Barrett's esophagus can progress to esophageal cancer, but it doesn't always. Current treatment is frequent surveillance via upper endoscopy with multiple biopsies to look for changes (dysplasia). Pathologists vary dramatically in their interpretation of Barrett's Metaplasia versus dysplasia and consensus is very difficult to achieve. The investigators propose a longitudinal study of subjects with confirmed Barrett's intestinal metaplasia without dysplasia to look for predictive factors for transformation to dysplasia or cancer. Potential biomarkers can be found in serum, plasma, urine, frozen or fixed Barrett's and Normal esophageal mucosa. In addition, the investigators are testing a brushing technique from CDx, Inc. for predictive factors. Subjects must have pathologically confirmed Barrett's intestinal metaplasia without history of dysplasia to be on this longitudinal study.

Inclusion Criteria:

• Adults (> 18 years old)
• Subjects with pathologically confirmed Barrett's esophagus, including:
• Intestinal metaplasia without dysplasia, long and short segments (>1 cm)
• Intestinal metaplasia without dysplasia, long and short segments (>1 cm), previously in GLNE 003
• Intestinal metaplasia without dysplasia with indefinite-for-dysplasia (or history of indefinite-for-dysplasia) provided there is no history of HGD, or EAC.
• Intestinal metaplasia without dysplasia or indefinite-for-dysplasia with a history of LGD provided the last surveillance endoscopy showed IM alone, the LGD history was at least 12 or more months ago and there is no history of HGD or EAC.
• Able to physically tolerate removal of 34 ml of blood
• Tolerate extra research related biopsies and brushings
• Willing to permit extra biopsies at future endoscopic procedures
• Ability and willingness to complete questionnaires
• Willing to sign informed consent Exclusion Criteria
• Subjects with a pathologically confirmed history of Barrett's, HGD or EAC
• Subjects with pathologically confirmed history of Barrett's LGD within the last 12 months.
• Subjects in whom esophageal biopsy would be contraindicated (eq. varices)
• Subjects with serious infections requiring IV antibiotics
• Subjects with known HIV or chronic viral hepatitis
• Subjects on active chemotherapy or radiation treatment
• Subjects who have had an esophagectomy
• Subjects with an active malignancy diagnosed or treated within 3 years except for squamous cell carcinoma of the skin, basal cell carcinoma of the skin; Carcinoma in situ, Stages Ia or Ib invasive squamous cell carcinoma of the cervix treated by surgery and/or radiation therapy; Stage Ia Grade 1 adenocarcinoma of the endometrium treated with surgery

Subjects undergoing clinically-indicated upper endoscopy for surveillance of their pathologically-confirmed Barrett's intestinal metaplasia. Recruitment is from the Endoscopy schedules of the collaborating locations.