[Carcinoma of the oesophagogastric junction and Barrett's esophagus: an almost clear oncologic model?].

From a clinical and biological point of view, the term "adenocarcinoma of the esophagogastric junction" (AEG) encompasses several distinct tumor entities. The topographic anatomic classification into adenocarcinoma of the distal esophagus (AEG I), true carcinoma of the cardia (AEG II), and subcardiac gastric cancer (AEG III) also reflects differences regarding the pathogenesis of these tumors and is increasingly accepted worldwide. Associated Barrett's esophagus, which usually develops as a consequence of chronic gastroesophageal reflux, can be documented in practically all patients with AEG I tumors and constitutes the most important precancerous lesion. A metaplasia-dysplasia-carcinoma sequence has been confirmed for these tumors. Barrett's esophagus is thus considered a model for studies on carcinogenesis and the prevention of esophageal adenocarcinoma. Its pathogenetic role in AEG II and III tumors must, however, be discussed differently. Our own experience shows that pathogenetic mechanisms similar to those in AEG I tumors may be present in up to 30% of tumors classified as AEG II. The majority of AEG II tumors, however, show morphologic, biologic and pathogenetic similarities with AEG III tumors and proximal gastric cancer.