Cost-effectiveness of using recombinant human TSH prior to radioiodine ablation for thyroid cancer, compared with treating patients in a hypothyroid state: the German perspective

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Recombinant or endogenous thyroid-stimulating hormone for radioactive iodine therapy in thyroid cancer: state of knowledge and current controversies

For patients undergoing radioiodine therapy (RIT) of differentiated thyroid carcinoma (DTC), thyroid-stimulating hormone (TSH) stimulation prior to RIT can be achieved using thyroid hormone withdrawal (THW) or administration of recombinant human TSH (rhTSH). As THW can lead to nausea, headaches, vomiting, fatigue, and dizziness secondary to transient acute hypothyroidism, rhTSH could be a good alternative. Recombinant human TSH has been administered in patients in order to stimulate TSH for RIT since 2005. According to the Martinique criteria formulated by the leading professional societies involved in care of patients with DTC, rhTSH can be applied in 3 settings: for remnant ablation, adjuvant treatment, and treatment of known disease. Numerous studies have investigated the effects of rhTSH as a method of TSH stimulation on the thyroid cell, the systemic effects, biokinetics, and clinical outcomes; however, no consensus has been reached about many aspects of its potential use. Recombinant human TSH is able to stimulate sufficient TSH levels (>30 mIU L-1) and is hypothesized to decrease risks of tumor cell proliferation. As rhTSH-use avoids the transiently impaired renal function associated with THW, radioiodine excretion is faster with the former, leading to a lower iodine-131 uptake and a difference in fractional remnant uptake, effective half-life, mean residence time, and dose to the blood. Differences between rhTSH and THW were observed in radioiodine genotoxic effects and endothelial-dependent vasodilation and inflammation. For thyroid remnant ablation, THW and rhTSH lead to similar remnant ablation rates. For adjuvant therapy and treatment of known disease, insufficient trials have been conducted and future prospective studies are recommended. The current review provides a state-of-the-science overview on the issues and debates surrounding TSH stimulation through either rhTSH adminsitration orendogenous TSH production after levothyroxin withdrawal.

Quality of life comparison in thyroxine hormone withdrawal versus triiodothyronine supplementation prior to radioiodine ablation in differentiated thyroid carcinoma: a prospective cohort study in the Indian population

BACKGROUND

Thyroid withdrawal in preparation for radioiodine ablation (RIA) may have a profound impact on health-related quality of life (HRQL). Cost implications and scheduling limit the use of recombinant TSH and triiodothyronine (T3) with its shorter half-life is a conceptually attractive alternative.

METHODS

Prospective cohort study design with patients having withdrawal of thyroxine (n = 37) or T3 supplementation (n = 33). HRQL was assessed using EORTC QLQ-C30, QLQ-H&N35 and modified Billewicz questionnaires. Time interval to achieve optimal TSH levels (at least 30 mIU/ml) prior to RIA was determined.

RESULTS

With the exception of emotional domain (QLQ-C30 p = 0.045), LT3 supplementation did not confer significant benefit when compared to LT4 withdrawal. Target serum TSH levels was achieved in 95% of patients by week 4 post thyroidectomy.

CONCLUSIONS

LT3 supplementation delivered equivocal benefit and therefore the alternate strategies to minimize the impact on HRQL of reduction in the duration of hypothyroidism in T4 withdrawal are suggested.

Health Utility Book (HUB)-Cancer: Protocol for a Systematic Literature Review of Health State Utility Values in Cancer

Background. Treatment options in oncology are rapidly advancing, and public payer systems are increasingly under pressure to adopt new but expensive cancer treatments. Cost-utility analyses (CUAs) are used to estimate the relative costs and effects of competing interventions, where health outcomes are measured using quality-adjusted life years (QALYs). Health state utility values (HSUVs) are used to reflect health-related quality of life or health status in the calculation of QALYs. To support reimbursement agencies in the appraisal of oncology drug submissions, which typically include a CUA component, we have proposed a systematic literature review of published HSUV estimates in the field of oncology. Methods. The following databases will be searched: MEDLINE, EMBASE, EconLit, and CINAHL. A team of reviewers, working independently and in duplicate, will evaluate abstracts and full-text publications for eligibility against broad inclusion criteria. Studies using a direct, indirect, or combination approach to eliciting preferences related to cancer or cancer treatments are eligible. Data extraction will capture details of study methodology, participants, health states, and corresponding HSUVs. We will summarize our findings with descriptive analyses at this stage. A pilot review in thyroid cancer is presented to illustrate the proposed methods. Discussion. This systematic review will generate a comprehensive summary of the oncology HSUV literature. As a component of the Health Utility Book (HUB) project, we anticipate that this work will assist both health economic modelers as well as critical reviewers in the development and appraisal of CUAs in oncology.

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

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

Cost-effectiveness of using recombinant human thyroid-stimulating hormone before radioiodine ablation for thyroid cancer treatment in Spanish hospitals

OBJECTIVES

In thyroid cancer treatment, the thyroid-stimulating hormone (TSH) must be elevated before radioiodine ablation, either by exogenous (with recombinant human thyrotropin [rhTSH]) or endogenous stimulation by thyroid hormone withdrawal (THW). The use of rhTSH avoids hypothyroidism and favours the subsequent elimination of radioiodine, but involves the cost of the product. For this reason, a cost-effectiveness analysis was performed, taking into account all costs involved and the benefits associated with the use of this therapy.

