This is an interesting one - and the whole paper is available.
Intake of wholegrain products and risk of colorectal cancers in the Diet, Cancer and Health cohort study
Take a look through and see what you think, but at first glance it seems that (at least for women) there is no justification to saying that eating whole grains gives a better chance of avoiding gut cancer. Even for men the effect seems limited and there look to be a few confounding variables.
It might just be me or maybe the hype about wholegrains continues to be unjustified.