Barrett's esophagus (BE) refers to an abnormal change (metaplasia) in the cells of the inferior portion of the esophagus. About 10% of patients with symptomatic gastroesophageal reflux disease (GERD) have BE. In some cases, BE develops as an advanced stage of erosive esophagitis. The risk of esophageal cancer appears to be increased in patients with BE. The only way to diagnose BE is by endoscopy and histology. Some studies suggest that intensive treatment of Barrett's esophagus with effective acid suppression can reduce the amount of abnormal lining in the esophagus. It is not clear whether such treatment also prevents esophageal cancer. Generally, the cancer starts out as carcinoma of the esophagus on the surface, and then invades the surrounding tissue. Surgery offers the best chance of long-term survival. There are many events that occur in Barrett's esophagus that lead to the development of cancer and most of them appear to occur early, before high-grade dysplasia or cancer develops. No one knows what the late events are and how cells acquire the ability to leave their normal growth boundaries. It is now widely accepted that the development of most cancers is due to something called genomic or genetic instability. The aim of this review is to show BE pathology in its progression to cancer looking for new biomarkers to distinguish between BE -dysplasia (low grade and high grade)- adenocarcinoma (ADC) and to characterize the ADC, giving more hope for its treatment.