[Clinicopathological differences in laterally spreading tumors between rectum and colon].

OBJECTIVE: To investigate the clinicopathological differences in laterally spreading tumor (LST) from the rectum and colon. Methods: Clinicopathological records of 198 patients with LST (116 cases in rectum, 82 cases in colon) from the Second Xiangya Hospital of Central South University between January 2012 and January 2017 were evaluated. Results: A total of 198 colorectal LST were included. According to the endoscopic classification, nodular mixed type (LST-GM), homogeneous type (LST-GH), flat elevated type(LST-FE) and pseudodepressed type (LST-PD) were 127(64.1%), 13(6.6%), 41(20.7%) and 17(8.6%), respectively. LST-GM was predominant in the rectum (71.7%), while LST-FE was predominant in the colon (78.0%), with significant difference (P<0.01). The mean size of LST was (52.03±35.62) mm or (25.37±11.56) mm in the rectum or the colon, with significant difference between them (P<0.01). High grade intraepithelial neoplasia frequency was higher in the rectum than that in the colon (31.0% vs 18.3%), while the low grade intraepithelial neoplasia frequency was lower in the rectum than that in the colon (61.2% vs 75.6%) (both P<0.05). The mean size of LST-GM and LST-GH diameter were larger in the rectum than that in the colon, and the malignant potential of LST-GM was higher in the rectum than that in the colon. The percentage of high grade intraepithelial neoplasia + invasive carcinoma was 41.8% and 22.2%, respectively (both P<0.05). LST in colon was mostly treated with endoscopic mucosal resection, while LST in rectum was treated by endoscopic submucosal dissection predominantly. Conclusion: LSTs from the rectum and colon show different clinicopathological characteristics to some extent. LST-GM is predominant in the rectum, while LST-FE is predominant in the colon. The malignant potential of LST-GM is higher in the rectum than that in the colon.