Can the Japanese guidelines for endoscopic submucosal dissection be safely applied to Korean gastric cancer patients? A multicenter retrospective study based on the Korean Gastric Cancer Association nationwide survey

According to the guidelines of the Japanese Gastric Cancer Association, endoscopic submucosal dissection (ESD) is safe for gastric cancer (GC) patients with absolute indications because the possibility of lymph node metastasis (LNM) is 0%. The aim of this study was to reveal the exact proportion of Korean GC patients with LNM whose pathological examination revealed indications for ESD. Data were extracted from the '2019 Korean Nationwide Retrospective Database' managed by the Korean Gastric Cancer Association. Among the 14,076 patients, 4,220 patients with stage T1a cancer after radical gastrectomy were enrolled. Pathological examination was performed to ascertain the tumor diameter, depth of invasion, tumor differentiation, presence of lymphovascular/perineural invasion, and presence of ulceration. The proportion of patients with LNM and absolute indications was 2.4% (49 of 2,012). The 95% confidence interval for the proportion of patients with LNM was greater than 1.0% across all subgroups in terms of absolute indications. According to the multivariate regression model, the risk factors for LNM were lymphovascular invasion (odds ratio [OR], 7.56), perineural invasion (OR, 3.02), a tumor size >2 cm (OR, 2.37), undifferentiated tumors (OR, 2.30), and ulceration (OR, 1.66). Compared with Japanese studies, this study revealed a relatively high proportion of Korean GC patients with LNM and absolute indications for ESD. The Japanese guidelines for ESD could be applied to Korean GC patients if done carefully.