Former U.S. President Jimmy Carter will start radiation treatment Thursday for brain cancer, a week after he revealed that recent liver surgery found the disease had spread to other parts of his body.

Carter, 90, disclosed the diagnosis at 10 a.m. at the non-profit center bearing his name in Atlanta. He will receive treatment every three weeks after doctors detected four spots of melanoma on his brain following liver cancer surgery.

He announced last week that he was rearranging his schedule to receive treatment at Emory Healthcare in Atlanta, where he previously underwent elective surgery to remove a small mass in his liver. His prognosis was then considered excellent, the Carter Center said in a statement earlier this month.

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Yet with his father and his three siblings having died of pancreatic cancer, the disease has long been a concern for the Carter. His mother also had pancreatic cancer in addition to breast and bone cancer.

Carter, a peanut farmer from Georgia, served as president from 1977 to 1981, his one-term in the White House defined by national economic struggles and the embarrassing Iran hostage crisis.

Yet the centrist former governor of Georgia was also praised for helping to stabilize the Middle East with the 1978 Camp David accords between Israel and Egypt.

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After losing re-election to Republican Ronald Regan, he went on to champion wide-ranging international humanitarian efforts. Carter won a Nobel Peace Prize in 2002.

He published his latest book last month, titled "A Full Life: Reflections at Ninety."

Carter and his wife, Rosalynn, have three sons and a daughter. They live in rural Plains, Georgia, about 150 miles south of Atlanta, where he has remained a Baptist church deacon and a Sunday School teacher, according to the Carter Center.