Brain cancer McCain has killed Gene Siskel, Tim Weigel, Ted Kennedy

The usually fatal brain cancer that Arizona Sen. John McCain has been diagnosed with is the same type that killed Chicago media icons Gene Siskel and Tim Weigel, as well as Sen. Edward M. Kennedy, D-Mass.

McCain, 80, was having a blood clot removed from above his left eye when doctors discovered his cancer, which is called glioblastoma multiforme, or GBM, and is considered uncurable.

Siskel, who came to fame with Chicago Sun-Times critic Roger Ebert when they started doing movie reviews on TV, had a brain tumor removed in May 1998. The cancer returned, and he died at 53 in February 1999.

Weigel died in June 2001 at 56, about a year after doctors found a brain tumor when he started having vision problems. Weigel was a staple on Chicago television while delivering sports on WLS-Channel 7 and briefly writing a Chicago Sun-Times sports column.

Within 15 months after being diagnosed with glioblastoma and having surgery, Kennedy died in 2009.

Beau Biden, the son of former Vice President Joe Biden, died of the same type of cancer last year, as did former Sun-Times dining critic Pat Bruno in 2012. Other well-known victims have included actor Sam Bottoms and investment author Gordon Murray.

Median survival is around 12 to 16 months after treatment, and that hasn’t changed much in decades because of the particular difficulties in treating glioblastoma. Patients over 55 have only about a 4 percent chance of surviving McCain’s condition for five years, according to the American Cancer Society.

Here are some other things to know about glioblastoma (GLEE’-oh-blas-TOH’-muh):

• Aggressive: Though McCain’s doctors at the Mayo Clinic said they managed to remove all of the tumor that was visible on brain scans, this kind of tumor is aggressive and sneaky. It puts out microscopic roots that go deeper into brain tissue, according to Dr. Joshua Bederson, chairman of neurosurgery at Mount Sinai Health System in New York, who has no direct knowledge of McCain’s care. Still, a tumor above the eye is in a location that permits removal with far less risk of damage to language, motor and other brain functions than in many other areas, Bederson said.

• Standard treatment: McCain’s Mayo doctors said the senator’s next treatment options might include a combination of chemotherapy and radiation. That’s standard after surgery to remove as much of the tumor as can be found and is safe to operate on, and that can take weeks to months. But even among those who respond to initial treatment, the cancer can come back, often within 12 to 24 months.

Bederson tells his glioblastoma patients that he knows they’ll look up the grim statistics, but he wants them to remember that some people do beat the odds for long periods. “It’s a small number, but that’s the hope my patients have when they leave my office,” he said.

• Uncommon: Glioblastomas typically occur in adults and are fairly rare. According to the American Brain Tumor Association, an estimated 12,390 new cases are expected to be diagnosed this year. McCain is a long-term survivor of melanoma, a deadly skin cancer. But doctors classified this new cancer as a “primary tumor,” meaning it’s not related to his former malignancies.

• How they kill: Though gliblastomas don’t spread elsewhere beyond the brain, they ultimately kill by getting in the way of the body’s normal functions.

• New approaches: Scientists are trying new approaches to treat glioblastomas. Doctors are testing a novel treatment that uses the patient’s immune system to attack the cancer. The treatment, called CAR-T cell therapy, has been used for blood cancers, but its value for solid tumors like brain tumors is unknown. A cap-like device that makes electric fields to fight cancer has been shown to improve survival odds for people with glioblastomas, though it has to be worn for 18 hours at a time.

At Northwestern University, scientists have developed an investigational drug that uses spherical nucleic acids — an incredibly tiny structure invented by Chad Mirkin, who heads Northwestern’s International Institute for Nanotechnology — to get past the blood-brain barrier to treat the deadly brain cancer.

“We know this drug works in mice,” Alexander Stegh, a Northwestern scientist, said in May when that was announced. “Now, we need to know if it can cross the human blood-brain barrier and accumulate in the tumor of a human being.”

Contributing: AP