RecruitingProcedureCerebrospinal Fluid Biomarkers for Brain TumorsThis study examines cerebrospinal biomarkers in patients with brain tumors. A biomarker is a measurable indicator of the severity or presence of your disease state. Collecting and storing samples of cerebrospinal fluid from patients with brain tumors to study in the laboratory may help doctors develop new strategies to better diagnose, monitor, and treat brain tumors.