It is true that most die from infections. The immune system gets so lowered during treatment. I know they are trying to do everything the can. We have had one firend child beat the odds of Leukimia and another beautiful angel not.
The best thing you can do is pray. It is important that you be honest with your daughter. If you are close enough to them to help take care of the house or other kids offer. Do not take it personally if they can't /wont talk or except help. Please if you know what type of cancer she has use the site sugggested previously, that way you can better understand what they tell you. I know it helped my close friend not having to repeat everything to me. And hope for them all the best. Honestly her situatuin does sound very bad, although it is common to use drug induced commas to try and fight as hard and humanely as the possibly can.
My thoughts are with your daughter and her friends. Peace and love