desjardins: now, show me your smile. >> pelley: on nancy's way home that same day, oncologist dr. howed her how it went. >> desjardins: so we can exactly see where the polio virus went. so that's the m.r.i. you and i looked at on monday. then, you see here the brighter area there? can you see that? >> nancy justice: yes. >> desjardins: that's the polio virus. >> nancy justice: wow. >> desjardins: exactly where we needed it. >> nancy justice: oh. cool. okay. >> desjardins: right where it should be. >> pelley: in a few months they'll take another m.r.i. to see which is stronger, glioblastoma or polio. >> henry friedman: the number of calls are increasing. >> pelley: this is duke's polio team. as usual in such studies several of them have a financial stake, so they'll benefit too if it becomes commercial. can you pick out the deputy director of the brain tumor center? well, when you're one of the world's leading cancer doctors turns out you can wear what you like. and after 34 years, folks at duke are used to how dr. henry friedman's brain views fashion. >> friedman: it's really good

dr. desjardins wanted to go back to traditional treatment but stephanie decided against her advice to wait, five months after her infusion and mri showed that the tumor hadn't been growing at all, it turned out it only looked worse because it was inflamed. stephanie's immune system had awakened to the cancer and gone to war. why didn't the immune system react to the cancer to begin with? >> so cancers -- all human cancers, they develop a shield or sh rould of protective measures that make them invisible to the immune system, and this is precisely what we try to reverse with our virus. so by infecting the tumor, we are actually removing this protective shield and telling -- enabling the immune system to come in and attack. >> so essentially what's happening here inside the tumor is you have a polio infection. >> yes. >> and that sets off an alarm for the immune system. >> yes. >> the immune system says there's a powe owe infection, we'd better go kill it. >> yes, exactly. >> and it turns out to be the tumor. >> yes. >> reporter: it appears it's the polio that starts but the immune system do