title: Radioactive iodine administered for thyroid remnant ablation following recombinant human thyroid stimulating hormone preparation also has an important adjuvant therapy function.
abstract: BACKGROUND
  In December 2007, the USFDA approved recombinant human thyroid stimulating hormone (rhTSH) for radioiodine remnant ablation after total thyroidectomy in patients with well-differentiated thyroid cancer without evidence of metastatic disease. Because previously undetected radioactive iodine (RAI)-avid metastatic lesions can be identified during remnant ablation, we sought to determine if rhTSH-stimulated uptake of RAI into these incidentally discovered metastases is associated with a significant therapeutic (tumoricidal) effect.
  
  
  METHODS
  This retrospective review describes the clinical outcome of 84 well-differentiated thyroid cancer patients in whom RAI-avid lesions outside the thyroid bed were first identified at the time of RAI remnant ablation (64 rhTSH stimulated, 20 thyroid hormone withdrawal [THW]) on either the diagnostic (63/84, 75%) or posttherapy (21/84, 25%) whole body scan (76 with locoregional metastasis only and 8 with pulmonary uptake). Following ablation, patients were classified as having either no evidence of disease or persistent disease on the basis of subsequent diagnostic whole body RAI scans, stimulated thyroglobulin, and cross-sectional imaging studies.
  
  
  RESULTS
  Despite having RAI-avid metastatic disease identified outside the thyroid bed at the time of initial ablation, 70% (45/64) of rhTSH-assisted patients and 55% (11/20) of the THW group had no evidence of disease at a median of 2.7 years following the initial RAI ablation (p = 0.159). THW and rhTSH-stimulated RAI ablation had similar efficacy in eliminating RAI-avid locoregional metastases (42/60, 70% of rhTSH and 10/16, 63% of THW, p = 0.65) and pulmonary metastases (3/4, 75% of rhTSH and 1/4, 25% of THW, p = 0.41).
  
  
  CONCLUSIONS
  Preparation with either rhTSH or THW in this retrospective study appears to have similar therapeutic (tumoricidal) effects on small volume RAI-avid metastatic disease incidentally discovered at the time of ablation in both locoregional lymph nodes and pulmonary parenchyma.
authors.affiliation: Endocrinology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. tuttlem@mskcc.org
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
authors.forename: Norma
authors.initials: N
authors.lastname: Lopez
authors.forename: Rebecca
authors.initials: R
authors.lastname: Leboeuf
authors.forename: Shaye M
authors.initials: SM
authors.lastname: Minkowitz
authors.forename: Ravinder
authors.initials: R
authors.lastname: Grewal
authors.forename: Matvey
authors.initials: M
authors.lastname: Brokhin
authors.forename: Gal
authors.initials: G
authors.lastname: Omry
authors.forename: Steve
authors.initials: S
authors.lastname: Larson
mesh_terms: D055011:Ablation Techniques; D018263:Adenocarcinoma, Follicular / Q000628:therapy*; D000231:Adenocarcinoma, Papillary / Q000628:therapy*; D000328:Adult; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000627:therapeutic use*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000628:therapy*; D013965:Thyroidectomy; D013972:Thyrotropin / Q000627:therapeutic use*; D016896:Treatment Outcome; D051598:Whole Body Imaging
chemical_list: D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D013972:Thyrotropin