Genetic Testing of Cerebrospinal Fluid to Diagnose and Monitor Glioblastoma

Inclusion Criteria: Cohort A * Participants must be able to understand and be willing to sign a written informed consent document * Age ≥ 18 years * MRI with contrast-enhancing lesion concerning for high-grade glioma in absence of known systemic malignancy * Clinical consensus of presumed diagnosis of high grade glioma between (1) neuroradiology (2) neurosurgery; and (3) principal investigator * No prior tumor directed therapy * Planned radiation therapy for glioblastoma * Patients must be willing and able to tolerate MRI scans and/or CT scans w/ contrast * Patients must be willing to consent to MSK IRB#12-245 Cohort B * Participants must be able to understand and be willing to sign a written informed consent document * Age ≥ 18 years * Histologic confirmed glioblastoma (WHO grade IV), IDH wild type per IHC * No prior tumor-directed therapies except surgical resection or biopsy * Patients who have gliadel wafers placed during upfront surgery are excluded * Planned radiation therapy for glioblastoma * Patients must be willing and able to tolerate MRI scans and/or CT scans w/ contrast * Patients must be willing to consent to MSK IRB#12-245 Exclusion Criteria: Cohorts A and B * Any case for which there is a medical contraindication or safety concern regarding a lumbar puncture under standard medical guidelines at MSK * Refusal to undergo serial lumbar punctures