WCNC-TV, Charlotte

Stephanie Lipscomb was supposed to be dead by now.

The University of South Carolina nursing student was just 20 when diagnosed with a rare and deadly stage four glioblastoma, a brain tumor the size of a tennis ball.

"The odds weren't good," Lipscomb said. "They didn't expect me to live more than two years, I don't think."

Lipscomb had surgery, radiation therapy and chemotherapy. But the cancer came back.

In May 2012, as part of an experimental treatment, doctors at Duke University Medical Center injected a modified version of the poliovirus into the tumor in Lipscomb's brain. Last July, doctors told her the tumor was gone.

Lipscomb is cancer-free as she gets ready to celebrate the 23rd birthday doctors said she'd never see. Watch the video to learn more about her incredible story.