title: Fluorodeoxyglucose positron emission tomography/computerized tomography in differentiated thyroid cancer management: Importance of clinical justification and value in predicting survival.
abstract: BACKGROUND
  The purpose of this study was to evaluate the added value of follow-up fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) to clinical assessment and predicting survival outcome in patients with differentiated thyroid cancers.
  
  
  METHODS
  This is an institutional review board approved, retrospective study of 202 biopsy-proven thyroid cancer patients at a single tertiary centre. A total of 327 follow-up or surveillance PET/CT scans done 6 or more months from initial treatment completion were included in this study. Median follow-up from completion of primary treatment was 94 months (range, 6.17-534.1 months). Overall survival benefit was measured using Kaplan-Meier plots with a Mantel-Cox log-rank test. Multivariate Cox regression model is provided with clinical covariates.
  
  
  RESULTS
  Of the 327 PET/CT scans from 202 patients, 161 were positive and 166 as negative for recurrence or metastasis. A total of 23 patients died during the study period. Patients with a positive PET/CT scan had shorter overall survival than those who had a negative scan (P < 0.0001, hazard ratio 6.1 (3.0-14.3) ). In the context of clinical assessment, PET/CT identified recurrence in 50% (25/50) of scans without prior clinical suspicion and ruled out recurrence in 36.8% (102/277) of scans with prior clinical suspicion. In a multivariate Cox regression model, factors associated with overall survival were stage (P < 0.0001), time to scan (P = 0.0005) and PET/CT result (P < 0.0001).
  
  
  CONCLUSIONS
  FDG PET/CT performed in follow-up more than 6 months from primary treatment completion adds value to clinical judgment and a prognostic marker of overall survival in thyroid cancer patients.
authors: Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors: Charles
authors: C
authors: Marcus
authors: Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors: Alexander
authors: A
authors: Antoniou
authors: Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors: Arman
authors: A
authors: Rahmim
authors: Department of Endocrinology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.|Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors: Paul
authors: P
authors: Ladenson
authors: Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.|Department of Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.|Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors: Rathan M
authors: RM
authors: Subramaniam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: PET/CT; differentiated thyroid cancer; follow-up