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

Abstract

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.

Does 131I Radioactivity Interfere with Thyroglobulin Measurement in Patients Undergoing Radioactive Iodine Therapy with Recombinant Human TSH?

“…Hypothyroidism is inevitable before RIT, and hypothyroidism decreases patient QOL. rhTSH improves a patient's QOL by avoiding long-term hypothyroidism [11]. rhTSH is expensive; hence, there is considerable controversy surrounding the cost-effectiveness of using rhTSH [17].…”

“…However, recently, recombinant human thyroid-stimulating hormone (rhTSH) was approved for RIT for thyroid hormone stimulation, thereby substituting thyroid hormone withdrawal. Compared to the use of conventional thyroid hormone withdrawal, the use of rhTSH for TSH stimulation significantly improved the quality of life (QOL) during RIT, avoided iatrogenic hypothyroidism symptoms, and sustained the liver and kidney functions [11,12]. 131 I predominantly emits 363 and 637 keVof energy in a twostep decay process.…”

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

“…In general agreement scanning time of 24 h after oral administration of 131 I is useful [1,22,26]. Rani et al [26] calculated the radiation absorbed dose in lung or skeletal metastases by DTC and found s slight no statistically difference in 24 h 131 I %uptake between THW and rhTSH protocol. The mean 24 h 131 I % uptakes of lesions were 4.84% after THW and 3.56% after rhTSH (p ¼ 0.301).…”

Recombinant Human Thyroid-Stimulating Hormone Versus Thyroid Hormone Withdrawal in124I PET/CT–Based Dosimetry for131I Therapy of Metastatic Differentiated Thyroid Cancer

“…Multiple previous reports demonstrated reduced absorbed dose to the blood (e.g., bone marrow) in patients prepared with rhTSH injections (3)(4)(5)(6)(7)(8). The reduced absorbed dose to the organs is attributed to the more rapid clearance of radioiodine when the patient is euthyroid versus hypothyroid (21).…”

“…For the absorbed dose to nontumor tissues, more reports have been published. These publications typically evaluated whole-body or bone marrow dosimetry using 131 I or 123 I; used dosimetry calculation methods that were not specifically developed for radiopharmaceutical therapy, which are not as quantitative as 124 I PET/CT-based methods, and were not necessarily performed in patients with metastatic disease; or did not compare THW versus rhTSH injections in the same patient (3)(4)(5)(6)(7)(8). The objective of this study was 3-fold: to calculate the absorbed dose to bone marrow and multiple other critical organs (e.g., lung, liver, heart, and kidneys) using 124 I PET/CT and dosimetry software that specifically accounts for patient anatomy and activity distribution (e.g., 3D-RD) in patients with metastatic DTC; to calculate the absorbed dose to tumors and the tumor-to-dose-limiting organ absorbed dose ratio for both studies (rhTSH and THW); and to compare the absorbed doses to those critical organs and tumors after preparation with THW versus rhTSH, with the patient being his own control.…”