You really want to see "Let's Play: The Witcher II, in the Lowest Settings Possible"?
pmp - I can't say for the cancer reference since I've never seen it in my game. Suffice to say that I agree it's a silly and unnecessary line to insert, but I think it's blown way out of proportion, and one or two comments like this definitely doesn't break down the verisimilitude... especially given we have mutagens and the like.
The cancer reference is right before the screenshot I posted. Basically triss comments that the Kyran has a series of mutated cells, almost like cancer, on it that are causing it much pain and will probably kill it.
Thing is, all this talk of mutations and cancer and an understanding of both, makes me wonder why medics and doctors (particularly in the first game) still are running around in little more than smock and seem to have about as much information as the medics of the time period in THIS reality.