People are always making this kind of stuff up because they can't accept the world is dumber and less exciting than they think.
Look, as far as Brazil goes, Lula liked his drinks and everyone knows it, besides his deep voice always pointed out to some kind of malformation or acquired damage. And axilar lymphoma which Dilma had, is more common in Brazil than most people think, probably due to most women living their whole lives with nail infection due to constantly removing nail cuticules, which the country is number one worldwide. Whether it was Dilma's case or not, she healed anyways, so the evil alien cancer weapon seems pretty crappy still, don't you think. Chaves is probably more bitter about it all because he's apparently got terminal bone cancer.
In the end, who knows, they are being punished by the One True God to show the errors of their populist ways, lol.