Pretherapeutic prognostic impact of FDG-PET in high-grade gliomas: A multivariate analysis including all consensual prognostics factors

Abstract

2080 Background: The prognostic value of positron emission tomography with [18F]-fluoro-2-deoxy-D-glucose (FDG-PET) has been previously reported in high-grade gliomas (HGG) with inconstant results using different statistical methods in nonhomogeneous population. Indeed, most of these studies are based on univariate or limited multivariate analysis, not including all consensual prognostics factors. The objective of this study was to determine the independent prognostic value of pretherapeutic FDG-PET on overall (OS) and event-free survival (EFS) in HGG. Methods: We retrospectively included 41 histologically-proven HGG: 31 glioblastomas multiforme, WHO grade IV (GBM) and 10 anaplasic gliomas, WHO grade III (AG). Pretherapeutic FDG-PET was performed on hybrid PET/computerized tomography. The uptake of FDG was assessed by a five visual-step metabolic grading (MG), and the ratio between tumour and controlateral maximal standardized uptake value (T/CL). OS and EFS following PET were determined by Kaplan-Meier analysis and correlated with FDG uptake by univariate and multivariate analysis (MVA) using log-rank test and Cox Regression. MVA included FDG uptake, age, Karnofsky performance status (KPS), extend of surgery, histologic grade (HG), and first-line chemotherapy in GBM. A second MVA was performed with FDG uptake and RPA (recursive partitioning analysis) classification of the RTOG. Results: Median OS and EFS of were respectively 18.4 and 9.2 months, significantly higher for AG than GBM (respectively p=0.040 and p=0.027). MG was nearly correlated with OS in the whole group and in the GBM (respectively p=0.077 and 0.059). T/CL ratio was significantly correlated with OS (p=0.003) and nearly significantly with EFS (p=0.052), independently from age, KPS, histological grade, surgery and RPA classification. In GBMs subgroup, T/CL ratio still predicted OS (p=0.018), independently from age, KPS, surgery, RPA classification and 1st-line chemotherapy. Conclusions: On preoperative FDG-PET, the ratio between tumour and controlateral uptake can provide additional prognostic information in the management of HGG, independently from consensual prognostic factors. No significant financial relationships to disclose.