Barrett's esophagus

In Barrett’s esophagus, tissue in the tube connecting your mouth and stomach (esophagus) is replaced by tissue similar to the intestinal lining.
Barrett’s esophagus is often diagnosed in people who have long-term gastroesophageal reflux disease (GERD) — a chronic regurgitation of acid from the stomach into the lower esophagus. Only a small percentage of people with GERD will develop Barrett’s esophagus.
https://www.mayoclinic.org/diseases-conditions/barretts-esophagus/home/ovc-20322957?p=1