Prognostic value of early [18F]fluoroethyltyrosine positron emission tomography after radiochemotherapy in glioblastoma multiforme.
OBJECTIVE
Early detection of treatment response in glioma patients after radiochemotherapy (RCX) is uncertain because treatment-related contrast enhancement in magnetic resonance imaging can mimic tumor progression. Positron emission tomography (PET) using the amino acid tracer [(18)F]fluoroethyltyrosine (FET) seems to be a promising tool for treatment monitoring. The aim of this prospective study was to evaluate the prognostic value of early changes of FET uptake after postoperative RCX in glioblastomas.


METHODS
Twenty-two patients with glioblastoma were treated by surgery and subsequent RCX (whole dose 60-72 Gy). The FET-PET studies were performed before RCX, 7-10 days and 6-8 weeks after completion of RCX. Early treatment response in PET was defined as a decrease of the maximal tumor-to-brain ratio (TBR(max)) of FET uptake after RCX of more than 10%. The prognostic value of early changes of FET uptake after RCX was evaluated using Kaplan-Maier estimates for median disease-free survival and overall survival.


RESULTS
The median overall and disease-free survival of the patients was 14.8 and 7.8 months. There were 16 early responders in FET-PET (72.7%) and 6 nonresponders (27.3%). Early PET responders had a significantly longer median disease-free survival (10.3 vs. 5.8 months; p < 0.01) and overall survival ("not reached" vs. 9.3 months; p < 0.001). No statistically significant differences between the patient subgroups were found concerning the defined prognostic parameters.


CONCLUSIONS
FET-PET is a sensitive tool to predict treatment response in patients with glioblastomas at an early stage after RCX.
Piroth
Marc D
MD
Department of Radiation Oncology, RWTH Aachen University Hospital, Aachen, Germany. mpiroth@ukaachen.de
Pinkawa
Michael
M
Holy
Richard
R
Klotz
Jens
J
Nussen
Sandra
S
Stoffels
Gabriele
G
Coenen
Heinz H
HH
Kaiser
Hans J
HJ
Langen
Karl J
KJ
Eble
Michael J
MJ
D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy; D003131:Combined Modality Therapy / Q000379:methods; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000627:therapeutic use; D018572:Disease-Free Survival; D005260:Female; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D000077204:Temozolomide; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
D018906:Antineoplastic Agents, Alkylating; D019275:Radiopharmaceuticals; C545932:(18F)fluoroethyltyrosine; D014443:Tyrosine; D003606:Dacarbazine; D000077204:Temozolomide