The Chemoprevention for Barrett's Esophagus Trial (CBET) is a multicenter, masked, placebo controlled study of the cyclooxygenase-2 (COX-2) inhibitor celecoxib. Two hundred participants with high or low grade Barrett's dysplasia will be randomized to placebo or celecoxib. Study medication (celecoxib or placebo) will be administered orally, 200 mg twice per day.

Randomization will be stratified by dysplasia grade and by clinic. Eligible individuals are 18 years of age or older and have an established diagnosis of Barrett's dysplasia with specific information on the location of the highest grade of dysplasia from a biopsy.