Systematic review: Cyclo-oxygenase-2 in human oesophageal adenocarcinogenesis

Abstract

Background: Published in vitro and animal in vivo studies have demonstrated that cyclo-oxygenase-2 plays an important role during oesophageal adenocarcinogenesis. However, the extent to which these studies are directly relevant to events in the human lower oesophagus is questionable. Aim: To perform a systematic review of all available human studies that have evaluated levels of cyclo-oxygenase-2 expression during the progression from Barrett's metaplasia to oesophageal adenocarcinoma. Methods: A literature search was performed to identify all studies which qualitatively or quantitatively assessed cyclo-oxygenase-2 protein or gene expression in either Barrett's, dysplastic or adenocarcinoma tissue in humans. Results: A total of 27 studies met the inclusion criteria. There was general agreement that cyclo-oxygenase-2 was either absent or very weakly expressed in normal oesophageal squamous mucosa, but considerable disagreement regarding the presence of cyclo-oxygenase-2 in Barrett's and low-grade dysplasia. All studies agreed that high-grade dysplasia and adenocarcinoma expressed cyclo-oxygenase-2 to some extent although levels varied considerably between tissue samples. Conclusions: There is conflicting evidence in the literature for cyclo-oxygenase-2 playing an important role in early oesophageal adenocarcinogenesis. Other non-cyclo-oxygenase-2 targets may account for the epidemiological data supporting the use of non-steroidal anti-inflammatory drugs in the chemoprevention of oesophageal adenocarcinoma. © 2006 The Authors.