(NEW YORK) -- Heather Knies was given a death sentence at the age of 24. She battled not one, but two brain tumors -- one of them a grade 4 glioblastoma, the same kind of cancer that killed Sen. Edward Kennedy in 2010.
But today, six years later, she is cancer-free, and her doctors at the Barrow Neurological Institute in Arizona cannot explain it. Her latest MRI is clean, and she is neurologically intact.
The now-32-year-old Knies has not only outlived her life expectancy, she has married and become a mother. Her successful parenthood is remarkable, as intense radiation and chemotherapy can render cancer patients infertile.
Knies' daughter, Zoe, who is 7 months old, celebrated her first Christmas in December.
Knies' doctors say that in rare instances, a patient can break the "biological rules." But most often in those cases, the initial pathology of the tumor was suspect.
In her case, the pathology was "not controversial," according to her surgeon, Dr. Robert Spetzler, director of the Barrow Neurological Institute at Joseph's Hospital and Medical Center in Phoenix.
In his 35 years as a neurosurgeon in the United States, Spetzler said he has never seen such a triumph against a stage 4 glioblastoma.
"It's one of the most malignant tumors there is," he said. "Invariably it will come back and pop up somewhere else in the brain and it's uniformly fatal."
"It's not unheard of that that a few survive -- it's a bell curve and there are outliers," Spetzler said. "But in her case, not only has she survived, but she is perfectly normal and there is absolutely no evidence of a tumor on her MRI scan."
Knies has a few of her own theories for why she is still alive today.
"One, being God had a plan for me," said Knies. "I also had a great team of doctors and wonderful family and friends with a positive attitude."
"The mind is so much more powerful than anyone can imagine," she said. "People believe that when they get cancer, it will kill them. But I never once thought that."
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