The purpose of this study is to determine whether the EnteroTracker can obtain biomarkers that have been studied to be significant in screening BE and EAC. The current standard of care is endoscopic biopsy where the pathologist will visualize the tissue under a microscope to interpret diagnosis. Another goal of this study is to understand tolerance of the procedure so it might be used in an at-home setting.

This study seeks to determine the ability of a minimally invasive capsule-string device, the EnteroTracker®, to capture biomarkers associated with Barrett's Esophagus (BE) and Esophageal Adenocarcinoma (EAC). Identification of biomarkers in samples will support development of this simple-to-use, scalable, method for early screening of EAC, a cancer that accounts for the majority of esophageal cancers in the United States. In this study, the investigators plan to capture esophageal luminal content using the EnteroTracker® from patients with confirmed BE and/or EAC (test group) and healthy adults (control group). Samples will then be analyzed for series of biomarkers associated with BE and/or EAC. The investigators will test the hypothesis that the EnteroTracker® is able to capture biomarkers of interest in subjects with BE and EAC compared to healthy controls. To address this hypothesis, the investigators propose a pilot study with the following two specific aims. Evaluate the ability and tolerability of the EnteroTracker® to capture esophageal mucosal samples in adults with BE and/or EAC as well as controls and determine the ability of the EnteroTracker®-obtained BE/EAC biomarkers to distinguish between BE and/or EAC from control subjects.

Inclusion Criteria:

1. Provision to sign and date the consent form.
2. Stated willingness to comply with all study procedures and be available for the duration of the study.
3. Be a male or female aged 45 years or older.
4. Fit in the below listed inclusion criteria

Inclusion Criteria for Test Population (BE and EAC subjects):

1. Previous diagnosis of indefinite Barrett's Esophagus (IND), non-dysplastic (ND), low grade dysplasia (LGD), high grade dysplasia (HGD), and/or esophageal adenocarcinoma (EAC)
2. Able to swallow a Tylenol sized capsule
3. Diagnostic endoscopy performed within past 3 months or able to arrive early to endoscopy for EnteroTracker® to be swallowed before endoscopy

Inclusion Criteria for Control Population (otherwise healthy adults with no evidence of BE or EAC or other esophageal cancer but with GERD) 4. Able to swallow a Tylenol sized capsule 5. 45 years of age or older

1. The majority of BE and EAC patients are age 50 years and older. Fewer than 15% of the cases are found in people younger than age 55. However current literature has suggested that there has been an increase in cases among 45-65 years old [47].

6. Apparently healthy or ≥5 years of:

1. Gastroesophageal Reflux Disease (GERD) symptoms, or
2. GERD treated with proton pump inhibitor (PPI) therapy (whether symptom control was achieved or not), or
3. Any combination of treated and untreated periods if the cumulative total is at least 5 years

Exclusion Criteria:

1. History of difficulty swallowing (dysphagia) or painful swallowing (odynophagia), including swallowing pills within 3 months of EnteroTracker® procedure
2. Inability to provide written informed consent
3. Pregnant women
4. Prior EGD during which a therapeutic procedure such as, but not limited to, ablation, cryotherapy, or endoscopic mucosal resection, was performed for the treatment of BE and/or EAC
5. Known history of esophageal varices or esophageal stricture
6. Any contraindication, as deemed in Investigator's medical judgment, to undergoing the EnteroTracker® procedure
7. Oropharyngeal cancer
8. History of esophageal or gastric surgery, with exception of uncomplicated surgical fundoplication
9. History of esophageal motility disorder
10. Currently implanted Linx device