Predictive factors to diagnosis undifferentiated early gastric cancer after endoscopic submucosal dissection

It is difficult to predict precisely whether the lesion corresponds to endoscopic resection indication. Furthermore, discrepancy may occur between endoscopic forceps biopsy (EFB) and finally resected specimen, which may be diagnosed as undifferentiated cancer and additional surgery may be required. Our study aimed to evaluate predictive factors to diagnose undifferentiated cancer after endoscopic submucosal dissection (ESD). Among the 532 patients diagnosed by ESD between January 2009 and December 2015, 557 early gastric cancer (EGC) cases were studied. Factors predicting diagnosis of undifferentiated cancer and clinical outcomes of the lesions were retrospectively analyzed. Among the 557 cases with EGC, 535 (96.1%) were diagnosed as differentiated cancer and 22 (3.9%) as the undifferentiated type with ESD. Tumor size was larger (mean size 20.67 vs 13.59 mm, P < .001) and age was lower (60.24 vs 64.50 years, P < .001) in the group with undifferentiated cancer. En bloc resection rate was similar (95.5% vs 95.9%, P = .886), but the complete resection rate was lower (72.7% vs 92.4%, P < .001) in the group with undifferentiated cancer. On multivariate analysis, tumor size ≥10 mm (OR = 11.340, P = .032), age <55 years (OR = 5.972, P = .004), surface redness (OR = 11.562, P = .024), and whitish discoloration (OR = 35.368, P < .001) were predominantly associated with undifferentiated cancer. Young age (<55 years), large tumor size (≥10 mm), surface redness, and whitish discoloration are predictors of undifferentiated cancer, and lesions with these features detected need to be treated cautiously.