He admitted his guilt in an interview with Oprah Winfrey to be aired on Thursday and Friday.
Armstrong has always denied he doped, while teammates claim he did.
Cancer survivor Gary Bonacker and founder of the Tour Des Chutes Bike Race that raises money for cancer survivors says he's disappointed, but not surprised by the revelation.
"I'm not totally unsympathetic. On the other hand, his lies became his truth. That's how lying works. You say it so much you believe it. For him that was his reality. I certainly hope he didn't come clean to be an Ironman winner."
Bonacker says he's disappointed that Armstrong cheated and hopes he apoloigzes to al lthe cancer patients and survivors who worked and raised money for his cancer fighting organization -- Live Strong.