The mechanistic rationale in support of dietary cancer prevention.

Mechanistic studies are an essential component of dietary cancer prevention trials. In breast and prostate cancer, a low-fat diet with a reduction in omega-6 fatty acid may prove effective, not only because of related decreases in sex steroid hormones, but as a result of altered eicosanoid biosynthesis. An optimal approach to primary and secondary prevention is likely to be a dietary change combined with one or more pharmacologically based chemopreventive agents. Patients with in situ carcinoma of the breast or prostate are candidates for dietary intervention as a means of secondary prevention.