Outcome of Patients With Differentiated Thyroid Cancer Treated With 131-Iodine on the Basis of a Detectable Serum Thyroglobulin Level After Initial Treatment

Stimulating thyroglobulin to TSH ratio predict long-term efficacy of 131I therapy in patients with differentiated thyroid cancer after total thyroidectomy: a retrospective study

OBJECTIVE

This study utilized the stimulated thyroglobulin (sTg) to thyroid stimulating hormone (TSH) ratio to predict the long-term efficacy of 131I therapy in patients with moderate-to-high-risk differentiated thyroid cancer (DTC).

METHODS

This study retrospectively analyzed 960 DTC patients with a median follow-up time of 30 months (6-92 months). The median age was 44 years. All patients underwent total thyroidectomy, lymph node dissection, and at least one 131I therapy. Patients were subjected to a final efficacy evaluation according to American Thyroid Association's 2015 guidelines. Patients were grouped according to their TSH levels before the initial 131I therapy and the final efficacy evaluation, and factors influencing TSH levels and final efficacy were analyzed. Construction of nomograms using independent risk factors affecting long-term outcomes. The cut-offs of sTg and sTg/TSH ratios were calculated for different long-term outcomes. Progression-free survival (PFS) of patients was analyzed by making Kaplan-Meier survival according to the cut-offs of sTg and sTg/TSH ratio.

RESULTS

TSH (mU/L) levels were more concentrated at 60-90 in females (71.5%) and 30-60 in males (39.0%), while patients with younger age, more lymph node metastases, shorter time interval between surgery and the first 131I therapy, and lower dose of levothyroxine sodium taken prior to the first 131I therapy would have higher TSH levels (All P < 0.05).Patients who are male, have primary tumor involvement of the strap muscles, lymph node metastasis, distant metastasis, and higher sTg and sTg/TSH are more likely to have poor long-term outcomes (All P < 0.05).The cut-offs of sTg and sTg/TSH for long-term efficacy were 7.515 and 0.095. STg, sTg/TSH, tumor size, lymph node metastasis, and distant metastasis were shown to be independent risk factors for long-term efficacy. The mean PFSs were longer for patients who had sTg/TSH ≤ 0.095 and/or sTg≤7.515 ug/L.

CONCLUSIONS

For patients with moderate-to-high-risk DTC, when sTg>7.515 ug/L and/or sTg/TSH > 0.095 before the first 131I therapy, patients are more likely to have a poor long-term efficacy after full 131I therapy. This means that this group of patients may require further surgical treatment or targeted drug therapy after 131I therapy.

Metastatic differentiated thyroid cancer with negative serum stimulated Tg but positive post-therapeutic 131I-SPECT/CT scintigraphy: a single-center retrospective study

PURPOSE

This study aimed to describe the characteristics of patients with metastatic differentiated thyroid carcinoma (DTC) who had positive 131I-scintigraphy but negative stimulated thyroglobulin (sTg), and to evaluate their short-term response to radioiodine therapy (RAI).

METHODS

A total of 2250 consecutive postoperative DTC patients, who underwent RAI treatment from July 2019 to June 2022, were analyzed retrospectively. The target group was defined as stimulated Tg < 2 ng/mL with TgAb < 100 IU/mL but with post-therapeutic 131I-SPECT/CT metastases. The characteristics of these patients were analyzed and the metastatic profiles were compared with TgAb positive or sTg positive ones. A cross-sectional efficacy was evaluated 6-12 months after the RAI therapy and the treatment course until the end of the study was recorded.

RESULTS

105 (4.67%) DTC patients were post-therapeutic 131I-SPECT/CT positive and sTg negative (target group). Metastatic profiles were found significant differences between sTg negative and sTg positive ones (P < 0.001). Excellent response (ER) was achieved in 72.4% of the target group between 6-12 months of cross-sectional efficacy assessment, compared with only 12.8% in sTg positive ones (P < 0.001). The majority of the target group didn't require aggressive treatment in short-term follow-up compared with sTg positive group (P < 0.001).

CONCLUSION

The percentage of DTCs with negative sTg but positive post-therapeutic 131I-SPECT/CT was relatively low, but still significant. Moreover, the majority of these patients showed an ER to RAI and may not require the next course of therapy. Long-term follow-up is still necessary to assess recurrence and adapt surveillance in these patients.

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.

Prognostic value of 12-month response to therapy in pediatric patients with differentiated thyroid cancer

PURPOSE

In pediatric patients with differentiated thyroid cancer (DTC) we assessed the prognostic value of the 12-month response to therapy after initial treatment with surgery and radioactive iodine (RAI).

