Study to Evaluate EnteroTracker® as a Sampling Method to Screen for Barrett's Esophagus/Esophageal Cancer

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