Residual enhancing tumor volume associated with OS, PFS in glioblastoma

Early post-treatment enhancing tumor volume, as well as volumetric percentage change, can help stratify survival among patients with recurrent glioblastoma who are treated with bevacizumab, according to results of a retrospective study.

“Despite a high radiographic response rate in patients with recurrent glioblastoma following bevacizumab therapy, the survival benefit has been relatively modest,” the researchers wrote. “We assessed whether tumor volume measurements based on baseline and early post-treatment MRI can stratify patients in terms of PFS and OS.”

Researchers examined the baseline and post-treatment MRI exams of 91 patients for volume of enhancing tumor and volume of the T2/FLAIR hyperintensity. The investigators used a Cox regression model adjusted for significant clinical parameters to assess OS and PFS.

Residual tumor volume, percentage change in tumor volume, steroid change from baseline to post-treatment scan and the number of recurrences were associated with both OS and PFS.

Those with a residual enhancing tumor volume less than 7.8 cm³ had longer median OS (64.1 weeks vs. 27.7 weeks) and PFS (20.9 weeks vs. 12 weeks). In addition, patients with more than a 52% reduction of enhancing volume on post-treatment scan when compared with baseline scan had a longer median PFS (20.9 weeks vs. 11.9 weeks; P=.009) and OS (52.3 weeks vs. 31 weeks; P=.013).

“Our results support a potential advantage for quantitative volumetric analysis early during bevacizumab treatment to identify patients who may benefit more durably from bevacizumab therapy,” the researchers wrote.

Disclosure: The researchers reported board service, speakers bureau and consulting roles with, as well as research support and lecture fees from, Amgen, AstraZeneca, Boehringer Ingelheim, EMD, Esai, Genentech/Roche, GlaxoSmithkline, Merck, Novartis, Sanofi-Aventis and other pharmaceutical companies.