17 year old wants to refuse chemo

I don’t know that this 17 year old is fundamentally different from who she will be at 18, but I guess the line has to be drawn somewhere. I have a relative who declined to take the last of her chemo treatments because she couldn’t bear it and was willing to let things ride. She’s got young kids. Of course, we worry for her, but I don’t judge because I have not had to walk in her shoes. If this young lady refuses treatment after her birthday in September, so be it.