A comparison of recombinant human thyrotropin and thyroid hormone withdrawal for the detection of thyroid remnant or cancer

A tribute to Ernest L. Mazzaferri, MD and the lasting impact that he had on thyroid cancer care ten years after his death

This viewpoint highlights the contributions of Dr. Ernest Mazzaferri, a prominent figure in the field of thyroid cancer care, who made significant contributions to the diagnosis and treatment of this disease. Dr. Mazzaferri's first paper on thyroid cancer, published in 1977, established fundamental principles that remain fundamental to differentiated thyroid cancer management. He was an advocate of total thyroidectomy and of postoperative radioiodine therapy and contributed to improving thyroid fine needle aspiration techniques. Dr. Mazzaferri's leadership in developing guidelines for the management of thyroid cancer and thyroid nodules has been influential and widely accepted. His groundbreaking work established a systematic and data-driven approach to the diagnosis and treatment of thyroid cancer that continues to shape the field of thyroid cancer care today. This Viewpoint reflects on his lasting impact ten years after his death.

Laboratory Thyroid Tests: A Historical Perspective

Background: This review presents a timeline showing how technical advances made over the last seven decades have impacted the development of laboratory thyroid tests. Summary: Thyroid tests have evolved from time-consuming manual procedures using isotopically labeled iodine as signals (¹³¹I and later ¹²⁵I) performed in nuclear medicine laboratories, to automated nonisotopic tests performed on multianalyte instruments in routine clinical chemistry laboratories. The development of isotopic radioimmunoassay techniques around 1960, followed by the advent of monoclonal antibody technology in the mid-1970s, led to the development of a nonisotopic immunometric assay methodology that forms the backbone of present-day thyroid testing. This review discusses the development of methods for measuring total thyroxine and triiodothyronine, direct and indirect free thyroid hormone measurements and estimates (free thyroxine and free triiodothyronine), thyrotropin (TSH), thyroid autoantibodies (thyroperoxidase, thyroglobulin [Tg] and TSH receptor autoantibodies), and Tg protein. Despite progressive improvements made in sensitivity and specificity, current thyroid tests remain limited by between-method differences in the numeric values they report, as well as nonspecific interferences with test reagents and interferences from analyte autoantibodies. Conclusions: Thyroid disease affects ∼10% of the U.S. population and is mostly managed on an outpatient basis, generating 60% of endocrine laboratory tests. In future, it is hoped that interferences will be eliminated, and the standardization/harmonization of tests will facilitate the establishment of universal test reference ranges.

Novel recombinant human thyroid-stimulating hormone in aiding postoperative assessment of patients with differentiated thyroid cancer-phase I/II study

PURPOSE

Thyroid hormone withdrawal (THW) inevitably induced hypothyroidism in patients with differentiated thyroid cancer (DTC), and we aimed to evaluate the safety and efficacy of a novel recombinant human thyroid-stimulating hormone (rhTSH, ZGrhTSH) as an alternative of THW in China.

METHODS

Totally, 64 DTC patients were enrolled with 24 in the dose-escalation cohort equally grouped into 0.9 mg × 1 day, 0.9 mg × 2 day, 1.8 mg × 1 day, and 1.8 mg × 2 day dosage, and 40 further enrolled into 0.9 mg × 2 day dose-expansion cohort. All patients underwent both ZGrhTSH phase and levothyroxine (L-T₄) withdrawal phase for self-comparison in terms of TSH levels, the radioactive iodine (RAI) uptake, stimulated thyroglobulin level, and the quality of life (QoL).

RESULTS

In ZGrhTSH phase, no major serious adverse events were observed, and mild symptoms of headache were observed in 6.3%, lethargy in 4.7%, and asthenia in 3.1% of the patients, and mostly resolved spontaneously within 2 days. Concordant RAI uptake was noticed in 89.1% (57/64) of the patients between ZGrhTSH and L-T₄ withdrawal phases. The concordant thyroglobulin level with a cut-off of 1 μg/L was noticed in 84.7% (50/59) of the patients without the interference of anti-thyroglobulin antibody. The QoL was far better during ZGrhTSH phase than L-T₄ withdrawal phase, with lower Billewicz (- 51.30 ± 4.70 vs. - 39.10 ± 16.61, P < 0.001) and POMS (91.70 ± 16.70 vs. 100.40 ± 22.11, P = 0.011) scores which indicate the lower the better. Serum TSH level rose from basal 0.11 ± 0.12 mU/L to a peak of 122.11 ± 42.44 mU/L 24 h after the last dose of ZGrhTSH. In L-T₄ withdrawal phase, a median of 23 days after L-T₄ withdrawal was needed, with the mean TSH level of 82.20 ± 31.37 mU/L. The half-life for ZGrhTSH clearance was about 20 h.

CONCLUSION

The ZGrhTSH held the promise to be a safe and effective modality in facilitating RAI uptake and serum thyroglobulin stimulation, with better QoL of patients with DTC compared with L-T₄ withdrawal.

Radiation exposure to allied health personnel handling blood specimens from patients receiving radioactive iodine-131 and recombinant human TSH (thyrogen®) stimulation

With increasing use of recombinant human TSH (rhTSH) stimulation protocol in radioactive iodine-131 treatment of thyroidectomised differentiated thyroid carcinoma (DTC), there is increasing concern regarding radiation safety during collection and processing of radioactive blood samples. Our study aims to quantify this radiation exposure in the context of current radiation guidelines to provide a practical safety framework. We analysed 45 patients prospectively referred to a tertiary centre in Singapore, who had histologically proven DTC, and who were thyroidectomised and planned for I-131 with rhTSH stimulation. Each patient received rhTSH for two consecutive days, with I-131 administered 24 h after, and a stimulated Thyroglobulin blood sample collected and processed 72 h after the last rhTSH dose. We measured radiation exposures with dosimeters. Based on the average and maximum exposure rates calculated, we extrapolated and derived the number of radioactive blood samples that could be safely collected and processed. Mean hand and body radiation exposures during venepuncture and blood processing were generally significantly higher than background radiation. Based on average exposure rates, the permissible number of blood samples that can be collected and processed is 9.09 × 10³per year (24 per day) and 8.70 × 10⁴per year (238 per day), respectively. This is the first study to date to extrapolate permissible thresholds that can serve as a practical guideline to the number of radioactive blood samples which can be safely collected and processed, following radioactive iodine therapy, within the limits of current radiation guidelines. Once validated, generalisations to other radioactive therapies may be considered.

Only peak thyroglobulin concentration on day 1 and 3 of rhTSH-aided RAI adjuvant treatment has prognostic implications in differentiated thyroid cancer

OBJECTIVE

In patients with differentiated thyroid carcinoma (DTC), serum thyroglobulin levels measured at the time of remnant ablation after thyroid hormone withdrawal were shown to have prognostic value for disease-free status. We sought to evaluate serial thyroglobulin measurements at the time of recombinant human thyroid-stimulating hormone (rhTSH)-aided iodine 131 (131I) adjuvant treatment as prognostic markers of DTC.

METHODS

Six hundred-fifty patients with DTC given total/near-total thyroidectomy and adjuvant radioiodine post-rhTSH stimulation were evaluated. Thyroglobulin was measured on day 1 (Tg1; at the time of the first rhTSH injection), day 3 (Tg3; 1 day after the second, final rhTSH injection), and day 6 (Tg6; 3 days post-radioiodine administration). Treatment failure was defined as histopathologically confirmed locoregional recurrence, or radiologically-evident distant metastases (signs of disease on computer tomography (CT) or magnetic resonance imaging (MRI), or abnormal foci of radioiodine or [18F] fluorodeoxyglucose ([18F]FDG) uptake.

RESULTS

In univariate analysis, Tg1 (p < 0.001) and Tg3 (p < 0.001), but not Tg6, were significantly associated with structural recurrence. In multivariate analysis of the overall cohort, only Tg3 was independently associated with structural recurrence. In multivariate analysis of the subgroup (n = 561) with anti-Tg antibodies titers below the institutional cut-off, 115 IU/mL, Tg1 was an independent prognostic marker. Tg1 and Tg3 cutoffs to best predict structural recurrence were established at 0.7 ng/mL and 1.4 ng/mL, respectively.

CONCLUSIONS

Tg1 and Tg3, measurements made after rhTSH stimulation but before radioiodine treatment, independently predict a low risk of treatment failure in patients with DTC. Levels measured post-radioiodine application (e.g., Tg6) are highly variable, lack prognostic value, and hence can be omitted.

Advances in Functional Imaging of Differentiated Thyroid Cancer

Simple Summary

Since the 1940s, radioactive iodine has been used for functional imaging and for treating patients with differentiated thyroid cancer (DTC). During this long-lasting experience, the use of iodine isotopes evolved, especially during the last years due to improved knowledge of thyroid cancer biology and improved performances of imaging tools. The present review summarizes recent advances in the field of functional imaging and theragnostic approach of DTC.

Abstract

The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with ¹⁸F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond ¹⁸F-FDG PET/CT, other tracers including ¹²⁴I, ¹⁸F-TFB and ⁶⁸Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments.

Recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal preparation for radioiodine ablation in differentiated thyroid cancer in children, adolescents and young adults

OBJECTIVE

Recombinant human TSH (rhTSH) is commonly used to prepare patients for postoperative radioiodine (I-131) ablation after surgery for differentiated thyroid cancer (DTC). In adults, rhTSH is associated with equivalent oncologic efficacy in comparison to thyroid hormone withdrawal (THW), but its use has not been well studied in children. We aimed to measure time to disease progression after rhTSH stimulation vs. THW in paediatric patients under the age of 21 with DTC following total thyroidectomy.

DESIGN

Retrospective cohort study (March 2001-July 2018).

PATIENTS

Sixteen children and adolescents (75% female, median age, 17.4 years) who received rhTSH were compared to 29 historical controls (72% female, median age, 18.5 years) prepared with THW, followed for a median of 2.4 years (range, 0.5-14).

MEASUREMENTS

Stimulated serum TSH concentrations prior to I-131 ablation and time to disease progression, as determined by a component outcome variable encompassing both structural and biochemical disease persistence/recurrence.

RESULTS

No differences were observed in tumour characteristics and I-131 dose (median 2.3 [1.8-2.90] mCi/kg rhTSH) between groups. Patients who received rhTSH achieved a similar median stimulated TSH level (163 [127-184] mU/L), compared to those who underwent THW (136 [94.5-197] mU/L; p = .20). Both groups exhibited similar time to progression (p = .13) and disease persistence/recurrence rates (rhTSH 31% vs. THW 59%, p = .14).

