title: Ablative treatment of thyroid cancer with high doses of 131I without pre-therapy scanning.
abstract: OBJECTIVE
  To determine the success of ablative treatment using fixed high doses of 131I in patients with thyroid cancer.
  
  
  METHODS
  A retrospective study was conducted on 274 patients who received ablative treatment without previous scanning, with the dose being based on surgical staging: stage I patients (tumour restricted to the thyroid) received 3.7 GBq, and stage II (lymph node metastases) and stage III patients (extra-thyroid invasion) were treated with 5.5 GBq. Successful treatment was defined as a negative control scan.
  
  
  RESULTS
  One hundred and sixty patients were classified as stage I and 114 as stages II or III. Forty-six patients presented ectopic uptake on post-therapy scans (10% in stage I and 26% in stage II or III). Among stage I patients, the efficacy of treatment was 78.7%. A 47% failure rate was associated with metastases, and among patients without metastases who did not respond to treatment, thyroid bed uptake >5% on post-therapy scans was observed in 61%. Patients with stage II or III showed 62.2% efficacy. Twenty-three of the 43 (53%) unsuccessfully treated patients in this group had metastases and of the 20 patients without metastases, 14 (70%) presented thyroid bed uptake >5%. There were no differences between the responsive and non-responsive groups in terms of age, gender, histological type or size of the primary tumour.
  
  
  CONCLUSIONS
  Empirical treatment presented 72% efficacy (higher in stage I) and failure was associated with the presence of metastases and large thyroid remnants; factors that can be evaluated by pre-therapy whole-body scanning.
authors.affiliation: Nuclear Medicine Service and Department of Thyroid, Endocrinology Service, Santa Casa de Belo Horizonte, Minas Gerais, Brazil. pedrorosario@globo.com
authors.forename: Pedro W S
authors.initials: PW
authors.lastname: Rosário
authors.forename: Alvaro L
authors.initials: AL
authors.lastname: Barroso
authors.forename: Leonardo L
authors.initials: LL
authors.lastname: Rezende
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: Padrão
authors.forename: Michelle A R
authors.initials: MA
authors.lastname: Borges
authors.forename: Tales A
authors.initials: TA
authors.lastname: Fagundes
authors.forename: Saulo
authors.initials: S
authors.lastname: Purisch
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals