In platinum-refractory or multiply-relapsed NSGCT with 1–2 progressive sites and no good surgical option, is there a role for local radiotherapy (e.g., SBRT) to those sites?  

If considered, what clinical selection (marker status, histology/teratoma concern) and goals (local control vs palliation) do you use?
Suggested dose/fractionation and organs-at-risk constraints?
Does your approach differ for brain vs extracranial oligoprogression?