Familial adenomatous polyposis (FAP) leads to adenomas and eventual adenocarcinomas in colon
and less frequently, duodenum. Chemopreventive strategies have been studied in FAP patients
to delay the development of adenomas and cancers. The non-steroidal anti-inflammatory drugs
(NSAIDs) and selective cyclooxygenase-2 inhibitor have shown the regression of colorectal and
duodenal adenomas in FAP patients. However, these drugs showed gastrointestinal damage and
cardiovascular risks, and new preventive strategies are needed. Niclosamide, an
anti-helminthic drug, has recently been suggested to have a suppressive effect on
tumorigenesis via inhibition of Wnt pathway, and have no significant safety issues. The
investigators devised a double-blind randomized controlled trial to evaluate the effect of
niclosamide on polyps of colorectum and duodenum in FAP patients.