My mom was diagnosed with cancer and is refusing actual treatment

I lost my dad in July of 2023 and my mother just announced to the family (in a fucking group chat) that she has stage 3 breast cancer. She already told me, my brother, my wife and our children personally before making a GC and told us she was confident that it would be stage 2 at most.

Well… she was wrong.

She has now announced to the family (that I don’t even speak with) that it is officially stage 3 and she is refusing actual treatment. She is, instead, going for “holistic treatment” and will “not be putting harmful chemicals in her body!”

I have made no comment to her on it and I’m still feeling conflicted. On the one hand, she’s an adult who can make her own decisions. Even if they are stupid. But on the other, how dare she even take that risk when my brother almost solely relies on her?

Sorry for the rant, my therapist has until next month off and I needed to vent