Here is a brief and basic summary of the concept of why we're concerned not only about the cancer we can see but the potential cancer we can't.

This is the first presentation I've done that uses a format called a "slidedoc", essentially a more detailed set of images that provides a visual version of complex ideas in a way that can stand alone without someone presenting slides to you. Those who are interested can leard more about the concept here, as explained in a slidedoc by presentation guru Nancy Duarte.