WASHINGTON, United States (AFP) — Jimmy Carter, the former US president turned Nobel peace laureate and global humanitarian, revealed yesterday he has cancer on his brain but said he feels at peace and grateful for having lived a full life.

The 90-year-old Carter told a press conference that the finding of the four melanoma spots stemmed from a procedure in which a tumour was removed from his liver earlier this month.

“They did an MRI and found that there were four spots of melanoma on my brain,” Carter told reporters in Atlanta. “I get my first radiation treatment for the melanoma in my brain this afternoon.”

Carter said that as his treatment continues, it is likely doctors will find cancer elsewhere in his body.

Melanoma usually shows up in the skin, but a small percentage of cases are internal, Carter said his doctors had told him. It is a very aggressive form of cancer.

The 39th president sounded quite serene and in high spirits as he discussed his illness. He joked with reporters and smiled often, his Georgia drawl still pronounced.

Carter, a former peanut farmer who only served one term in office from 1977 to 1981, is arguably better known for his decades of humanitarian work around the world since leaving the White House.

“I feel good. I haven’t felt any weakness or debility,” Carter said, adding he said he plans to carry on teaching Sunday school and hopes doctors will allow him to travel to Nepal with Habitat for Humanity.

Carter said he has received well-wishing phone calls from a host of powerful people, including President Barack Obama, Vice President Joe Biden, former president Bill Clinton and his wife and presidential hopeful Hillary, and both former presidents Bush.

“First time they’ve called me in a long time,” Carter joked, drawing guffaws at a news conference that seemed almost light-hearted — not an unusually frank explanation by a former president of cancer that could spread.

Carter said that after doctors diagnosed the melanoma in his brain, he initially thought he was quickly nearing the end of his life, but was still at ease.

“You know, I have had a wonderful life. I have got thousands of friends and I have had an exciting and adventurous and gratifying existence,” Carter said.

“So I was surprisingly at ease, much more so than my wife was, but now I feel, you know, it’s in the hands of God… and I’ll be prepared for it when it comes,” Carter said.