Clinical cancer genetics: Part I: Gastrointestinal.

There is an increasing recognition of the importance of genetic and familial cancer syndromes in routine clinical practice. Although most of gastrointestinal cancers are sporadic, a number of important cancer predisposition syndromes are now recognized and well characterized. In this review, we discuss some of the basic principles of clinical cancer genetics and clinically relevant aspects of the more common gastrointestinal cancer syndromes from the perspective of practicing radiation oncologists.