Recombinant human thyrotropin is helpful in the follow-up and 131I therapy of patients with thyroid cancer: a report of the results and benefits using recombinant human thyrotropin in clinical routine

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.

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.

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.

Review on the occasion of a decade of recombinant human TSH: prospects and novel uses

The introduction of recombinant human thyroid-stimulating hormone (rhTSH) almost a decade ago represents a remarkable achievement in the history of clinical thyroidology. rhTSH now contributes substantially to the diagnostic approach to thyroid cancer, offering a reliable and safe alternative to thyroid hormone withdrawal by avoiding the morbidity of hypothyroidism. Several recent studies have also demonstrated the efficacy of radioiodine ablation of thyroid remnants after preparation with rhTSH. Moreover, the use of rhTSH in this context is associated with a lower whole body exposure to radiation compared to thyroid hormone withdrawal. Although not approved officially, rhTSH-assisted treatment of locoregional or distant metastatic disease may be the treatment of choice for patients in whom hypothyroidism may be relatively contraindicated, such as the very young and the aged, although additional efficacy studies are necessary. The compound has also been shown to be useful in the treatment of nontoxic multinodular goiter, especially when the radioiodine uptake is low. Finally, rhTSH may prove to be useful in studying the functional reserve of thyroid in the aging process, as well as the putative role of the TSH receptor in extrathyroidal tissue, such as lymphocytes, osteocytes, and adipocytes.

Recombinant thyrotropin in the diagnosis of congenital hypothyroidism

CONTEXT

A modern approach to congenital hypothyroidism requires a definitive diagnosis of the underlying mechanisms; this can be achieved within the first weeks of life. When uncertainty persists, treatment is commenced, and the definitive diagnosis of congenital hypothyroidism is deferred to the age of 3 yr.

OBJECTIVES

The interruption of thyroid replacement treatment is perceived as risky by parents and physicians. The aim of this pilot study was to test the possibility of a definitive diagnosis during thyroid replacement treatment, using stimulation of thyroid tissue by recombinant human (rh)TSH.

SUBJECTS

Eight patients, three boys and five girls, age 5-15 yr (mean, 9.5+/-3.7 yr), with congenital hypothyroidism that had been diagnosed by the neonatal screening program, and having their diagnosis verified between the ages of 3-4 yr, were reevaluated while on thyroid replacement therapy.

INTERVENTIONS

Patients received im 0.6 mg/m2 rhTSH on two consecutive days.

RESULTS

rhTSH pharmacokinetics, maximal concentration, t1/2, and area under the curve in children were different as compared with adults. In the patients with intact TSH receptors, free T4 levels decreased after the first and the second injection of rhTSH (P=0.0137 and P=0.0149, respectively). All eight children showed identical scintigraphy after rhTSH administration as compared with thyroid replacement withdrawal.

CONCLUSIONS

The use of rhTSH is effective for definitive diagnosis of congenital hypothyroidism during thyroid replacement treatment, and no safety issues were encountered.

Short-term hypothyroidism after Levothyroxine-withdrawal in patients with differentiated thyroid cancer: clinical and quality of life consequences

Acute hypothyroidism induced by thyroid hormone withdrawal in patients with differentiated thyroid cancer during monitoring for remnant or metastatic disease, seriously affects multiple organs and systems, and especially in severe cases can impair quality of life. Indeed, it may induce untoward cardiovascular effects and can be hazardous in patients with underlying cardiovascular disease, particularly in the elderly. Moreover, acute hypothyroidism deranges the lipid profile and exacerbates neuropsychiatric illness. The introduction of recombinant human TSH (rhTSH) as a diagnostic and therapeutic tool in the care of patients with thyroid cancer has widened the scope of disease management. The use of rhTSH prevents derangement of various systems at approximately equivalent societal costs to that of withdrawal and promotes compliance while preserving the patient's normal daily functioning and productivity. Its reliability allied with its safety render this compound a valid alternative in the monitoring of patients with differentiated thyroid carcinoma as well as providing an alternative therapeutic procedure whenever LT4-withdrawal may be hazardous or in cases of patient non-compliance.

Unique treatment policy for well-differentiated thyroid cancer in Japan: results of a questionnaire distributed to members of the Japanese Society of Thyroid Surgery and the International Association of Endocrine Surgeons

Although surgery has been the mainstay of treatment for patients with well-differentiated thyroid cancer, the extents of thyroid resection and lymph node dissection adopted in Japan differ from those in other countries. Furthermore, regarding the indications for postoperative radiation therapy and hormonal therapy, and treatment modalities for cancer recurrence, there are marked discrepancies between Japan and other countries. A questionnaire survey was thus conducted among domestic and overseas thyroid surgeons to ascertain the actual treatment policy for well-differentiated thyroid cancer in Japan and various foreign countries. For small papillary carcinomas of 2.0 cm or less (T1), thyroid resection was more extensive in foreign countries than in Japan, although the extent of lymph node dissection was limited in the former. For large papillary carcinomas exceeding 3.0 cm (T2), on the other hand, total thyroidectomy was the treatment of first choice for all overseas respondents, but of only 20% in Japan, despite lymph node dissection being more extensive in Japan than in other countries. Overseas surgeons were much more likely to favor postoperative TSH suppression therapy and high-dose (131)I therapy. For recurrence following surgery for papillary thyroid cancer, both domestic and overseas respondents indicated surgical resection to be the most common treatment option, and favored high-dose (131)I therapy as well. In Japan, however, high-dose (131)I therapy is available only in a few institutions. Such limited indications for high-dose (131)I therapy in Japan may reflect a discrepancy in the frequency of total thyroidectomy, a prerequisite for postoperative high-dose (131)I therapy, between Japan and other countries. This is the first questionnaire study conducted in both Japan and other countries in relation to treatment modalities for thyroid cancer. The results reveal that there is a clear disparity in treatment policies between Japan and foreign countries.

