An old thread, but I am pluging this research stuff here.

""... a startling study shows men who have the highest levels of these compounds – the kinds found in fish but not in vegetable sources -- have a higher risk of prostate cancer. Men with the very highest levels had a 71 percent higher risk of high-grade prostate cancer – the kind most likely to spread and kill, they report in the Journal of the National Cancer Institute.""

Prostate cancer+fish oil-research