Thyroid Hormone Withdrawal versus Recombinant Human TSH as Preparation for I-131 Therapy in Patients with Metastatic Thyroid Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Differentiated thyroid carcinoma (DTC) is characterized by an excellent prognosis with a 10-year survival rate > 90%. However, when DTC develops in a metastatic form, it has been shown to significantly impact patient survival and quality of life. Although I-131 has been shown to be an effective therapy in patients with metastatic DTC, whether its efficacy after recombinant human TSH (rhTSH) is comparable to endogenous TSH stimulation by thyroid hormone deprivation (THW) is still debated. Our present study was prompted to compare clinical results obtained in metastatic DTC by I-131 administered after rhTSH and THW stimulation protocols, respectively.

METHODS

A systematic search on PubMed, Web of Science, and Scopus was performed from January to February 2023. Pooled risk ratios with 95% CI were determined for evaluating the initial response after to I-131 therapy after preparation with rhTSH or THW and the disease progression. To track the accumulation of evidence and reduce type I errors because of small data, a cumulative meta-analysis was performed. A sensitivity analysis was also performed to examine the impact of individual studies on overall prevalence results.

RESULTS

Ten studies were included with a total of 1929 patients pre-treated with rhTSH (n = 953) and THW (n = 976), respectively. The cumulative data of our systematic review and meta-analysis showed an increase in the risk ratio over the years without any change in favour of a pre-treatment or the other on the effectiveness of I-131 therapy of metastatic DTC.

CONCLUSIONS

Our data suggest that pretreatment with rhTSH or THW has no significant impact on the effectiveness of I-131 therapy for metastatic DTC. This implies that concerns about the use of one or the other pretreatment should be deferred to clinical evaluations made considering patient characteristics and reduction in side effects.

Outcomes of Thyrotropin Alfa Versus Levothyroxine Withdrawal-Aided Radioiodine Therapy for Distant Metastasis of Papillary Thyroid Cancer

Background: Thyrotropin alfa (rhTSH) is not currently approved by the Food and Drug Administration or European Medicines Agency for the preparation of radioactive iodine therapy (RAIT) in patients with distant metastatic papillary thyroid cancer (PTC). There are only a few studies comparing rhTSH with levothyroxine withdrawal (LTW) in this context. Our main aim was to compare the two methods of RAIT preparation in terms of avidity and structural/biochemical response in distant metastatic PTC. We also intended to evaluate whether the two methods of RAIT preparation represented independent prognostic factors for progression-free survival (PFS) and disease-specific survival (DSS) in this subset of patients. Methods: We performed a retrospective analysis of all patients with PTC treated with RAIT for distant metastatic disease between 2006 and 2018. We included 95 PTC patients-27 (28.4%) had LTW and 68 (71.6%) had rhTSH for RAIT. Results: The two groups presented similar clinicopathological characteristics, except for median age at PTC diagnosis, which was higher in the rhTSH group (p = 0.001), but the median age at first RAIT for distant metastatic disease was not different between the two methods of preparation, 63 years old (interquartile range [IQR] 23) in the LTW group versus 70 (IQR 26.75), p = 0.06. Avidity was similar between the two groups (p = 0.973). Median estimate PFS (p = 0.076) and DSS (p = 0.084) were also similar between LTW and rhTSH. Regarding RAIT-related side effects, only 1 (3.7%) patient and 5 (7.4%) patients in the LTW and rhTSH groups, respectively, reported sialadenitis (p = 0.670). Conclusions: There were no differences between the two methods of RAIT preparation regarding avidity and clinical response. rhTSH may be used as an alternative method of preparation for RAIT in patients with known distant lesions, as it presents similar clinical outcomes to LTW and a good safety profile.

Radio-Iodide Treatment: From Molecular Aspects to the Clinical View

Simple Summary

This year marks the 80th commemoration of the first time that radio-iodide treatment (RAI) was used. RAI is one of the most effective targeted internal radiation anticancer therapies ever devised and it has been used for many decades, however, a thorough understanding of the underlying molecular mechanisms involved could greatly improve the success of this therapy. This is an in-depth innovative review focusing on the molecular mechanisms underlying radio-iodide therapy in thyroid cancer and how the alteration of these mechanisms affects the results in the clinic.

