Value of [¹⁸F]-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 [¹⁸F]-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_max), peak standardized uptake value (SUV_peak), 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 P < .05 considered significant.

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

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