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 [ 18 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 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.