Inclusion Criteria:

- Barrett's (BE): Patients who have Barrett's esophagus (all stages: Barrett's
metaplasia, low-grade dysplasia, high-grade dysplasia) based upon standard endoscopic
and histologic criteria.

- Adenocarcinoma (EAC): Patients who have esophageal adenocarcinoma.

- The control cohort will include patients ages 18 and older with no prior history of
BE and EAC. These may include patients who are being seen or have been previously
seen at MGH GI Associates for conditions including gastroesophageal reflux disease,
peptic esophagitis, eosinophilic esophagitis, esophageal motility disorders such as
achalasia and nutcracker esophagus.

Exclusion Criteria:

- Inability or unwillingness to provide blood samples.

- History of known bleeding disorders.

- Currently awaiting organ transplantation.

- Having an acute or severe chronic illness such as congestive heart failure or any
other condition that would prohibit performing the endoscopy.