I don't use flax oil as it oxidises too easily and is probably going to be rancid before you even get it home from the store but I have been eating ~25g of freshly ground flaxseeds per day for the past 20 or so years and I've seen no evidence so far that would make me stop doing so.
Flaxseed Supplementation (Not Dietary Fat Restriction) Reduces Prostate Cancer Proliferation Rates in Men Presurgery.
Nutrition and cancer: A review of the evidence for an anti-cancer diet
whfoods.com - flaxseeds.