Slit2/Robo1 expression is related to aggressive behaviors of brain glioma cells in the tumor progression. Slit2/Robo1 expression is used to evaluate development of brain gliomas and the disease severity. Absence of Slit2 expression obviously shortens the length of survival time of brain glioma patients. Slit2 severing as a biomarker is superior to Robo1 in assessing poor prognosis of the glioma patients.