ObjectivesTo summarize the latest advances about definition, classification, and TNM stage of adenocarcinoma of esophagogastric junction (AEG).MethodThe available guidelines, consensuses, international conference proceedings, and clinical studies were reviewed and summarized.ResultsThe AEG trended to be an independent entity of malignant tumor at the special location. The previous misunderstanding of AEG definitions from the WHO needed to be corrected and unified in China. The Siewert classification was still a practical clinical approach to guiding treatment strategy, while the new draft of JGCA classification needed to be evaluated and verified in the clinical practice. By contrast, the 8th edition AJCC/UICC classification was relatively controversial in the guiding treatment strategies, mainly due to the staging system, surgical approach, and extent of lymphadenectomy of Siewert Ⅱ type AEG. Based on the available research results, the TNM staging system of the 8th edition of gastric cancer tended to be more reasonable for the Siewert Ⅱ and Ⅲ types AEG.ConclusionWith increasing incidence of AEG, more experimental and clinical studies on AEG are ongoing, and it is expected to have more optimized classification and exclusive staging system for AEG in future.