MATERIAL AND METHODS

Using a Markov modelling with two analysis arms (rhTSH and THW), stratified into high (100mCi/3700 MBq) and low (30mCi/1110 MBq) radioiodine doses, and using 17 weekly cycles, the incremental cost per quality-adjusted life-year (QALY) related to the use of rhTSH was determined. The clinical inputs included in the model were based on published studies and in a treatment survey conducted in Spain.

RESULTS

Radioablation preparation with rhTSH is superior to THW, showing additional benefits (0.048 AVAC), as well as cost savings (-€614.16), with an incremental cost-effectiveness rate (ICER) of -€12,795/QALY. The univariate and multivariate sensitivity analyses showed the result to be robust.

CONCLUSIONS

The use of rhTSH previous to radioablation in Spain has cost savings, as well as a series of health benefits for the patient, making it highly cost-effective.

Interrupted 131I Procedures for Patients With Differentiated Thyroid Cancer: Comparing Thyroxine Withdrawal With Recombinant Thyrotropin Preparation Techniques

OBJECTIVE

In patients with differentiated thyroid carcinoma scheduled to receive doses of I for diagnostic or therapeutic purposes, we compared patients prepared with thyroid hormone withdrawal (THW) versus recombinant human thyroid stimulating hormone (rh-TSH) to evaluate the incidence of cancelled procedures because of inadequate thyroid stimulation.

METHODS

Thyroid cancer patients after thyroidectomy who were scheduled for diagnostic or therapeutic I procedures between January 2012 and June 2015 were retrospectively reviewed. Patients were divided based on preparation modality (THW vs rh-TSH), and the incidence of cancelled procedures was compared.

RESULTS

Charts from 761 patients were reviewed, 292 THW and 569 rh-TSH. A total of 10 patients (3.4%) in the THW group had cancelled procedures because of insufficient thyroid stimulation (TSH < 20 mU/L). If a TSH threshold of 30 mU/L were used, 57 patients (17.1%) would have been cancelled. Comparing the groups with chi-squared analysis for both TSH thresholds yielded significantly more cancellations in the THW group (P < 0.001).

CONCLUSIONS

Our study has shown that THW in preparation for I procedures leads to significantly more cancellations because of insufficient thyroid stimulation as compared with rh-TSH, which led to no cancellations. The added cost and inconvenience to this cancer population should therefore be considered when selecting a preparation modality.

LEVEL OF EVIDENCE

Retrospective cohort-Level III.

Measurement and Variation in Estimation of Quality of Life Effects of Patients Undergoing Treatment for Papillary Thyroid Carcinoma

BACKGROUND

Thyroid cancer incidence is increasing. The effect of diagnosis and treatment on health-related quality of life (HRQoL) is an essential variable in the absence of a change in life span for the majority of patients. HRQoL instruments, with data useful for between-disease comparisons, are being increasingly used for health policy and outcomes evaluation. Variation exits among the instruments based on the impact of a specific disease. We assessed which of four well-validated, preference-based surveys detect changes in health and clinical intervention in patients diagnosed with papillary thyroid cancer (PTC).

METHODS

Four commonly used HRQoL questionnaires (Short Form-12v2® [SF6D], EuroQol-5D [EQ5D], and Health Utilities Index Mark 2 and 3 [HUI2, HUI3]) were administered to patients with the diagnosis of PTC at three perioperative time points during the first year of treatment. Clinicopathological and treatment course data were assessed for HRQoL impact including complications from surgery, re-operation for persistence/early recurrence, and adjuvant radioactive iodine treatment. We compared standard metrics, including ceiling effect, intraclass correlation coefficient, effect sizes, and quality-adjusted life-years between the four instruments.

RESULTS

Of 117 patients, 27% had a preoperative diagnosis of anxiety or depression, 41% had regional lymph node metastases, three had distant metastases and 49% underwent adjuvant radioactive iodine treatment. The ceiling effect (i.e., proportion with a perfect score) was greatest with EQ5D and least with SF6D. Index scores ranged from 0.77 (SF6D) to 0.90 (EQ5D). All scores declined at two weeks postoperatively and returned to pretreatment levels at six months. The SF6D was the only instrument to exceed the conventional minimally important difference between all three time points. Quality-adjusted life-years were as follows: SF6D, 0.79; EQ5D, 0.90; HUI2, 0.88; and HUI3, 0.86.

CONCLUSIONS

Our results reflect the general good health of PTC patients. The effect on quality of life is primarily related to emotional and social impacts of treatment. The results support the measurement of a similar underlying construct, although variation in detecting changes in health exists between the instruments. Of the instruments assessed, the SF6D is the most responsive to treatment effects and should be utilized in future economic analyses in this patient population.

Economic Evaluation of Recombinant Human Thyroid Stimulating Hormone Stimulation vs. Thyroid Hormone Withdrawal Prior to Radioiodine Ablation for Thyroid Cancer: The Korean Perspective

BACKGROUND

Previous studies have suggested that recombinant human thyroid stimulating hormone (rhTSH) stimulation is an acceptable alternative to thyroid hormone withdrawal (THW) when radioiodine remnant ablation is planned for thyroid cancer treatment, based on superior short-term quality of life with non-inferior remnant ablation efficacy. This study evaluated the cost-effectiveness of radioiodine remnant ablation using rhTSH, compared with the traditional preparation method which renders patients hypothyroid by THW, in Korean perspective.

METHODS

This economic evaluation considered the costs and benefits to the Korean public healthcare system. Clinical experts were surveyed regarding the current practice of radioiodine ablation in Korea and their responses helped inform assumptions used in a cost effectiveness model. Markov modelling with 17 weekly cycles was used to assess the incremental costs per quality-adjusted life year (QALY) associated with rhTSH. Clinical inputs were based on a multi-center, randomized controlled trial comparing remnant ablation success after rhTSH preparation with THW. The additional costs associated with rhTSH were considered relative to the clinical benefits and cost offsets.

