This trial is testing whether adding whole brain radiation therapy with hippocampal avoidance (to protect memory) and memantine (to protect thinking) to standard stereotactic radiosurgery (a high dose of radiation only to the small areas of cancer in the brain) is more effective than stereotactic radiosurgery alone in treating patients with cancer that has spread to the brain and come back in other areas of the brain after earlier stereotactic radiosurgery.