GFAP and central nervous system cancer: Preoperative:Higher levels of GFAP in grade IV compared to grade III.Higher levels of GFAP in grade IV compared to controls.Correlation to enhancing tumor volume (primary/recurrence).Correlation to necrotic tumor volume (primary/recurrence).Lower levels in IDHmut glioma.Correlation to Ki67 expression.No correlation of GFAP expression in tumor to serum levels.High GFAP levels related to poor PFS in primary tumors.Postoperative:Increased GFAP levels in 65% of glioma patients.No correlation to tumor volume.No difference between day 2, 3, 4, and 5 postsurgery.