Does radiation help with stage 4 breast cancer that has mets to the brain?

Yes: Radiation is very important to control symptoms like headaches or seizures. In rare cases, surgery or gamma knife are used but only if there are only a few mets and the rest of the disease is under control.

Yes: Brain metastases are often treated witih various forms of radiation. If many lesion exist, whole brain radiation is used. If a few are there, recent data suggest stereotactic radiosurgery (radiation therapy really) is useful. It can allow people to live much better after they have brain metastases. How your particular situation is best handled depends on many things. But form most, it helps.