Stereotactic Radiosurgery Compared With Hippocampal-Avoidant Whole Brain Radiotherapy (HA-WBRT) Plus Memantine for 5 or More Brain Metastases

The purpose of this research study is to compare the effects (good or bad) of receiving stereotactic radiosurgery (SRS) versus receiving hippocampal-avoidant whole brain radiotherapy (HA-WBRT) plus a drug called memantine, on brain metastases. Receiving SRS could control cancer that has spread to the brain. This study will allow the researchers to know whether this different approach is better, the same, or worse than the usual approach. To decide if it is better, the study doctors will be looking to see if the stereotactic radiosurgery (SRS) helps to either slow the growth of cancer or stop it from coming back, compared to the usual approach. Doctors will also look to see if this new approach increases the life span of patients with this type of cancer, and if it helps with quality of life and cancer related symptoms. The usual approach for patients who are not in a study is treatment with whole brain radiation therapy alone (WBRT).