Definition

An inherited disorder in which many polyps (usually hundreds to thousands) form on the inner walls of the colon and rectum. Polyps are abnormal growths that may become cancer if they are not removed. People with FAP have a very high risk of developing colorectal cancer at an early age and are also at risk of developing cancers of the stomach, small intestine, pancreas, bile duct, liver, adrenal gland, thyroid, and brain. They may also have dental and eye problems and benign (not cancer) tumors in the stomach, small intestine, bone, soft tissue, skin, and adrenal glands. FAP is caused by mutations (changes) in a gene called APC that are inherited in an autosomal dominant manner. It is a type of hereditary cancer syndrome. Also called classic familial adenomatous polyposis, classic familial polyposis, classic FAP, and familial adenomatous polyposis.