Comment by mariusor
What makes this mildly funny, though I admit in quite poor taste, is the fact that Armstrong did indeed suffer of cancer to which he lost a testicle before his comeback to win multiple Tour de France back to back. So theoretically his EPO positive results could be attributed to those tumors producing it, if this research is to be believed. Maybe not all of the times though.
Or, consider that the causation could have been the other way around. The EPO could have made him more susceptible to cancer.
There is a mountain of evidence that the drug cheating was systematic. You can read The Secret Race, or draw your own conclusions from the $5 million false claims act settlement.