With today's news about Lance Armstrong it is an excellent time to read this Outside Magazine profile on Armstrong and his Livestrong non-profit.
The key takeaway is that when you donate money to Livestrong you are not giving money for cancer research - you are giving money for hope (many people don't realize that Livestrong actually doesn't give any funds towards research). And Armstrong's image becomes the beneficiary of that message as the exemplar of that hope.
In no way am I sitting in judgement on this. Rationally I feel that the cure from cancer will be found via research. But that rationality is coming from someone who does not have cancer. If I had cancer I'm guessing the hope. message and example of Lance Armstrong would become much more important to me.