I find this post by Seth Roberts relevant: http://blog.sethroberts.net/2012/04/03/lack-of-repeatability-of-cancer-research-the-mystery/

Most people are aware that publication bias exists, but it could be much worse than we think. If researchers do an experiment 6 times and only get their P=0.05 result once, does P really equal 0.05? Who knows how many of the "statistically significant" studies published in the medical literature are being misrepresented this way.