RESULTS

The additional benefits of rhTSH (0.036 QALY) are achieved with an additional cost of Korean won W961,105, equating to cost per QALY of W26,697,361. Sensitivity analyses had only a modest impact upon cost-effectiveness, with one-way sensitivity results of approximately W33,000,000/QALY.

CONCLUSION

The use of rhTSH is a cost-effective alternative to endogenous hypothyroid stimulation prior to radioiodine ablation for patients who have undergone thyroidectomy in Korea.

Health state utility valuation in radioactive iodine-refractory differentiated thyroid cancer

PURPOSE

The aim of this study was to elicit utilities for radioactive iodine-refractory differentiated thyroid cancer (RR-DTC) and evaluate the impact of treatment response and toxicities on quality of life.

PATIENTS AND METHODS

RR-DTC health states were developed based on data from a previous qualitative study and iterative review by clinical experts. Following piloting, health states underwent valuation by 100 members of the UK public during time trade-off interviews. Mean utilities and descriptive distribution statistics were calculated, and a logistic regression analysis was conducted.

RESULTS

The demographic characteristics of the study sample were generally reflective of the UK population. Clear differentiation in valuation between health states was observed. No response/stable disease had an adjusted utility value of 0.87, with a corresponding gain of +0.04 following a treatment response and a decline of -0.35 for disease progression. Adverse events were associated with utility decrements between -0.47 (grade III diarrhea) and -0.05 (grade I/II alopecia).

CONCLUSION

The trade-off interviews derived utility weights show clear differentiation between RR-DTC health states in response to treatment. The values reported in this study are suitable for cost-effectiveness evaluations for new treatments in RR-DTC.

Quality of Life and Cost-Effectiveness Assessment of Radioiodine Ablation Strategies in Patients With Thyroid Cancer: Results From the Randomized Phase III ESTIMABL Trial

Purpose

In the ESTIMABL phase III trial, the thyroid ablation rate was equivalent for the two thyroid-stimulating hormone (TSH) stimulation methods (thyroid hormone withdrawal [THW] and recombinant human TSH [rhTSH]) and the two iodine-131 (131I) activities (1.1 or 3.7 GBq). The objectives of this article were to present health-related quality-of-life (HRQoL) results and a cost-effectiveness evaluation performed alongside this trial.

Patients and Methods

HRQoL and utility were longitudinally assessed, from random assignment to the follow-up visit at 8 ± 2 months for the 752 patients with thyroid cancer, using the Short Form-36 and the EuroQoL-5D questionnaires, respectively. A cost-effectiveness analysis was performed from the societal perspective in the French context. Resource use (hospitalization for 131I administration, rhTSH, sick leaves, and transportation) was collected prospectively. We used the net monetary benefit approach and computed cost-effectiveness acceptability curves for both TSH stimulation methods and 131I activities. Sensitivity analyses of the costs of rhTSH were performed.

Results

At 131I administration, THW caused a clinically significant deterioration of HRQoL, whereas HRQoL remained stable with rhTSH. This deterioration was transient with no difference 3 months later. rhTSH was more effective than THW in terms of quality-adjusted life-years (QALYs; +0.013 QALY/patient) but more expensive (+€474/patient). The probability that rhTSH would be cost effective at a €50,000/QALY threshold was 47% in France. The use of 1.1 GBq of 131I instead of 3.7 GBq reduced per-patient costs by €955 (US$1,018) but with slightly decreased efficacy (−0.007 QALY/patient).

Conclusion

rhTSH avoids the transient THW-induced deterioration of HRQoL but is unlikely to be cost effective at its current price.

Cost-effectiveness of FDG-PET/CT for cytologically indeterminate thyroid nodules: a decision analytic approach

CONTEXT

Patients with thyroid nodules of indeterminate cytology undergo diagnostic surgery according to current guidelines. In 75% of patients, the nodule is benign. In these patients, surgery was unnecessary and unbeneficial because complications may occur. Preoperative fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) was found to have a very high negative predictive value (96%) and might therefore avoid futile surgery, complications, and costs. In the United States, two molecular tests of cytology material are routinely used for this purpose.

OBJECTIVE

Five-year cost-effectiveness for routine implementation of FDG-PET/CT was evaluated in adult patients with indeterminate fine-needle aspiration cytology and compared with surgery in all patients and both molecular tests.

DESIGN

A Markov decision model was developed to synthesize the evidence on cost-effectiveness about the four alternative strategies. The model was probabilistically analyzed. One-way sensitivity analyses of deterministic input variables likely to influence outcome were performed.

SETTING AND SUBJECTS

The model was representative for adult patients with cytologically indeterminate thyroid nodules.

MAIN OUTCOME MEASURES

The discounted incremental net monetary benefit (iNMB), the efficiency decision rule containing outcomes as quality-adjusted life-years and (direct) medical cost, of implementation of FDG-PET/CT is displayed.

RESULTS

Full implementation of FDG-PET/CT resulted in 40% surgery for benign nodules, compared with 75% in the conventional approach, without a difference in recurrence free and overall survival. The FDG-PET/CT modality is the more efficient technology, with a mean iNMB of €3684 compared with surgery in all. Also, compared with a gene expression classifier test and a molecular marker panel, the mean iNMB of FDG-PET/CT was €1030 and €3851, respectively, and consequently the more efficient alternative.

