It is challenging to explain probabilities that go beyond the difference between the words, probabilities, and odds.  In fact, when we use words to describe numbers, it often increases the ambiguity of their meaning – something is lost between sender and receiver in the translation.
For all the regulation of what's written in direct-to-consumer health ads (and for all the hand-wringing about informed consent), there's little said about what patients understand. As it turns out, health literacy is a problem. And those with the biggest problems are looking for help in all the wrong places.