title: Implication of different clinical and pathological variables in patients with differentiated thyroid cancer on successful ablation for 3700 MBq (131)I: a single Egyptian institutional experience over 14 years.
abstract: OBJECTIVE
  Is to investigate possible factors predicting success of ablation for 3700 MBq radioactive iodine 131 in patients with differentiated thyroid cancer (DTC) following near total thyroidectomy.
  
  
  METHODS
  This retrospective study enrolled 272 patients between 2000 and 2014. The success or failure of ablation was assessed 6 months after given the dose and our criteria for complete successful remnant ablation defined as: Negative (131)I whole body scan with no residual functioning thyroid tissue or distant functioning metastases and stimulated thyroglobulin (Tg) level less than 2 ng/ml. Different clinical and pathological factors, such as age, gender, tumor histology, grade and variants, size of primary malignant lesion, stage, and risk assessment according to the American (ATA) and European Thyroid Association (ETA) guidelines, associated pathology, tumor mutifocality, lymph node (LN) metastases and their number, invasiveness of the tumor (capsular invasion of the nodule, extra-thyroidal extension, and vascular invasion), baseline stimulated Tg level, and pre-ablative diagnostic scan were assessed.
  
  
  RESULTS
  There were 185 successful ablations (68 %). The baseline-stimulated Tg measured before the ablation was the only independent predictor of ablation success in multivariate analysis (P < 0.0001) with odds ratio (OR) of 2.64 (95 % CI: 1.54-4.54) and the optimal cutoff for this was 3.8 ng/mL. On the univariate analysis, LN metastases was predictor of ablation failure (P value = 0.03).
  
  
  CONCLUSIONS
  Baseline-stimulated Tg level is clinically important and had a significant predictive value for successful ablation; therefore, higher pre-ablation Tg should potentially be incorporated in the decision making for (131)I dosage or other treatment. In accordance with other studies, this is also applicable to cervical lymph nodal involvement and thyroid capsule invasion.
authors.affiliation: Nuclear Medicine Unit, Department of Radiotherapy and Nuclear Medicine (NEMROCK), Kasr Al-Ainy Hospital, Cairo University, Cairo, 11562, Egypt. maha_abdelkareem@yahoo.com.
authors.forename: Maha Abd Elkareem
authors.initials: MA
authors.lastname: Husseini
mesh_terms: D055011:Ablation Techniques; D000328:Adult; D000368:Aged; D004534:Egypt; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes
keywords: Differentiated cancer thyroid; Radioactive iodine 131; Successful ablation; Thyroglobulin level