Duodenal carcinomas are the leading cause of mortality in patients with Familial Adenomatous Polyposis (FAP) who underwent prophylactic colorectal surgery. The purpose of this study is to determine wether celecoxib combined with ursodeoxycholic acid is an effective chemoprevention strategy to influence the progression of duodenal adenomas to carcinomas in patients with FAP.

Inclusion Criteria:

• Patients with Familial adenomatous Polyposis: APC-mutation identified or more than 100 colorectal polyps on diagnosis
• Spigelman score of duodenal adenoma equal to II or III

Exclusion Criteria:

• Incapability of signing informed consent

• Active gastric or duodenal ulcer, gastrointestinal bleeding

• Cardiovascular disease or risk:

  • Congestive cardiac failure: NYHA class II to IV
  • Proven ischemic heart disease and/or cerebrovascular disease
  • Risk factors: hypertension, hyperlipidaemia, diabetes mellitus, family history of cardiovascular events (≥2 first degree family members <55 years)

• Renal dysfunction: creatinine clearance below 50mL/min

• Liver dysfunction: albumin below 25 g/L or Child-Pugh-score equal to or below 10

• Known allergic reaction to sulfonamides, NSAIDs or ursodeoxycholic acid

• Use of NSAIDs or ursodeoxycholic acid for more than 1 week during the 6 months prior to the start of the study

• Use of lithium

• Symptomatic gallstones

• Inflammatory bowel disease

• (Possible) pregnancy or breast feeding