Ditto to what Jeff and Donna said.

There are things that can be done to slow progression/provide relief. Even radiation can be used that way without getting into all the problems that you get when you are treated in the curative mode which is what you have been reading on these boards.
What is feasible, makes sense and/or can be tolerated by your mother has to be evaluated by your team.
Hopefully, you will hear from GC that have experience with palliative treatment. (If that is what makes sense).

I wished I could help more....

Markus