METHODS

We retrospectively evaluated 94 pediatric patients with DTC, treated with surgery and RAI who were initially classified as low, intermediate or high risk of relapse of disease according to the American Thyroid Association (ATA) guidelines. Twelve months after RAI administration the response to therapy was assessed by serum thyroglobulin (Tg) measurement and neck ultrasound and patients were classified as having excellent response (ER) or no-ER.

RESULTS

At the 12 months evaluation, 62 (66%) patients had ER and 32 (34%) no-ER. During a mean follow-up time of 86 months (range 9-517), 19 events occurred (20% cumulative event rate). Events occurred more frequently in younger patients (p < 0.05), in those at ATA intermediate/high risk (p < 0.01) and with a pre-RAI therapy Tg level > 10 ng/mL (p < 0.001), and in those with no-ER (p < 0.001). At multivariate analysis, the evidence of no-ER was the only independent predictor of events.

CONCLUSION

In pediatric patients with DTC, the response to therapy evaluated 12 months after initial treatment has an independent prognostic impact and is able to predict mid-term outcome. Patients with no-ER at 12 months after RAI therapy should be closely followed-up.

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.

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.

Clinicopathological features and outcome of thyroglobulin elevation and negative iodine scintigraphy (TENIS) patients with negative neck ultrasound: Experience from a thyroid carcinoma clinic in India

Management of differentiated thyroid carcinoma (DTC) patients with thyroglobulin (Tg) elevation and negative iodine scintigraphy (TENIS) and negative neck ultrasound scan causes considerable diagnostic and therapeutic dilemma, especially in resource-poor settings. The aim of this study was to evaluate clinicopathological features and outcome of TENIS patients with negative neck US attending a thyroid cancer clinic in India. From a DTC database of 722 containing 193 TENIS patients, subjects with negative neck US and negative Tg antibody (TgAb) were selected retrospectively and analyzed using appropriate statistical methods. The study group included 64 patients (male – 17, female – 47, mean age – 44.7 ± 12.8 years) with 54 papillary and 10 follicular thyroid carcinomas, American Thyroid Association (ATA) recurrence risk categorization (2009) – low – 16, intermediate – 28, and high – 2 0. Most of the patients became TENIS within 1 year of diagnosis with median Tg level of 6.5 ng/mL (1.2–996 ng/mL) and mean follow-up of 7.8 years. On follow-up, Tg dropped spontaneously in 27 patients, more among the low and intermediate-risk categories. For those with high or increasing Tg level, further imaging (fluorodeoxyglucose positron emission tomography/computed tomography) was done and 14 out of 18 were positive. Treatment included empiric radioactive iodine therapy-16, external beam radiation therapy (EBRT)-7, and lymph node dissection (LND)-10. A favorable outcome was seen in 36 patients and unfavorable in 28. Distant metastases were associated with unfavorable outcome and poor survival. Progression-free survival was significantly better in the Tg group of <10 at the time of TENIS (111 months) compared to the Tg group >10 (72 months). Tg level dropped spontaneously in nearly half the patients, especially if levels were <10 and more so among the low-risk category. Distant metastasis was predictive of unfavorable outcomes. Along with Tg level, the ATA risk category might help to predict clinical course and reduce unnecessary expensive imaging in resource-poor settings.

Long-Term Prognostic Value of the Response to Therapy Assessed by Laboratory and Imaging Findings in Patients with Differentiated Thyroid Cancer

Simple Summary

In patients with differentiated thyroid cancer (DTC), the American Thyroid Association dynamic risk stratification system has been proposed to identify patients at higher risk of recurrence during follow-up. This system is based on a combination of serum thyroglobulin determination and neck ultrasonography obtained 12-months after radioactive iodine (RAI) therapy. Radioiodine diagnostic whole-body scan (WBS) is performed less frequently due to its low sensitivity. In this retrospective study we assessed the long-term predictive value of the response to therapy at 12 months, evaluated by serum thyroglobulin determination and neck ultrasound, and estimated the potential additional impact of diagnostic WBS in patients with DTC treated with surgery and RAI therapy. Our findings could help in the identification of DTC patients at higher risk of recurrence that could benefit from a closer follow-up.

