We do have tremendously skilled doctors here and the James Graham Brown cancer center is a fine facility to receive chemo and radiation. But, the fact remains that if you want to dramatically increase survival rate for a serious cancer like a highly malignant brain tumor, you need to go to the places that specialize in the treatment. There are skilled surgeons here, but I'd rather go to someone who does 20 of these in a month rather than 20 in a career.
When the person in my family was diagnosed with a brain tumor, our neurosurgeon said that he could do the surgery, but if it was his brain he would go the surgeon who teaches everyone else how to do it. He gave us the name, we went to that surgeon, and my family member is alive today because of it.
For a glioblastoma, I would start here:
http://brain.mgh.harvard.edu/PatientGuide.htm