Barrett's esophagus is the precursor to esophageal adenocarcinoma. Esophageal adenocarcinoma detected from endoscopic surveillance programs accounts for <
10% of all cases, suggesting majority of patients with Barrett's esophagus are likely unaccounted for. Previous observational studies have estimated the observed prevalence of Barrett's esophagus to be approximately 1%, but others suggest may be an underestimate. The aim of this study was twofold: (i) calculate lifetime risk of esophageal adenocarcinoma and (ii) estimate overall and age-specific prevalence of Barrett's esophagus. A tree cohort model was created for progression to esophageal adenocarcinoma from birth to death (100 years) for USA and Australian population. Lifetime risk of esophageal cancer and adenocarcinoma were necessary for calculating Barrett's esophagus prevalence. The model incorporated age- and sex-specific incidence data from national cancer registries: the Australian Institute of Health and Welfare and the Surveillance, Epidemiology, and End Results database for the USA. The model was calibrated using an optimization algorithm, which matched progression rates from Barrett's esophagus to esophageal adenocarcinoma with known national cancer data. A Monte Carlo simulation, with 10,000 iterations, was conducted to derive error margins. Estimates of age-specific and overall prevalence of Barrett's esophagus in the population were generated through a similar process. Results: The lifetime risk of esophageal cancer and adenocarcinoma in USA non-Hispanic White population was 0.56% and 0.36%, respectively, while it was somewhat higher at 0.81% and 0.61% (range 0.57%-0.65%) in the Australian population. Estimated overall prevalence of Barrett's esophagus was ~3% (±0.3%) and ~ 5.4% (±0.6%) in USA White and Australian populations (male and female). Prevalence for age brackets was estimated at 0.06% (±0.02%), 1.6% (±0.7%), 3.2% (±1.3%), 8% (±3%), and 12% (±4%) for USA, and 0.05% (±0.02%), 0.9% (±0.5%), 2.8% (±1.2%), 7% (±3%), and 12% (±4%) for Australian population for ages 0-29, 30-44, 45-59, 60-74, and 75+, respectively. Observed estimates of Barrett's esophagus prevalence are likely lower than projected overall prevalence. This study also presents age-specific prevalence estimates of Barrett's esophagus, which are key in developing screening programs for esophageal adenocarcinoma.