688 Background: The management of patients with a positive resection margin after endoscopic resection of early colorectal cancer (ECC) depends on various clinical factors, including the pathology. There is little information on the clinical outcomes according to the subsequent management of a positive resection margin in patients with ECC treated by endoscopic resection. We assessed the management according to the pathology of the positive margin and evaluated the clinical outcomes. Methods: Consecutive patients with ECC who underwent endoscopic resection from January 2004 to December 2014 were reviewed. This study retrospectively analyzed 363 lesions from 338 patients (mean age, 60.1 years; 68% [230/338] male). Results: The resection margin was positive in 29.2% of patients, including cancer cells in 9.9%, adenoma in 16.5%, and high-grade dysplasia (HGD) in 2.8%. Subsequent surgery was performed on 11.8% of patients, 72.2% (26/43) of whom were cancer cell–positive, while 23.3% (10/43) were resection margin–negative but had deep submucosal (SM) or lymphatic invasion. Remnant cancer cells were identified in 25.6% (11/43) of the operated group and 81.8% (9/11) of the cancer cell–positive group. On early follow-up surveillance colonoscopy (mean interval, 3.57 months) in 88.2% of patients (320/363), including 95.7% (67/70) of the adenoma and HGD-positive group, only one (0.3%, 1/320) case of remnant adenoma was found. In the multivariate analysis, deep SM invasion ( p=0.026), number of pieces of piecemeal resection (p=0.03) and cancer cell positivity ( p=0.001) predicted subsequent surgery. In the multivariate analysis, an endoscopic appearance of incomplete resection ( p=0.002) and cancer cell positivity (p=0.041) were related to the identification of remnant cancer cells after subsequent surgery. Conclusions: Patients with an adenoma-positive resection margin had favorable clinical outcomes during subsequent surveillance. The choice of subsequent surgery was related to deep SM invasion and cancer cell–positive resection margins, and subsequent surgery group showed a high rate of remnant cancer cells.
Clinical outcomes of positive resection margin after endoscopic mucosal resection of early colon cancers