GFAP and astrocytoma (excluding glioblastoma): Higher GFAP mRNA in 5/7 grade I, 2/5 grade III, 10/18 grade IV astrocytoma compared to healthy brain tissue.GFAP mRNA in four peri‐tumor and tumor pairs: 1/1 grade IV pair increased in tumor; 1/1 grade III pair increased in tumor; 1/1 grade I and II pair increased in tumor.Significant effect? NA