CONCLUSION

In this cohort of children and adolescents with DTC, we observed similar time to disease progression among those who received rhTSH or underwent THW prior to postoperative I-131 ablation.

Change of Therapeutic Response Classification According to Recombinant Human Thyrotropin-Stimulated Thyroglobulin Measured at Different Time Points in Papillary Thyroid Carcinoma

Purpose

We investigated whether response classification after total thyroidectomy and radioactive iodine (RAI) therapy could be affected by serum levels of recombinant human thyrotropin (rhTSH)-stimulated thyroglobulin (Tg) measured at different time points in a follow-up of patients with papillary thyroid carcinoma (PTC).

Methods

A total of 147 PTC patients underwent serum Tg measurement for response assessment 6 to 24 months after the first RAI therapy. Serum Tg levels were measured at 24 h (D1Tg) and 48-72 h (D2-3Tg) after the 2^nd injection of rhTSH. Responses were classified into three categories based on serum Tg corresponding to the excellent response (ER-Tg), indeterminate response (IR-Tg), and biochemical incomplete response (BIR-Tg). The distribution pattern of response classification based on serum Tg at different time points (D1Tg vs. D2-3Tg) was compared.

Results

Serum D2-3Tg level was higher than D1Tg level (0.339 ng/mL vs. 0.239 ng/mL, P < 0.001). The distribution of response categories was not significantly different between D1Tg-based and D2-3Tg-based classification. However, 8 of 103 (7.8%) patients and 3 of 40 (7.5%) patients initially categorized as ER-Tg and IR-Tg based on D1Tg, respectively, were reclassified to IR-Tg and BIR-Tg based on D2-3Tg, respectively. The optimal cutoff values of D1Tg for the change of response categories were 0.557 ng/mL (from ER-Tg to IR-Tg) and 6.845 ng/mL (from IR-Tg to BIR-Tg).

Conclusion

D1Tg measurement was sufficient to assess the therapeutic response in most patients with low level of D1Tg. Nevertheless, D2-3Tg measurement was still necessary in the patients with D1Tg higher than a certain level as response classification based on D2-3Tg could change.

Current practice in patients with differentiated thyroid cancer

Considerable changes have occurred in the management of differentiated thyroid cancer (DTC) during the past four decades, based on improved knowledge of the biology of DTC and on advances in therapy, including surgery, the use of radioactive iodine (radioiodine), thyroid hormone treatment and availability of recombinant human TSH. Improved diagnostic tools are available, including determining serum levels of thyroglobulin, neck ultrasonography, imaging (CT, MRI, SPECT-CT and PET-CT), and prognostic classifications have been improved. Patients with low-risk DTC, in whom the risk of thyroid cancer death is <1% and most recurrences can be cured, currently represent the majority of patients. By contrast, patients with high-risk DTC represent 5-10% of all patients. Most thyroid cancer-related deaths occur in this group of patients and recurrences are frequent. Patients with high-risk DTC require more aggressive treatment and follow-up than patients with low-risk DTC. Finally, the strategy for treating patients with intermediate-risk DTC is frequently defined on a case-by-case basis. Prospective trials are needed in well-selected patients with DTC to demonstrate the extent to which treatment and follow-up can be limited without increasing the risk of recurrence and thyroid cancer-related death.

A systematic review of health state utility values for thyroid cancer

Purpose

Health state utility values are commonly used to inform economic evaluations and determine the cost-effectiveness of an intervention. The aim of this systematic review is to summarise the utility values available to represent the health-related quality of life (HRQoL) of patients with thyroid cancer.

Methods

Eight electronic databases were searched from January 1999 to April 2019 for studies which included assessment of HRQoL for patients with thyroid cancer. Utility estimates derived from multiple sources (EuroQol questionnaire 5-dimension (EQ-5D), time trade-off [TTO] and standard gamble [SG] methods) were extracted. In addition, utility estimates were generated by mapping from SF-36 and EORTC QLQ-30 to the EQ-5D-3L UK value set using published mapping algorithms.

Results

Searches identified 33 eligible studies. Twenty-six studies reported HRQoL for patients with differentiated thyroid cancer and seven studies for patients with general thyroid cancer. We identified studies which used different methods and tools to quantify the HRQoL in patients with thyroid cancer, such as the EQ-5D-3L, SF-36, EORTC QLQ-30 and SG and TTO techniques to estimate utility values. Utility estimates range from 0.205 (patients with low-risk differentiated thyroid cancer) to utility values approximate to the average UK population (following successful thyroidectomy surgery and radioiodine treatment). Utility estimates for different health states, across thyroid cancer sub-types and interventions are presented.

Conclusion

A catalogue of utility values is provided for use when carrying out economic modelling of thyroid cancer; by including mapped values, this approach broadens the scope of health states that can be considered within cost-effectiveness modelling.

Electronic supplementary material

The online version of this article (10.1007/s11136-020-02676-2) contains supplementary material, which is available to authorised users.

Evaluation of SNA001, a Novel Recombinant Human Thyroid Stimulating Hormone Injection, in Patients With Differentiated Thyroid Carcinoma

SNA001 is a novel recombinant human thyroid stimulating hormone (rhTSH). rhTSH has long been approved in several countries to facilitate monitoring and ablation of thyroid carcinoma without hypothyroidism caused by thyroid hormone withdrawal (THW). To assess the safety, tolerance, pharmacokinetic and pharmacodynamic properties of SNA001, the two-period (SNA001 period and THW period), dose-ascending study in well-differentiated thyroid cancer (DTC) patients was designed. Three doses (0.45 mg, 0.9 mg, and 1.35 mg) of SNA001 were intramuscularly injected, twice in the SNA001 period to stimulate iodine-131 uptake and thyroglobulin (Tg) release. 24 h after the last dose of SNA001, iodine-131 (111-185 MBq) was administrated, followed by whole-body scan (WBS) 48 h later. THW period began just after SNA001 washout and lasted for about 3-6 weeks. When TSH level was above 30 mU/L, iodine-131 (111-185 MBq) was administrated, followed by a WBS and Tg detection 48 h later. Twenty-four DTC patients after thyroidectomy were enrolled; mean peak concentrations of SNA001 in 0.45, 0.9, and 1.35 mg groups were 18.5, 26.7, and 37.0 ng/ml (about 244.7, 354.2, and 489.6 mU/L) respectively, within 28-32 h after first dose of SNA001. SNA001 was metabolized in a dose-dependent manner. The results of WBS and Tg release in the SNA001 period were compared with those in the THW period. Compared to Tg level in baseline, the Tg levels in SNA001 and THW periods were increased, with 78% of subjects showing higher Tg levels in the THW period. 100% of the patients had concordant qualitative results of the scans within two periods in three groups. Symptoms of hypothyroidism were relieved in the SNA001 period compared with THW period, though there was no significant difference in most of the scale scores. There were no serious adverse events related to SNA001; the most common adverse events were gastrointestinal symptoms of mild and transient nature. Thus, SNA001 promises to be a safe and effective method to stimulate iodine-131 uptake and Tg secretion during monitoring and ablation for DTC without the disadvantages of incidental hypothyroidism.

Clinical utility of an ultrasensitive thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer: can the stimulation test be avoided in patients with an intermediate recurrence risk?

SUMMARY

Serum thyroglobulin (Tg) measurement during suppression with levothyroxine (LT4) using an ultrasensitive assay (OnT4-Tg) has been proposed as a replacement of TSH-stimulated Tg measurement (OffT4-Tg) in management of patients with differentiated thyroid cancer (DTC). The aim of this study is to evaluate the capacity of an ultrasensitive Tg assay in predicting an OffT4-Tg > 2.0 ng/mL based on the OnT4-Tg in patients with DTC and an intermediate recurrence risk. We analysed 101 patients with DTC and an intermediate (n = 92) or high risk of recurrence (n = 9) who were treated with total thyroidectomy and ablation with ¹³¹I, and followed for an average of 6 years. OnT4-Tg was undetectable in 64 of 101 patients; OffT4-Tg was #x003C; 2.0 ng/mL in 61 of these 64 patients, all with negative imaging results. Furthermore, 37 of 101 patients had detectable OnT4-Tg; 32 of these 37 patients also presented OffT4-Tg > 2.0 ng/mL, and only 3 of these 32 patients had metastases detected by neck ultrasound. Considering a cutoff point of 0.1 ng/mL for OnT4-Tg, the assay had a sensitivity of 91%, specificity of 92%, positive predictive value (PPV) of 86% and the negative predictive value (NPV) of 95% when predicting an OffT4-Tg > 2.0 ng/mL (biochemical disease). The use of an ultrasensitive Tg assay allows prediction of which patients will remain disease-free even if they are at an intermediate risk of recurrence, and to decrease the need for stimulated Tg assays in two-thirds of these patients.

The minimum amount of fluids needed to achieve the fastest time to reach permissible level for release in well-differentiated thyroid patients undergoing high-dose I-131 therapy

Radioiodine (131I) therapy is the mainstay of treatment for patients who had undergone total thyroidectomy for well differentiated thyroid carcinoma. Increased fluid intake has always been encouraged to minimize the risk of non-target organ exposure to I-131radiation. This study aimed to determine the minimum amount of fluids needed for patients to have the fastest time to achieve permissible level for release after high dose I-131therapy. Methodology: All the patients who were treated with high dose I-131from 18^th January 2016 till 31^st December 2016 in Hospital Pulau Pinang, Malaysia were recruited. The data from 126 patients on thyroxine hormone withdrawal (THW) group and 18 patients on recombinant human thyroid stimulating hormone (rhTSH) group were analysed. There is no change in patient management in terms of preparation, dose or post therapy whole-body scan. Fluid intake of patients were monitored strictly and whole-body retention of I-131are measured using ionizing chamber meter immediately after ingestion of I-131then at 1 hour, 24 hours, 48 hours, 72 hours and 96 hours. Results: The median time to achieve permissible release limit (50 μSV/hr at 1 meter) was 21.6 hours and 22.1 hours post-ingestion of I-131in the THW and rhTSH group respectively. The minimum amount of fluid needed to reach permissible release limit in the fastest time was 2,103 ml and 2,148ml for the THW and TSH respectively. Conclusion: Clinicians would be able to evidently advise their patient on the amount of fluid to consume and utilize their isolation wards faster to treat more patients.

