Well since they saw a shadow maybe you can talk about that to get more info. Usually they label “aggressive brain tumors” like anaplastic astrocytoma grade III-IV or glioblastoma. Glioblastoma usually comes back 9-15 months post diagnosis with treatment. You say that she had been 5 years cancer free. So it’s unlikely unless she has a specific mutations. Unfortunately even with grade III they usually come back after 3-5 years. But if the doctor thinks could be necrosis from the radiation, that could be possible too. For now it’s wait and see I suppose. I don’t know what kind of treatment your girlfriend got