I have never heard that vitamins are a cancer risk before, but even back when I was in grammar school we were taught that overdosing on vitamins (via tablets) was a bad idea, and that multivitamins were only really suitable for the very young or very old. Anyone else was recommended to determine which vitamins they were deficient in, and try as much as possible to redress this in their diet, and if not, to take those specific vitamins in a reasonable quantity.
There is a possibility my doctor may prescribe me Orlistat to aid my weight loss. In which case I will be advised to take vitamins to supplement those fat soluble ones I will lose (ie poop right out). I'm aware that these are toxic in high quantities, stored in the liver and only a small amount is needed by the body. See, I might not even get the drug and I'm already read up on it
I will admit, I have taken multivitamins myself, I certainly don't have a higher ground in the balanced diet stakes. But this news doesn't represent a 180 degree swing for me. I have never taken super-high doses of anything though.