Comparison of day 3 and day 5 thyroglobulin results after thyrogen injection in differentiated thyroid cancer patients

BACKGROUND

It is necessary to stimulate serum thyroid-stimulating hormone (TSH) levels either endogenously by thyroid hormone withdrawal (THW) or exogenously by administration of recombinant human TSH (rhTSH) for radioactive iodine (RAI) therapy. Thyrotropin alfa (Thyrogen) has many advantages over THW. Radiation dose to laboratory staff while drawing blood for tests on the day 5 is one of the disadvantages of preferring Thyrogen. Our aim was to compare day 3 and day 5 blood test results after Thyrogen injections.

MATERIAL AND METHOD

In our study, Thyrogen was preferred in 32 differentiated thyroid cancer patients with a mean age of 50.5 ± 12.3 years. Thyrogen was injected on day 1 and day 2 intramuscularly in all patients before I-131 was given on day 3. A total of 22 patients received 5 mCi RAI for ablation control scintigraphy and 10 patients received 100-250 mCi RAI for ablation or therapy (high-dose group). Blood tests were performed on day 3 and day 5 after Thyrogen injections.

RESULTS

Mean TSH level was 98.1 mg/dl for day 3 and 29.5 mg/dl for day 5. In the diagnostic group, thyroglobulin (Tg) and anti-Tg levels were nearly the same on day 3 and day 5. In the therapy group, day 5 Tg levels were higher than day 3.

CONCLUSION

After Thyrogen injection of two consecutive days, blood sampling might be enough on day 3. Day 5 blood sampling may not be necessary routinely for radiation protection of laboratory staff. For the diagnostic group, if Tg and anti-Tg is normal then 5 mCi imaging may not be necessary.

Recombinant human TSH stimulated thyroglobulin levels at remnant ablation predict structural incomplete response to treatment in patients with differentiated thyroid cancer

In patients with differentiated thyroid cancer, stimulated thyroglobulin (sTg) levels after thyroid hormone withdrawal (THW) at remnant ablation (RA) and at 6 to 12 months are known to have good prognostic value. This study aimed to evaluate the prognostic impacts and best cutoff values of sTg levels under recombinant human thyroid stimulating hormone (rhTSH) treatment at RA and at follow-up. A total of 151 patients were enrolled, of whom 77 were followed up with rhTSH-stimulated Tg (rhTSH-sTg) and 74 with THW-stimulated Tg (THW-sTg) at 6 to 12 months after rhTSH-aided RA. Risk stratification, response to treatment (excellent, indeterminate, biochemical incomplete, and structural incomplete response [SIR]), and clinical outcome were accessed by revised American Thyroid Association (ATA) guideline criteria. Seven out of 151 (4.6%) patients were confirmed to have SIR during the median follow-up of 79.0 months; 3 in the rhTSH group and 4 in the THW group. One hundred thirty-two out of 151 (87.4%) patients were confirmed to have excellent response; 68 (51.5%) in the rhTSH group and 64 (48.5%) in the THW group. The cutoff values of sTg for predicting SIR to treatment at rhTSH-aided RA, THW-sTg, and rhTSH-sTg were 4.64 ng/mL (sensitivity 85.7%, specificity 76.4%, negative predictive value [NPV] 99.2%), 2.41 ng/mL (sensitivity 100%, specificity 94.3%, NPV 100%), and 1.02 ng/mL (sensitivity 66.7%, specificity 94.6%, NPV 98.6%), respectively. sTg levels using rhTSH at both RA and follow-up has a high NPV and are as effective as using THW for predicting SIR. The risk classification according to the revised ATA guidelines can be used effectively to supplement rhTSH-aided sTg levels to predict better clinical outcomes.

Thyroglobulin levels measured at the time of remnant ablation to predict response to treatment in differentiated thyroid cancer after thyroid hormone withdrawal or recombinant human TSH

The objective of our study was to evaluate the prognostic value of stimulated thyroglobulin levels at the moment of remnant ablation for predicting an initial excellent or a structural incomplete response to treatment according to the risk of recurrence in patients with differentiated thyroid cancer. Patients were divided into two groups according to the preparation mode for remnant ablation (thyroid hormone withdrawal or recombinant human TSH). We included 219 patients followed-up for at least for 24 months after remnant ablation. The primary endpoint was the best response to initial therapy assessed in the first 9-18 months of follow-up. An excellent response was observed in 45.1 % of patients prepared after recombinant human TSH compared to 44.6 % of patients prepared after thyroid hormone withdrawal (P = NS). The cutoff value of thyroglobulin level after recombinant human TSH for predicting an excellent response was 8 ng/ml (n = 51), with a sensitivity of 73.9 %, and a positive predictive value of 61 %. It was similar for patients with low vs. intermediate to high risk of recurrence. This cutoff value for thyroglobulin level after thyroid hormone withdrawal was 22 ng/ml (n = 168), with a sensitivity of 94.7 % and a positive predictive value of 61.7 %. In the thyroid hormone withdrawal group the thyroglobulin cutoff level was 12 ng/ml for low-risk patients compared to 16 ng/ml for those with intermediate to high risk of recurrence (P = 0.003). The cutoff value of the thyroglobulin level for predicting a structural incomplete response to initial treatment was 20 ng/ml after rhTSH, with a negative predictive value of 91.4 %. This level was higher in thyroid hormone withdrawal group, and it was established at 25 ng/ml, with a negative predictive value of 97.7 %. The stimulated Tg level seems to be different depending on the preparation mode (rhTSH or THW) for RA. It has a high NPV to predict the absence of a structural incomplete response and it is also a good predictor of the initial excellent response and the NED status at the end of follow-up.

Pediatric papillary thyroid cancer: current management challenges

Although with a standardized incidence of 0.54 cases per 100,000 persons, differentiated thyroid cancer (DTC) is a rare disease in children and adolescents, it nonetheless concerns ~1.4% of all pediatric malignancies. Furthermore, its incidence is rising. Due to the rarity and long survival of pediatric DTC patients, in most areas of treatment little evidence exists. Treatment of pediatric DTC is therefore littered with controversies, many questions therefore remain open regarding the optimal management of pediatric papillary thyroid cancer (PTC), and many challenges remain unsolved. In the present review, we aim to provide an overview of these challenging areas of patient and disease management in pediatric PTC patients. Data on diagnosis, surgery, radionuclide, and endocrine therapy are discussed, and the controversies therein are highlighted.

Endogenous TSH levels at the time of 131I ablation do not influence ablation success, recurrence-free survival or differentiated thyroid cancer-related mortality

PURPOSE

Based on a single older study it is established dogma that TSH levels should be ≥30 mU/l at the time of postoperative ¹³¹I ablation in differentiated thyroid cancer (DTC) patients. We sought to determine whether endogenous TSH levels, i.e. after levothyroxine withdrawal, at the time of ablation influence ablation success rates, recurrence-free survival and DTC-related mortality.

METHODS

A total of 1,873 patients without distant metastases referred for postoperative adjuvant ¹³¹I therapy were retrospectively included from 1991 onwards. Successful ablation was defined as stimulated Tg <1 μg/l.

RESULTS

Age, gender and the presence of lymph node metastases were independent determinants of TSH levels at the time of ablation. TSH levels were not significantly related to ablation success rates (p = 0.34), recurrence-free survival (p = 0.29) or DTC -elated mortality (p = 0.82), but established risk factors such as T-stage, lymph node metastases and age were. Ablation was successful in 230 of 275 patients (83.6 %) with TSH <30 mU/l and in 1,359 of 1,598 patients (85.0 %) with TSH ≥30 mU/l. The difference was not significant (p = 0.55). Of the whole group of 1,873 patients, 21 had recurrent disease. There were no significant differences in recurrence rates between patients with TSH <30 mU/l and TSH ≥30 mU/l (p = 0.16). Ten of the 1,873 patients died of DTC. There were no significant differences in DTC-specific survival between patients with TSH <30 mU/l and TSH ≥30 mU/l (p = 0.53).

CONCLUSION

The precise endogenous TSH levels at the time of ¹³¹I ablation are not related to the ablation success rates, recurrence free survival and DTC related mortality. The established dogma that TSH levels need to be ≥30 mU/l at the time of ¹³¹I ablation can be discarded.

Radioiodine Remnant Ablation: A Critical Review

Radioiodine remnant ablation (RRA) is considered a safe and effective method for eliminating residual thyroid tissue, as well as microscopic disease if at all present in thyroid bed following thyroidectomy. The rationale of RRA is that in the absence of thyroid tissue, serum thyroglobulin (Tg) measurement can be used as an excellent tumor marker. Other considerations are like the presence of significant remnant thyroid tissue makes detection and treatment of nodal or distant metastases difficult. Rarely, microscopic disease in the thyroid bed if not ablated, in the future, could be a source of anaplastic transformation. On the other hand, microscopic tumor emboli in distant sites could be the cause of distant metastasis too. The ablation of remnant tissue would in all probability eliminate these theoretical risks. It may be noted that all these are unproven contentious issues except postablation serum Tg estimation that could be a good tumor marker for detecting early biochemical recurrence in long-term follow-up strategy. Radioactive iodine is administered as a form of “adjuvant therapy” for remnant ablation. There have been several reports with regard to the administered dose for remnant ablation. The first report of a prospective randomized clinical trial was published from India by a prospective randomized study conducted at the All India Institute of Medical Sciences, New Delhi in the year 1996. The study reported that increasing the empirical ¹³¹I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high-dose remnant ablation needs critical evaluation. Recently, two important studies were published: One from French group and the other from UK on a similar line. Interestingly, all three studies conducted in three different geographical regions of the world showed exactly similar conclusion. The new era of low-dose remnant ablation has taken a firm scientific footing across the continents.

The Cut-Off Level of Recombinant Human TSH-Stimulated Thyroglobulin in the Follow-Up of Patients with Differentiated Thyroid Cancer

Background

The treatment of differentiated thyroid cancer (DTC) ends in full recovery in 80% of cases. However, in 20% of cases local recurrences or distant metastases are observed, for this reason DTC patients are under life-long follow-up. The most sensitive marker for recurrence is stimulated thyroglobulin (Tg) which, together with neck ultrasound (US), enables correct diagnosis in nearly all cases of the active disease. For many years the only known stimulation was a 4–5 week withdrawal from the L-T4 therapy (THW). For the last couple of years stimulation with the use of recombinant human TSH (rhTSH) has been available. This method of stimulation may have a significant influence in obtaining the Tg level. However, it is important to determine the cut-off level for rhTSH-stimulated Tg (rhTSH/Tg).

