Gastrointestinal cancers represent a heterogeneous complex array of disorders and diseases. They may be divided into rare inherited forms and more frequent sporadic forms. There is a critical interplay of genetic and environmental factors that foster the conversion of normal tissue to precursor, premalignant lesions, and eventually to frank malignancy. The gastrointestinal (GI) tract is a -foot-long pathway that extends from the mouth to the anus. Everything you eat passes through the esophagus and gets processed in the stomach and small intestines to extract nutrients.