There was a rumor that he may have doped right after surviving cancer. I totally doubt it, because there is no proof either way (He wasn't famous enough then), and the person who put out that claim said that after being dropped from Team Discovery (shens). But even if he did do it right after cancer, that doesn't preclude the fact that he has won so many without doping. All it proves is that the once who hate Lance Armstrong, are either insecure and jealous, or just @$$holes trying to start conflict. In either case, they are both childish morons.
The truth is, he has so many people working on the best way to optimize his performance without doping: food, exercise, breathing/O2 levels, bike geometry, bike weight, ... and above all that, he trains harder than anyone else on the Tour, that everyone on the Tour was really competing for 2nd place. I guarantee that if you rode every day at your maximum performance on hilly terrain (CAT1/2) about 150-225 miles, slept in an oxygen deprivation tent almost every night, watched your calories so much that you are less than 3-4% body fat, and had trained since you were young to bolster the growth of your heart and lungs + genetics, you would win the Tour as well.