The CEO of Livestrong, the cancer charity started by disgraced cyclist Lance Armstrong, is leaving after 14 years.

AUSTIN, AP - The chief executive of the cancer charity Livestrong is leaving after 14 years, a period in which the small local charity grew into a $US500 million global brand before it was rocked by founder Lance Armstrong's confession that he used performance-enhancing drugs during his cycling career.

Doug Ulman helped Livestrong ride Armstrong's sports career and celebrity into rapid and worldwide expansion. He also had to guide it through the two-year fallout of Armstrong's cheating revelations that prompted corporate sponsors and private donors to flee.

Ulman said on Monday he will leave Livestrong in January to become president and chief executive officer of Pelotonia, a Columbus, Ohio, charity bike ride that has raised more than $US61 million for cancer research in its first five years.

Ulman and Livestrong board chairman Jeff Garvey said Ulman leaves on good terms despite Livestrong's recent struggles. Livestrong's 2013 financial reports showed a 34 per cent slump in donations and a 38 per cent dive in total revenue after commercial sponsorships were cancelled or not renewed.

Armstrong founded the charity in 1997 and it grew on his star power as the swaggering cancer survivor who dominated one of the world's toughest sporting events. The charity sold more than 80 million yellow Livestrong wristbands across the globe.

But Armstrong's feel-good story was blown apart in October 2012 when the US Anti-Doping Agency exposed his cheating. In a January 2013 televised interview with Oprah Winfrey, Armstrong confessed to doping throughout his career. He was stripped of his Tour de France titles and banned from Olympic competition.

Armstrong's revelation led big corporate sponsors and partners such as Nike and Dick's Sporting Goods to flee Livestrong by either cancelling contracts or not renewing them.

Armstrong was removed from the charity's board of directors in late 2012, and he no longer has any formal association with the charity, which changed its name from the Lance Armstrong Foundation.

Ulman called the fallout of the past two years "the most stressful period of my life, by a landslide, and my family's life". Still, Ulman said he's "so proud at what we've accomplished (at Livestrong)".

Garvey and Ulman said Livestrong remains on solid financial ground, noting its $US100 million in assets and an endowment of more than $US30 million. Last month, Livestrong agreed to give $US50 million over 10 years to the University of Texas' new medical school for a program emphasising "patient-centred" cancer care. Garvey praised Ulman's role in establishing a partnership he said is critical for the charity's future.

Pelotonia gives the money it raises from riders to cancer research at The Ohio State University Comprehensive Cancer Center - James Cancer Hospital and Solove Research Institute.

"We wanted a leader who was a builder and had clear and strategic thinking, to build a brand and raise even more money for cancer research," Dan Rosenthal, chairman of the board at Pelotonia, said.

Copyright AAP 2014