Abstract

Thyroid radio-iodide therapy (RAI) is one of the oldest known and used targeted therapies. In thyroid cancer, it has been used for more than eight decades and is still being used to improve thyroid tumor treatment to eliminate remnants after thyroid surgery, and tumor metastases. Knowledge at the molecular level of the genes/proteins involved in the process has led to improvements in therapy, both from the point of view of when, how much, and how to use the therapy according to tumor type. The effectiveness of this therapy has spread into other types of targeted therapies, and this has made sodium/iodide symporter (NIS) one of the favorite theragnostic tools. Here we focus on describing the molecular mechanisms involved in radio-iodide therapy and how the alteration of these mechanisms in thyroid tumor progression affects the diagnosis and results of therapy in the clinic. We analyze basic questions when facing treatment, such as: (1) how the incorporation of radioiodine in normal, tumor, and metastatic thyroid cells occurs and how it is regulated; (2) the pros and cons of thyroid hormonal deprivation vs. recombinant human Thyroid Stimulating Hormone (rhTSH) in radioiodine residence time, treatment efficacy, thyroglobulin levels and organification, and its influence on diagnostic imaging tests and metastasis treatment; and (3) the effect of stunning and the possible causes. We discuss the possible incorporation of massive sequencing data into clinical practice, and we conclude with a socioeconomical and clinical vision of the above aspects.

INITIAL ADOPTION OF RECOMBINANT HUMAN THYROID-STIMULATING HORMONE FOLLOWING THYROIDECTOMY IN THE MEDICARE THYROID CANCER PATIENT POPULATION

OBJECTIVE

Recombinant human thyroid-stimulating hormone (rhTSH) has been approved for diagnostic (1998) and therapeutic (2008) indications in conjunction with radioactive iodine (RAI) administration post-thyroidectomy. Potential benefits of rhTSH, including avoidance of hypothyroidism side effects and shorter, less costly hospital stays, have not been assessed at the population level within the United States. In this study we quantify utilization, outcomes, and associated costs of rhTSH within the nationally representative Surveillance, Epidemiology, and End Results (SEER)-Medicare patient population.

METHODS

We conducted a retrospective analysis of beneficiaries aged >65 years diagnosed within the SEER-Medicare data with differentiated thyroid cancer. Endpoints examined included ( 1) rhTSH utilization in the 2 years post-thyroidectomy (patients diagnosed 1996-2011 [utilization cohort]) and ( 2) comparison of resource utilization and costs as a function of rhTSH receipt in the 30 days prior to and 1 year following therapeutic RAI administration (patients diagnosed 2008-2011 [resource use cohort]). All costs were adjusted to reflect 2013 dollars.

RESULTS

A total of 6,482 patients met inclusion criteria, of which, 1,363 (21.0%) received rhTSH. Receipt varied by region and was higher in the South (18%), Northeast (28%), and West (44%) compared to the Midwest (10%), and lower in census tracts in the bottom quartile of high school education rates (odds ratio 0.68, 95% confidence interval [CI] 0.55-0.83). rhTSH receipt was not associated with patient sex, age, comorbidities, or stage. Post-therapeutic RAI, 1,444 patients were assessed for resource utilization (2008-2011). The average cost of rhTSH was $905 per patient, with $2,483 being spent on average among patients who received rhTSH in association with therapeutic RAI. rhTSH receipt was not significantly associated with total inpatient days or number of outpatient and emergency department visits. Multivariable analyses showed similar overall costs among patients who did versus did not receive rhTSH (cost ratio [CR] 0.96, 95% CI 0.86-1.09), partially due to increased mean outpatient costs ($5,213 vs. $4,190) being offset by lower inpatient costs ($3,493 vs. $6,143). Overall costs were significantly higher in multivariable analyses among patients with distant metastatic disease (CR 1.92, 95% CI 1.58-2.32) and multiple comorbidities (CR 2.15, 95% CI 1.83-2.53).

CONCLUSION

rhTSH recipients had higher outpatient, lower inpatient, and similar total Medicare payments as those not receiving rhTSH in conjunction with RAI, lending support to the use of rhTSH as a cost-neutral treatment option from the payer perspective.

ABBREVIATIONS

CI = confidence interval; CMS = Centers for Medicare & Medicaid Services; CR = cost ratio; HCPCS = Healthcare Common Procedure Coding System; IQR = interquartile range; mCi = millicurie; OR = odds ratio; PET = positron emission tomography; RAI = radioactive iodine; rhTSH = recombinant human thyroid-stimulating hormone; RR = risk ratio; SEER = Surveillance, Epidemiology, and End Results.

