Sen. John McCain has been diagnosed with brain cancer, the senator’s office confirmed Wednesday. The aggressive form of tumor was discovered after the Republican senator from Arizona underwent surgery at the Mayo Clinic Hospital in Phoenix last Friday to remove a blood clot above his left eye. McCain was diagnosed with glioblastoma, a rare form of tumor that is considered the “deadliest type of brain cancer.” The survival rate for the cancer is usually a year or two, with only a small percentage of patients surviving more than five years.

CNN’s Dr. Sanjay Gupta suggested on air Wednesday night, after speaking with McCain’s doctors, that some combination of surgery, chemotherapy, and radiation would likely be required to combat the tumor. “The Senator’s doctors say he is recovering from his surgery ‘amazingly well’ and his underlying health is excellent,” the hospital said in a statement.

Concerns about McCain’s health were raised last month when the 80-year-old appeared confused and somewhat disoriented while questioning former FBI director James Comey at a Senate Intelligence Committee hearing. Glioblastoma is the same tumor that Joe Biden’s son, Beau Biden, died of two years ago and also took the life of former senator Ted Kennedy in August 2009.*

*Correction, July 21, 2017: This post originally misstated that Sen. Ted Kennedy died in May 2008; he passed away in August 2009.