title: Recombinant TSH stimulated remnant ablation therapy in thyroid cancer: the success rate depends on the definition of ablation success--an observational study.
abstract: BACKGROUND
  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.
  
  
  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%).
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Dutch Trial Registration NTR2395.
authors: Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Anouk N A
authors: AN
authors: van der Horst-Schrivers
authors: Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Wim J
authors: WJ
authors: Sluiter
authors: Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Anneke C
authors: AC
authors: Muller Kobold
authors: Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Bruce H R
authors: BH
authors: Wolffenbuttel
authors: Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: John T M
authors: JT
authors: Plukker
authors: Academic Medical Center, University of Amsterdam, Department of Endocrinology, Amsterdam, the Netherlands.
authors: Peter H
authors: PH
authors: Bisschop
authors: Meander Medical Center Amersfoort, Department of Nuclear Medicine, Amersfoort, the Netherlands.
authors: John M
authors: JM
authors: de Klerk
authors: Leiden University Medical Center, Department of Nuclear Medicine and Molecular Imaging, Leiden, the Netherlands.
authors: Imad
authors: I
authors: Al Younis
authors: VU University Medical Center, Department of Internal Medicine/Endocrinology, Amsterdam, the Netherlands.
authors: Paul
authors: P
authors: Lips
authors: Radboud University Nijmegen Medical Center, Department of Internal Medicine, Nijmegen, the Netherlands.
authors: Jan W
authors: JW
authors: Smit
authors: Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Adrienne H
authors: AH
authors: Brouwers
authors: Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Thera P
authors: TP
authors: Links
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D013954:Thyroglobulin / Q000378:metabolism; D013961:Thyroid Gland / Q000473:pathology / Q000601:surgery; D013964:Thyroid Neoplasms / Q000473:pathology / Q000601:surgery*; D013965:Thyroidectomy; D013972:Thyrotropin / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D013972:Thyrotropin; D013954:Thyroglobulin