I agree with Qwerty. Cancer is probably the least likely cause of a misaligned eye.
My daughter's eyes began to turn inwards when she was around 9 months old (strabismus). Whenever she looked to the side, one would turn in and also up. I consulted a pediatric ophthalmologist, who prescribed glasses at 12 months of age. I remember thinking, "How the heck do you keep glasses on a baby?," but the doctor pointed out that a baby usually WILL keep them on if s/he notices they can see better. The glasses didn't help, unfortunately, and then my daughter developed amblyopia. Simply put, the brain gets tired of seeing conflicting images and "turns" off vision to one eye. This can lead to blindness, even though there is nothing actually wrong with the vision in that eye. Patching takes care of that; in our case, within two weeks. Never thought I could keep an eye patch on a toddler for 3-4 hours/day, but she LOVED it (go figure!). Still no improvement, though, so she had surgery at 2.5 years. We achieved 100% correction and I was extremely pleased. It's been 2 years since her surgery and I rarely remember she even had an eye problem.
Sorry to be so long-winded, but I just wanted to let you know I've been in the same boat. Of course, we don't know if your daughter has strabismus, but if she does, there are treatment options to explore.
Good luck and keep us updated