title: Prognostic role of 18F-FDG PET/CT in the postoperative evaluation of differentiated thyroid cancer patients.
abstract: OBJECTIVE
  The aim of this study was to evaluate the role of F-FDG PET/CT performed after surgery but before radioiodine therapy in patients with differentiated thyroid cancer.
  
  
  METHODS
  FDG PET/CT was performed off l-thyroxine in 60 newly diagnosed differentiated thyroid cancer patients. Clinical and hematological evaluation as well as high-resolution neck ultrasound were performed. All patients underwent a complete follow-up (range, 6-67 months; mean [SD], 31.7 [20.6] months). The date of recurrence or the most recent office visit was recorded. Progression-free survival (PFS) is the primary end point of this study. Analysis was performed by Cox proportional hazards model. Survival curves were generated using Kaplan-Meier estimates, and the log-rank test was used to assess significance.
  
  
  RESULTS
  FDG PET/CT was negative in 63% of patients, 20% had FDG thyroid bed uptake, 5% distant metastases, and 12% lymph node FDG uptake. In patients with positive FDG PET/CT scan (ie, those with distant metastases or lymph node uptake), a higher rate of recurrence was observed (50% vs 6%, P < 0.05). Thyroglobulin, neck ultrasound, stage, and FDG PET/CT correlated with PFS at univariate analysis. At multivariate analysis, only thyroglobulin and FDG PET/CT continued to be predictors of PFS. Patients with a negative FDG PET/CT scan have a better PFS either in the whole group or in those with elevated thyroglobulin level (both >2 ng/mL and >10 ng/mL).
  
  
  CONCLUSIONS
  FDG PET/CT was abnormal in 17% of patients. Moreover, FDG PET/CT has an independent prognostic role, with a better PFS in patients with a negative scan.
authors.affiliation: From the *Dipartimento di Medicina e Chirurgia, Università degli Studi di Salerno, Salerno; †Dipartimento di Scienze Biomediche Avanzate, Università degli Studi di Napoli Federico II; ‡Istituto di Biostrutture e Bioimmagini, CNR; §IRCSS SDN, Napoli; and ║IRCSS CROB, Rionero in Vulture, Italia.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pace
authors.forename: Michele
authors.initials: M
authors.lastname: Klain
authors.forename: Barbara
authors.initials: B
authors.lastname: Salvatore
authors.forename: Emanuele
authors.initials: E
authors.lastname: Nicolai
authors.forename: Emilia
authors.initials: E
authors.lastname: Zampella
authors.forename: Roberta
authors.initials: R
authors.lastname: Assante
authors.forename: Teresa
authors.initials: T
authors.lastname: Pellegrino
authors.forename: Giovanni
authors.initials: G
authors.lastname: Storto
authors.forename: Rosa
authors.initials: R
authors.lastname: Fonti
authors.forename: Marco
authors.initials: M
authors.lastname: Salvatore
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000601:surgery; D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011184:Postoperative Period; D011379:Prognosis; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18