18-Fluorodeoxyglucose uptake and survival of patients with suspected recurrent malignant glioma

Abstract

BACKGROUND. After intensive initial radiation therapy for malignant glioma, magnetic resonance imaging (MRI) and computerized tomography (CT) cannot distinguish tumor progression from radiation injury. METHODS. The authors studied the prognostic value of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in 55 patients with malignant glioma for whom MRI obtained after initial surgery and radiation therapy demonstrated enlarging, entrancing lesions consistent with either tumor progression or radiation necrosis. Forty patients (73%) had an initial diagnosis of Grade 4 malignant glioma and 15 (27%) had Grade 3 malignant glioma. The FDG-PET scans were graded visually on a four-level scale at the time of acquisition. RESULTS. In univariate analysis, the FDG-PET score was a significant predictor of survival time after FDG-PET scanning (P = 0.005). Median survival was 10 months for patients with FDG-PET scores of 2 or 3 (glucose uptake ≤ adjacent cortex) and 20 months for those with scores of 0 or 1 (glucose uptake < adjacent cortex). In multivariate proportional hazards analysis, the FDG-PET score was a significant predictor of survival (P= 0.019) in a model that included patient age, recurrence number, and FDG-PET score. There was no significant difference in the FDG-PET score hazard ratio for patients with Grade 3 or 4 tumors at initial diagnosis, first or later suspected recurrence, initial photon irradiation given with standard fractions or hyperfractionation, or stereotactic irradiation prior to FDG- PET scanning. CONCLUSIONS. This analysis demonstrates that FDG-PET scanning has prognostic value in a cohort limited to patients with suspected recurrent high grade glioma.