Materials and Methods

This is a retrospective analysis of consecutive patients from one facility who have qualified over a period of two years for repeated radioiodine therapy (RIA). In our facility the ablation effectiveness evaluation is always carried out with the use of rhTSH, with the repeated therapy following THW. Such a procedure enables two Tg measurements in the same patient after both types of stimulation within 4–5 weeks. The obtained values were compared, cut-off levels in THW conditions were used (2.0 ng/ml for patients in remission and 10.0 ng/ml for patients with an active disease). In order to determine the cut-off level for rhTSH/Tg, regression analysis and ROC curves were used.

Results

In 63 patients the Tg measurement of both methods of stimulation were obtained. It was observed that there was a high correlation between rhTSH/Tg and THW/Tg. However, the rhTSH/Tg level was significantly lower than THW/ Tg. The rhTSH/ Tg cut-off levels which corresponded to the 2.0 ng/ml and 10.0 ng/ml limits for THW/Tg were calculated and the values were 0.6 ng/ml and 2.3 ng/ml respectively.

Conclusions

The method of stimulation has a significant impact on the obtained Tg concentrations. The assumed THW/Tg cut off levels must not be transferred to rhTSH/Tg.

Effect of a Low Iodine Diet vs. Restricted Iodine Diet on Postsurgical Preparation for Radioiodine Ablation Therapy in Thyroid Carcinoma Patients

PURPOSE

The radioiodine ablation therapy is required for patients who underwent a total thyroidectomy. Through a comparative review of a low iodine diet (LID) and a restricted iodine diet (RID), the study aims to suggest guidelines that are suitable for the conditions of Korea.

MATERIALS AND METHODS

The study was conducted with 101 patients. With 24-hour urine samples from the patients after a 2-week restricted diet and after a 4-week restricted diet, the amount of iodine in the urine was estimated. The consumed radioiodine amounts for 2 hours and 24 hours were calculated.

RESULTS

This study was conducted with 47 LID patients and 54 RID patients. The amounts of iodine in urine, the 2-week case and 4-week case for each group showed no significant differences. The amounts of iodine in urine between the two groups were both included in the range of the criteria for radioiodine ablation therapy. Also, 2 hours and 24 hours radioiodine consumption measured after 4-week restrictive diet did not show statistical differences between two groups.

CONCLUSION

A 2-week RID can be considered as a type of radioiodine ablation therapy after patients undergo a total thyroidectomy.

Recombinant TSH stimulated remnant ablation therapy in thyroid cancer: the success rate depends on the definition of ablation success--an observational study

INTRODUCTION

Patients with differentiated thyroid cancer (DTC) are treated with (near)-total thyroidectomy followed by remnant ablation. Optimal radioiodine-131 (131I) uptake is achieved by withholding thyroid hormone (THW), pretreatment with recombinant human Thyrotropin Stimulating Hormone (rhTSH) is an alternative. Six randomized trials have been published comparing THW and rhTSH, however comparison is difficult because an uniform definition of ablation success is lacking. Using a strict definition, we performed an observational study aiming to determine the efficacy of rhTSH as preparation for remnant ablation.

PATIENTS AND METHODS

Adult DTC patients with, tumor stage T1b to T3, Nx, N0 and N1, M0 were included in a prospective multicenter observational study with a fully sequential design, using a stopping rule. All patients received remnant ablation with 131I using rhTSH. Ablation success was defined as no visible uptake in the original thyroid bed on a rhTSH stimulated 150 MBq 131I whole body scan (WBS) 9 months after remnant ablation, or no visible uptake in the original thyroid bed on a post therapeutic WBS when a second high dose was necessary.

RESULTS

After interim analysis of the first 8 patients, the failure rate was estimated to be 69% (90% confidence interval (CI) 20-86%) and the inclusion of new patients had to be stopped. Final analysis resulted in an ablation success in 11 out of 17 patients (65%, 95% CI 38-86%).

CONCLUSION

According to this study, the efficacy of rhTSH in the preparation of 131I ablation therapy is inferior, when using a strict definition of ablation success. The current lack of agreement as to the definition of successful remnant ablation, makes comparison between different ablation strategies difficult. Our results point to the need for an international consensus on the definition of ablation success, not only in routine patient's care but also for scientific reasons.

TRIAL REGISTRATION

Dutch Trial Registration NTR2395.

Targeting the thyroid-stimulating hormone receptor with small molecule ligands and antibodies

INTRODUCTION

The thyroid-stimulating hormone receptor (TSHR) is the essential molecule for thyroid growth and thyroid hormone production. Since it is also a key autoantigen in Graves' disease and is involved in thyroid cancer pathophysiology, the targeting of the TSHR offers a logical model for disease control.

AREAS COVERED

We review the structure and function of the TSHR and the progress in both small molecule ligands and TSHR antibodies for their therapeutic potential.

EXPERT OPINION

Stabilization of a preferential conformation for the TSHR by allosteric ligands and TSHR antibodies with selective modulation of the signaling pathways is now possible. These tools may be the next generation of therapeutics for controlling the pathophysiological consequences mediated by the effects of the TSHR in the thyroid and other extrathyroidal tissues.

Recombinant human thyroid-stimulating hormone-aided remnant ablation achieves a response to treatment comparable to that with thyroid hormone withdrawal in patients with clinically relevant lymph node metastases

It has already been shown that remnant ablation in patients with thyroid cancer and lymph node (LN) metastases has similar results when patients are prepared after recombinant human thyroid-stimulating hormone (rhTSH) therapy or thyroid hormone withdrawal (THW). Due to the current changes in the risk-of-recurrence classifications, we decided to evaluate the initial response to treatment and the outcome at medium-term follow-up in 40 consecutive patients with clinically relevant lymph nodes who received radioiodine remnant ablation after rhTSH therapy (n = 20) or THW (n = 20). Each patient received either 100 or 150 mCi 131-I for ablation based on TNM status, and the mean amounts of 131-I used in the 2 groups were not significantly different. An excellent response to treatment was observed in 45% of the patients prepared after rhTSH therapy compared to 20% of those prepared after THW (p = 0.08). Three patients (2 in the THW group and 1 in the rhTSH group) who had N1a in the initial surgery presented with structural persistence as an initial response to treatment. One patient in the THW group had a follow-up of the persistent disease with no surgical treatment, and 2 others received a lateral LN dissection. When the status at final follow-up was considered (median follow-up 3.3 years, range 3-4.2), 60% of the patients ablated after rhTSH therapy were considered with no evidence of disease, compared to 30% of those who underwent THW. The frequency of structural persistence (metastatic LN) was similar in the 2 groups (15 vs. 25%), and the distribution of the responses at final follow-up was not statistically significantly different (p = 0.12). We conclude that preparation after rhTSH therapy seems to be as effective as after THW for patients with clinically relevant LN metastases.

Radioactive body burden measurements in (131)iodine therapy for differentiated thyroid cancer: effect of recombinant thyroid stimulating hormone in whole body (131)iodine clearance

Protocols in the management of differentiated thyroid cancer, recommend adequate thyroid stimulating hormone (TSH) stimulation for radioactive ¹³¹I administrations, both for imaging and subsequent ablations. Commonly followed method is to achieve this by endogenous TSH stimulation by withdrawal of thyroxine. Numerous studies worldwide have reported comparable results with recombinant human thyroid stimulating hormone (rhTSH) intervention as conventional thyroxine hormone withdrawal. Radiation safety applications call for the need to understand radioactive ¹³¹I (RA¹³¹I) clearance pattern to estimate whole body doses when this new methodology is used in our institution. A study of radiation body burden estimation was undertaken in two groups of patients treated with RA¹³¹I; (a) one group of patients having thyroxine medication suspended for 5 weeks prior to therapy and (b) in the other group retaining thyroxine support with two rhTSH injections prior to therapy with RA¹³¹I. Sequential exposure rates at 1 m in the air were measured in these patients using a digital auto-ranging beta gamma survey instrument calibrated for measurement of exposure rates. The mean measured exposure rates at 1 m in μSv/h immediately after administration and at 24 h intervals until 3 days are used for calculating of effective ½ time of clearance of administered activity in both groups of patients, 81 patients in conventionally treated group (stop thyroxine) and 22 patients with rhTSH administration. The ¹³¹I activities ranged from 2.6 to 7.9 GBq. The mean administered ¹³¹I activities were 4.24 ± 0.95 GBq (n = 81) in “stop hormone” group and 5.11 ± 1.40 GBq (n = 22) in rhTSH group. The fall of radioactive body burden showed two clearance patterns within observed 72 h. Calculated T_½eff values were 16.45 h (stop hormone group) 12.35 h (rhTSH group) for elapsed period of 48 h. Beyond 48 h post administration, clearance of RA¹³¹I takes place with T_½eff> 20 h in both groups. Neck and stomach exposure rate measurements showed reduced uptakes in the neck for rhTSH patients compared with “stop thyroxine” group and results are comparable with other studies. Whole body clearance is faster for patients with rhTSH injection, resulting in less whole body absorbed doses, and dose to blood. These patients clear circulatory radioactivity faster, enabling them to be discharged sooner, thus reduce costs of the hospitalization. Reduction in background whole body count rate may improve the residual thyroid images in whole body scan. rhTSH provides TSH stimulation without withdrawal of thyroid hormone and hence can help patients to take up therapy without hormone deficient problems in the withdrawn period prior to RA¹³¹I therapy. This also will help in reducing the restriction time periods for patients to mix up with the general population and children.

Differentiated thyroid cancer-personalized therapies to prevent overtreatment

The concept of individualized therapy is rapidly gaining recognition in the management of patients with differentiated thyroid cancer (DTC). This Review provides an overview of the most important elements of this paradigm shift in DTC management and discusses the implications for clinical practice. In the majority of patients with DTC who have an inherently good prognosis, the extent of surgery, the dosage of (131)I therapy and the use of levothyroxine therapy are all aspects suitable for individualization, on the basis of both the stage of disease and the response to treatment. In individuals with advanced disease, newer imaging techniques, advances in (131)I therapy and the use of targeted molecular therapies (such as multitargeted kinase inhibitors) have provided new options for the personalized care of patients, for whom until recently no effective therapies were available. Individualized therapies could reduce adverse effects, including the sometimes debilitating hypothyroidism that used to be required before initiation of (131)I treatment, and major salivary gland damage, a common and unpleasant side effect of (131)I therapy. Highly individualized interdisciplinary treatment of patients with DTC might lead to improved outcomes with reduced severity and frequency of complications and adverse effects. However, in spite of ongoing research, personalized therapies remain in their infancy.

