Value of [F]-FDG positron emission tomography in patients with recurrent glioblastoma receiving bevacizumab.

Background: Treatment of recurrent glioblastoma (GBM) with bevacizumab can induce MRI changes that confound the determination of progression. We sought to determine the value of [F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) in GBM patients receiving bevacizumab at the time of suspected progression and, thereby, its utility as a potential prognostic adjunct in progressive disease.

Methods: This retrospective study included patients who underwent brain FDG PET within 4 weeks of receiving bevacizumab for recurrent GBM with suspected progression. Volumes-of-interest were placed over the reference lesion with measurement of maximum standardized uptake value (SUV), peak standardized uptake value (SUV), metabolic tumor volume, total lesion glycolysis (TLG), and tumor-to-normal contralateral white matter ratios (TNR-WM). Tumors were additionally categorized as non-avid or avid based on qualitative FDG uptake. Associations between baseline variables and overall survival (OS) were examined using univariable and multivariable Cox proportional hazards regression, with < .05 considered significant.

Results: Thirty-one patients were analyzed. Qualitative FDG uptake was significantly associated with OS ( = .03), with a median OS of 9.0 months in non-avid patients versus 4.5 months in avid patients. SUV, SUV, TNR-WM, and TLG were significantly associated with OS ( < .001, TLG: = .009). FDG avidity and SUV remained significantly associated with OS ( = .046 and .048, respectively) in the multivariable analysis including age, KPS, and status. Dichotomizing patients using an SUV cutoff of 15.3 was associated with OS (adjusted = .048).

Conclusion: FDG PET is a promising imaging tool to further stratify prognosis in recurrent GBM patients on antiangiogenic therapy.