Hereditary gastrointestinal cancer.

Gastrointestinal (GI) cancer, including gastric and colorectal cancer, is a major cause of death worldwide. A substantial proportion of patients with GI cancer have a familial history, and several causative genes have been identified. Gene carriers with these hereditary GI syndromes often harbor several kinds of cancer at an early age, and genetic testing and specific surveillance may save their lives through early detection. Gastroenterologists and GI surgeons should be familiar with these syndromes, even though they are not always associated with a high penetrance of GI cancer. In this review, we provide an overview and discuss the diagnosis, genetic testing, and management of four major hereditary GI cancers: familial adenomatous polyposis, Lynch syndrome, hereditary diffuse gastric cancer, and Li-Fraumeni syndrome.