The Rationale and Efficacy of Primary and Secondary Prevention in Adenocarcinomas of the Upper Gastrointestinal Tract.

While the primary risk factor for oesophageal adenocarcinoma (OAC) and its precursor lesion Barrett's oesophagus (BO) is gastro-oesophageal reflux, the infection with Helicobacter pylori (H. pylori) is the dominant risk factor for gastric cancer. Reduction of reflux by dietary measures and proton pump inhibitors has some merits in OAC prevention, and the chemopreventive effect of Aspirin and statins is being widely investigated; however, improved outcome in OAC occurs primarily as the result of secondary prevention. Early detection of neoplastic lesions in Barrett's metaplasia can be achieved by surveillance endoscopies. Novel endoscopic imaging modalities carry similar importance as the endoscopic treatment techniques as without detection of early lesions, therapy cannot be applied. Minimally invasive approaches are currently being investigated to identify patients with BO who are at particular risk of neoplastic progression. While dietary factors also play an important role in the prevention of gastric cancer and chemoprevention seems to be promising, the most beneficial effect has been shown for the eradication of H. pylori infection, which results in at least a one third reduction of gastric cancer risk. This effect can be further improved if the eradication takes place prior to the development of pre-neoplastic gastric conditions such as mucosal atrophy or intestinal metaplasia (IM). The definition of the "point of no return", after which eradication is less effective, is of high importance, although H. pylori eradication can still be beneficial even at more advance stages of mucosal changes. For this reason, patients with advanced atrophy and IM should undergo endoscopic surveillance in the same way as patients with BO. There is also need for development of non-invasive tests to identify patients at high risk of progression to gastric cancer to improve outcome of these surveillance approaches.