Recombinant human thyrotropin-assisted radioiodine therapy for patients with metastatic thyroid cancer who could not elevate endogenous thyrotropin or be withdrawn from thyroxine

The value of recombinant human thyrotropin (rhTSH) as preparation for radioiodine therapy was assessed in 115 patients with metastatic thyroid cancer. Patients who were either unable to elevate endogenous TSH during thyroxine withdrawal, or in whom thyroxine withdrawal was contraindicated for medical reasons were eligible. Their physicians requested rhTSH as part of the Thyrogen Compassionate Use Program. This is a retrospective summary of the nonrandomized uncontrolled experience. We assessed the ability of rhTSH to elevate the serum TSH; to avoid the complications of hypothyroidism; to stimulate radioiodine uptake; and to stimulate the serum thyroglobulin. Disease response and adverse events were also assessed. After rhTSH, the serum TSH levels rose to >or=25mU/L in every patient in whom levels were measured (n = 112). Hypothyroid complications were avoided in 22 of 25 patients who had experienced them in the past, and in 47 of 51 patients who were at high risk for hypothyroid complications. Radioiodine uptake was present on whole-body scans (WBS) in 105 of the 115 patients. Serum thyroglobulin levels were lower than baseline in 73% of patients assessed at 12 months. Cancer-related symptoms were improved in approximately 25%. Two patients had serious adverse events that were thought to be related to rhTSH. rhTSH elevates serum TSH and facilitates radioiodine uptake in patients who cannot produce endogenous TSH or who cannot tolerate hypothyroidism.

Estudio comparativo entre la utilización de TSH recombinante y la estimulación endógena con TSH. Valoración en el seguimiento de los pacientes con carcinoma diferenciado de tiroides

Recombinant human thyrotropin (rhTSH) has been introduced recently in follow up of differentiated thyroid cancer (DTC) patients, as an alternative of thyroid hormone withdrawal. The aim of this retrospective study is to compare recombinant human thyrotropin versus endogenous stimulation.

MATERIAL AND METHODS

Thirty-three patients with DTC with previous thyroidectomy and thyroid ablation were selected. All patients underwent whole-body radioiodine scanning and third day serum thyroglobulin (TG) measurement by two techniques, the first one after conventional thyroid hormone withdrawal (TSHe, TGe), and the second one after rhTSH stimulation (TSHr, TGr). Measurement of TG was performed on the third day due to the infrastructure. We only included patients with stable disease, without therapeutic interventions between two consecutive controls in an interval inferior to one year. Two qualitative categories were defined for TG (positive TG > 2 ng/ml or negative TG<2 ng/ml) and whole-body radioiodine scan (positive or negative).

RESULTS

TSHe: 62.9 +/- 55.48; TSHr: 113.16 +/- 50.6; (p: ns); TGe: 62.5 +/- 115.7; TGr: 54.6 +/- 111.1; (p: 0.044). Quantitative data analysis showed significant differences between two techniques. Qualitative data analysis showed no significant differences in clinical setting based in TG and radioiodine scan.

CONCLUSIONS

Administration of rhTSH produces a significantly higher increase of TSH than thyroid hormone withdrawal and lower increase in TG levels. There were no significant differences in the stage of disease (TG and whole-body radioiodine scan).

Respective Roles of Thyroglobulin, Radioiodine Imaging, and Positron Emission Tomography in the Assessment of Thyroid Cancer

Depending on the iodine supply of an area, the incidence of thyroid cancer ranges between 4 and 12/100,000 per year. To detect thyroid cancer in an early stage, the assessment of thyroid nodules includes ultrasonography, ultrasonography-guided fine-needle aspiration biopsy, and conventional scintigraphic methods using (99m)Tc-pertechnetate, (99m)Tc-sestamibi or -tetrofosmin, and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in selected cases. After treatment of thyroid cancer, a consequent follow-up is necessary over a period of several years. For following up low-risk patients, recombinant thyroid-stimulating hormone-stimulated thyroglobulin and ultrasonography is sufficient in most cases. After total thyroidectomy and radioiodine ablation therapy, thyroid-stimulating hormone-stimulated thyroglobulin should be below the detection limit (eg, <0.5 ng/mL, R: 70-130). An increase of thyroglobulin over time is suspicious for recurrent or metastatic disease. Especially in high-risk patients, aside from the use of ultrasonography for the detection of local recurrence and cervial lymph node metastases, nuclear medicine methods such as radioiodine imaging and FDG-PET are the methods of choice for localizing metastatic disease. Radioiodine imaging detects well-differentiated recurrences and metastases with a high specificity but only moderate sensitivity. The sensitivity of radioiodine imaging depends on the activity administered. Therefore a low activity diagnostic (131)I whole-body scan (74-185 MBq) has a lower detection rate than a high activity post-therapy scan (3700-7400 MBq). In patients with low or dedifferentiated thyroid cancer and after several courses of radioiodine therapy caused by metastatic disease, iodine negative metastases may develop. In these cases, despite clearly elevated levels of thyroglobulin, radioiodine imaging is negative or demonstrates only faint iodine uptake. The method of choice to image these iodine negative metastases is FDG-PET. In recent years the combination of PET and computed tomography has been introduced. The fusion of the metabolic and morphologic information was able to increase the diagnostic accuracy, reduces pitfalls and changes therapeutic strategies in a reasonable number of patients.