has a very high success rate of preventing or removing cancer, without recurrence, since the locations giving rise to cancer are physically removed in toto by the surgery. Following surgery, if a partial colectomy has been performed, colonoscopic surveillance of the remaining colon is necessary as the individual still has a risk of developing colon cancer. However, if this happened, it would be a fresh incident from polyps developing anew in the unremoved part of the colon subsequent to surgery, rather than a return or metastasis of any cancer removed by the original surgery. Epidemiology The incidence of the mutation is between 1 in 10,000 and 1 in 15,000 births. By age 35 years, 95% of individuals with FAP (>100 adenomas) have polyps. Without colectomy, colon cancer is virtually inevitable. The mean age of colon cancer in untreated individuals is 39 years (range 34–43 years). Attenuated FAP arises when APC is defective but still somewhat functional. As a result, it retains part of its ability to suppress polyps. Therefore, attenuated FAP manifests as colorectal cancer unusually late (age 40–70, average=55), and typically with few, or at least far fewer polyps (typically 30), than the more usual version of FAP, at an age when FAP is no longer considered much of a likelihood or risk according to usual FAP epidemiology. Comparison of FAP variants This table compares the different subtypes of FAP: Polyposis registries Because of the genetic nature of FAP, polyposis registries have been developed around the world. The purpose of these registries is to increase knowledge about the transmissibility of FAP, but also to document, track, and notify family members of affected individuals. One study has shown that the use of a registry to notify family members (call-ups) significantly reduced mortality when compared with probands. The St. Mark's polyposis registry is the oldest in the world, started in 1924, and many other polyposis registries now exist. See also Colorectal cancer Polyp (medicine) Adenoma Adenomatous polyps Colorectal polyp Genetic testing References Further reading — full clinical summary of FAP and attenuated FAP, including lifetime risks, epidemiology etc. Familial Adenomatous Polyposis—eMedicine Gastroenterology Colon, Polyposis Syndromes National Cancer Institute: Genetics of Colorectal Cancer information summary External links Benign neoplasms Gastrointestinal cancer Hereditary cancers