The molecular changes driving the carcinogenesis in Barrett's esophagus: Which came first, the chicken or the egg?

Esophageal adenocarcinoma originates from columnar metaplastic epithelium of the distal esophagus. Various steps for this carcinogenetic process are known. Before the onset of high-grade dysplasia and adenocarcinoma, endoscopic surveillance is possible. However, because of the high cost of long-term surveillance, predictive factors for cancer are being evaluated to identify subjects with metaplasia who have a higher risk of developing malignancy. Molecular changes seem suitable for this purpose, but could require a high resource expenditure. While trying to identify the best predictive factors for cancer risk, molecular changes and differences in miRNA expression profile between the various steps leading to cancer could help to clarify Barrett's carcinogenesis. In this attempt to find a molecular explanation for the onset of esophageal adenocarcinoma, it is still difficult to understand whether the molecular changes are causes or effects of the neoplastic phenotypic modifications.