Polio virus, benevolent or virulent?

Polio virus to kill malignant brain cancer instead of causing paralysis? Too good to be true. It seems like Duke Uni. is making a miracle according to CBS "60 Minutes" tonight. In the US, 12,000 patients died of glioblastoma (惡性膠質腦瘤,12% of all primary brain cancers). Now, doctors can inject re-engineered polio virus into the brain and let polio virus fight with glioblastoma cells during which the dormant human immune system awakes and continues to do the majority of glioblastoma cancer eliminations. This immunotherapy has a stunning success rate with 50% of patients showing the continuous cancer cell shrinkage, even at phase 1 without knowing the appropriate dose, . Cancer is usually dubbed as "emperor of all maladies". Now, there is a slight glimmer at the end of tunnel to fight with cancer.   http://www.cbsnews.com/news/polio-cancer-treatment-duke-university-60-minutes-scott-pelley/