For patients with primary CNS lymphoma and less than a CR to chemotherapy, in what situation would you consider partial or focal radiation?

For the sake of discussion, I will assume that this patient achieved a PR after a high-dose MTX regimen. If the patient is young (<60 yo) and has a good KPS (>70), I would consider using a reduced dose of WBRT (30-36) followed by a boost to the residual lesion to an equivalent dose of 45 Gy (either ...