well, there ARE papers that show it kills cancer cells.Oh yeah, link some studies that say it cures cancer lol. U don't know how to consult or extrapolate any good info. If you don't know how to put study in a contest they are useless.
what you talk about carcinogenic etc is nothing but mainstream talk coming from people that have no clue.
long term side-effects are not known right now because they have not been studied. It could be carcinogenic long-term, but there is no proof for that.
It has also a host of favorable feats like restoring insulin sensitivity like nothing else etc.
but of course it isnt the most pleasent thing to run and they are dangers. Enough care and preparation should be enough to avoid those mostly though.