Indirect Basal Metabolism Estimation in Tailoring Recombinant Human TSH Administration in Patients Affected by Differentiated Thyroid Cancer: A Hypothesis-Generating Study

PURPOSE

Recombinant human TSH (rhTSH) is currently used in follow-up of patients affected by differentiated thyroid cancer (DTC). Age, sex, weight, body mass index, body surface area (BSA) and renal function are known factors affecting serum TSH peak levels, but the proper rhTSH dose to deliver to single patient remains elusive. In this study, the correlations of basal metabolic rates with serum TSH peak following rhTSH administration were investigated.

METHODS

We evaluated 221 patients affected by thyroid cancer that received a standard dose rhTSH. Blood samples were collected at pre-established time points. Data on body weight, height, and BSA were collected. The Mifflin-St Jeor and Fleisch equations were used to assess basal metabolism.

RESULTS

The median value (range) of serum TSH peaks was 142 ± 53 μU/ml. Serum TSH peaks were significantly lower in males than in females (p = 0.04). TSH values also increased with age. Data showed a significant decrease of TSH peak levels at day 3 from the administration of rhTSH when basal metabolic rates increased (p = 0.002 and p = 0.009, respectively). Similar findings were observed at day 5 (p = 0.004 and p = 0.04, respectively). A multivariate analysis of several factors revealed that patients' basal metabolism (obtained using the Mifflin-St Jeor but not Fleisch equation) predicts serum TSH level peak at day 3 (p < 0.001). These results were used to generate a new formula based on Mifflin-StJeor equation which reveals as a promising tool in tailoring rhTSH dose.

CONCLUSION

Basal metabolism appears an improving factor in tailoring diagnostic rhTSH dose in patients affected by DTC.

Radioiodine remnant ablation in differentiated thyroid cancer after combined endogenous and exogenous TSH stimulation

Aim: Radioiodine remnant ablation (RRA) after (near-)total thyroidectomy (TE) is a key element in patients with differentiated thyroid cancer (DTC). The use of exogenous TSH stimulation (rhTSH) prior to RRA has shown promising results as compared to conventional thyroid hormone withdrawal (THW). As yet, the efficacy of RRA after brief THW and single rhTSH administration has not been assessed. Patients, methods: The study sample comprised 147 patients with DTC referred to our center between May 2008 and September 2010. All patients received TE with subsequent RRA. None of these 147 patients had evidence of distant metastasis. 93 patients had endogenous TSH stimulation 4–5 weeks after surgery (group I) and twenty-six received two rhTSH injections (group II). 28 patients were treated with a single rhTSH injection after a brief THW (group III). RRA-Efficacy was assessed three months after therapy by diagnostic whole-body scan and measurement of the tumour marker thyroglobulin (Tg) under TSH stimulation. Results: Three categories of success were defined for remnant ablation. Based on the definition of successful remnant ablation no visible uptake and a Tg ≤ 2.0 ng/ ml (category 1) was seen in 62/93 patients in group I, in 17/26 patients in group II (p = n.s.) and in 12/28 patients in group III (p < 0.05). Visible radioiodine uptake and a Tg ≤ 2.0 ng/ml (category 2) was seen in 16/28 patients of group III and thus significantly more frequent than in group I (28/93 patients) (p < 0.01). However, patients in group III (16/28 patients) and group II (8/26 patients) showed no significant difference in this category (p = n.s.). Visible radioiodine uptake and a Tg > 2.0 ng/ml (category 3) was found in 3/93 patients in group I and 1/26 patients in group II but in no patient in group III. Conclusion: The third strategy of remnant ablation using a single injection of rhTSH after a brief THW period resulted in a significant higher rate of patients with residual uptake in the thyroid bed and a Tg level below 2 ng/ml three months after remnant ablation in comparison to THW. However, the overall efficacy of the third protocol was not significantly different as compared to two rhTSH injections. Under the aspect of the supply shortage of rhTSH the combined endogenous and exogenous TSH stimulation may be an attractive alternative for remnant ablation in differentiated thyroid cancer.

Analysis of Clinical Factors for the Determination of Optimal Serum Level of Thyrotropin After Recombinant Human Thyroid-Stimulating Hormone Administration

PURPOSE

To determine the optimal levels of thyroid-stimulating hormone (TSH) levels after administration of recombinant human TSH (rhTSH) to patients with differentiated thyroid cancer (DTC), we have analyzed the clinical parameters that affected the degree of the increase in serum levels of TSH.

METHODS

We retrospectively analyzed 276 patients with differentiated thyroid cancer (DTC), post-thyroidectomy and remnant ablation. Pearson's correlation coefficient test was used to evaluate the correlation between serum levels of TSH after rhTSH stimulation and various clinical factors, including age, sex, height, weight, body mass index (BMI), body surface area (BSA), serum blood urea nitrogen, creatinine, and estimated glomerular filtration rate (GFR). Linear regression analysis was used to determine the predictors of the degree of increase in serum TSH level after rhTSH stimulation.

