By David Beasley

ATLANTA (Reuters) – Former U.S. President Jimmy Carter said on Thursday he will start radiation treatment for cancer on his brain later in the day.

Carter, 90, said he will cut back dramatically on his schedule to receive treatment every three weeks after doctors detected four spots of melanoma on his brain following liver cancer surgery.

Carter 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. He won the Nobel Peace Prize in 2002.

(Writing by David Adams; Editing by Bill Trott)

Photo: Former U.S. President Jimmy Carter attends the 2008 Democratic National Convention in Denver, Colorado August 25, 2008. REUTERS/Eric Thayer