title: Comparison between low and high radioactive iodine (131I) reablation dose in patients with papillary thyroid cancer.
abstract: OBJECTIVE
  The aim of this study was to assess ablation outcome after a second ablation dose and compare the ablation rate after low and high reablation doses of iodine-131 ((131)I) after failure of the first ablation with 3700 MBq.
  
  
  METHODS
  The study included 81 patients with papillary thyroid cancer; they failed to achieve complete ablation after a first ablative dose of 3700 MBq. Their first follow-up (131)I whole-body scan carried out 6-9 months after ablation showed small residual functioning tissue in the thyroid bed, with no functioning metastases. This is associated with unsuppressed serum thyroglobulin level (Tg) higher than 2 ng/ml. The patients received a second ablation dose, which was low (1110 MBq) in 37 patients and high in the remaining 44 patients (2960 MBq in 36 patients and 3700 MBq in eight patients). A whole-body scan and Tg level assessment were carried out 6-9 months later. The criteria for complete ablation included absence of residual functioning thyroid tissue and a Tg level lower than 2 ng/ml.
  
  
  RESULTS
  The overall successful complete ablation rate after the second reablation dose was 75%. This was achieved in 27 of 37 patients (73%) who received a low reablation dose and in 34 of 44 patients (77%) who received a high reablation dose; no statistically significant difference was found between the two groups (P>0.05).
  
  
  CONCLUSIONS
  In patients with papillary thyroid cancer who failed to achieve complete ablation after the first ablation dose of 3700 MBq, the overall complete ablation rate after both a low and a high second (131)I dose was 75%, with no statistically significant difference in ablation rate between low (1110 MBq) and high (2960 and 3700 MBq) doses (73 and 77%, respectively).
authors.affiliation: aDepartment of Radiotherapy and Nuclear Medicine (NEMROCK), Nuclear Medicine Unit, Kasr Al-Ainy Hospital, Cairo University, Cairo, Egypt bKing Abdulla Medical City (KAMC), Jeddah, Kingdom of Saudi Arabia.
authors.forename: Sherif
authors.initials: S
authors.lastname: M El-Refaei
authors.forename: Shereen
authors.initials: S
authors.lastname: W Yassin
authors.forename: Khaled
authors.initials: K
authors.lastname: Salman
authors.forename: Tarek
authors.initials: T
authors.lastname: Al Munshy
authors.forename: Manal
authors.initials: M
authors.lastname: Al-Ezzi
authors.forename: Yasser
authors.initials: Y
authors.lastname: M Al-Sayed
authors.forename: Maha
authors.initials: M
authors.lastname: Abd Elkareem Husseni
mesh_terms: D055011:Ablation Techniques / Q000379:methods*; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000097:blood / Q000175:diagnosis / Q000628:therapy*; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D013954:Thyroglobulin / Q000097:blood; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis / Q000628:therapy*; D016896:Treatment Outcome; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin