Mo1685 INVESTIGATION OF PATHOLOGICAL RESECTED MARGIN UNCERTAIN CASES UNDERGOING ENDOSCOPIC PICEMEAL MUCOSAL RESECTION OF COLORECTAL POLYPS

Abstract

Of the patients undergoing endoscopic mucosal resection (EMR), endoscopic piecemeal mucosal resection (EPMR) is often performed instead of en bloc resection. The problem with EPMR is that the complete resection rates are low, and the margins of resection are uncertain in pathological diagnosis. This study aimed to retrospectively evaluate the risk factors for the local recurrence in these EPMR cases. Our subjects included 76 patients (mean age: 68.8±11.1 years, males:48, females: 28, total 80 lesions) who had undergone EPMR between January 2013 and October 2019. These lesions were divided into sessile polyps ( 0-Is), 0-Isp, pedunculated polyps ( 0-Ip), and slightly elevate polyps (0-IIa) depending on their endoscopic shape, and the size, the location of the large intestine, pathological findings, and the local recurrence were examined retrospectively. For statistical analysis, multiple regression analysis and multiple comparison tests were performed, with a p-value of less than 0.05 considered indicating statistical significance. The breakdown of lesions consisted of type 0-Is:38, 0-Ip: 3, and 0- IIa: 39. The tumor size (mm) by type was average 0-Is: 12.8 ± 8.4, 0-Ip: 19.3 ± 11.0, and 0-IIa: 15.7 ± 6.4, respectively. A significant difference(P<0.001) was observed between 0-Is and 0-IIa. The tumors were located in the large intestine, cecum: 10 lesions (0-Is: 3, 0-Ip: 0, 0-IIa: 7), ascending colon: 14 lesions (0-Is: 6, 0-Ip: 0, 0-IIa: 8), transverse colon: 10 lesions (0-Is: 2, 0-Ip: 0, 0-IIa:8), descending colon: 4 lesions (0-Is: 2, 0-Ip: 0, 0-IIa: 2), sigmoid colon: 29 lesions (0-Is:23, 0-Ip: 1, 0I-IIa: 5), rectum: 13 lesions (0-Is: 2, 0-Ip: 2, 0-IIa: 9). The complete resection rates (%) that no residual tumor was found by both endoscopic and histologic examination were 0-Is: 15.8 (6/38), 0-Ip: 66.7 (2/3), 0-IIa: 20.5 (8/39). The follow-up endoscopic examinations were performed for 27 patients in whom the resected margins were uncertain in pathological diagnosis. The local recurrence developed in 29.6% (8/27) of patients and the breakdown of the recurrence rates(%) was 0-Is: 23.1 (3/13), 0-Ip: 100 (1/1), 0-IIa: 30.1 (4/13). The average diameter of the tumors was 28.1 ± 4.5 mm, and the histological examination of the resected tumor tissues revealed high-grade adenoma or adenocarcinoma in 75% ( 6/8) of the patients. Multiple regression analysis demonstrated a significant correlation between local recurrence and tumor sizes (r =0.0031; P<0.019). This study showed that the tumor size (>20mm) and high-grade lesions were risk factors for local recurrence among EPMR cases of resected margin uncertain in pathological diagnosis. Follow-up endoscopic examinations within 6 to 12 months are necessary for the detection of recurrence in these cases.