PURPOSE: Glioblastoma multiforme (GBM) is the most lethal type of primary brain 
tumor, and patients that undergo the maximum tumor resection that is safely 
possible and standard radiochemotherapy only achieve a median survival time of 
14.6 months. Several clinical studies have reported that valproic acid could 
prolong survival of GBM patients. However, the results of these studies are 
inconsistent. We examined relevant studies and conducted a meta-analysis to 
assess the effects of VPA on survival times and recurrence.
METHODS: A bibliographic search was performed in the EMBASE, MEDLINE, 
ClinicalTrials.gov and Cochrane Central Register of the Controlled Trials 
databases to identify potentially relevant articles or conference abstracts that 
investigated the effects of VPA on the outcome of glioma patients. Five 
observational studies were included.
RESULTS: Pooled estimates of the hazard ratio (HR) and 95% confidence intervals 
(CI) were calculated. Our meta-analysis confirmed the benefit of using VPA (HR, 
0.56; 95% CI, 0.44-0.71). Sub-group analysis shows that patients treated with 
VPA had a hazard ratio of 0.74 with a 95% confidence interval of 0.59-0.94 vs. 
patients treated by other-AEDs and a hazard ratio of 0.66 with a 95% confidence 
interval of 0.52-0.84 vs. patients treated by administration of non-AEDs. No 
heterogeneity was observed in the subset analysis.
CONCLUSION: The results of our study suggest that glioblastoma patients may 
experience prolonged survival due to VPA administration. Sub-analysis confirmed 
the benefit of VPA use compared to a non-AEDs group and an other-AEDs group. 
Further RCTs of this subject should be performed.