I had a friend that died from throat cancer when I was 15 years old.
She was 14.
She fought the desease for about 5 years. She was such a happy person nobody would know she was fighting so hard.
The one thing I remember the most is her smile, her voice (kind of deep) and how strong she was. I don't remember much about her being sick.
The one thing I can tell you is, that the times when she got sick she would always tell everybody things such as "don't worry, I'll be back". But when the time came, she did tell her mom "this is it, I've been very happy" and indeed that was the last time she was sick.

It seemed like the illness was much harder on everybody else than her, and for what you are saying, this might be the case for you too.

My prayers are with you, your daughter, your friend and her family. All you can do is love her

gab