Biomarkers for non-endoscopic examination of esophageal mucosa

Gastroesophageal reflux disease (GERD) is a multifactorial disease; an individual´s genetic predisposition may contribute to the development of this disorder. Endoscopic methods and histological examination are commonly used to diagnose GERD and its complications such as Barretts esophagus (BE) and esophageal adenocarcinoma (EAC). For BE screening in high-risk individuals as well as monitoring the development of BE dysplasia, esophageal mucosa samples could be taken using modern non-endoscopic procedures to minimize invasiveness of the procedure and improve patient adherence and compliance with a treatment. Esophageal mucosa samples taken by non-endoscopic or endoscopic biopsy can be analyzed both by immunohistochemistry and molecular biology analysis for specific biomarkers. Markers such as caudal type homeobox 2 (CDX2) and protein p53 have found their use in GERD diagnosis, and therefore research in recent years has focused on identifying other biomarkers that could reliably predict the development and progression of BE or EAC. This review article summarizes information on modern non-endoscopic methods of sampling from the esophagus mucosa and biomarkers, which have been studied in connection with the prediction and diagnosis of BE and EAC and have a potential for the use in clinical practice.