title: Low postoperative nonstimulated thyroglobulin as a criterion for the indication of low radioiodine activity in patients with papillary thyroid cancer of intermediate risk 'with higher risk features'.
abstract: This study evaluated low-activity (131) I therapy in patients with papillary thyroid carcinoma (PTC) of intermediate risk 'with higher risk features' who had low nonstimulated thyroglobulin (Tg) after thyroidectomy.
  
  
  
  This was a prospective study including 102 patients with tumours >1 cm and aggressive histology; and/or >3 positive lymph node (LN) or LN >1·5 cm or exhibiting macroscopic extracapsular extension, and clinically apparent (cN1); and/or a combination of a tumour >4 cm, microscopic extrathyroidal extension and LN metastases (cN1). After thyroidectomy, all patients had nonstimulated Tg < 0·3 ng/ml and negative antithyroglobulin antibodies (TgAb) and neck ultrasonography (US). The patients were treated with a low activity of (131) I (1110 or 1850 MBq).
  
  
  
  Post-therapy whole-body scanning (RxWBS) showed ectopic uptake in four patients. When evaluated 12 months after (131) I therapy, nonstimulated Tg ≤ 0·2 ng/ml with negative TgAb and US, defined as excellent response to initial therapy, was achieved in 101 patients (99%). Only one patient with positive initial RxWBS had structural disease. During follow-up, four patients (4%) relapsed, including LN metastases in two, pulmonary metastases in one, and elevated Tg in one. The other 98 patients remained with nonstimulated Tg ≤ 0·2 ng/ml and negative TgAb and US. There was no case of death due to the tumour.
  
  
  
  We conclude that in intermediate-risk patients 'with higher risk features', low nonstimulated Tg measured with a second-generation assay can be used as criterion for the administration of low (131) I activities (1850 MBq or less).
authors.affiliation: Santa Casa de Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Pedro Weslley
authors.initials: PW
authors.lastname: Rosario
authors.affiliation: Santa Casa de Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Gabriela Franco
authors.initials: GF
authors.lastname: Mourão
authors.affiliation: Santa Casa de Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Maria Regina
authors.initials: MR
authors.lastname: Calsolari
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D012306:Risk; D013954:Thyroglobulin / Q000097:blood*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin