Prediction of survival in patients with IDH-wildtype astrocytic gliomas using dynamic O-(2-[ ¹⁸ F]-fluoroethyl)-L-tyrosine PET

Ziel/Aim Integrated histomolecular diagnostics of gliomas according to the World Health Organization (WHO) classification of 2016 has refined diagnostic accuracy and prediction of prognosis. This study aimed at exploring the prognostic value of dynamic O-(2-[¹⁸F]-fluoroethyl)-L-tyrosine (FET) PET in newly diagnosed, histomolecularly classified astrocytic gliomas of WHO grades III or IV.

Methodik/Methods Before initiation of treatment, dynamic FET PET imaging was performed in patients with newly diagnosed glioblastoma (GBM) and anaplastic astrocytoma (AA). Static FET PET parameters such as maximum and mean tumour/brain ratios (TBR_max/mean), as well as the dynamic FET PET parameters time-to-peak (TTP) and slope, were obtained. The predictive ability of FET PET parameters was evaluated concerning the progression-free and overall survival (PFS, OS). Using ROC analyses, threshold values for FET PET parameters were obtained. Subsequently, univariate Kaplan-Meier and multivariate Cox regression survival analyses were performed to assess the predictive power of these parameters for survival.

Ergebnisse/Results Sixty patients (45 GBM and 15 AA patients) of two university centers were retrospectively identified. Patients with isocitrate dehydrogenase (IDH)-mutant or O⁶-methylguanine-DNA-methyltransferase (MGMT) promoter-methylated tumors had a significantly longer PFS and OS (both P25 minutes (AUC, 0.90; sensitivity, 90 %; specificity, 87 %; Pmax and TBR_mean were only prognostic for longer OS (P = 0.004 and P = 0.038, respectively). Besides complete resection and a methylated MGMT promoter, TTP remained significant in multivariate survival analysis (all P≤0.02), indicating an independent predictor for OS.

Schlussfolgerungen/Conclusions Our data suggest that dynamic FET PET allows the identification of patients with longer OS among patients with newly diagnosed IDH-wildtype GBM and AA.