Ellingson BM, et al. - Using contrast-enhanced T1 subtraction maps, researchers assessed if early changes in enhancing tumor volume can predict overall survival (OS) in newly diagnosed glioblastoma (GBM) patients treated with chemoradiation with or without bevacizumab (BV). A higher OS was observed in patients on the placebo arm with a sustained decrease in tumor volume using a post-chemoradiation baseline. In BV-treated patients, a trend toward longer OS was seen. Overall, for the assessment of efficacy in newly diagnosed GBM, the post-chemoradiation time point was found to be a better baseline. In predicting OS, early progression during the maintenance phase was considered consequential, supporting the use of progression-free survival rates as a meaningful surrogate for GBM.