Biochemical persistence in thyroid cancer: is there anything to worry about?

To evaluate the outcome of differentiated thyroid cancer (DTC) patients with biochemical persistence of disease (BP) after initial treatment (total thyroidectomy with or without lymph node dissection (LND) and thyroid remnant ablation). BP was defined as suppressed thyroglobulin (Tg) levels <1 ng/ml and rhTSH-stimulated thyroglobulin (St-Tg) >1ng/ml, with no evidence of structural disease. Structural persistence/recurrence (SPR): clinically identifiable disease. We reviewed 278 records of DTC patients. Tg-Ab positive patients (n = 73) were excluded and 32 were included in the analysis (median age 45 years, range 18-77 years); risk of recurrence ATA was: low in 38 %, Intermediate in 47 %, and high in 15 % of patients. All subjects had Tg levels <1 ng/ml under thyroid hormone therapy. Patients were divided into three groups: Group 1: St-Tg 1-2 ng/ml, n = 6; Group 2: St-Tg 2-10 ng/ml, n = 17; Group 3: St-Tg > 10 ng/ml, n = 9. In 5/32 (16 %) patients, SPR was observed after a median follow-up of 6 years (range 2-23 years). In Group 1: all patients were considered with no evidence of disease after a median follow-up of 2 years (range 1-2.5 years). In Group 2: 13/17 (76.5 %) patients continued with only a BP after a median follow-up of 4 years (range 2-10 years) and 4/17 (23.5 %) patients with intermediate risk of recurrence had a structural persistence (lymph nodes metastasis) diagnosed between 1 and 3.5 years after initial assessment. Following LND, all of them remained with BP after a median of 2 years (range 1.5-5 years). In Group 3: 8/9 (89 %) patients had BP after a median follow-up of 7 years (range 2-23 years) and 1/9 (11 %) had a SPR diagnosed 28 months after initial assessment, LND was indicated but he continued with BP, 5 years after the second surgery. Most patients with DTC and BP present an indolent course of the disease. In these patients the diagnosis of the structural recurrence did not change the outcome because all of them continued with BP.

Recurrent differentiated thyroid cancer: towards personalized treatment based on evaluation of tumor characteristics with PET (THYROPET Study): study protocol of a multicenter observational cohort study

BACKGROUND

After initial treatment of differentiated thyroid carcinoma (DTC) patients are followed with thyroglobulin (Tg) measurements to detect recurrences. In case of elevated levels of Tg and negative neck ultrasonography, patients are treated 'blindly' with Iodine-131 (131I). However, in up to 50% of patients, the post-therapy scan reveals no 131I-targeting of tumor lesions. Such patients derive no benefit from the blind therapy but are exposed to its toxicity. Alternatively, iodine-124 (124I) Positron Emission Tomography/Computed Tomography (PET/CT) has become available to visualize DTC lesions and without toxicity. In addition to this, 18F-fluorodeoxyglucose (18F-FDG) PET/CT detects the recurrent DTC phenotype, which lost the capacity to accumulate iodine. Taken together, the combination of 124I and 18F-FDG PET/CT has potential to stratify patients for treatment with 131I.

METHODS/DESIGN

In a multicenter prospective observational cohort study the hypothesis that the combination of 124I and 18F-FDG PET/CT can avoid futile 131I treatments in patients planned for 'blind' therapy with 131I, is tested.One hundred patients planned for 131I undergo both 124I and 18F-FDG PET/CT after rhTSH stimulation. Independent of the outcome of the scans, all patients will subsequently receive, after thyroid hormone withdrawal, the 131I therapy. The post 131I therapeutic scintigraphy is compared with the outcome of the 124I and 18F-FDG PET/CT in order to evaluate the diagnostic value of the combined PET modalities.This study primary aims to reduce the number of futile 131I therapies. Secondary aims are the nationwide introduction of 124I PET/CT by a quality assurance and quality control (QA/QC) program, to correlate imaging outcome with histopathological features, to compare 124I PET/CT after rhTSH and after withdrawal of thyroid hormone, and to compare 124I and 131I dosimetry.

DISCUSSION

This study aims to evaluate the potential value of the combination of 124I and 18F-FDG PET/CT in the prevention of futile 131I therapies in patients with biochemically suspected recurrence of DTC. To our best knowledge no studies addressed this in a prospective cohort of patients. This is of great clinical importance as a futile 131I is a costly treatment associated with morbidity and therefore should be restricted to those likely to benefit from this treatment.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01641679.

The effectiveness of recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal prior to radioiodine remnant ablation in thyroid cancer: a meta-analysis of randomized controlled trials

We evaluated the efficacy of recombinant human thyroid-stimulating hormone (rhTSH) versus thyroid hormone withdrawal (THW) prior to radioiodine remnant ablation (RRA) in thyroid cancer. A systematic search of MEDLINE, EMBASE, the Cochrane Library, and SCOPUS was performed. Randomized controlled trials that compared ablation success between rhTSH and THW at 6 to 12 months following RRA were included in this study. Six trials with a total of 1,660 patients were included. When ablation success was defined as a thyroglobulin (Tg) cutoff of 1 ng/mL (risk ratio, 0.99; 95% confidence interval, 0.96-1.03) or a Tg cutoff of 1 ng/mL plus imaging modality (RR 0.97; 0.90-1.05), the results of rhTSH and THW were similar. There were no significant differences when ablation success was defined as a Tg cutoff of 2 ng/mL (RR 1.03; 0.95-1.11) or a Tg cutoff of 2 ng/mL plus imaging modality (RR 1.02; 0.95-1.09). When a negative (131)I-whole body scan was used solely as the definition of ablation success, the effects of rhTSH and THW were not significantly different (RR 0.97; 0.93-1.02). Therefore, ablation success rates are comparable when RRA is prepared by either rhTSH or THW.

Examining recombinant human TSH primed ¹³¹I therapy protocol in patients with metastatic differentiated thyroid carcinoma: comparison with the traditional thyroid hormone withdrawal protocol

PURPOSE

Recombinant human thyroid-stimulating hormone (rhTSH)-based protocol is a promising recent development in the management of differentiated thyroid carcinoma (DTC). The objectives of this prospective study were: (1) to assess the feasibility and efficacy of the rhTSH primed (131)I therapy protocol in patients with DTC with distant metastatic disease, (2) to perform lesional dosimetry in this group of patients compared to the traditional protocol, (3) to document the practical advantages (patient symptoms and hospital stay) of the rhTSH protocol compared to the traditional thyroid hormone withdrawal protocol, (4) to document and record any adverse effect of this strategy, (5) to compare the renal function parameters, and (6) to compare the serum TSH values achieved in either of the protocols in this group of patients.

METHODS

The study included 37 patients with metastatic DTC having lung or skeletal metastases or both. A comparison of lesional radiation absorbed dose, hospital stay, renal function tests, and symptom profile was undertaken between the traditional thyroid hormone withdrawal protocol and rhTSH-based therapy protocol. Dosimetric calculations of metastatic lesions were performed using lesion uptake and survey meter readings for calculation of effective half-life. Non-contrast-enhanced CT was used for assessment of tumor volume. Quality of life was assessed using the European Organization for Research and Treatment of Cancer (EORTC) QOL forms. A comparison of pretreatment withdrawal thyroglobulin (TG) was done with the withdrawal TG level 3 months after treatment.

RESULTS

The mean effective half-life of (131)I in metastatic lesions was less during the rhTSH protocol (29.49 h) compared to the thyroid hormone withdrawal protocol (35.48 h), but the difference was not statistically significant (p = 0.056). The mean 24-h % uptake of the lesions during the traditional protocol (4.84 %) was slightly higher than the 24-h % uptake during the rhTSH protocol (3.56 %), but the difference was not found to be statistically significant (p = 0.301). The mean tumor radiation absorbed dose per mCi was less during the rhTSH protocol (6.04 rad/mCi) than during the thyroid hormone withdrawal protocol (8.68 rad/mCi), and the difference was statistically significant (p = 0.049), though visual analysis of the rhTSH posttherapy scans showed avid concentration of (131)I in the metastatic sites and revealed more lesions in 30 % of the patients compared to the traditional large dose scan and equal number of lesions in 65 % of the patients. Visual analysis of the traditional large dose scan, rhTSH pretreatment scan, and rhTSH posttherapy scans showed that the traditional large dose scan is better compared to the rhTSH 1 mCi scan as it showed more lesions in 19 of 37 patients (51.35 %). rhTSH posttherapy scans were better compared to the traditional large dose scans and rhTSH pretreatment scans. More lesions were seen on rhTSH posttherapy scans in 11 of 37 patients (29.7 %) compared to the traditional large dose scans and in 24 of 37 (64.86 %) patients compared to the rhTSH 1 mCi scans. Our findings demonstrate that the rhTSH primed pretreatment scan undertaken at 24 h after diagnostic dose is suboptimal to evaluate whether a metastatic lesion concentrates (131)I. The majority of these lesions demonstrated radioiodine accumulation in the posttreatment scan. Quality of life as assessed using EORTC QOL-3 forms clearly showed that rhTSH improved the quality of life of patients compared to the thyroid hormone withdrawal protocol. Functional scale and global health status were significantly better in the rhTSH protocol compared to the thyroid hormone withdrawal protocol (p < 0.001). The mean symptom scale score was significantly higher in the thyroid hormone withdrawal protocol (45.25) compared to the rhTSH protocol (13.59) (p < 0.001). Of the 20 patients, 4 (20 %) had more than 25 % increase in the TG value on follow-up. The median hospital stay of patients receiving (131)I therapy with the rhTSH protocol was shorter (2 days, range 2-8 days) compared to the thyroid hormone withdrawal protocol (3 days, range 1-8 days) and the difference was found to be statistically significant (p = 0.007). The mean serum creatinine level was significantly lower in the rhTSH protocol (0.826 mg/dl) than the thyroid hormone withdrawal protocol (0.95 mg/dl) (p = 0.013), though the mean blood urea level of patients during the rhTSH therapy protocol was slightly higher (22.81 mg/dl) than during the thyroid hormone withdrawal protocol (21.91 mg/dl) without statistical significance (p = 0.55). The mean serum TSH on day 2 of the rhTSH protocol was 140.99 μIU/ml (range 71-176 μIU/ml) compared to 72.62 μIU/ml (range 2.05-154 μIU/ml) in the traditional protocol after around 4-6 weeks of thyroid hormone withdrawal (p < 0.05).

