HNPCC and Rare Syndromes

Lynch syndrome, previously called hereditary nonpolyposis colorectal cancer (HNPCC), is one of the most common digestive genetic diseases, occurring in 1 person out of 2,000. Involvement of the small bowel is much less frequent (about 4 % cumulative risk of cancer) than colorectal involvement (50–60 % cumulative risk). However, prospective studies have shown an 8.5 % detection rate of neoplasia (adenoma, cancer) at capsule endoscopy in asymptomatic patients [1] (Figs. 37.1 and 37.2), including advanced cancer without anemia. It is likely that capsule endoscopy has lower sensitivity for adenocarcinoma detection [2, 3]. Systematic screening using capsule endoscopy is not recommended for these patients and is probably not cost-effective, but capsule endoscopy should be performed if unexplained anemia is present. Some specialized centers do routinely perform capsule endoscopy in these patients as screening for small-bowel cancer. Whenever upper digestive endoscopy is performed, careful attention should be paid to flat, distal duodenal adenomas, best detected by classic, forward-viewing gastroscopy.