After a tumor was removed from his liver, the 90-year-old Carter said an MRI revealed the four "very small" melanoma spots on his brain.
Carter said the pain following the surgery (in which he said about 1/10th of his liver was removed)l was "very slight," but the news of the cancer spots spotted in his brain came as a jolt.
"At that point, I just thought I had a few weeks (to live)," Carter said.
His first radiation treatment for the melanoma spots in his brain will be Thursday afternoon.
"I'm ready for anything and a new adventure," Carter said. "It's in the hands of God."
There has been no evidence of pancreatic cancer, which there is a genetic history of in Carter's family.
Carter said that the Carter Center, which he founded in 1982 with his wife Rosalynn, will continue to run as normal even without his direct oversight.
"Im going to cut back fairly dramatically on my obligations," Carter said.
The center works to advance human rights and alleviate human suffering.
Carter said he hopes to continue working as a professor at Emory University.
"The rest of my plans will be determined by my consultations with my doctors," he said.
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