Endoscopic submucosal dissection for undifferentiated-type early gastric cancer: short- and long-term outcomes

Application of endoscopic submucosal dissection (ESD) for undifferentiated-type early gastric cancers (EGCs) remains controversial owing to limited data regarding long-term outcomes. We aimed to evaluate the feasibility of ESD for undifferentiated-type EGCs that meet the expanded criteria (EC). We performed a retrospective analysis of 66 patients who underwent ESD for undifferentiated-type EGC between January 2005 and December 2014. We evaluated the rates of en bloc, complete, and curative resections along with overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS). Of the 66 patients, the EC group included 38 patients and the beyond-EC group included 28 patients. The overall rates of en bloc, complete, and curative resection of the 66 lesions were 92.4% (61/66), 65.2% (43/66), and 48.5% (32/66), respectively. Of the 34 patients with non-curative resection, 18 underwent additional surgery. Local remnant cancer was detected in 1 patient (1/18, 5.6%), and none of the 18 patients had lymph node metastasis. On multivariate analysis, tumors > 2 cm [odd ratio (OR) 6.183, 95% confidence interval (CI) 1.279-29.880, p = 0.023) and submucosal invasion depth (OR 6.226, 95% CI 1.881-20.606, p = 0.003) were independent predictors of incomplete resection. All 26 patients with more than 1 year of follow-up after curative resection survived without any evidence of local or distant recurrences over a median follow-up period of 36 months. The OS, DSS, and RFS rates of patients with curative ESD were 93.8, 100, and 100%, respectively. ESD may have favorable long-term outcomes in patients with undifferentiated-type EGC after curative resection.