Esophageal dysbiosis and neoplasia: Moving from Barrett's esophagus to adenocarcinoma

The esophagus hosts a specific microbiome that changes concerning different disease conditions. Unique microbial communities have been identified across healthy esophagus, the precancerous lesion Barrett Esophagus (BE), and other progression stages of esophageal adenocarcinoma (EAC). A shift from gram-positive in a healthy esophagus to gram-negative bacteria in a metaplastic esophagus, as well as a shift at phyla level appear to indicate pathogenesis. The decline in Helicobacter pylori infection rates correlating with the rise in EAC seem to be a further indicator. The established links between the microbiome and EAC-development suggest that microbial alterations might contribute to inflammatory or carcinogenic changes in the esophageal microenvironment. These links remain correlative and fail to prove direct functional causalities, highlighting the need to perform more comprehensive and systemic studies that not only assess the effect of the local microbiome but also on extern microbiome such as the intestinal.