The former president said on Thursday that cancer that had been removed from his liver has been discovered more recently in his brain.
"I'm perfectly at ease with whatever comes," he said. "I'm ready for anything. I’m looking forward to a new adventure.”
Carter is getting two cutting-edge radiation and drug therapies.
The drug pembrolizumab uses the body’s immune system to fight the disease.
The radiation technique, known as stereotactic radiation, gives doctors the ability to tightly focus beams on each specific tumor.
“Several years ago if he had been diagnosed with this, the prognosis would have been dismal and we probably wouldn't have treated him at all," says CBS News medical contributor Dr. David Agus. "But in today's world with this immunotherapy he's getting, along with this very targeted radiation therapy of the small lesions in the brain, his prognosis for the next year or two is actually somewhat optimistic."