Mets to brain...please help me feel better about this

My mom is 56 and two months into treatment for stage four breast cancer. So far she is responding well with hormones, radiation, and IV medication once every 3 weeks. She has cancer in her breast, a single lymph node, spine, hip, and skull. The spine was rebuilt and she is recovering like a champ. They had to do an MRI of her brain since it was in her spine, which shows a lesion the size of half a pea towards the middle back. We are upset, are there even treatments for the brain? By the way, she has zero neurological issues. We are at the Cleveland Clinic too. Thanks.