed by RAI therapy, with available BIR at 12 months and follow-up evaluations. The patients were categorized according to the administration of empiric therapy (ET). To account for differences between patients with (n = 119) and without (n = 701) ET, a propensity-score-matched cohort of 119 ET and 119 no-ET patients was created. The need for additional therapy and the occurrence of structural disease were considered as end-points. During a median follow-up of 53 months (range 3-285), 57 events occurred (24% cumulative event rate). The rate of events was significantly higher in the no-ET compared to the ET patients (30% vs. 18% p < 0.001). The multivariate Cox analysis identified age (p < 0.01), pre-therapy Tg (p < 0.05) and empiric RAI therapy (p < 0.01) as predictors of outcome. The Kaplan-Meier analysis found that progression-free survival was lower in no-ET patients compared to the ET group (p < 0.01). In patients with DTC treated with surgery and RAI, and with biochemical incomplete response at the 12-month evaluation, their prognosis seemed to be affected by Tg values and the empiric treatment. The identification of candidates for this approach may improve prognosis.

Outcome of patients with differentiated thyroid cancer treated with empirical radioiodine therapy on the basis of Thyroglobulin Elevation Negative Iodine Scintigraphy (TENIS) syndrome without structural disease: a retrospective cohort study

BACKGROUND

For differentiated thyroid cancer (DTC) patients with thyroglobulin (Tg) elevation and negative iodine scintigraphy (commonly termed "TENIS" syndrome) after thyroidectomy, radioactive iodine (RAI) therapy, and thyroid-stimulating hormone (TSH) suppression therapy, empirical RAI therapy may be considered. However, the outcome data of TENIS syndrome without structural disease after empirical RAI therapy have not shown clear evidence of improvement in survival. We assessed the efficacy of such empirical RAI therapy in TENIS syndrome without structural disease and evaluated the progression-free survival (PFS).

METHODS

A total of 80 papillary thyroid cancer (PTC) patients with TENIS syndrome without structural disease were included in this retrospective study. 52 patients were treated with empirical RAI therapy while another 28 patients were untreated. The progression-free survival (PFS) of both groups was defined as the main outcome. The secondary outcome was the comparison of serum Tg levels 12 months after being diagnosed as TENIS syndrome.

RESULTS

The PFS of the empirical RAI therapy group was better than the untreated group (p < 0.001). Moreover, there was significant difference in Tg normalization between patients treated with empirical therapy and without treatment (p = 0.001). Empirical RAI therapy (p = 0.001) predicts better PFS. Male gender (p = 0.041) and empirical RAI therapy (p = 0.002) predict better remission in serum Tg level.

CONCLUSION

Patients with TENIS syndrome without structural disease can benefit from empirical RAI therapy in both PFS and Tg normalization.

Advanced imaging and theranostics in thyroid cancer

PURPOSE OF REVIEW

Thyroid cancers are endocrine neoplasms with diverse gene expression and behavior, for which constantly evolving anatomic and functional imaging/theranostic agents have an essential role for diagnosis, staging, and treatment.

RECENT FINDINGS

To achieve definitive diagnosis, neck ultrasound and associated risk stratification systems, notably Thyroid Imaging Reporting and Data System (TI-RADS), allow improved thyroid nodule characterization and management guidance. Radioactive iodine-131 (RAI) has long played a role in management of differentiated thyroid cancer (DTC), with recent literature emphasizing its effectiveness for intermediate-high risk cancers, exploring use of dosimetry for personalized medicine, and potential for retreatment with RAI following tumor redifferentiation. Iodine-124 positron emission tomography/computed tomography (PET/CT) has promising application for DTC staging and dosimetry. F18-fluorodeoxyglucose (FDG) PET/CT is used for staging of high risk DTC and identification of noniodine-avid disease recurrences, with metabolic uptake consistently portending poor prognosis. Poorly differentiated and anaplastic thyroid cancers are best assessed with anatomic imaging and F18-FDG PET/ CT, though recent studies show a potential theranostic role for Ga68/Lu177-prostate-specific membrane antigen. Medullary thyroid cancers are evaluated with ultrasound, CT, magnetic resonance imaging, and various positron-emitting radiotracers for PET imaging (F18-DOPA, F18-FDG, and recently Ga68-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE)); the latter may enable treatment with Lu177-DOTATATE.

SUMMARY

Multidisciplinary collaboration is essential to streamline appropriate management, given the wide array of available imaging and new therapies for metabolic and genetically complex cancers.

Prognostic value of post-ablation stimulated thyroglobulin in differentiated thyroid cancer patients with biochemical incomplete response: a bi-center observational study

OBJECTIVE

Little is known regarding parameters predicting persistence/recurrence for differentiated thyroid cancer (DTC) patients exhibiting biochemical incomplete response (BIR) to initial therapy. High post-ablation stimulated thyroglobulin (ps-Tg) levels have undetermined prognostic significance in DTC patients with BIR. The goal of this bi-center study was to systemically assess the prognosis of DTC patients with BIR in relation to ps-Tg levels and to establish the determinants of clinical outcomes.

DESIGN AND METHODS

The retrospective study of consecutive 81 DTC patients from two tertiary centers who were classified as BIR after total thyroidectomy and radioiodine ablation between January 2010 to December 2019 were analyzed. BIR was defined as ps-Tg > 10 ng/mL measured under thyroid hormone withdrawal at 9-12 months followed by radioiodine ablation, negative anti-Tg antibodies, and no structural evidence of disease. Multivariable regression models were used to evaluate potential risk factors associated with clinical outcomes.

RESULTS

With a median follow-up of 5.4 years, 28 patients (34.6%) showed no evidence of disease and 50 patients (61.7%) were of a biochemical persistent status at the time of final follow-up. Conversely, 3 patients (3.7%) developed structural evidence of disease. Ps-Tg of 20.2 ng/mL or greater displayed the high positive predictive value (81%) for disease persistence/recurrence. Multivariate analysis revealed that only a high ps-Tg level (>20.2 ng/mL) was an independent risk factor for persistent/recurrent disease (odds ratio = 5.6; p < 0.001).

CONCLUSION

The ps-Tg (>20.2 ng/mL) was a valuable predictor of disease persistence/recurrence in DTC patients with BIR.

Radioiodine adjuvant therapy in differentiated thyroid cancer: An update and reconsideration

Radioiodine (¹³¹I) therapy (RAI) has been utilized for treating differentiated thyroid cancer (DTC) for decades, and its uses can be characterized as remnant ablation, adjuvant therapy (RAT) or treatment for known diseases. Compared with the definite ¹³¹I treatment targets for remnant ablation and known disease, ¹³¹I adjuvant therapy (RAT) aims to reduce the risk of recurrence by destroying potential subclinical disease. Since it is merely given as a risk with no imaging confirmation of persistence/recurrence/metastases, the evidence is uncertain. With limited knowledge and substance, the indication for RAT remains poorly defined for everyday clinical practice, and the benefits of RAT remain controversial. This ambiguity results in a puzzle for clinicians seeking clarity on whether patients should receive RAT, and whether patients are at risk of recurrence/death from undertreatment or adverse events from overtreatment. Herein, we clarified the RAT indications in terms of clinicopathological features, postoperative disease status and response to therapy evaluation, and retrospectively examined the clinical outcomes of RAT as reported in current studies and guidelines. Furthermore, given the evolution of nuclear medicine imaging techniques, it can be expected that the future of RAT may be advanced by nuclear medicine theranostics (i.e., ¹³¹I whole-body scan, PET/CT) by accurately revealing the biological behaviors, as well as the underlying molecular background.