CONCLUSION

Full implementation of preoperative FDG-PET/CT in patients with indeterminate thyroid nodules could prevent up to 47% of current unnecessary surgery leading to lower costs and a modest increase of health-related quality of life. Compared with an approach with diagnostic surgery in all patients and both molecular tests, it is the least expensive alternative with similar effectiveness as the gene-expression classifier.

A qualitative evaluation of the validity of published health utilities and generic health utility measures for capturing health-related quality of life (HRQL) impact of differentiated thyroid cancer (DTC) at different treatment phases

PURPOSE

This study explored the impact of differentiated thyroid cancer (DTC) on health-related quality of life (HRQL) at different treatment phases and evaluated the validity of published DTC utilities and generic health utility measures (EQ-5D and SF-6D) for economic evaluation of treatments for radio-iodine (RAI) refractory DTC.

METHODS

Focus groups and interviews were conducted with DTC patients grouped by treatment phase. Qualitative thematic analysis was conducted on interview/focus group transcripts. A thematic coding framework was developed to compare experiences between treatment phases and inform development of a conceptual model. Model concepts were mapped to EQ-5D and SF-6D domains/items.

RESULTS

Eight focus groups and 11 individual interviews were conducted with 52 DTC patients. Fifty symptoms and HRQL concepts were identified. The impact of DTC and DTC treatment on emotional and cognitive functioning was reported across the treatment phases. The impact on daily activities, mobility, and energy levels was greatest for patients with recurring/persistent or RAI-refractory DTC. Of the 50 concepts, 25 and 27 mapped directly onto domains/items in the EQ-5D and SF-6D, respectively. The SF-6D covered a broader range of DTC impact on emotional/physical problems and daily/social activities than did the EQ-5D.

CONCLUSIONS

The conceptual model summarizes the wide-ranging impact of DTC and its treatment on patients' HRQL, particularly for those with recurring/persistent or RAI-refractory DTC. Findings suggest that published DTC utilities lack validity for RAI-refractory DTC and that the SF-6D may be more sensitive to HRQL impact of DTC than the EQ-5D.

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.

rhTSH-aided low-activity versus high-activity regimens of radioiodine in residual ablation for differentiated thyroid cancer: a meta-analysis

The effects of low-activity versus high-activity radioiodine regimens in thyroid remnant ablation for patients with differentiated thyroid carcinoma (DTC) under recombinant human thyrotropin (rhTSH) stimulation have been widely quoted but there has been no systematic review of the evidence. We undertook a systematic review of randomized controlled trials to assess the effects of low-activity radioiodine in thyroid remnant ablation in patients with DTC under rhTSH stimulation compared with high-activity radioiodine. Studies were obtained from computerized searches of MEDLINE, EMBASE, and the Cochrane Library (all until September 2012). Randomized controlled trials were included. Altogether, 637 patients with DTC who participated in three trials for residual ablation were included. Overall, studies had a low risk of bias. We found no statistically significant differences between low-activity (1.11/1.85 GBq) and high-activity (3.7 GBq) radioiodine treatment aided by rhTSH in terms of successful ablation rates on the basis of diagnostic scans [odds ratio (OR) 0.85, 95% confidence interval (CI) 0.49–1.47, P=0.56], thyroglobulin levels (OR 0.66, 95% CI 0.38–1.15, P=0.14), and health-related quality of life (mean difference 0.07, 95% CI −0.96 to 1.09, P=0.9). In addition, the subgroup analysis of 1.11 versus 3.7 GBq (OR 0.83, 95% CI 0.46–1.49, P=0.53) and 1.85 versus 3.7 GBq (OR 1, 95% CI 0.23–4.35, P=1) also showed no significant differences. The lower activity of 1.11 GBq showed significant benefit in terms of reduction in adverse events including neck pain, radiation gastritis, and salivary dysfunction during and after ablation (OR 0.63, 95% CI 0.42–0.93, P=0.02). Limited data from three randomized controlled trials suggested that an rhTSH-aided low radioiodine activity level of as low as 1.115 GBq may be sufficient for thyroid remnant ablation when compared with 3.7 GBq, with fewer common adverse effects in patients with metastasis-free DTC. Further evidence is needed to confirm the effects of low-activity radioiodine for thyroid remnant ablation. Radioiodine treatment of 1.11 GBq showed significant benefit in terms of reduction in adverse events including neck pain, radiation gastritis, and salivary dysfunction during and after ablation (OR 0.63, 95% CI 0.42–0.93, P=0.02). rhTSH-aided low radioiodine activity levels of 1.11 and 1.85 GBq are sufficient for thyroid remnant ablation as compared with 3.7 GBq, with fewer common adverse effects in patients with metastasis-free DTC. A well-designed study that compares low-activity with high-activity radioiodine ablation is needed to fully understand the long-term adverse effects and relapse or metastases.

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.

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

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.

Radioiodine for remnant ablation and therapy of metastatic disease

Radioiodine is considered an effective and low-risk therapy modality of advanced differentiated thyroid cancer. For patients without lymph-node or distant metastases and low stages of the primary tumor, debate is ongoing about the necessity of thyroid remnant tissue ablation in an adjuvant setting. On the basis of evidence from retrospective studies, and until results of ongoing controlled prospective randomized trials become available, (131)I ablation of remnant thyroid tissue in patients with primary tumors >1 cm is advisable. For thyroid remnant ablation, individual dosimetry is not obligatory. By contrast, the effectiveness of (131)I therapy of locally advanced and/or metastatic disease can be improved by individual dosimetry. For practical reasons, an approach delivering the maximal possible radiation dose to the tumor without exceeding a critical blood dose of approximately 2 Gy seems advantageous. The availability of recombinant human TSH (rhTSH) has improved the quality of life of patients and reduces the radiation exposure of healthy nonthyroid tissue compared with TSH stimulation through levothyroxine withdrawal. In patients with distant metastases, rhTSH stimulation is possible only in off-label use, from which especially elderly and frail patients may benefit, as they most severely suffer from hypothyroidism caused by thyroid hormone withdrawal.

