Cure for Cancer: Cancer Patients Cured With Polio Virus in Duke University Trial By Nayomi Chibana | Mar 30, 2015 04:13 PM EDT Stephanie Lipscomb was diagnosed with a brain tumor the size of a tennis ball when she was only 20. The University of South Carolina nursing student was only expected to live two years after doctors concluded that she had a rare and fatal stage four glioblastoma. Lipscomb had surgery, then tried radiation therapy and chemotherapy, but the cancer came back. As part of an experimental treatment, doctors at Duke University Medical center injected polio virus into the tumor. Three years later, she has been declared cancer free. Have scientists found the cure for cancer? While it is still too soon to say, researchers say that this is the closest they have come to finding an effective cancer treatment. "This, to me, is the most promising therapy I have seen in my career, period," says Dr. Henry Friedman, a neuro-oncologist who is the deputy director of the Brain Tumor Center at Duke University. Watch video According to CBS news, he has been researching a cure for glioblastoma for more than 30 years and was originally skeptical of the idea, which is the brain-child of Dr. Matthias Gromeier, a molecular biologist at Duke Medical Center. "I really thought he was using a weapon that produced paralysis," said Friedman. Now, 15 years after Gromeier first proposed the idea, Friedman admits he has been swayed by the results of animal and human clinical trials. 60 Minutes spent a year following the ups and downs of this experiment, chronicling how doctors sometimes had to make tough decisions, such as increasing the dosage to determine how the virus would react. This had fatal consequences in several instances. Of the 22 patients in the polio trial, 11 have died. The other 11 with lower doses continue to improve; four of them have been cancer free for the past six months. Gromeier explains that the polio treatment removes the shield human cancers put up against the immune system, which then allows the body's own immune system to start killing the cancer. "All human cancers, they develop...protective measures that make them invisible to the immune system and this is precisely what we try to reverse with our virus," he says. "We are actually removing this protective shield...enabling the immune system to come in and attack." Gromeier re-engineered the polio virus by removing a key genetic sequence and replacing it with a harmless bit of cold virus. This way, he explains to CBS news, the modified virus can't cause paralysis or death because it is not able to reproduce in normal cells. It can, however, reproduce in cancer cells, which leads to the release of toxins that kill the cell. Dr. Darell Bigner, the head of the study and of Duke's Brain Tumor Center, says that he's never seen results like these in the 50 years that he's been researching brain cancer. "I'm very reluctant to use the cure word, the C word as we call it because we don't know how long it takes to say that a glioblastoma has been cured. But I am beginning to think about it," he says.