Molecular biology of Barrettʹs cancer

Oesophageal adenocarcinoma (OA) remains one of the more deadly forms of gastro-intestinal cancer with a mortality rate exceeding 90%. The incidence of OA remains unabated and has a reported fivefold increase since 1970 [Pera M, Cameron AJ, Trastek VF, Carpenter HA & Zinsmeister AR. Increasing incidence of adenocarcinoma of the esophagus and esophagogastric junction. Gastroenterology 1993; 104(2): 510–513]. Gastro-oesophageal reflux disease and its sequelae, Barrettʹs oesophagus, is one of the principle risk factors in the development of OA, with a 30-fold increased risk in Barrettʹs patients compared with the general population [Tytgat GNJ. Does endoscopic surveillance in esophageal columnar metaplasia (Barretts-Esophagus) have any real value. Endoscopy 1995; 27(1): 19–26]. OA is thought to be a microcosm of evolution, developing sequentially along the metaplasia–dysplasia–adenocarcinoma sequence. Progression is attributed to a series of genetic and epigenetic events that ultimately allow for clonal selection of Barrettʹs cells via subversion of intrinsic control mechanisms regulating cellular proliferation and/or apoptosis. This review will describe the current suppositions of the mechanisms behind the selection and subsequent expansion of Barrettʹs clones, and focus on some of the principle hallmarks associated with this transition.