title: Effect of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography-guided management of suspected recurrent papillary thyroid carcinoma: long-term follow-up with tumour marker responses.
abstract: OBJECTIVE
  To investigate the use of recombinant human thyroid-stimulating hormone-stimulated co-registered (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for detecting suspected recurrent papillary thyroid carcinoma among patients with rising tumour markers but negative whole-body iodine-131 scans. Tumour marker responses to (18)F-FDG PET/CT-guided therapy were also measured for these patients.
  
  
  METHODS
  A prospectively gathered (18)F-FDG PET/CT database and patient charts were reviewed. Patients having previously undergone total thyroidectomy and ablative iodine-131 therapy for papillary carcinoma before (18)F-FDG PET/CT were analysed.
  
  
  RESULTS
  Nineteen patients formed the study population: 12 women and seven men, median age 49 years, with elevated thyroglobulin (n = 15), elevated anti-thyroglobulin antibody (n = 4); the median follow-up was 46 months, range 27-56 months. Sixteen patients (84%) had a positive PET/CT scan (15 with disease confined to the head and neck and one with distant disease), whereas three patients (16%) had a negative scan. Eleven of the 15 patients with disease confined to the head and neck underwent potentially curative salvage therapy: surgery (n = 7), external beam radiotherapy (n = 2) or both (n = 2). All patients undergoing surgery had histological confirmation of malignancy. At a median follow-up of 50 months for these 11 patients, eight had detectable tumour markers at levels below pre-scan values, two had levels above, and one patient had an undetectable level. All three patients with negative PET/CT scans were placed on surveillance. At a median follow-up of 45 months for these three patients, two had tumour marker levels below pre-scan values and one had an undetectable level.
  
  
  CONCLUSIONS
  Recombinant human thyroid-stimulating hormone-stimulated (18)F-FDG PET/CT detected recurrent disease in most patients. Although subsequent treatment of (18)F-FDG PET/CT-detected disease reduced tumour marker levels in most patients, markers remained detectable, suggesting that not all residual or metastatic disease had been identified, which compromised salvage therapy. This is the largest and most mature study to date reporting tumour marker responses to PET- or PET/CT-guided therapy in this setting.
authors.affiliation: Department of Radiation Oncology and Developmental Radiotherapeutics, British Columbia Cancer Agency, Vancouver, British Columbia, Canada. kebdennis@gmail.com
authors.forename: K
authors.initials: K
authors.lastname: Dennis
authors.forename: J H
authors.initials: JH
authors.lastname: Hay
authors.forename: D C
authors.initials: DC
authors.lastname: Wilson
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D013965:Thyroidectomy; D014057:Tomography, X-Ray Computed
chemical_list: D001323:Autoantibodies; D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; C006606:anti-thyroglobulin; D019788:Fluorodeoxyglucose F18