Thyroid cancer: burden of illness and management of disease

OBJECTIVE

The incidence of thyroid cancer, the most common endocrine malignancy, has increased dramatically in the last fifty years. This article will review the standard approach to thyroid cancer treatment as well as novel therapies under investigation. We will also address potential cost considerations in the management of thyroid cancer.

STUDY DESIGN

A comprehensive literature search was performed.

METHODS

Review article.

RESULTS

The high prevalence of thyroid cancer and the availability of novel therapies for patients with metastatic disease have potential economic implications that have not been well-studied. Because many patients likely have very low morbidity from their cancers, better tools to identify the lowest risk patients are needed in order to prevent overtreatment. Improved risk stratification should include recognizing patients who are unlikely to benefit from radioactive iodine therapy after initial surgery and identifying those with indolent and asymptomatic metastatic disease that are unlikely to benefit from novel therapies. In patients with advanced incurable disease, randomized-controlled studies to assess the efficacy of novel agents are needed to determine if the costs associated with new agents are warranted.

CONCLUSIONS

Health care costs associated with the increased diagnosis of thyroid cancer remain unknown but are worthy of further research.

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.

To stimulate or withdraw? A cost-utility analysis of recombinant human thyrotropin versus thyroxine withdrawal for radioiodine ablation in patients with low-risk differentiated thyroid cancer in the United States

CONTEXT

Use of recombinant human TSH (rhTSH) prior to radioactive iodine remnant ablation for patients with differentiated thyroid cancer avoids the hypothyroid state and improves quality of life. European studies have shown that use of rhTSH vs. thyroid hormone withdrawal is a cost-effective method for preparing patients for ablation.

OBJECTIVE

The objective of the study was to determine the cost-utility of rhTSH prior to ablation in the United States.

DESIGN/SETTING/SUBJECTS

A Markov decision model was developed for a hypothetical group of adult patients with low-risk differentiated thyroid cancer who were prepared for ablation by either rhTSH or thyroid hormone withdrawal. Patients entered the model after initial thyroidectomy; follow-up was in accordance with current American Thyroid Association guidelines. Input data were obtained from the literature, Medicare reimbursement schedule, and U.S. Bureau of Labor Statistics. Sensitivity analyses were performed for all clinically relevant inputs.

MAIN OUTCOME MEASURES

Cost-utility, measured in U.S. dollars per quality-adjusted life-year ($/QALY), was measured.

RESULTS

Use of rhTSH yielded an incremental cost-utility of $52,554/QALY (95% confidence interval $52,058-53,050/QALY) (incremental societal cost of $1,365/patient; incremental benefit of 0.026 QALY/patient). The majority of cost and benefit occurs during the preablation, ablation, and postablation period; differences in cost are due to cost of rhTSH and differences in productivity loss (days off work). The model was most sensitive to changes in time off work, cost of rhTSH, and differences in utilities of health states.

CONCLUSIONS

In the United States, the cost-effectiveness of rhTSH for ablation in patients with low-risk differentiated thyroid cancer is highly dependent on potential variations in cost of rhTSH, rates of remnant ablation, time off work, and quality of life.

Cost-effectiveness of using recombinant human thyroid-stimulating hormone before radioiodine ablation for thyroid cancer: the Canadian perspective

OBJECTIVES

Radioiodine ablation for the treatment of thyroid cancer is traditionally performed after preparing patients by inducing hypothyroidism. Exogenous stimulation of thyroid-stimulating hormone (TSH) using recombinant human TSH (rhTSH) avoids hypothyroidism and hastens the clearance of radioiodine from the patient. These advantages are achieved without jeopardizing the success rate of remnant ablation. An economic analysis was performed to place the increased acquisition cost of rhTSH in the context of the health benefits achieved and the earlier discharge from radioprotection.

METHODS

Markov modeling, using 17 individual weekly cycles, was used to assess the incremental cost per quality-adjusted life-year (QALY) associated with exogenous stimulation. Clinical inputs were largely sourced from a multicenter, randomized, controlled trial comparing remnant ablation success after either rhTSH or hypothyroid preparation. The model applied Canadian unit costs, taking a societal perspective. Additional costs associated with rhTSH were considered in the context of the clinical benefits and cost offsets. These included avoidance of hypothyroidism, increased work productivity, earlier administration of ablation after surgery, and earlier discharge from the radio-protective ward because of faster radioiodine clearance following rhTSH preparation. The model duration avoided the need for discounting.

RESULTS

The additional benefits of rhTSH (0.0576 QALY) are obtained with an incremental cost of CDN$87, generating an incremental cost per QALY of CDN$1520. Deterministic one-way and two-way sensitivity analyses demonstrated the result to be robust.

CONCLUSIONS

The use of rhTSH before radioiodine ablation represents a reasonable allocation of costs, with the benefits to patients, hospitals, and society as a whole, obtained at modest cost.

Follow-up of low-risk differentiated thyroid cancer patients who underwent radioiodine ablation of postsurgical thyroid remnants after either recombinant human thyrotropin or thyroid hormone withdrawal

BACKGROUND

We previously demonstrated comparable thyroid remnant ablation rates in postoperative low-risk thyroid cancer patients prepared for administration of 3.7GBq (131)I (100 mCi) after recombinant human (rh) TSH during T(4) (L-T4) therapy vs. withholding L-T4 (euthyroid vs. hypothyroid groups). We now compared the outcomes of these patients 3.7 yr later.

PATIENTS AND METHODS

Fifty-one of the 63 original patients (28 euthyroid, 23 hypothyroid) participated. Forty-eight received rhTSH and serum thyroglobulin (Tg) sampling. A (131)I whole-body scan was performed in 43 patients, and successful ablation was defined by criteria from the previous study. Based on the criterion of uptake less than 0.1% in thyroid bed, 100% (43 of 43) remained ablated. When no visible uptake instead was used, five patients (four euthyroid, one hypothyroid) had minimal visible activity. When the TSH-stimulated Tg criterion was used, only two of 45 (one euthyroid, one hypothyroid) had a stimulated Tg level greater than 2 ng/ml.

RESULTS

No patient in either group died, and no patient declared disease free had sustained tumor recurrence. Nine (four euthyroid, five hypothyroid) had received additional (131)I between the original and current studies due to detectable Tg or imaging evidence of disease; with follow-up, all now had a negative rhTSH-stimulated whole-body scan and seven (three euthyroid, four hypothyroid) had a stimulated serum Tg less than 2 ng/ml.

CONCLUSIONS

In conclusion, after a median 3.7 yr, low-risk thyroid cancer patients prepared for postoperative remnant ablation either with rhTSH or after L-T4 withdrawal were confirmed to have had their thyroid remnants ablated and to have comparable rates of tumor recurrence and persistence.

Preparation with recombinant humanized thyroid-stimulating hormone before radioiodine ablation after thyroidectomy: a systematic review

BACKGROUND

Standard treatment for differentiated thyroid cancer is thyroidectomy followed in selected cases by radioiodine ablation (RA). Recombinant humanized thyroid-stimulating hormone (rhTSH) is an exogenous source of tsh that can be administered to obviate the need for hormone withdrawal. In this systematic review, we analysed the evidence for the therapeutic use of (rhTSH for RA preparation.

METHOD

A systematic review of the MEDLINE and EMBASE databases from 1996 through January 2008 selected articles reporting randomized controlled trials, cohort studies, and retrospective studies published in English that compared ra using rhTSH with standard hormone withdrawal.

RESULTS AND INTERPRETATION

Stimulation by rhTSH is equivalent to thyroid hormone withdrawal in achieving ablation while avoiding detrimental symptoms of hypothyroidism and significantly lowering the whole-body radiation dose. Furthermore, rhTSH may be the only option for patients who either cannot raise endogenous tsh or who would be at risk from the morbidity of hypothyroidism. Based on the results of validated instruments of physical and mental performance, there is agreement that rhTSH maintains a better quality of life. Studies of cost-effectiveness found that rhTSH-prepared patients lost less time from work and required fewer encounters with health care providers.

The therapeutic management of differentiated thyroid cancer

BACKGROUND

The management of thyroid cancer is difficult because the tumors comprise a wide range of biologic behaviors, from small papillary thyroid microcarcinomas that pose little or no threat to survival for the patient, to anaplastic thyroid cancers that are arguably the most lethal tumor. Although it may be difficult initially to determine at which end of the prognostic spectrum a patient resides, one can ordinarily estimate a patient's risk for tumor recurrence and mortality based on a triad of features as simple as the patient's age at the time of diagnosis, the tumor stage at presentation, and its initial response to therapy. While staging systems are available to assist in the management process, all are inexact and leave wide gaps in the treatment plan for a given patient. This is largely because randomized controlled trials are lacking as a result of the low incidence and generally favorable prognosis of the disease. As a practical matter, it may sometimes be difficult to reassure a patient, given the generally favorable prognosis of this group of tumors, knowing that without adequate therapy some become unexpectedly aggressive and recur years after initial management. The treatment of these tumors rests on a fine balance of providing care that reflects the anticipated course of the disease without overtreating the patient or providing reassurance that is unfounded.

OBJECTIVE

To outline the treatment strategy for patients with differentiated thyroid cancer based on the available literature and to guide clinicians through a management algorithm utilizing patient and tumor characteristics.

METHODS

This review is limited to the treatment of patients with differentiated thyroid cancer - papillary and follicular thyroid cancer - and the standard therapy required for the majority of patients.

RESULTS/CONCLUSION

The treatment of differentiated thyroid cancer requires a multidisciplinary approach, involving an experienced surgeon, radiologists and an endocrinologist. There are many unanswered questions in the management algorithm and ongoing research is needed to further define the best treatment strategy for patients with differentiated thyroid cancer.

Recombinant human thyroid stimulating hormone in 2008: focus on thyroid cancer management

Radioiodine (RAI) ablation following thyroidectomy is standard of care treatment for patients with intermediate or high risk differentiated thyroid cancer. Traditionally, this has been achieved by forgoing thyroid hormone replacement postoperatively, allowing endogenous thyroid stimulating hormone (TSH) levels to rise. This rise in TSH provides the stimulus for RAI uptake by the thyroid remnant, but is associated with clinical hypothyroidism and its associated morbidities. Recombinant human TSH (rhTSH, thyrotropin alfa [Thyrogen^®], Genzyme Corporation, Cambridge, MA, USA) was developed to provide TSH stimulation without withdrawal of thyroid hormone and clinical hypothyroidism. Phase III studies reported equivalent detection of recurrent or residual disease when rhTSH was used compared with thyroid hormone withdrawal (THW). These trials led to its approval as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without RAI imaging in the surveillance of patients with differentiated thyroid cancer. Recently, rhTSH was given an indication for adjunctive preparation for thyroid remnant ablation after phase III studies demonstrated comparable outcomes for rhTSH preparation when compared with THW. Importantly, rhTSH stimulation has been found to be safe, well tolerated, and to result in improved quality of life. Here, we review the efficacy and tolerability studies leading to the approval for the use of rhTSH in well-differentiated thyroid cancer management.

Diagnostic and therapeutic use of recombinant human TSH (rhTSH) in differentiated thyroid cancer

Traditionally, withdrawal of thyroid hormone to increase serum levels of thyroid-stimulating hormone (TSH) has been used in patients with differentiated thyroid carcinoma (DTC) to optimize radio-iodine uptake and serum thyroglobulin (Tg) stimulation during follow-up and in preparation for radio-iodine therapy. However, this procedure is associated with signs and symptoms of hypothyroidism which negatively affect the patient's quality of life. Recombinant human thyrotropin (rhTSH) has provided an effective alternative to thyroid hormone withdrawal. After favourable experimental trials in humans, rhTSH obtained regulatory approval in North America and in Europe as a diagnostic tool, and more recently as a preparation for radio-iodine thyroid remnant ablation. Since then, rhTSH has radically changed the diagnostic and therapeutic management of DTC patients. This review will focus on the clinical application of rhTSH in the management of DTC, highlighting current indications and future perspectives.

Radio-iodine therapy in differentiated thyroid cancer: indications and procedures

Post-surgical ablative iodine-131 therapy is recommended for all differentiated thyroid cancer primary tumors>1 cm in diameter. Regarding smaller primary tumors, 131I ablation may be helpful in special cases: tumor close to the thyroid capsule, previous percutaneous radiation to the neck, familial occurrence of thyroid cancer, tumor diameter 5-10 mm, and unfavorable histological variants. In this context, the patient's preferences for safety should be considered. In most centers, standard fixed activities of 1-3 GBq are used for 131I ablation. Preparation for the procedure with such activities requires a low-iodine diet for 2-3 weeks and stimulation of thyroid stimulating hormone (TSH) by withholding of thyroid hormone for 3 weeks following thyroidectomy or by use of recombinant human TSH. The advantages of recombinant TSH are avoidance of hypothyroid morbidity and consequently a better quality of life, as well as a lower radiation dose to extra-thyroidal compartments. To treat metastastic differentiated thyroid cancer, higher activities of radio-iodine (in the range 4-11 GBq) are necessary; if possible, individual dosimetry is recommended. The standard approach to preparation for 131I therapy in patients with metastases is endogenous hypothyroidism after thyroid hormone withdrawal.

Length and cost of hospital stay of radioiodine ablation in thyroid cancer patients: comparison between preparation with thyroid hormone withdrawal and thyrogen

PURPOSE

Treatment of thyroid cancer consists of thyroidectomy and radioiodine ablation following thyroid-stimulating hormone (TSH) stimulation. Similar ablation rates were obtained with either thyroid hormone withdrawal (THW) or rhTSH. But with rhTSH, the elimination of radioiodine is more rapid, thus reducing its whole-body retention and potentially resulting in a shorter hospital stay. The aim of this study was to assess the financial impact of a reduced length of hospital stay with the use of rhTSH.

METHODS

This was a case-control study of thyroid cancer patients treated postoperatively with 3,700 MBq (100 mCi) radioiodine; 35 patients who received rhTSH were matched with 64 patients submitted to THW according to covariates influencing radioiodine retention. The length of hospitalization (LOH) was estimated for each method according to the threshold of radioiodine retention below which the patient can be discharged from the hospital. The economic analysis was conducted from a hospital perspective. Simulations were performed.

RESULTS

For a threshold of 400 MBq, the LOH was 2.4 days and 3.5 days with rhTSH and THW, respectively, and the cost for an ablation stay was, respectively, 2,146 and 1,807 <euro>. In the French context, 57% of the acquisition cost of rhTSH was compensated by the reduction of the length of hospitalization.

CONCLUSION

By increasing the iodine excretion, rhTSH allows a shorter hospitalization length, which partially compensates its acquisition cost.

Management of low-risk differentiated thyroid cancer

OBJECTIVE

To summarize the definitions of and management recommendations for low-risk thyroid cancer made by the American and European Thyroid Associations and synthesize this information with the recent literature, including systematic evaluations of tumor staging systems guiding therapy.

METHODS

The American Thyroid Association and European Thyroid Association guidelines were compared and pertinent literature since 2005 was reviewed.

RESULTS

Of papillary thyroid microcarcinomas (PTMC), up to 50% breach the thyroid capsule, 64% have lymph node metastases, up to 43% are multifocal, and as many as 2.8% have distant metastases. Locoregional and distant recurrences are, respectively, as high as 5.9% and 1.5%. As many as 1 in 4 patients with a papillary thyroid carcinoma 1.5 cm or smaller develop persistent disease. Cancer-related mortality rates are usually less than 1%, but are as high as 2% in some reports. Tumor staging systems are too inaccurate to guide therapy.

CONCLUSION

It is unlikely that many patients will forgo treatment after understanding their risk, especially when total thyroidectomy and radioiodine (131I) therapy can reduce the PTMC recurrence or persistence disease rate to zero. Preoperatively diagnosed PTMC should be treated with total or near-total thyroidectomy, regardless of tumor size. For very low-risk patients with unifocal PTMC smaller than 1 cm that is removed by chance during surgery to treat benign thyroid disease, lobectomy alone without 131I therapy may be sufficient therapy if there are no concerning histologic features and no tumor extension beyond the thyroid, metastases, history of head and neck irradiation, or positive family history--any of which requires total or near-total thyroidectomy and remnant ablation with 30 mCi.