RESULTS

After the rhTSH injections, all subjects achieved TSH levels of >30 μU/mL, with a mean of 203.8 ± 83.4 μU/mL. On univariate analysis, age (r = 0.255) and serum creatinine (r = 0.169) level were positive predictors for higher levels of serum TSH after rhTSH stimulation, while weight (r = -0.239), BMI (r = -0.223), BSA (r = -0.217), and estimated GFR (r = -0.199) were negative predictors. Multiple linear regression analysis revealed that serum creatinine was the most powerful independent predictor for serum levels of TSH, followed by age, BSA, and BMI.

CONCLUSIONS

An increment in serum TSH after rhTSH stimulation was significantly affected by age, BSA, BMI, and creatinine, with creatinine being the most powerful predictor. By understanding the difference in the increased levels of TSH in various subjects, their dose of rhTSH can be adjusted during scheduling for radioiodine ablation, or during follow-up (recurrence surveillance) after surgery and ablation.

Sensitivity of preparation with rhTSH or thyroid hormone withdrawal using ¹³¹I-whole body scans to identify metastases of differentiated thyroid cancer

It has been reported that there is a higher sensitivity for Thyroid Hormone Withdrawal (THW) in detection of metastases of Differentiated Thyroid Cancer (DTC) when compared to Recombinant Human Thyroid-Stimulating Hormone (rhTSH). This study aims to confirm this reported difference in the sensitivity using radioiodine whole body scans (WBS).

MATERIALS AND METHODS

In a retrospective study forty three patients with evidence or suspicion of metastatic differentiated thyroid cancer DTC (evaluated by thyroglobulin or abnormal findings in previous WBS) underwent WBS using of 24 h after oral administration of 370 MBq (131)I. The WBS was interpreted by two independent experienced observers categorizing their findings into a positive or negative for metastatic disease. The findings were controlled by stimulated thyroglobulin (TG) measurement and a two years follow-up.

RESULTS

Of the evaluated patients, 14 patients were prepared with rhTSH and 29 with THW. No statistical differences in patient characteristics were documented between the two groups (age, sex, thyroglobulin level, TSH level, type of cancer). In this study, no differences in the sensitivity of WBS of patients prepared with rhTSH or THW were found. There were 11 of 14 patients (78%) that were positive after rhTSH and 19 of 29 patients (65%) after THW. Metastatic disease was confirmed by stimulated thyroglobulin value and follow-up.

CONCLUSION

In contrast to previously published data, this study couldn't found any differences in the sensitivity of rhTSH or THW for the preparation of DTC patients undergoing (131)I imaging.

Age and body composition influence TSH concentrations after administration of rhTSH

AIM

Previous studies listed body surface area (BSA), lean body mass (LBM), and age as modifying factors on the TSH concentrations after administration of recombinant human thyrotropin (rhTSH). The purpose of this study was to identify the main modifying factors on serum TSH levels and to compare the stimulation via single rhTSH injection after a short thyroid hormone withdrawal (THW) with that of the standard stimulating protocol.

PATIENTS, METHODS

106 patients with differentiated thyroid cancer (DTC) undergoing radioiodine therapy (RIT) after rhTSH administration were obtained through chart review. Two groups were evaluated: Group I was treated with a single rhTSH administration after two weeks of T3 therapy followed by one week of THW. Group II was stimulated according to the international standard protocol via rhTSH injections for two consecutive days. Serum TSH concentrations were documented prior to rhTSH administration (day 1 TSH), one day after (day 3 TSH) and 3-6 days after (mean 4.2 days, day 6 TSH) the last rhTSH injection. The following data was collected: age, gender, weight, height, BMI, LBM, BSA, residual thyroid tissue, CRP, creatinine, GFR, liver enzymes, alkaline phosphatase, cholesterol, and triglycerides.

RESULTS

Group I: Age combined with anthropometric factors like BMI (TSH increase and day 6 TSH), BSA (TSH decrease), and gender (day 6 TSH) are the main modifying factors on serum TSH concentrations after rhTSH administration. Group II: Age and lean body mass (LBM) showed a significant impact on day 3 TSH, TSH increase (day 3-day 1), and TSH decrease (day 6-day 3). Day 6 TSH was found to be influenced by GFR (group II).

