Ursodeoxycholic Acid in Barrett's Endotherapy

Inclusion Criteria: * Barrett's esophagus, defined as endoscopic evidence of BE with esophageal biopsies showing intestinal metaplasia. * Pre-treatment histology of low- or high-grade dysplasia or intramucosal adenocarcinoma. * BE length ≥2 cm (Prague classification: any C, M≥2). The decision was made to exclude patients with BE segments shorter than 2 cm, as assessment of % neosquamous regrowth in shorter segments is likely neither reliable nor highly reproducible. * Prior endoscopic resection of focal lesions is permitted. Endoscopic resection of nodular lesions must be performed prior to initiating ablation therapy. * Taking UDCA 13-15 mg/kg divided into twice daily dosing. * Either one of the following: * No prior endoscopic ablation therapy, OR * Single prior ablation treatment and \<50% response (i.e. \<50% neosquamous replacement of original BE segment) and ≥2 cm of residual BE Exclusion Criteria: * Allergy, hypersensitivity, or intolerance to UDCA. * Age ≤18 years. * Pregnant or planning to get pregnant during the study period. * Unable to give informed consent. * Known acute cholecystitis, cholangitis, biliary obstruction, gallstone pancreatitis, or biliary-gastrointestinal fistula (contraindications to UDCA use).