Circulating thyroid cancer markers

PURPOSE OF REVIEW

To describe the progress in the field of circulating markers of thyroid cancer.

RECENT FINDINGS

Thyroid cancer cells in the circulation can be detected by measuring the mRNA of thyroid-specific genes. Among these, thyroglobulin, and more recently thyroid-stimulating hormone receptor mRNAs' provide high diagnostic sensitivity and specificity for thyroid cancer detection. These markers can be used in synergy with current diagnostic modalities, i.e. fine-needle aspiration and ultrasound, for preoperative diagnosis and serum thyroglobulin measurement for monitoring.

SUMMARY

For the detection of recurrent/residual thyroid cancer, serum thyroglobulin remains the sole circulating marker, but lacks sensitivity and is unreliable in the presence of antithyroglobulin antibodies. The measurement of thyroid-specific mRNA in blood may provide sensitive/specific markers, but significant variability exists among various studies for thyroglobulin mRNA in particular, questioning the validity of this marker. Recent studies have demonstrated the high sensitivity and specificity of thyroid-stimulating hormone receptor mRNA in detecting recurrent/residual disease even in the presence of thyroglobulin antibodies. Fine-needle aspiration biopsy is currently the sole method for evaluating thyroid nodules. Indeterminate fine-needle aspiration cytology is found in approximately 15-30% of specimens. Thyroid-stimulating hormone receptor mRNA measurement in patients with indeterminate fine-needle aspiration may enhance cancer detection and save unnecessary surgeries.

How the availability of recombinant human TSH has changed the management of patients who have thyroid cancer

Recombinant human TSH (rhTSH) is used in patients who have had surgery for thyroid cancer but are at low risk of recurrence. The rhTSH is used for the preparation of postoperative administration of 3.7 GBq (100 mCi) of radioiodine for thyroid-remnant ablation and for the determination of serum thyroglobulin levels during follow-up. In these two conditions, the efficiencies of levothyroxine withdrawal and rhTSH administration are similar; however, rhTSH can be administered during levothyroxine treatment, and its use avoids the hypothyroid period induced by levothyroxine withdrawal, reduces whole body exposure after radioiodine administration, avoids potential morbidity and maintains a better quality of life compared with hormone withdrawal.

Uso do TSH humano recombinante no câncer diferenciado de tireóide

O seguimento imediato após tireoidectomia total (TT), em pacientes com câncer diferenciado de tireóide (CDT), tradicionalmente é feito com a ablação de remanescentes tireoidianos (RT) com 131I, na vigência de hipotireoidismo. O seguimento tardio do CDT inclui o uso de doses supressivas de T4, dosagem seriada da tireoglobulina (Tg), pesquisa de corpo inteiro (PCI) com 131I e ultra-sonografia (US) cervical. Nos últimos anos, tem-se mostrado que a ablação de RT com a ajuda do TSH recombinante humano (rhTSH) tem a mesma eficácia que a ablação de RT observada com a elevação endógena do TSH, mas sem os sintomas e piora de qualidade de vida descritos no hipotireoidismo. A dosagem da Tg estimulada com TSH endógeno ou exógeno, 9 a 12 meses após o tratamento inicial do CDT, associado à US cervical, pode identificar pacientes de baixo risco potencialmente curados de sua doença e nos quais a supressão do TSH não necessita ser tão intensa, evitando as complicações cardíacas e ósseas da tireotoxicose exógena prolongada. Finalmente, apesar de não existirem estudos randomizados que avaliem o papel do rhTSH no tratamento do CDT metastático, os resultados do tratamento combinado do rhTSH e 131I mostram um benefício clínico na maioria dos pacientes tratados.

Radioiodine ablation of post-surgical thyroid remnants after preparation with recombinant human TSH: Why, how and when

AIMS

The use of recombinant human TSH (rhTSH) represents one of the most exciting innovations in the field of differentiated thyroid cancer (DTC) management, but the use of rhTSH for radioiodine post-surgical thyroid remnant ablation is still controversial. The aim of this review is to provide the reader with an analysis of the literature regarding the use of rhTSH for the radioiodine ablation of post-surgical thyroid remnants.

METHODS

We performed a literature search of the most relevant papers in the PubMed database.

FINDINGS AND CONCLUSIONS

To date, five prospective studies have been published regarding this topic and there is strong evidence of the effectiveness of rhTSH, at least when high doses of 131I are used. Vice-versa, data regarding the outcome of ablation using low doses (30 mCi) are quite different in the studies published. So the problem of the amount of 131I to be administered and the influence of iodine intake is still open. In fact, the results of some studies suggest that 131I uptake could be particularly dependent on iodine intake during the euthyroid state and when low doses of 131I are used. This could be the reason for the reduced radioiodine uptake observed in other studies. However, also when rhTSH stimulation had produced a reduced iodine uptake, this was at least partially compensated for by an increased half-time in thyroid cells. So rhTSH stimulation appears to have pathophysiological bases which all lead to a powerful destructive effect by 131I on thyroid cells. All the data in the literature appear concordant that rhTSH is safe and associated to a good quality of life and the problem of costs appears negligible when compared to the benefits for the patient. In most cases, the use of rhTSH, for radioiodine ablation of post-surgical thyroid remnants can represent the best therapeutic option that we can offer to the patient.