title: Prognostic significance of successful ablation with radioiodine of differentiated thyroid cancer patients.
abstract: OBJECTIVE
  Currently, little is known about the prognostic significance of achieving successful ablation with the first dosage of I-131 in patients with differentiated thyroid cancer. This study aimed to assess the following: (i) whether successful or unsuccessful ablation at post-ablation follow-up has prognostic consequences; (ii) possible factors predicting success of ablation in a patient.
  
  
  METHODS
  In order to do this, we retrospectively studied 180 patients with a median follow-up of 55 months. Ablation was considered to be successful if 1 year after the initial dosage of I-131 patients fulfilled all of the following criteria: not dead from thyroid cancer, no additional therapy needed for any kind for thyroid cancer within the first year, undetectable thyroglobulin (Tg) levels under TSH stimulation, and negative I-131 scintigraphy. Tg levels at the time of ablation (P < 0.001), lymph node metastasis (P = 0.04) and distant metastasis (P < 0.001) have a significant influence on the success of ablation. P values were calculated by Mann-Whitney U test and Chi-square test, respectively.
  
  
  RESULTS
  Patients with successful ablation had a better prognosis than those with unsuccessful ablation: disease-free survival was 87% versus 49% after 10 years; additionally, thyroid-cancer related survival was 93% versus 78%.
  
  
  CONCLUSIONS
  We conclude that the extent of the remaining normal or neoplastic thyroid tissue influences the outcome of ablation, and that successful ablation leads to a better prognosis. It seems that it is very important to achieve complete ablation as soon as possible in order to ensure the best possible prognosis for a patient.
authors.affiliation: Department of Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. e.verburg@azu.nl
authors.forename: Frederik A
authors.initials: FA
authors.lastname: Verburg
authors.forename: Bart
authors.initials: B
authors.lastname: de Keizer
authors.forename: Cornelis J M
authors.initials: CJ
authors.lastname: Lips
authors.forename: Pierre M J
authors.initials: PM
authors.lastname: Zelissen
authors.forename: John M H
authors.initials: JM
authors.lastname: de Klerk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018265:Carcinoma, Papillary, Follicular / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D016019:Survival Analysis; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin