10068- NI-4 PREDICTIVE FACTOR OF TUMOR-SHRINKING EFFECTS FROM BEVACIZUMAB IN NEWLY DIAGNOSED AND RECURRENT GLIOBLASTOMAS

Abstract PURPOSE Even after short-term administration of bevacizumab (Bev) demonstrates dramatically rapid volume reduction of glioblastoma. However, an extent of effect varies among patients. This study aimed to search prediction factors for tumor reduction in contrast-enhanced area (CEA) and peritumoral high intensity on FLAIR after Bev. METHODS Thirty patients with untreated primary glioblastoma and 34 patients with recurrent glioblastoma enrolled in this study. The former and latter received one-shot and two-shot Bev, respectively. MRI including arterial spin labeling (ASL) were performed before and after administrating Bev. We calculated tumor reduction rate (1-pre-volume/post-volume %) of CEA and HIA from MRI before and after Bev in each patient. Based on reduction rates, all patients were divided into three groups, Group A, patients with reduction rate more than mean value in both CEA and HIA; Group B, patients with reduction rate more than mean value in either CEA or HIA; Group C, patients with reduction rate more than mean value in neither CEA nor HIA. We compared findings of plausible factors, including volumes of CEA and HIA, tumor locations, presence of central necrosis, and CBFT/N on ASL, between three groups. RESULTS The reduction rates of CEA and HIA were 29.2% and 42.2% in untreated primary glioblastoma, and 46.5% and 36.3% in recurrent glioblastoma, respectively. The number of patients assigned into Groups A, B, and C were 9, 12, 9 in primary glioblastoma, and 8, 16, 8 in recurrent glioblastoma, respectively. Among factors, only CBFT/N showed a significant difference between 3 groups in both primary and recurrent glioblastomas in univariate analysis. Multi-variate analysis also showed CBFT/N could be a prediction factor in primary glioblastoma. CONCLUSION The present study suggested that CBFT/N becomes a prediction factor for reductions of tumor volumes after short-term administration of Bev in glioblastoma.