Abstract
PURPOSE: Despite advances in diagnosis and use of different therapeutic regimen in high grade gliomas (HGG), the prognosis for patients remains grim. Additional pre-therapeutic information is needed to tailor the management. In order to gain additional prognostic information at primary diagnosis we investigated the value of dynamic [18F]fluoroethyltyrosine (FET)-PET in patients with newly diagnosed HGG. METHODS: 131 patients with histologically verified HGG (61 WHO III°; 70 WHO IV°) and dynamic FET-PET prior to histopathological assessment were retrospectively evaluated. FET-PET analysis comprised the assessment of maximal tumor uptake (SUVmax/BG) and biological tumor volume (BTV), as well as kinetic evaluation including time-to-peak (TTP). The prognostic influence of PET parameters and clinical parameters on progression free and overall survival (PFS and OS) was evaluated using uni- and multivariate Cox-regression and Kaplan-Meier survival estimates. RESULTS: Median PFS and OS were 19.2 and 46.2 months in gliomas WHO III° and 10.3/14.2 months in IV° respectively. SUVmax/BG and BTV were significantly higher in WHO IV° compared to WHO III° gliomas. Median TTP was 12.5 minutes in both groups. The OS of WHO III° glioma patients with TTP > 12.5 minutes was significantly longer compared to TTP ≤ 12.5 minutes. In multivariate analysis, TTP was a significant prognostic factor for both OS and PFS besides WHO°, MGMT, and age. WHO and TTP reached a similar fit for the prognostic evaluation. CONCLUSIONS: Early TTP is associated with worse outcome in patients with newly diagnosed HGG. In the preoperative setting, TTP can be a valuable non-invasive prognostic marker with comparable significance to WHO grade. Additionally, TTP can help identify highly aggressive tumors among WHO III° glioma and might help adjusting standard treatment towards an individualised, risk-adapted therapy regime.