title: Prognostic impact of postoperative, pre-irradiation (18)F-fluoroethyl-l-tyrosine uptake in glioblastoma patients treated with radiochemotherapy.
abstract: OBJECTIVE
  Resection is considered as essential for the efficacy of modern adjuvant treatment of glioblastoma multiforme (GBM). Previous studies have indicated that amino acid PET is more specific than contrast enhancement on MRI for detecting residual tumor tissue after surgery. In a prospective study we investigated the prognostic impact of postoperative tumor volume and tumor/brain ratios (TBR) in PET using O-(2-[(18)F]fluoroethyl)-l-tyrosine (FET) in comparison with MRI.
  
  
  METHODS
  Forty-four patients with GBM were investigated by FET PET and MRI after surgery. Tumor volume in FET PET with a tumor/brain ratio (TBR)>1.6 and a TBR>2, mean and maximum TBR and gadolinium contrast-enhancement on MRI (Gd-volume) were determined. Thereafter patients received a fractionated radiotherapy with concomitant temozolomide (RCX). The median follow-up was 15.4 (3-35) months. The prognostic value of postoperative residual tumor volume in FET PET, TBR(mean,) TBR(max) and Gd-volume was evaluated using Kaplan-Maier estimates for disease-free survival (DFS) and overall survival (OS).
  
  
  RESULTS
  Postoperative tumor volume in FET PET had a significant independent influence on OS and DFS (OS 20.0 vs. 6.9 months; DFS 9.6 vs. 5.1 months, p<0.001; cut-off 25 ml). Similar results were observed when a TBR ≥ 2 (cut-off 10 ml) was used to define the tumor volume in (18)F-FET PET. The TBR(mean) and TBR(max) of FET uptake had a significant influence on DFS (p<0.05). Gd-volume in MRI had significant effect on OS and DFS in the univariate analysis. No independent significant influence in OS or DFS could be observed for Gd-volume in MRI.
  
  
  CONCLUSIONS
  Our data indicate that the tumor volume in FET PET after surgery of GBM has a strong prognostic impact for these patients. FET PET appears to be helpful to determine the residual tumor volume after surgery of GBM and may serve as a valuable tool for optimal planning of radiation treatment.
authors.affiliation: Department of Radiation Oncology, RWTH Aachen University Hospital, Germany. mpiroth@ukaachen.de
authors.forename: Marc D
authors.initials: MD
authors.lastname: Piroth
authors.forename: Richard
authors.initials: R
authors.lastname: Holy
authors.forename: Michael
authors.initials: M
authors.lastname: Pinkawa
authors.forename: Gabriele
authors.initials: G
authors.lastname: Stoffels
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Kaiser
authors.forename: Norbert
authors.initials: N
authors.lastname: Galldiks
authors.forename: Hans
authors.initials: H
authors.lastname: Herzog
authors.forename: Heinz H
authors.initials: HH
authors.lastname: Coenen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Eble
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Langen
mesh_terms: D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery*; D003131:Combined Modality Therapy; D003287:Contrast Media / Q000493:pharmacokinetics; D016371:Cranial Irradiation / Q000379:methods; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000627:therapeutic use; D019583:Dose Fractionation, Radiation; D005260:Female; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D049268:Positron-Emission Tomography; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D015996:Survival Rate; D000077204:Temozolomide; D016896:Treatment Outcome; D047368:Tumor Burden; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
chemical_list: D018906:Antineoplastic Agents, Alkylating; D003287:Contrast Media; D005462:Fluorine Radioisotopes; C117289:O-(2-fluoroethyl)tyrosine; D014443:Tyrosine; D003606:Dacarbazine; D019786:Gadolinium DTPA; D000077204:Temozolomide