Carcinoma of the cardia: classification as esophageal or gastric cancer?

The cardia is the anatomical borderland between the esophagus and stomach. Carcinomas of the cardia are regarded to share features of both, esophageal and gastric cancers. Controversy exists concerning their appropriate classification and whether these tumors comprise—in respect to tumor biology, pathophysiology as well as clinical features—an entirely separate entity.

In order to distinguish cardia carcinomas from other adenocarcinomas arising within the vicinity of the esophagogastric junction, a classification system has been introduced from a surgical viewpoint, and is now well established and increasingly used worldwide. According to the topography of the main tumor mass, cardia carcinomas (AEG II) are distinguished from adenocarcinomas of the distal esophagus (AEG I) and subcardiac gastric cancers (AEG III). The tumor-node-metastasis (TNM) staging system by the International Union Against Cancer (UICC) does not provide a separate classification for tumors of the esophagogastric junction. The use of the classification for esophageal or for gastric cancers is recommended, irrespective of the elementary differences in the classification of lymphatic spread implemented herein.

New aspects concerning this controversial debate are discussed based on current insights into the pathogenesis and the cellular origin of these entities. The controversies concerning the classification of cardia carcinomas and the failure of the current esophageal and gastric cancer staging systems to reflect the peculiarities of this entity accurately, present a strong argument in favor of a new classification system.