Hereditary colorectal cancer syndromes characterized by the development of hundreds to thousands of colorectal adenomas. The attenuated form leads to the formation of fewer than 100 polyps.
Caused by germline mutations of the adenomatous polyposis coli (APC) gene.
Colorectal cancer arises in close to 100% of patients with familial adenomatous polyposis (FAP) by 40 years of age and in 80% of attenuated FAP patients by 60 years of age in the absence of either total colectomy or endoscopic polyp clearance.
Prophylactic proctocolectomy is the main means for preventing colorectal cancer in FAP.
Duodenal and periampullary polyps lead to an increased risk for duodenal cancer, which is the most common cause of cancer death in FAP/attenuated FAP patients who have had prophylactic colectomy.
Familial adenomatous polyposis (FAP) syndrome is an autosomal-dominant condition caused by germline adenomatous polyposis coli (APC) gene mutations. Patients with classical FAP have hundreds to thousands of colorectal adenomas and a nearly 100% risk for colorectal cancer by age 40 if prophylactic colectomy is not performed. Attenuated FAP is also caused by APC mutations and is characterized by fewer than 100 adenomas and a later age of colorectal cancer onset.
FAP features that occur outside of the gastrointestinal tract include skin cysts, lipomas and fibromas, supernumerary teeth, thyroid nodules and cancer, osteomas, desmoid tumors, adrenal adenomas, and congenital hypertrophy of the retinal pigment epithelium. Previously, patients with FAP and extraintestinal features were diagnosed with Gardner syndrome and patients with FAP and medulloblastomas were said to have Turcot syndrome. Use of the terms Gardner syndrome and Turcot syndrome are historical and should be avoided as they are FAP spectrum phenotypes and are part of APC-associated polyposis. Patients may also find these terms confusing.
History and exam
Priyanka Kanth, MD, FACG
University of Utah
Salt Lake City
PK is a co-investigator for multicenter clinical trials in familial adenomatous polyposis funded by the National Cancer Institute and Janssen Pharmaceutica.
Dr Priyanka Kanth would like to gratefully acknowledge Dr Charles A. Ternent, Dr Alan G. Thorson, Dr Lisa A. Boardman, and Dr Douglas L. Riegert-Johnson, the previous contributors to this topic.
CAT, AGT, LAB, and DLRJ declare that they have no competing interests.
Yann Parc, MD, PhD
Professor of General Surgery
Department of Digestive Surgery
Universite Pierre et Marie Curie Paris VI
YP declares that he has no competing interests.
Gabriela Moslein, MD
Allgemein- und Viszeralchirurgie
St Josefs-Hospital Bochum-Linden
GM declares that she has no competing interests.
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