title: [18F]Fluorodeoxyglucose positron emission tomography predicts outcome for Ewing sarcoma family of tumors.
abstract: OBJECTIVE
  Response to neoadjuvant chemotherapy is a significant prognostic factor for the Ewing sarcoma family of tumors (ESFTs). [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) is a noninvasive imaging modality that accurately predicts histopathologic response in several malignancies. To determine the prognostic value of FDG PET response for progression-free survival (PFS) in ESFTs, we reviewed the University of Washington Medical Center experience.
  
  
  METHODS
  Thirty-six patients with ESFTs were evaluated by FDG PET. All patients received neoadjuvant and adjuvant chemotherapy. FDG PET standard uptake values before (SUV1) and after (SUV2) chemotherapy were analyzed and correlated with chemotherapy response, as assessed by histopathology in surgically excised tumors. Thirty-four patients had both SUV1 and SUV2.
  
  
  RESULTS
  The mean SUV1, SUV2, and ratio of SUV2 to SUV1 (SUV2:1) were 7.9 (range, 2.3 to 32.8), 2.1 (range, 0 to 4.3), and 0.36 (range, 0.00 to 1.00), respectively. Good FDG PET response was defined as SUV2 less than 2.5 or SUV2:1 < or = 0.5. FDG PET response by SUV2 or SUV2:1 was concordant with histologic response in 68% and 69% of patients, respectively. SUV2 was associated with outcome (4-year PFS 72% for SUV2 < 2.5 v 27% for SUV2 > or = 2.5, P = .01 for all patients; 80% for SUV2 < 2.5 v 33% for SUV2 > or = 2.5, P = .036 for localized at diagnosis patients). SUV2:1 < or = 0.5 was not predictive of PFS.
  
  
  CONCLUSIONS
  FDG PET imaging of ESFTs correlates with histologic response to neoadjuvant chemotherapy. SUV2 less than 2.5 is predictive of PFS independent of initial disease stage.
authors.affiliation: Children's Hospital and Regional Medical Center, 4800 Sandpoint Way, Mailstop B-6553, Seattle, WA 98105-0371, USA. Doug.Hawkins@seattlechildrens.org
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Hawkins
authors.forename: Scott M
authors.initials: SM
authors.lastname: Schuetze
authors.forename: James E
authors.initials: JE
authors.lastname: Butrynski
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Rajendran
authors.forename: Cheryl B
authors.initials: CB
authors.lastname: Vernon
authors.forename: Ernest U
authors.initials: EU
authors.lastname: Conrad
authors.forename: Janet F
authors.initials: JF
authors.lastname: Eary
mesh_terms: D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000628:therapy; D002648:Child; D018572:Disease-Free Survival; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards; D011379:Prognosis; D011446:Prospective Studies; D018714:Radiotherapy, Adjuvant; D015203:Reproducibility of Results; D012512:Sarcoma, Ewing / Q000175:diagnosis* / Q000628:therapy; D012680:Sensitivity and Specificity; D013514:Surgical Procedures, Operative; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18