On July 19, 2017 Doctor Jamie Wells posted an article, Understanding Sen. McCain’s Glioblastoma Diagnosis, on the American Council on Science and Health website discussing Senator John McCain’s cancer situation and I got the impression he had a good chance of recovery. I'm not so sure of that.
From other articles I 've read being diagnosed with "primary glioblastoma" is pretty much a death sentence. It's a type of brain tumor that's considered particularly aggressive and malignant, meaning the cancer cells divide uncontrollably. While starting in the brain or spinal cord it has the ability to "invade and stay within normal brain tissue", but it can also invade sourrounding tissue including other parts of the body through the blood stream or pumped through lympahatic system. All of which means he'll being going through a lot more treatment involving chemotherapy and radiation.
So then why is this a death sentence? Some cancers can be pretty much cured or at the very least held at bay for long periods of time but some cancers are so devastating the end result is often short from the day of diagnosis, much like pancreatic cancer. While there may have been some survivors - a diagnosis of pancreatic cancer is normally a short term death sentence.
Apparently 10% of patients with glioblastoma may live five years or longer, but the "average survival time for malignant glioblastoma is around 14 months, and that's with treatment". Both Ted Kennedy and Beau Biden died from this affliction.