Recurrent Glioblastoma Volumetric Assessment and Stratification of Patient Survival With Early Posttreatment Magnetic Resonance Imaging in Patients Treated With Bevacizumab

BACKGROUNDDespite a high radiographic response rate in patients with recurrent glioblastoma following bevacizumab therapy, survival benefit has been relatively modest. We assess whether tumor volume measurements based on baseline and early posttreatment MRI can stratify patients in terms of progression-free survival (PFS) and overall survival (OS). METHODSBaseline (-4 +/- 4 days) and posttreatment (30 +/- 6 days) MRI exams of 91 patients with recurrent glioblastoma treated with bevacizumab were retrospectively evaluated for volume of enhancing tumor as well as volume of the T2/FLAIR hyperintensity. Overall survival (OS) and progression-free survival (PFS) were assessed using volume parameters in a Cox regression model adjusted for significant clinical parameters. RESULTSIn univariable analysis, residual tumor volume, percentage change in tumor volume, steroid change from baseline to posttreatment scan, and number of recurrences were associated with both OS and PFS. With dichotomization by sample median of 52% change of enhancing volume can stratify OS (52 weeks vs. 31 weeks, P=.013) and PFS (21 weeks vs. 12 weeks, P=.009). Residual enhancing volume, dichotomized by sample median of 7.8 cm(3), can also stratify for OS (64 weeks vs. 28 weeks, P<.001) and PFS (21 weeks vs. 12 weeks, P=.036). CONCLUSIONSVolumetric percentage change and absolute early posttreatment volume of enhancing tumor can stratify survival for patients with recurrent glioblastoma receiving bevacizumab therapy. Cancer 2013;119:3479-3488.. (c) 2013 American Cancer Society. Volumetric percentage change and absolute early posttreatment volume of enhancing tumor can stratify survival for patients with recurrent glioblastoma initiated on bevacizumab. A volumetric approach may be used to identify patients most likely to have a durable benefit from bevacizumab therapy.