Clinical factors associated with noncurative endoscopic submucosal dissection for the expanded indication of intestinal‐type early gastric cancer: Post hoc analysis of a multi‐institutional, single‐arm, confirmatory trial (JCOG0607)

Objectives The multi‐institutional, single‐arm, confirmatory trial JCOG0607 showed excellent efficacy of endoscopic submucosal dissection (ESD) for the expanded indication of intramucosal intestinal‐type early gastric cancer (EGC), which consists of two groups: lesions >2 cm if clinical finding of ulcer (cUL)‐negative, or those ≤3 cm if cUL‐positive because of the expected low risk of lymph node metastasis. However, the proportion of noncurative resections (NCR) requiring additional surgery was high (32.4%). This post hoc analysis aimed to explore the clinical factors associated with NCR. Methods As the expanded indication includes two different groups, we explored the clinical factors associated with NCR separately in cUL‐negative (>2 cm) and cUL‐positive (≤3 cm) groups using the log–linear model. Results Two hundred and sixty cUL‐negative and 206 cUL‐positive EGCs were analyzed. The proportions of NCR were 33.8% in the cUL‐negative group and 29.6% in the cUL‐positive group. A multivariable analysis demonstrated that moderately differentiated predominant histology diagnosed in pretreatment biopsy (risk ratio [RR] 1.93, 95% confidence interval [CI] 1.34–2.77, P < 0.001) and lesion in the upper stomach (RR 1.75, 95% CI 1.03–2.96, P = 0.038) in the cUL‐negative EGCs, and tumor size >2 cm (RR 1.78, 95% CI 1.22–2.58, P = 0.003) and female sex (RR 1.62, 95% CI 1.07–2.44, P = 0.021) in the cUL‐positive EGCs were independent factors associated with NCR. Conclusions Clinical risk factors associated with NCR were different between cUL‐negative and cUL‐positive EGCs. To avoid NCR, we need to take these factors into account when deciding expanded indications for ESD.