CONCLUSION

Age and anthropometric parameters have significant independent influence on TSH concentrations after rhTSH injection in both groups. Anthropometric parameters (BSA, LBM) and demographic parameters (female gender) show strong influence on TSH concentrations. Further research should be conducted to examine the influence of body compartments on TSH levels through measuring total body water.

Impact of renal function and demographic/anthropomorphic variables on peak thyrotropin after recombinant human thyrotropin stimulation: a stepwise forward multiple-regression analysis

BACKGROUND

When applying the recommended standard doses of recombinant human thyrotropin (rhTSH) in the diagnostic/therapeutic management of patients with differentiated thyroid cancer (DTC), the resulting peak TSH levels vary extensively. Previous studies applying multivariate statistics identified patient-inherent variables influencing the rhTSH/peak TSH relation. However, those results were inconclusive and partly conflicting. Notably, no independent role of renal function was substantiated, despite the fact that the kidneys are known to play a prominent role in TSH clearance from blood. Therefore, the study's aim was to investigate the impact of renal function on the peak TSH concentration after the standard administration of rhTSH used in the management of thyroid cancer. The second objective was to calculate a ranking regarding the effect sizes of the selected variables on the peak TSH.

METHODS

There were 286 patients with DTC included in the study. Univariate and multivariate analyses were performed, testing the correlation of serum creatinine and glomerular filtration rate (GFR) as surrogate parameters of renal function, age, sex, weight, height, and body surface area (BSA) with the peak TSH level. In six additional patients, the subsequent TSH pharmacokinetics after the TSH peak were measured and qualitatively compared.

RESULTS

By univariate analyses, TSH correlated negatively with BSA, GFR, weight, and height, and positively with age, female sex, and serum creatinine (p<0.001). On the multivariate analysis, the stepwise forward multiple linear regression revealed BSA and renal function as the two most influential independent variables, followed by age, sex, and height. The pharmacokinetic datasets indicated that these identified parameters also influence the TSH decline over time.

CONCLUSION

Identifying those patients with a favorable combination of parameters predicting a high-peak TSH is the first step toward an individualization of rhTSH dosing. Additionally, the subsequent TSH decrease over time needs to be taken into account. A complete understanding of the interrelation of the identified key parameters and both the TSH peak and subsequent TSH pharmacokinetics might allow for a more personalized rhTSH dosage strategy to achieve sufficient TSH levels instead of the fixed dosing procedure used at present.

An easy schedule for postsurgical radioiodine administration in newly diagnosed differentiated thyroid carcinoma patients

OBJECTIVE

To validate the simplest approach to preparing patients with differentiated thyroid carcinoma (DTC) for (131) I-administration ((131) I-A), minimizing the impact of hypothyroidism.

DESIGN

Panel study.

PATIENTS

Ninety patients with DTC were enrolled in the study. Sixty (Group A) underwent total thyroidectomy (TT); L-T4 was not administered in preparation for (131) I-A planned for 3 weeks later. Thirty patients (Group B) with previous TT and (131) I-A stopped L-T4 in preparation for clinical evaluation, including whole-body scanning (WBS)/radioiodine therapy during thyrotrophin (TSH) stimulation planned for 3 weeks (or more) later.

MEASUREMENTS

Thyrotrophin was measured the day before TT for group A, during L-T4 for group B (baseline-time 1) and then every week until it reached ≥ 30 mIU/l (time 2). Quality of life (QoL) was evaluated by Billewicz index.

RESULTS

At week 3, 100% of patients in group A and 56.6% of group B exceeded TSH > 30 mIU/l. In group B, the cut-off was achieved in four patients at the fourth week (TSH 38.6 ± 8.7 mIU/l), in 3 at the fifth (53.2 ± 3) and in 6 at the sixth (42.3 ± 6.1). From time 1 to time 2, total QoL scores were less affected in group A (percentage decrease: 105%) than in group B (218%). At time 2, the total score was >+19 in group A in 46 patients and in 30 in group B. In group A, TSH levels in the higher tertile of QoL (61 ± 6 mIU/l) were not different from those in the lower tertile (62.3 ± 11.1)(P > 0.1); similar results were seen in group B (69.3 ± 13.3 vs 62.9 ± 13.1)(P > 0.1). There was a positive correlation between the time to obtain TSH ≥ 30 mIU/l and total QoL scores.

CONCLUSIONS

Quality of life scores were not affected by thyrotrophin was measured the day before TT levels as absolute values. A longer time to obtain TSH ≥ 30 mIU/l was positively correlated with worse scores of QoL. We suggest 3 weeks without therapy can be used as an easy schedule in patients who undergo TT for DTC.