Résumé

• Hereditary colorectal cancer syndromes characterised 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.