dr. mathias gromeier, seeking to use one disease over another. >> i'm a polio virolooingsgist, interested in targeting tumors with therapy. >> exist naturally on many cancers. >> polio virus naturally we didn't have to do anything to it. it naturally like to infect cancer cells and kill them. the virus is the spark that makes the tumor recognizable to the immune system. so this entails inserting a catheter into the patient's brain, into the area of the tombor and the virus is infused through this catheter. >> polio kills. and i didn't think that that was a good idea. >> she's like what? you're putting polio in my daughter's brain? are you serious? >> it took me a little bit to get used to that idea. but it was stephanie's decision. and i stood beside her. >> the doctor actually came in and explained that to me and i was just amazed. i was like why not try it, you know. >> it had not been used on a human yet. >> it had only been done on monkeys and that's exactly how they explained it to us. >> over a six hour period a surgeon injected over 1 million virus particles into stephanie's brain.