These are patients who are already at increased risk for polyps or cancer, and because they have a mutation at a younger age, they are therefore more at risk for polyps and cancer at a younger age. We now know several of these genes and how to identify them in at-risk families. Our screening strategies for these families and patients is to initiate more aggressive screening at earlier ages. The problem, of course, is finding these families and screening them appropriately. Up to now, we've been discussing secondary prevention.
Secondary prevention is removal of polyps or cancers before they have the opportunity to spread.
Wendy's question is about primary prevention. Primary prevention involves altering our body or our environment so that polyps or cancer never develop at all. The science behind this arose when we noticed that colon cancer has a higher prevalence in the U.S. and certain other westernized countries than it did in Japan and sub-Saharan Africa. This observation lead scientists to consider the possibility that dietary or environmental factors played a role. Our current understanding is that a diet rich in vegetable fiber may decrease your risk of developing colon cancer.