CONCLUSION

Overall, the rhTSH primed (131)I therapy protocol was found to be feasible and a good alternative to the thyroid hormone withdrawal protocol in patients with metastatic DTC. The lesional dosimetry findings need to be further examined in subsequent studies. The rhTSH primed pretreatment scan at 24 h after diagnostic dose is suboptimal to determine whether a metastatic lesion concentrates (131)I and the posttreatment scan is important for the correct impression.

Basal serum thyroglobulin measured by a second-generation assay is equivalent to stimulated thyroglobulin in identifying metastases in patients with differentiated thyroid cancer with low or intermediate risk of recurrence

BACKGROUND

Guidelines for the follow-up of differentiated thyroid cancer (DTC) recommend the measurement of TSH-stimulated thyroglobulin (s-Tg) instead of basal Tg on T4 therapy (b-Tg). However, these guidelines were established using first-generation Tg assays with a functional sensitivity (FS) of 0.5-1.0 ng/ml. Current more sensitive second-generation Tg assays (Tg2G; FS 0.05-0.10 ng/ml) have shown that low-risk DTC patients with undetectable b-Tg rarely have recurrences.

OBJECTIVES

This study was undertaken to compare b-Tg using a chemiluminescent Tg2G assay (Tg2GICMA; FS 0.1 ng/ml) with s-Tg in DTC patients with an intermediate risk of recurrence.

METHODS

We evaluated 168 DTC patients with a low (n = 101) and intermediate (n = 67) risk of recurrence treated by total thyroidectomy (147 also treated with radioiodine), with a mean follow-up of 5 years.

RESULTS

b-Tg was undetectable with the Tg2GICMA in 142 of 168 patients. s-Tg was <2 ng/ml in 138 of these 142 patients, and only 3 of these 138 (2%) presented metastases on cervical ultrasound (US). Of the 4 of 142 patients with s-Tg >2 ng/ml, 1 had cervical metastases seen after radioiodine. Furthermore, 26 of 168 patients presented detectable b-Tg with the Tg2GICMA; 17 of these 26 patients also presented s-Tg >2 ng/ml. In 10 of these 17 patients, metastases were detected. Cervical US or b-Tg were positive in 14 of 15 patients with recurrent disease. Globally, the sensitivity and negative predictive value of the Tg2GICMA plus US were 93 and 99%, respectively.

CONCLUSION

b-Tg measured with a Tg2GICMA and cervical US, used together, are equivalent to s-Tg in identifying metastases in patients with DTC with a low or intermediate risk of recurrence.

A placebo-controlled, blinded and randomised study on the effects of recombinant human thyrotropin on quality of life in the treatment of thyroid cancer

BACKGROUND

It is well known that thyroid hormone withdrawal (THW) in thyroid cancer patients can induce a decrease in quality of life (QOL). Recombinant human thyrotropin (rh-TSH) has been used to avoid this; however, no blinded studies have ever documented the effect.

OBJECTIVE

To compare QOL in patients with differentiated thyroid cancer (DTC) treated with either rh-TSH or liothyronine (L-T3) THW for 10 days.

STUDY DESIGN

Double-blind, randomised cross-over.

PATIENTS

Fifty-six patients with DTC treated by total thyroidectomy and indication for postsurgery radioiodine (RI) ablation therapy.

INTERVENTION

Randomisation to either L-T3 and rh-TSH prior to the first RI course and following this to ingest placebo tablets and receive placebo injections before a second RI uptake measurement 4-6 months later, or to receive placebo before the primary RI ablation and active therapy 4-6 months later.

MAIN OUTCOME MEASURES

QOL was measured by SF-36 and 2 visual analogue scale (VAS) scores at baseline and during RI therapy or RI uptake.

RESULTS

A significant difference in QOL was seen in 2 of 4 predefined SF-36 domains (7.2 and 6.6%) and 2 VAS scales (10 and 14%), favouring rh-TSH therapy.

CONCLUSION

This is the first blinded randomised clinical trial describing the effect of rh-TSH compared to L-T3 THW on QOL in DTC patients. A significant difference was demonstrated, though smaller than described in previous non-blinded studies.

Potential use of recombinant human thyrotropin in the treatment of distant metastases in patients with differentiated thyroid cancer

OBJECTIVE

In order to effectively treat differentiated thyroid cancer (DTC) with radioiodine (RAI) it is necessary to raise serum TSH levels either endogenously by thyroid hormone withdrawal (THW) or exogenously by administration of recombinant human TSH (rhTSH). The goal of this review is to present current data on the relative efficacy and side effects profile of rhTSH-aided versus THW-aided RAI therapy for the treatment of patients with distant metastases of DTC.

METHODS

We have searched the PubMed database for articles including the keywords "rhTSH", "thyroid cancer", and "distant metastases" published between January 1, 1996 and January 7, 2012. As references, we used clinical case series, case reports, review articles, and practical guidelines.

RESULTS

Exogenous stimulation of TSH is associated with better quality of life because it obviates signs and symptoms of hypothyroidism resulting from endogenous TSH stimulation. The rate of neurological complications after rhTSH and THW-aided RAI therapy for brain and spine metastases is similar. The rate of leukopenia, thrombocytopenia, xerostomia, and pulmonary fibrosis is similar after preparation for RAI treatment with rhTSH and THW. There is currently a controversy regarding RAI uptake in metastatic lesions after preparation with rhTSH versus THW, with some studies suggesting equal and some superior uptake after preparation with THW. Analysis of available retrospective studies comparing survival rates, progression free survival, and biochemical and structural response to a dosimetrically-determined dose of RAI shows similar efficacy after preparation for therapy with rhTSH and THW.

CONCLUSION

The rhTSH stimulation is not presently approved by the FDA as a method of preparation for adjunctive therapy with RAI in patients with metastatic DTC. Data on rhTSH compassionate use suggest that rhTSH stimulation is as equally effective as THW as a method of preparation for dosimetry-based RAI treatment in patients with RAI-avid metastatic DTC.

Management of differentiated thyroid cancer in the presence of resistance to thyroid hormone and TSH-secreting adenomas: a report of four cases and review of the literature

BACKGROUND

An increased or normal serum TSH concentration, despite elevated thyroid hormone levels, is observed in resistance to thyroid hormone (RTH) and TSH-secreting adenomas (TSHomas). When coexistent with a differentiated thyroid cancer (DTC), maintenance of a suppression of TSH is challenging.

OBJECTIVES

The aim of the study was to discuss the pitfalls arising from the failure to suppress TSH secretion in DTC and the strategies for proper treatment of DTC in association with RTH and TSHoma.

METHODS

Four unusual cases of DTC associated with TSHoma (2 cases), RTH (1 case), and an elevated TSH of unknown etiology (1 case) are presented, and the literature is reviewed.

RESULTS

Although a persistent mild TSH elevation may not be a risk factor for the development of DTC, it represents an important problem during the treatment of DTC. Aggressive treatment options should be applied in the proper order to prevent tumor recurrence and persistence in the absence of ideal TSH suppression.

CONCLUSIONS

Although there is no agreed consensus regarding the management of DTC in the presence of persistent hyperthyrotropinemia, complete tumor removal followed by radioablation and attempts to reduce the serum TSH to the lowest tolerable level are recommended. The outcomes in the reported cases have not been unfavorable, despite the persistence of nonsuppressed TSH.

In thyroidectomized patients with thyroid cancer, a serum thyrotropin of 30 μU/mL after thyroxine withdrawal is not always adequate for detecting an elevated stimulated serum thyroglobulin

BACKGROUND

The thyrotropin (TSH) level or duration of thyroid hormone withdrawal (THW) required to detect stimulated thyroglobulin (Tg) in differentiated thyroid cancer (DTC) monitoring is unknown. The objective of this study was to evaluate the TSH cutoff of >30 μU/mL as a means to detect stimulated Tg ≥2 ng/mL after THW (THW-Tg≥2), and sensitivity of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) questionnaire for detecting hypothyroid symptoms.

METHODS

This was a prospective longitudinal cohort study done at a tertiary academic medical center. Forty-seven patients with DTC undergoing their first Tg stimulation or after previously abnormal Tg stimulation had weekly measurements of TSH and Tg during the 4 weeks THW, and repeated questionnaire assessments.

RESULTS

TSH did not reach a plateau in any patient, and in those whose Tg did not remain undetectable, Tg continued to rise. Seventy-five percent of patients had an undetectable Tg <0.2 ng/mL at baseline (95% were <0.5 mg/mL) with 16% remaining undetectable throughout THW. The majority of patients (72.7% and 97.8%) achieved TSH >30 μU/mL by 3 and 4 weeks THW, respectively. Of the 15 patients with maximum stimulated THW-Tg≥2, 38% were detected before the minimal TSH >30 μU/mL cutoff. At 2 weeks THW, 3 had a TSH>30 μU/mL, and none of them had Tg ≥2 ng/mL. At 3 weeks THW, 11 had a TSH >30 μU/mL, and 64% of them had Tg ≥2 ng/mL. Only 60% were detected at 3-week THW regardless of their TSH level. Eighty-six percent were detected by TSH 60-<80 μU/mL. Conversely, all patients whose serum Tg was <0.2 ng/mL when their serum TSH was >20 μU/mL did not achieve a THW-Tg≥2.

CONCLUSION

The minimal TSH cutoff of >30 μU/mL was inadequate to detect many patients with final stimulated THW-Tg≥2 during complete THW. TSH >80-100 μU/mL was a better cutoff, achieved in only 53% after 4-week THW. Conversely, we propose a preliminary THW-stopping rule for ending THW early in selected patients. In patients with a Tg <0.2 ng/mL when TSH >20 μU/mL, all had a final stimulated Tg ≤2 ng/mL, potentially saving qualifying patients 40% of THW duration compared to 4-week THW. FACIT-F correlated with TSH, but was not sensitive to detect mild hypothyroidism.

Long-term consequence of elevated thyroglobulin in differentiated thyroid cancer

BACKGROUND

Serum thyroglobulin (Tg) is the most sensitive biomarker for recurrence of differentiated thyroid cancer (DTC). We have assessed the changing pattern of stimulated Tg (sTg) and the clinical course of patients with no structural evidence of disease (NSED), based on imaging studies such as neck ultrasonography (US), fluorodeoxyglucose positron emission tomography, and/or chest computed tomogram (CT). We sought to determine if, in patients with DTC who had been treated with bilateral thyroidectomy and remnant ablation with radioactive iodine, sTg 1 year (sTg1) after initial treatment and repeated sTg measurements, 1-2 years after sTg1, helped predict the long-term outcome with respect to structural recurrence and biochemical remission (BR), which is defined as sTg <1 ng/mL.

