URINARY VEGF Levels in GBM Patients on Radiation Treatment Protocol

Inclusion Criteria: * Patient must be enrolled on an RTOG GBM study that prescribes 6000 cGy of radiation therapy. * Patient must meet the eligibility requirements for the RTOG treatment study. (If the patient is deemed retrospectively ineligible for the RTOG treatment study, the patient will likewise be ineligible for this study.) * Patient must sign a study-specific informed consent for RTOG 0611 prior to study entry. Exclusion Criteria: * Patient not able to receive 6000 cGy of radiation therapy.