Why isn’t glioblastoma, the cancer John McCain had, more successfully treatable?

The news that Sen. John McCain decided to discontinue treatment for glioblastoma and died on Saturday from it had us wondering about the survival rates of this cancer and the treatments.  McCain was diagnosed in July 2017 after surgeons removed a blood clot above his eye.

We asked Dr. John Kuo, the chair of the department of neurosurgery at Dell Medical School and the surgical director of the Mulva Clinic for Neurosciences, about this form of brain cancer and the advances in treatments that have been made.

It’s a very rare cancer, Kuo says, even though it’s been in the news recently because of McCain’s diagnosis and the diagnoses and deaths of Bo Biden, Vice President Joe Biden’s son, and Sen. Teddy Kennedy.

Sen. John McCain has decided not to continue treatment for glioblastoma. Alex Wong/Getty Images 2017

Cancers that originate in the brain affect only about 7 or 8 people out of 100,000. We don’t know what causes glioblastoma, though. It’s not linked to known outside factors like smoking, and it’s not genetic, Kuo says.

Unlike other cancers in the brain that originate somewhere else, glioblastoma begins in the brain in support cells called astrocytes (they look like stars). Astrocytes support and surround neurons. Glioblastoma infiltrates the brain, Kuo says.

In other cancers, you can cut out the tumor and a margin of healthy cells around it. In glioblastoma, “you can’t do that in the brain safely,” Kuo says. “The nature (of glioblastoma) is the cells left behind are likely embedded and invaded in the brain. That’s why it’s incurable.”

Typically, doctors will try to surgically remove as much as they can do safely. Sometimes, depending on where it is in the brain, they might not be able to remove much.

Then patients get radiation to the remaining cavity and the surrounding region.

Then they get a new chemotherapy in the form of a pill that was show in 2005 to make a difference in the survival rates for six to 12 months. Doing all three — surgery, radiation and chemotherapy — gave people a 5 percent survival rate in the first five years.

Now, an innovative treatment developed in Israel has extended that from 5 percent to 13 percent when added to those three, Kuo says. It’s called tumor treating fields. Doctors place grids on a shaved scalp and using electricity and magnetic fields, they disrupt cells as the cells are dividing. Using tumor treating fields now has FDA approval.

With glioblastoma, Kuo says, the younger the patient is the better treatment tends to work.

The median length of survival once diagnosed is about 15 to 18 months, Kuo says, which means that half the people will live that long, half will not.

Dr. John Kuo

While 5 or 13 percent survival rate in five years, might not sound like a lot, Kuo is seeing improvements in everything related to glioblastoma. Surgeons are able to do better surgery, more safely using microscopes, GPS mapping and fluorescence to see where the cancerous cells are. They also have better radiation techniques, new chemotherapies and innovations like tumor treating fields.

He also believes that eventually immunotherapy treatments that look at the biology of that person’s specific cancer cells will be applied to glioblastoma. “I hold a lot of promise and hope that research will help us beat this,” Kuo says.

“People think very dismally of this and pancreatic cancer,” Kuo says. “There’s a lot of research going on in this and that carries over to other cancers. We’re really hoping to make dents in this in quality and length of survival. There’s hope.”

 

 


View Comments 0