METHODS

We retrospectively assessed the records of patients with DTC who had been treated with bilateral thyroidectomy and remnant ablation with radioactive iodine between 1995 and 2004. The study included 186 patients who had NSED with sTg1 ≥2 ng/mL and subsequent sTg measurements (sTg2) without additional treatment. Patients were classified into three groups based on their sTg1 measurements: Group A, 2-4.9 ng/mL; Group B, 5-19.9 ng/mL; and Group C, ≥20 ng/mL. Patients were also classified into two groups based on whether sTg2, 1-2 years after sTg1, had decreased by ≥50% (Group 1) or had either decreased by <50% or increased (Group 2). sTg was measured every 1-2 years until structural recurrence or BR.

RESULTS

Patients remaining in NSED showed a decrease in serial sTg. Of patients in Groups A, B, and C, 41%, 17%, and 1%, respectively, achieved BR, and there was a significant difference in the BR rate between Groups 1 and 2 (p<0.001). In patients with structural recurrence, serial sTg generally did not decrease from sTg1. There was a significant difference in the recurrence rate among Groups A, B, and C (p=0.005) and between Groups 1 and 2 (p<0.001).

CONCLUSIONS

We found that 41% of patients with sTg1 in the range 2-5 ng/mL achieved BR, and that sTg1 and percent change of subsequent sTg were predictive of BR. Repeated sTg measurements are useful for predicting patient prognosis in patients with DTC.

Long-term results after treatment of very low-, low-, and high-risk thyroid cancers in a combined setting of thyroidectomy and radio ablation therapy in euthyroidism

Introduction. Differentiated thyroid cancer treatment usually consists of thyroidectomy and radio ablation in hypothyroidism 4-6 weeks after surgery. Replacing hypothyroidism by recombinant human thyroid stimulating hormone can facilitate radio ablation in euthyroidism within one week after surgery. The outcome of this approach was investigated. Methods. This is a prospective randomized trial to compare thyroidectomy and radio ablation within a few days after preconditioning with recombinant human thyroid stimulating hormone versus thyroidectomy and radio ablation separated by four weeks of L-T4 withdrawal. Tumors were graded into very low-, low- , or high-risk tumors. Recurrence-free survival was confirmed at follow-up controls by neck ultrasound and serum thyroglobulin. Suspected tumor recurrence was treated by additional radio ablation or surgery. Quality-of-life questionnaires with additional evaluation of job performance and sick-leave time were used in all patients. Results. Radio ablation in euthyroidism in quick succession after thyroidectomy did not lead to higher tumor recurrence rates of differentiated thyroid cancers in any risk category and was significantly advantageous with respect to quality-of-life (P < 0.001), sick-leave time (P < 0.001), and job performance (P = 0.002). Conclusion. Recombinant human thyroid stimulating hormone can be used safely and with good efficacy to allow radio ablation under sustained euthyroidism within one week after thyroidectomy.

Evaluation of whole-body retention of iodine-131 ((131)I) after postoperative remnant ablation for differentiated thyroid carcinoma - thyroxine withdrawal versus rhTSH administration: A retrospective comparison

Previous studies demonstrated that preparation with recombinant human thyroid-stimulating hormone (rhTSH) for thyroid remnant ablation results in lower extrathyroidal radiation compared to hypothyroidism. The results of 50 radioiodine therapies (RITs) under rhTSH, regarding iodine half-life, were evaluated and compared with 50 RITs performed on patients with hypothyroidism following thyroxine withdrawal. The patients were treated with 3700 MBq (100 mCi) of (131)I. Forty-eight hours after RIT, patients were measured with a radiation detector at a 1-meter (m) distance for evaluation of the effective dose (μSv/h). TSH and thyroglobulin (Tg) maximal values were also compared. rhTSH-stimulated patients had a significantly lower whole-body retention of (131)I (8.5±7.3 μSv/h), extrapolated from the measurements of the effective dose at a 1-m distance, compared to endogenously stimulated patients (13.6±8.1 μSv/h; p=0.001). Furthermore, TSH mean and Tg median levels were significantly higher in the rhTSH-stimulated patients (89.9±15.3 mU/l and 7.7 ng/ml, respectively) compared to the hypothyroid group (59.2±25.1 mU/l and 3.3 ng/ml; p<0.001 and p=0.003, respectively). Compared to thyroid hormone withdrawal, the use of rhTSH prior to RIT was associated with significantly lower whole-body retention of (131)I and with greater efficacy in reaching TSH levels greater than 30 mU/l, confirming data previously described.

The sodium iodide symporter (NIS): regulation and approaches to targeting for cancer therapeutics

Expression of the sodium iodide symporter (NIS) is required for efficient iodide uptake in thyroid and lactating breast. Since most differentiated thyroid cancer expresses NIS, β-emitting radioactive iodide is routinely utilized to target remnant thyroid cancer and metastasis after total thyroidectomy. Stimulation of NIS expression by high levels of thyroid-stimulating hormone is necessary to achieve radioiodide uptake into thyroid cancer that is sufficient for therapy. The majority of breast cancer also expresses NIS, but at a low level insufficient for radioiodine therapy. Retinoic acid is a potent NIS inducer in some breast cancer cells. NIS is also modestly expressed in some non-thyroidal tissues, including salivary glands, lacrimal glands and stomach. Selective induction of iodide uptake is required to target tumors with radioiodide. Iodide uptake in mammalian cells is dependent on the level of NIS gene expression, but also successful translocation of NIS to the cell membrane and correct insertion. The regulatory mechanisms of NIS expression and membrane insertion are regulated by signal transduction pathways that differ by tissue. Differential regulation of NIS confers selective induction of functional NIS in thyroid cancer cells, as well as some breast cancer cells, leading to more efficient radioiodide therapy for thyroid cancer and a new strategy for breast cancer therapy. The potential for systemic radioiodide treatment of a range of other cancers, that do not express endogenous NIS, has been demonstrated in models with tumor-selective introduction of exogenous NIS.

Is there a role for unstimulated thyroglobulin velocity in predicting recurrence in papillary thyroid carcinoma patients with detectable thyroglobulin after radioiodine ablation?

Background

In the follow-up of papillary thyroid cancer (PTC) patients treated with curative thyroidectomy and radioiodine ablation, raised thyroglobulin (Tg) predicts recurrence with reasonable sensitivity and specificity. However, a proportion of patients present with raised Tg level but no other clinical evidence of disease. Only limited data on Tg kinetics have been reported to date. Here we aim to evaluate the prognostic and predictive significance of nonstimulated serum Tg velocity (TgV).

Methods

Consecutive PTC patients treated with curative thyroidectomy and radioiodine ablation between 2003 and 2010 were analyzed. Patients with at least one detectable Tg measurement (>0.2 ng/mL) were included. TgV was defined as the annualized rate of Tg change. Logistic regression analyses were performed to evaluate the role of TgV in the prediction of disease recurrence. The optimal TgV cutoff was assigned by receiver–operating characteristic curve analysis. Overall survival of patients above versus below the TgV cutoff were determined by the Kaplan–Meier method and compared.

Results

Of a total of 501 patients, 87 had at least one Tg value >0.2 ng/mL; in these latter patients, 29 (33.3 %) developed recurrence. TgV was an independent predictor of the recurrence. TgV ≥0.3 ng/mL per year predicted recurrence with a sensitivity of 83.3 % and specificity of 94.4 %. Patients with TgV below the cutoff had a significantly better overall survival (p = 0.038).

Conclusions

TgV predicts recurrence with high sensitivity and specificity, and is a prognosticator of survival in postthyroidectomy and postablation PTC patients with raised Tg.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-012-2391-6) contains supplementary material, which is available to authorized users.

Radioiodine treatment of metastatic thyroid cancer: relative efficacy and side effect profile of preparation by thyroid hormone withdrawal versus recombinant human thyrotropin

BACKGROUND

To effectively treat differentiated thyroid cancer (DTC) with radioiodine (RAI) it is necessary to raise serum thyrotropin (TSH) levels either endogenously by thyroid hormone withdrawal (THW) or exogenously by administration of recombinant human TSH (rhTSH). The aim of our study was to compare the relative efficacy and side effect profile of rhTSH versus THW preparation for RAI therapy of metastatic DTC.

METHODS

Fifty-six patients (31 women and 25 men) with RAI-avid distant metastases of DTC treated with either rhTSH-aided (n=15) or THW-aided RAI (n=41) and followed for 72±36.2 months were retrospectively analyzed. The groups were comparable in regard to mean size of target lesions (rhTSH vs. THW 6.4 vs. 4.8 cm, p=0.41), mean baseline thyroglobulin level (6995 vs. 5544 ng/mL, p=0.83), distribution of micronodular and macronodular pulmonary metastases (67% vs. 63%, p=0.54, 13% vs. 15% p=0.64, respectively), osseous (53% vs. 29%, p=0.09), brain (0% vs. 2%, p=0.73), and liver/kidney metastases (13% vs. 2%, p=0.61). Patients in the rhTSH group were older (rhTSH vs. THW mean 62 vs. 49 years, p=0.01), and received lower cumulative RAI dose (256 vs. 416 mCi, p=0.03), which was more frequently based on dosimetric calculations (80% vs. 46%, p=0.024). Responses to treatment were based on RECIST 1.1 criteria.

RESULTS

Adjusted by age rates of complete response (CR), stable disease (SD), progressive disease (PD), and progression free survival (PFS) were not different between the groups (rhTSH vs. THW CR hazard ratio [HR] 0.97, 95% CI 0.08-11.42, p=0.982; SD HR 3.22, 95% CI 0.79-13.18, p=0.104, PD HR 0.26, 95% CI 0.52-1.26, p=0.094; PFS HR 0.41, 95% CI 0.14-1.23, p=0.112). The only independent risk factor for nonresponding to treatment and presentation with PD was age (HR 1.06, 95% CI 1.02-1.11, p=0.008). Age was also an independent factor affecting PFS (HR 1.04 for each year, 95% CI 1.02-1.07, p=0.001). Rates of leukopenia, thrombocytopenia, xerostomia, and restrictive pulmonary disease after RAI were not significantly different (rhTSH vs. THW 30% vs. 28%, p=0.61, 10% vs. 0%, p=0.37, 0% vs. 12%, p=0.20, 0% vs. 2%, p=0.73, respectively).

