How would you approach re-irradiation for multiply recurrent medulloblastoma patient with a 'brain-only' recurrence pattern?

Would your approach differ base on group and subgroup? Specifically, what clinical or radiographic triggers are you using to pivot from focal SRS back to a comprehensive neuraxis approach in combination with salvage systemic therapy? Consider scenarios where the initial CSI was 36 Gy and early <2 yrs vs. >2 yrs from the initial RT. Consider whether spine disease (cytology or radiographic) should modify the decision making. Is there ever a preference for focal SRS approach for new lesions over salvage CSI? What should the sequencing of systemic therapy be in relationship to salvage radiotherapy?