Prognostic Value of the Metabolic and Volumetric Parameters of 11C-Methionine Positron-Emission Tomography for Gliomas: A Systematic Review and Meta-Analysis

BACKGROUND: Several studies have demonstrated that C-11-methionine positron-emission tomography provides information on prognosis. PURPOSE: We performed a systematic review and meta-analysis of the prognostic value of the metabolic and volumetric parameters of C-11-methionine-PET for gliomas. DATA SOURCES: A systematic search was performed using the following combination of keywords: methionine, PET, glioma, and prognosis. STUDY SELECTION: The inclusion criteria were the use of C-11-methionine-PET as an imaging tool, studies limited to gliomas, studies including metabolic parameters (tumor-to-normal ratio) and/or volumetric parameters (metabolic tumor volume), and studies reporting survival data. The electronic search first identified 181 records, and 14 studies were selected. DATA ANALYSIS: Event-free survival and overall survival were the outcome measures of interest. The effect of the tumor-to-normal ratio and metabolic tumor volume on survival was determined by the effect size of the hazard ratio. Hazard ratios were extracted directly from each study when provided or determined by analyzing the Kaplan-Meier curves. DATA SYNTHESIS: The combined hazard ratios of the tumor-to-normal ratio for event-free survival was 1.74 with no significance and that of the tumor-to-normal ratio for overall survival was 2.02 with significance. The combined hazard ratio of the metabolic tumor volume for event-free survival was 2.72 with significance and that of the metabolic tumor volume for overall survival was 3.50 with significance. LIMITATIONS: The studies selected were all retrospective, and there were only 4 studies involving the metabolic tumor volume. CONCLUSIONS: The present meta-analysis of C-11-methionine-PET suggests that the tumor-to-normal ratio for overall survival and the metabolic tumor volume for event-free survival and overall survival are significant prognostic factors for patients with gliomas.