I am so sorry to hear of your news, but I think I can give you some hope!!!
My 5 1/2 year old son was diagnosed with Leukemia (ALL) when he was 22 months old (not long after an incredible Disney trip). He went through 3 years of chemotherapy(boys have a longer treatment plan than girls for ALL) and completed his treatment this past June...just a couple of days after his 5th birthday!
With lots of faith and prayers, our son did remarkably well through his treatment...toddlers usually do b/c they don't know they are supposed to feel sick! I don't know the specifics of your daughter's disease (ALL, AML or other), but if you have any questions or just need to vent, feel free to post or PM me. It sometimes helps to talk to someone who has been there!!!
We are sending lots of prayers your way!!!