At five years old, Liberty Rose Finn has already lived through a lot. Finn and her sister Destiny Mai were born in December 2006, seemingly healthy. But six weeks after her birth, her parents Dawn and Carl noticed her eyes rolling back in their sockets. The condition was diagnosed as nystagmus, or involuntary eye movement.

Further tests revealed that the condition was caused by an optic chiasm glioma, a tumor wrapped around the nerve connecting Liberty's eyes and brain. Though the tumor was benign, it carried the risk that it would cause her to become blind and stunt her growth. And, because of its precarious position and size, doctors said that it could never be removed.

So, in October 2007, Liberty started an 18-month round of chemotherapy and a medical cocktail of drugs as part of a trial to reduce the tumor's size. By the end of the trial, conducted by the International Society for Pediatric Oncology, the tumor shrunk by 50 percent but, like most people who receive chemotherapy, had come with a large amount of side effects. Her parents decided not to begin chemotherapy again because of her ill health, even though they knew that, if the tumor regained its old size, their daughter could face blindness and other health complications.

Recently, the Finns looked at a new scan of their daughter's brain. The tumor had shrunk so much that it was imperceptible to brain scans. They were told that the cause was "spontaneous regression" and the treatments' after-effects.

Liberty will continue to have biannual follow-up checks, but if her progress continues like it has, researchers will consider seeing her only once a year. She has regained much of her sight, and her recovery has been extremely encouraging. It is also extremely rare - chemotherapy is often ineffective for optic chiasm gliomas.

Roz Osborne, speaking on behalf of the Samantha Dickinson Brain Tumor Trust, said, "The [tumor] could have disappeared through divine intervention or the fact that Liberty's body was so strong and fought off the cancer."