It used to be that we didn’t get biopsies in this location, and we treated suspected astrocytic tumors in the brainstem/upper spinal cord to 54 Gy in 30 fractions without tissue. The outcome was never good. But now we generally have at least a stereotactic biopsy. The outcome is still not good...

I also agree with @Laurie E. Gaspar that it makes little sense to overemphasize low-risk toxicity when you are faced with an aggressive, unresectable tumor. Like @Jiayi Huang, I think smaller volumes are fine in this situation. It is worth remembering that the ASTRO guideline lists a range of a...