The move comes a week after the U.S. Anti-Doping Agency said it had uncovered overwhelming evidence of Armstrong's involvement in a sophisticated doping program while a professional cyclist. Armstrong has consistently denied the claims.
Armstrong said Wednesday that his decision to step down from the Livestrong cancer charity he founded was to "spare the foundation any negative effects as a result of controversy surrounding my cycling career," according to a statement posted to the group's website.
CNN's Danielle Dellorto contributed to this report.
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