Early change in glucose metabolic rate measured using FDG-PET in patients with high-grade glioma predicts response to temozolomide but not temozolomide plus radiotherapy.
OBJECTIVE
To compare the ability of positron emission tomography (PET) to predict response to temozolomide vs. temozolomide plus radiotherapy.


METHODS
Nineteen patients with high-grade glioma (HGG) were studied. Patients with recurrent glioma received temozolomide 75 mg/m2 daily for 7 weeks (n=8). Newly diagnosed patients received temozolomide 75 mg/m2 daily plus radiotherapy 60 Gy/30 fractions over 6 weeks, followed by six cycles of adjuvant temozolomide 200 mg/m2/day (Days 1-5 q28) starting 1 month after radiotherapy (n=11). [18F]Fluorodeoxyglucose ([18F]FDG) PET scan and magnetic resonance imaging (MRI) were performed at baseline, and 7 and 19 weeks after initiation of temozolomide administration. Changes in glucose metabolic rate (MRGlu) and MRI response were correlated with patient survival.


RESULTS
In the temozolomide-alone group, patients who survived>26 vs. <or=26 weeks showed a greater reduction in MRGlu measured at 7 weeks with median changes of -34% and -4%, respectively (p=0.02). PET responders, defined as a reduction in MRGlu>or=25%, survived longer than nonresponders with mean survival times of 75 weeks (95% CI, 34-115 vs. 20 weeks (95% CI, 14-26) (p=0.0067). In the small group of patients studied, there was no relationship between MRI response and survival (p=0.52). For patients receiving temozolomide plus radiotherapy, there was no difference in survival between PET responders and nonresponders (p=0.32).


CONCLUSIONS
Early changes in MRGlu predict response to temozolomide, but not temozolomide plus radiotherapy.
Charnley
Natalie
N
Wolfson Molecular Imaging Centre, Academic Department of Radiation Oncology, The University of Manchester, Christie Hospital NHS Trust, Manchester, United Kingdom. natalie.charnley@mmic.man.ac.uk
West
Catharine M
CM
Barnett
Carolyn M
CM
Brock
Catherine
C
Bydder
Graeme M
GM
Glaser
Mark
M
Newlands
Ed S
ES
Swindell
Ric
R
Matthews
Julian
J
Price
Pat
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D001921:Brain / Q000378:metabolism; D001932:Brain Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D003131:Combined Modality Therapy / Q000379:methods; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D019788:Fluorodeoxyglucose F18; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D000077204:Temozolomide; D016896:Treatment Outcome
D018906:Antineoplastic Agents, Alkylating; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D003606:Dacarbazine; D005947:Glucose; D000077204:Temozolomide