CONCLUSIONS

Patients with metastatic DTC prepared with rhTSH achieve comparable benefit of RAI therapy as those treated after THW.

Recombinant TSH and Lithium Overcomes Amiodarone-Induced Low Radioiodine Uptake in a Thyrotoxic Female

INTRODUCTION

Recombinant human thyroid-stimulating hormone(rhTSH) increases radioactive iodine uptake(RAIU) in selected populations, while lithium is used as an adjunct to radioactive iodine (RAI) therapy in Graves' disease with low RAIU. In this report, both drugs used in combination, overcame low iodine-131 uptake in a Graves' patient.

CLINICAL CASE

A 39-year old female with Graves' disease, acquired thionamide-induced agranulocytosis, and severe hypokalemia, subsequently went into cardiorespiratory arrest. On resuscitation, she had ventricular tachyarrhythmias which were cardioverted using amiodarone. She was subsequently placed on IV hydrocortisone amiodarone and propranolol. On admission, she was normotensive, tachycardic, and afebrile. She had fine tremors, hyper reflexia, and diffuse, non-tender thyromegaly. Initial investigations showed normal complete blood count, hypokalemia and elevated alanine transaminase levels. Levels of thyroid stimulating hormone were low (0.03 uIU/L, N = 0.27-3.75). Thyroid ultrasound showed diffuse thyromegaly with uniform echopattern and normal color flow Doppler, radioiodine uptake showed low uptake at 0400h and 2400h (6% and 7%, respectively). In preparation for RAI therapy, she was given lithium 900mg/day for 12 days to increase RAI retention. To increase iodine-131 uptake, two doses of 0.9mg rhTSH were injected intramuscular, 24 hours apart, before RAI therapy. Repeat RAIU after the second dose of rhTSH showed more than a 5-fold increase in 0400h uptake compared with the baseline (32% vs. 6%). Exactly 24 hours after the second dose of rhTSH, she was given 25mCi of iodine-131. Thereafter, the patient's clinical and biochemical markers continued to improve. She became hypothyroid and is currently on levothyroxine replacement therapy.

CONCLUSIONS

This case demonstrates the efficacy of combining rhTSH and lithium to overcome amiodarone-induced low iodine-131 uptake in Graves' disease.

The use of ultrasensitive thyroglobulin assays reduces but does not abolish the need for TSH stimulation in patients with differentiated thyroid carcinoma

Measurement of serum Tg using ultrasensitive assays is proposed to replace TSH-stimulated Tg measurement in the follow-up of differentiated thyroid cancer (DTC). Aim of our study was to verify this possibility using two ultrasensitive Tg assays. We selected 215 DTC patients with undetectable (<1 ng/ml) basal serum Tg at the time of a recombinant human TSH (rhTSH) stimulation. According to standard criteria, 173 (80.4%) patients were considered free of disease, 17 (7.9%) had documented disease and 25 (11.7%) had no evidence of disease but detectable serum rhTSH-stimulated Tg (biochemical disease). The sera of these patients were re-assayed with two commercial ultrasensitive assays and the results were compared with the clinical data. Basal Access and E-Iason Tg assays were able to distinguish patients with persistent disease or free of disease with a sensitivity of 82.3 and 82.3%, specificity of 85.5 and 86.1%, positive predictive value (PPV) of 35.8 and 36.8%, negative predictive value (NPV) of 98 and 98.6%, respectively. With both assays the addition of neck ultrasound to basal Tg increased the sensitivity and the NPV to 100% and decreased the false negative rate to 0%. In patients with detectable basal Tg without evidence of disease, serum Tg converted from detectable to undetectable in about 80% of the cases during 2-yr follow-up. Our study indicates that the combination of neck ultrasound and basal ultrasensitive Tg allows to identify all patients free of disease and can decrease the need for rhTSH stimulation in nearly 80% of the patients.

Recombinant human thyrotropin-aided radioiodine therapy in patients with metastatic differentiated thyroid carcinoma

Our aim was to test the efficacy of 131-I therapy (RIT) using recombinant human TSH (rhTSH) in patients with differentiated thyroid carcinoma (DTC) in whom endogenous TSH stimulation was not an option due to the poor patient's physical condition or due to the disease progression during L-thyroxin withdrawal. The study comprised 18 patients, who already have undergone total or near-total thyroidectomy and radioiodine ablation and 0–12 (median 5) RITs after L-thyroxin withdrawal. Our patients received altogether 44 RITs using rhTSH while on L-thyroxin. Six to 12 months after the first rhTSH-aided RIT, PR and SD was achieved in 3/18 (17%) and 4/18 patients (22%), respectively. In most patients (n = 12; 61%) disease progressed despite rhTSH-aided RITs. As a conclusion, rhTSH-aided RIT proved to add some therapeutic benefit in 39% our patients with metastatic DTC, who otherwise could not be efficiently treated with RIT.

Serum thyroglobulin, a biomarker for iodine deficiency, is not associated with increased risk of upper gastrointestinal cancers in a large Chinese cohort

Iodine concentrates in gastric tissue and may act as an antioxidant for the stomach. We previously showed that self-reported goiter was associated with significantly increased risk of gastric noncardia adenocarcinoma (GNCA) and nonsignificantly increased risks of gastric cardia adenocarcinoma (GCA) and esophageal squamous cell carcinoma (ESCC) in a prospective case-cohort study in a high-risk population in China. Negatively correlated with iodine levels, serum thyroglobulin (Tg) is a more sensitive biomarker of iodine deficiency than goiter. Our study aimed to determine whether baseline serum Tg was also associated with development of GNCA, GCA and ESCC in the same cohort, the Linxian General Population Nutrition Intervention Trial. Sera from ∼200 subjects of each case type and 400 noncases were tested for serum Tg concentration using appropriate assays. Tg was modeled as sex- and assay-specific quartiles in Cox regression models adjusted for age, smoking, alcohol, Helicobacter pylori status, pepsinogens I/II ratio, family history and commune of residence. In the final combined analysis, participants in the highest quartile of serum Tg, compared to those in the lowest quartile, had adjusted hazard ratios of 0.88 (95% confidence interval 0.50-1.52), 1.14 (0.63-2.05) and 0.78 (0.47-1.31) for GNCA, GCA and ESCC, respectively. Using serum Tg, a sensitive biomarker of iodine deficiency, we found no association between serum Tg concentrations and risk of these upper gastrointestinal (UGI) cancers in the study population. Our results do not support the hypothesis that iodine deficiency, as assessed by serum Tg, is associated with an increased risk of UGI cancers.

Age modifies the response to recombinant human thyrotropin

BACKGROUND

A standardized protocol is used to administer recombinant human thyrotropin (rhTSH) in preparation for diagnostic studies and treatment in patients with thyroid cancer. The expectation is that serum TSH concentrations will peak on the day after the second injection and will be sufficiently elevated to stimulate uptake of radioiodine. We wished to test the hypothesis that TSH concentrations achieved after rhTSH injection are influenced by age.

METHODS

Patients with thyroid cancer undergoing diagnostic radioiodine scanning were identified by chart review. Serum TSH concentrations were documented 24 and 72 hours after two rhTSH injections (days 3 and 5, respectively). Responses were subdivided into four ascending patient age groups: <35, 35-49, 50-64, and >64 years. TSH concentrations after rhTSH administration were documented according to patient age.

RESULTS

There was a significant correlation between the serum TSH concentrations at both days 3 and 5 and patient age (p < 0.0001). None of the other factors examined (gender, menopausal status, weight, body mass index, baseline TSH, serum creatinine, and estimated glomerular filtration rate) were significant in multivariate analyses. The mean TSH concentration on day 3 increased significantly when patients were divided into the aforementioned groups of ascending age (96, 107, 142, and 196 mIU/L, p < 0.0001). Day 5 concentrations increased in a similar manner.

CONCLUSIONS

Both days 3 and 5 TSH concentrations were higher in older individuals after rhTSH administration. This finding did not appear to be related to body weight, body mass index, or glomerular filtration rate in a simple manner. The TSH concentration achieved may be a result of complex interactions between distribution within fat and muscle body compartments, hepatic function, and renal function. Prospective studies could examine whether the magnitude of the TSH elevation after rhTSH administration affects diagnostic or therapeutic efficacy.

Recombinant human thyrotropin (rhTSH) aided radioiodine treatment for residual or metastatic differentiated thyroid cancer

BACKGROUND

For patients with differentiated thyroid cancer (DTC) following thyroidectomy, thyroid hormone withdrawal (THW) for four to six weeks has been used for decades to increase serum thyroid-stimulating hormone (TSH) concentrations in order to enhance iodine-131 uptake by normal thyroid cells and differentiated thyroid tumour cells. Exogenous stimulation with recombinant human thyroid-stimulating hormone (rhTSH) offers an alternative to THW while avoiding the morbidity of hypothyroidism. However, the efficacy of rhTSH-aided iodine-131 treatment for residual or metastatic DTC has not been prospectively assessed.

OBJECTIVES

To assess the effects of rhTSH-aided radioiodine treatment for normal residual or metastatic DTC.

SEARCH STRATEGY

We obtained studies from computerised searches of MEDLINE, EMBASE and The Cochrane Library (all until November 2009), and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled clinical trials and quasi-randomised controlled clinical trials comparing the effects of rhTSH with THW on iodine-131 treatment for residual or metastatic differentiated thyroid cancer with at least six months of follow up.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data.

MAIN RESULTS

Altogether 223 patients with DTC participated in four trials. Overall, studies had a high risk of bias. We found no statistically significant differences between rhTSH and THW treatment in terms of successful ablation rate but significant benefits in radiation exposure to blood and bone marrow. One trial reported on benefits in some domains of health-related quality of life. There were no deaths and no serious adverse effects in DTC patients treated with either rhTSH or THW. Maximum follow up was 12 months. None of the included trials investigated complete or partial remission of metastatic tumour, secondary malignancies or economic outcomes. We did not find sufficient data comparing rhTSH with THW-aided radioiodine treatment for metastatic DTC.

AUTHORS' CONCLUSIONS

Results from four randomised controlled clinical trials suggest that rhTSH is as effective as THW on iodine-131 thyroid remnant ablation, with limited data on significant benefits in decreased whole body radiation exposure and health-related quality of life. It is still uncertain whether lower iodine-131 doses (1110 MBq or 1850 MBq versus 3700 MBq) are equally effective for remnant ablation under rhTSH stimulation. Randomised controlled clinical trials are needed to guide treatment selection for metastatic differentiated thyroid cancer.