Abstract

This study assessed the long-term predictive value of the response to therapy, evaluated by serum thyroglobulin (Tg) determination and neck ultrasound, and estimated the potential additional impact of diagnostic whole-body scan (WBS) in patients with differentiated thyroid cancer (DTC) treated with surgery and radioactive iodine (RAI) therapy. We retrospectively evaluated 606 DTC patients treated with surgery and RAI. Response to ¹³¹I therapy at 12 months was assessed by serum Tg measurement, neck ultrasound, and diagnostic WBS. According to American Thyroid Association (ATA) guidelines, patients were classified as having a low, intermediate or high risk of recurrence and at 12 months as having an excellent response (ER) or no-ER. Follow-up was then performed every 6–12 months with serum Tg determination and imaging procedures. With a median follow-up of 105 months (range 10–384), 42 (7%) events requiring further treatments occurred. Twenty-five patients had additional RAI therapy, 11 with structural disease in the thyroid bed, eight in both thyroid bed and neck lymph nodes, four had lung metastases and two had bone metastases. The other 17 patients had additional surgery for nodal disease followed by RAI therapy. The ATA intermediate and high risk of recurrence, post-operative and pre-RAI therapy Tg ≥ 10 ng/mL, and the absence of ER at 12 months were independent predictors of events. Diagnostic WBS at 12 months permitted the identification of only five recurrences among the 219 ER patients according to serum Tg levels and ultrasound. In DTC patients, the response to therapy at 12 months after RAI therapy could rely on serum Tg measurement and neck ultrasound, while diagnostic WBS was not routinely indicated in patients considered in ER.

A Three-Domain Scoring System to Customize the Risk of Relapse of Differentiated Thyroid Carcinoma

PURPOSE

the validation of a new scoring model considering the principal risk factors of differentiated thyroid cancer (DTC) relapse.

METHODS

we evaluated all DTC patients treated with thyroidectomy and radioactive iodine (RAI) therapy. Three domains were considered: the demographic domain (age and gender), the surgical domain (histology and the American Thyroid Association risk categories), and the RAI-related domain (pre-RAI thyroglobulin and post-therapeutic ¹³¹I whole-body scan). The progression-free survival was assessed. The patients' sample was randomly split into a training and validation set. The three-domain score was calculated as the weighted sum of the levels of each significant factor, then scaled to an integer range (0-100) and, finally, stratified into terciles: mild risk 0-33, moderate risk 34-66, and severe risk 67-100.

RESULTS

907 DTC patients were included. The RAI-related domain was the most relevant factor in the score calculation. The tercile stratification identified significantly different survival curves: patients within the two upper terciles showed approximately 6 to 30 times more progressive risk than patients at mild risk.

CONCLUSION

we have validated a three-domain scoring system and the principal impact on this score is provided by the peri-RAI findings, whose prognostic role seems to be essential in risk identification.

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

PURPOSE

Around 10-27% of patients will present elevated thyroglobulin (Tg) levels and negative diagnostic whole-body scan (dxWBS) during differentiated thyroid cancer (DTC) follow-up. Empiric radioactive iodine (RAI) therapy in this context is controversial due to the lack of good quality studies in the context. The main purpose of this study is to compare long-term response to therapy status and overall survival between empiric RAI treated and untreated DTC patients.

METHODS

A retrospective study comparing differentiated thyroid cancer patients with negative diagnostic whole-body scan and elevated thyroglobulin levels submitted or not to empiric radioactive iodine therapy in a thyroid cancer referral center. The main outcome measures were ATA Response to Therapy Stratification at 6-12 months after RAI ablative dose, at 6-18 months after negative dxWBS and last follow-up visits.

RESULTS

Overall, 120 DTC patients with stimulated Tg >10 ng/ml and negative dxWBS were included in this study. Overall, 53 patients were submitted to empiric RAI and 67 were in the control group. No difference was observed in ATA Response to Therapy Stratification after RAI ablation or at the end of follow-up between groups. Also, no difference was found in terms of Tg changes response. After more than 10 years of follow-up, 17 patients died (13 from treated and 4 from untreated group).

CONCLUSIONS

Empiric RAI treatment was not associated with better long-term ATA response to therapy status or overall survival.

