Endoscopic Features of Submucosal Invasion in Undifferentiated-type Early Gastric Cancer Less than 20 mm in Size without Ulceration

Background/Aims The prediction of invasion depth is important to decide the treatment modality for undifferentiated-type early gastric cancer (EGC) less than 20 mm in size without ulceration. We aimed to identify the endoscopic features associated with submucosal invasion in undifferentiated-type EGC that meet the criteria of size and ulcer status. Methods A total of 120 patients with undifferentiated-type EGC who underwent endoscopic submucosal dissection (ESD) or gastrectomy between August 2008 and December 2017 were enrolled and reviewed retrospectively. All lesions met the ESD indications except for the invasion depth. We analyzed the endoscopic features of the tumors before resection and invasion depth after resection. Results There were 97 mucosal and 23 submucosal cancer lesions. Multivariable analysis revealed that the polypoid (OR, 90.8; 95% CI, 3.5~2,346.2) or elevated (OR, 5.0; 95% CI, 1.2~21.3) types, deep depression (OR, 76.0; 95% CI, 4.5~1,284.6), and upper (OR, 22.7; 95% CI, 3.0~170.8) or middle location (OR, 10.3; 95% CI, 1.9~55.4) were significant risk factors of submucosal invasion. Conclusions The treatment modality for undifferentiated-type EGC of the polypoid/elevated type or with deep depression located in the upper two-thirds of the stomach should be carefully considered, even if the tumor size and ulcer status meet the ESD indications.