RecruitingPhase 2Radiation therapyMemory Avoidance Whole Brain Radiotherapy vs Hippocampal Avoidance Whole Brain Radiotherapy (Athena 2 Trial)Participants in this research study have cancer that has spread to their brain, called brain metastases. One treatment for this type of cancer is called whole brain radiotherapy that stays away from a specific neurocognitive substructure, called the hippocampus, combined with medication to preserve cognitive function. This study compares that approach to another approach of whole brain radiotherapy that stays away from additional structures that are thought to have a role in cognitive function. Researchers want to see if there is a difference in the preservation of cognitive function between these two approaches.