Memantine Hydrochloride and Whole-Brain Radiotherapy With or Without Hippocampal Avoidance in Reducing Neurocognitive Decline in Patients With Brain Metastases

PRIMARY OBJECTIVES: I. Determine whether the addition of whole-brain radiotherapy with hippocampal avoidance (HA-WBRT) increases time to neurocognitive failure at months 2, 4, 6, and 12 as measured by neurocognitive decline on a battery of tests: the Hopkins Verbal Learning Test-Revised (HVLT-R) for Total Recall, Delayed Recall, and Delayed Recognition, Controlled Oral Word Association (COWA), and the Trail Making Test (TMT) Parts A and B. SECONDARY OBJECTIVES: I. Determine whether the addition of HA-WBRT preserves neurocognitive function at months 2, 4, 6, and 12 as separately measured by each test, the HVLT-R for Total Recall, Delayed Recall, and Delayed Recognition; COWA; and TMT Parts A and B. II. Evaluate the potential benefit of HA-WBRT in symptom burden, as measured by the M. D. Anderson Symptom Inventory-Brain Tumor Module (MDASI-BT). III. Assessment of quality adjusted survival and cost analysis using the five-level version of the EuroQol five-dimensional (EQ-5D-5L). IV. Compare cumulative incidence of progression and overall survival after WBRT versus HA-WBRT. V. Compare adverse events between the treatment arms according to the Common Terminology Criteria for Adverse Events (CTCAE) version (v)4.0 criteria. TERTIARY OBJECTIVES: I. Collect serum, plasma, and imaging studies for future translational research analyses. II. Evaluate magnetic resonance (MR) imaging biomarkers of white matter injury and hippocampal volumetry at baseline and 6 months as potential predictors of neurocognitive decline and differential benefit from HA-WBRT as compared to WBRT. III. Association of symptom burden and anxiety/depression with neurocognitive function. IV. Evaluate the potential correlation between the prognostic scoring systems Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) and the diagnosis-specific graded prognostic assessment (DS-GPA) and neurocognitive function at baseline and overtime. After completion of study treatment, patients are followed up at 12 months.