PET/CT in the management of differentiated thyroid cancer

The standard treatment of differentiated thyroid cancer (DTC) consists of surgery followed by iodine-131 (¹³¹I) administration. Although the majority of DTC has a very good prognosis, more aggressive histologic subtypes convey a worse prognosis. Follow-up consists of periodically measurements of serum thyroglobulin, thyroglobulin antibodies and neck ultrasound and ¹²³I/¹³¹I whole-body scan. However, undifferentiated thyroid tumors have a lower avidity for radioiodine and the ability of DTC to concentrate ¹³¹I may be lost in metastatic disease. Positron emission tomography (PET)/computed tomography (CT) has been introduced in the evaluation of patients with thyroid tumors and the 2-[18F]-fluoro-2-deoxyd-glucose (¹⁸F-FDG) has been largely validated as marker of cell's metabolism. According to the 2015 American Thyroid Association guidelines, ¹⁸F-FDG PET/CT is recommended in the follow-up of high-risk patients with elevated serum thyroglobulin and negative ¹³¹I imaging, in the assessment of metastatic patients, for lesion detection and risk stratification and in predicting the response to therapy. It should be considered that well-differentiated iodine avid lesions could not concentrate ¹⁸F-FDG, and a reciprocal pattern of iodine and ¹⁸F-FDG uptake has been observed. Beyond ¹⁸F-FDG, other tracers are available for PET imaging of thyroid tumors, such as Iodine-124 (¹²⁴I), ¹⁸F-tetrafluoroborate and Gallium-68 prostate-specific membrane antigen. Moreover, the recent introduction of PET/MRI, offers now several opportunities in the field of patients with DTC. This review summarizes the evidences on the role of PET/CT in management of patients with DTC, focusing on potential applications and on elucidating some still debating points.

Risk of structural persistent disease in pediatric patients with low or intermediate risk differentiated thyroid cancer

PURPOSE

In pediatric patients with differentiated thyroid cancer (DTC), the risk of recurrence is high and the indication for postoperative ¹³¹I administration is still debated. The aim of this study was to assess the outcome in low and intermediate risk pediatric DTC patients.

METHODS

We retrospectively evaluated 45 pediatric patients with low or intermediate risk DTC, treated with surgery and ¹³¹I between 1992 and 2002 and with no detectable antithyroglobulin (Tg) antibodies. Follow-up was performed every 6-12 months with Tg blood level determination and imaging procedures.

RESULTS

During follow-up (64 ± 53 months), 15 events occurred (33% cumulative event rate, with an annual event rate of 5% person years). Five of these patients were submitted to additional surgery and all these 15 patients underwent a second ¹³¹I treatment course. All patients were alive at the end of the follow-up. Structural persistent disease occurred more frequently in patients at intermediate risk (p < 0.01) and in those with Tg values after thyroid hormone withdrawal >10 ng/ml before ¹³¹I therapy (p < 0.01). At multivariate analysis, only a postoperative thyroid stimulating hormone-stimulated Tg level >10 ng/ml was an independent predictor of persistent disease.

CONCLUSIONS

In pediatric patients with DTC, postoperative high stimulated Tg values (>10 ng/ml) should be taken into account for deciding the extent of both initial treatment and follow-up.

Distinguishing Patients With Distant Metastatic Differentiated Thyroid Cancer Who Biochemically Benefit From Next Radioiodine Treatment

BACKGROUND

Repeated radioiodine (¹³¹I) treatment (RT) are commonly performed in patients with ¹³¹I-avid distant metastatic differentiated thyroid cancer (DM-DTC), but more precise indications remain indeterminate. This prospective study was conducted to explore predictors for biochemical response (BR) to next RT.

METHODS

Totally thyroidectomized patients with ¹³¹I-avid DM-DTC demonstrated by initial post-therapeutic whole body scan (Rx-WBS) were consecutively recruited. Repeated RTs were performed at a fixed dose and a fixed interval, which was terminated once a decline in thyroid stimulating hormone-suppressed thyroglobulin (Tg_on) could not be achieved or Rx-WBS was negative. BR was evaluated by change rate of Tg_on level (ΔTg_on%).

RESULTS

After exclusion of 27 ineligible courses, a total of 166 neighboring course pairs from 77 patients were established and utilized. Univariate and multivariate analyses showed that the maximum target/background ratio (T/B_max) on the whole body scan and ΔTg_on% derived from the former RT were independently associated to the latter one. In predicting biochemical remission, the positive predictive value (PPV) and negative predictive value (NPV) of T/B_max at the cut-off value of 8.1 were 79.1% and 84.0%, respectively; whereas the PPV and NPV of ΔTg_on% at the cut-off value of 25.3% were 70.8% and 77.1%, respectively. Notably, the PPV of combined T/B_max ≥ 8.1 and ΔTg_on% ≥ 25.3% increased to 87.7%; while the NPV of T/B_max ≥ 8.1 or ΔTg_on% ≥ 25.3% reached as high as 97.7%.

CONCLUSIONS

This study revealed that combined use of the latest RT-derived T/B_max and ΔTg_on% may efficiently identify biochemical responders/non-responders to next RT, warranting management optimization of patients with ¹³¹I-avid DM-DTC.