Fat intake and cancer of the gastrointestinal tract and prostate.

The epidemiological evidence for and against the postulated role of dietary fat in the aetiology of human gastrointestinal and prostate cancers is critically reviewed. Evidence for a causal association is inconsistent, and much is of low validity. Several studies of colorectal cancer provide evidence to refute the fat hypothesis, at least in some populations. The expanding interest in precursor adenomas and the possible role of fat in their aetiology has led to case-control studies of colorectal adenomas and clinical preventive trials to see if fat is related to risk, but virtually no results have yet been published. The few studies done in relation to prostate cancer justify further investigation of the role of fat, but there appear to be no putative mechanisms to explain an association.