Division of Endoscopy;
Yokohama City University Medical Center;
Yokohama 232-0024;
Japan;
Department of Pathology;
Yokohama City University Graduate School of Medicine;
Yokohama 236-0004;
Japan;
Department of Data Science;
Yokohama City University School of Data Science;
Yokohama 236-0004;
Japan;
Department of Gastroenterology;
Yokohama City University Graduate School of Medicine;
Yokohama 236-0004;
Japan;
Early gastric cancer; Endoscopic submucosal dissection; Mixed-histologicaltype; Undifferentiated-type; Narrow-band imaging;