BACKGROUND In cases with a tumor-positive resection margin after endoscopic resection of early gastric cancer (EGC), not all patients are found to have residual or recurrent tumor. The aim of this study was to identify risk factors associated with residual/recurrent tumor in patients with incomplete endoscopic resection of EGC.

METHODS A retrospective analysis was performed on consecutive patients who underwent endoscopic resection of EGC at a single institution in South Korea. Patients with a tumor-positive resection margin in the specimen were divided into two groups, with and without residual/recurrent tumor, and the clinicopathologic characteristics were compared.

RESULTS A total of 102 patients with a tumor-positive lateral or vertical resection margin after endoscopic mucosal resection (n = 10) or submucosal dissection (n = 92) were enrolled. Overall, the rate of residual/recurrent tumor was 33.3 % (34/102): 17 residual tumors in 46 patients who immediately underwent additional endoscopic or surgical resection, and 17 recurrent tumors in 56 patients who were initially followed up with regular endoscopy during a median period of 17 (range = 2-70) months. Univariate analysis showed that the presence of ulcer, the direction of the tumor-positive resection margin, and length of lateral resection margin involvement by the tumor were associated with the incidence of residual/recurrent tumor. In multivariate analysis, total length (cm) of lateral resection margin involvement was the only independent risk factor for residual/recurrent tumor (OR 2.05; 95 % CI 1.22-3.44, p = 0.006).

CONCLUSIONS Patients with extensive tumor involvement of a lateral resection margin after endoscopic resection of EGC should consider additional endoscopic or surgical resection due to a high risk of residual/recurrent tumor.