The 80-year-old Republican has glioblastoma, an aggressive cancer, according to doctors at the Mayo Clinic in Phoenix. The senator and his family are reviewing further treatment, including a combination of chemotherapy and radiation.
The senator and chairman of the Armed Services Committee had been recovering at his Arizona home. His absence had forced Majority Leader Mitch McConnell, R-Ky., to delay action on health care legislation.
McCain was the GOP's presidential nominee in 2008, when he and running mate Sarah Palin lost to Barack Obama. A Navy pilot, he was shot down over Vietnam and held as a prisoner for 5 ½ years.
