Most Siewert type II esophagogastric junction adenocarcinomas in Chinese patients lack a Barrett esophagus background.

The histological origins and classification of Siewert II esophageal gastric junction (EGJ) adenocarcinomas are controversial. While the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system suggests that they be classified as esophageal cancer, some scholars insist that these cancers include a Barrett esophageal (BE) adenocarcinoma form and a gastric adenocarcinoma form. To obtain data relevant to this debate, in this study, a multi-center sample of 25 cases of Siewert II EGJ adenocarcinoma spanning a 6-year period were analyzed. The endoscopic characteristics of the tumor lesions and pathology characteristics of peritumoral mucosal background in biopsies were determined. Cases were classified as esophageal adenocarcinoma if the tumor center was located on the oral side of the EGJ and accompanied by BE. They were classified as gastric adenocarcinoma if the tumor center was located on the anal side of the EGJ and accompanied by atrophic gastritis. Of the 25 cases examined, 20 had evaluable background mucosal data, including 14 (56 %) classified as gastric adenocarcinoma and 3 (12 %) classified as BE adenocarcinoma. The remaining 3 cases (12 %) did not have signs of BE or atrophic gastritis, and thus were not classified. Siewert type II EGJ adenocarcinoma cases in China were found to be heterogeneous, with most cases being consistent with gastric adenocarcinoma. Thus, it would not be reasonable to classify all Siewert type II EGJ adenocarcinomas as esophageal cancer.