Background: We clarified the incidence of adenocarcinoma of the esophagogastric junction (AEG) at a Japanese high-volume cancer center and its clinicopathological features between the Siewert subtypes.
Methods: Patients with AEG were selected from a prospective database of gastric and esophageal tumors established by Kanagawa Cancer Center. The Siewert subtypes were determined retrospectively by examining pathological pictures of the resected specimens and by evaluating the pathology and endoscopy findings.
Results: From January 1986 to December 2005, 147 (4.0%) patients were determined to have AEG; 2,794 (75.8%) were diagnosed to be true gastric cancer, whereas 745 (20.2%) were true esophageal cancer. Of these 147 patients with AEG, 5 (3.4%) were classified as type I, 82 (55.8%) as type II, and 60 (40.8%) as type III tumors. The depth of tumor invasion was deeper and the nodal metastases were more frequent in type III compared with type II. The risk factors for nodal metastases included the depth and size of the tumor, but not the Siewert subtypes itself. Mediastinal nodal metastases were strongly influenced by a thoracotomy and the extent of the dissection. The pathological grade was higher in type III than in type II. Although the 5-year survival rate was significantly higher in type II than in type III tumors, the survival difference disappeared when the patients were restricted to an R0 resection, even though type III patients demonstrated a more advanced stage.
Conclusions: The proportions of AEG were strikingly different between Japan and western countries. Although each Siewert subtype had some different characteristics, nodal metastases were determined by both the tumor progression and the extent of the nodal dissection. An R0 resection was a key for the survival in AEG.