NI-16 RESPONSE ASSESSMENT OF BEVACIZUMAB THERAPY FOR GLIOBLASTOMA BY USING MULTIPLE PET TRACERS

Objective PET scans are useful for the diagnosis and treatment planning of glioma. Introduced in 2013, bevacizumab (Bev) treatment efficacy can be difficult to determine using MRI imaging. We instead performed PET scans to determine the efficacy of Bev-based glioblastoma treatment. Methods Eighty glioblastoma patients treated with Bev from July 2013 to December 2021 were included. The patients were divided into the following three groups: the first group received Bev added to the Stupp regimen after biopsy or subtotal resection (first-dose group), the second group received Bev added to the Stupp regimen after biopsy followed by tumor resection (neoadjuvant group), and the third group received the Stupp regimen after tumor resection followed by TMZ + Bev at recurrence (recurrent group). PET scans (FDG, MET, FLT, and FMISO) were performed before and 4 weeks after the start of the Bev treatment. FDG, MET, and FLT measured tumor-to-normal ratio (TNR), and FMISO measured tumor-to-blood ratio (TBR), as well as the percent change in SUVmax, TNR, TBR, and MTV before and after Bev treatment. Using the Cox proportional hazards model, we examined which of these rates of change were the prognostic factors. Results The median PFS (months) and median OS from Bev treatment were 8.87, 16.53, and 4.0 and 12.53, 22.13, and 8.0, respectively. Significant differences in the percent change in MTV for MET, FLT, and FMISO in the first-line group, the percent change in MTV for FDG and MET, the percent change in FDG TNR and FMISO TBR in the recurrent group, and the percent change in MTV for MET and FLT in the neoadjuvant group were shown in the Cox proportional hazards model. Conclusion Neoadjuvant treatment with Bev prolonged PFS and OS. The decrease in MET MTV change rate and FMISO TBR.