Endoscopic Submucosal Dissection For Laterally Spreading Tumors In The Rectum>50 Mm

Objective:The feasibility of endoscopic submucosal dissection(ESD)for large superficial colorectal tumors is undefined.The aim of this study was to assess the safety and efficacy for patients undergoing ESD of rectal laterally spreading tumors>50 mm.Methods:The record including demographics,the ESD procedure,and histopathology of patients with rectal laterally spreading tumors(LSTs)more than 20mm in diameter treated with ESD from June 2011 to June 2017 in Nanjing Drum Tower Hospital were retrospectively reviewed.The exclusion criteria including:1)patients with hereditary polyposis;2)patients with inflammatory bowel disease;3)patients combined with progressive colorectal cancer;4)Preoperative magnifying chromoendoscopy or endoscopic ultrasonography suggested deep submucosal infiltration;5)patients with multiple rectal LST;6)patients with incomplete data.a total of 131 patients were eventually enrolled.Results:86 patients in the 20-50mm group and 45 patients in the>50mm group were treated by ESD for rectal LSTs.There were statistically significant differences in tumor size between the two groups(P<0.001)while no significant differences were observed in age,gender ratio,tumor location,and tumor morphological type.In the lower rectal LST of the 20-50mm and>50mm groups,17 and 12 cases involved the dentate line respectively.The proportions of HGIN+cancer in the 20-50mm group and the>50mm group were 47.7%and 71.2%,respectively(P=0.01).No significant difference was observed in the proportion of submucosal carcinoma.Technically,although the total dissection time for lesions>50 mm was significantly longer than for lesions 20mm to 50mm(P<0.01),dissection speed for lesions>50mm was significantly faster than for lesions 20mm to 50mm(P<0.01).There was no significant differences in en bloc R0 resection rate and en bloc curative resection rate comparing both groups.In the 20-50mm group,there was 1 case of perforation(1.1%),5 cases of delayed hemorrhage(5.8%),and 1 case of stenosis(1.1%),of which 3 cases delayed hemorrhage involving the dentate dentition and 1 case stenosis involving the dentate line.In the 50mm group,there were 2 cases of perforation(4.4%),1 case of delayed hemorrhage(2.2%),and 2 cases of stenosis(4.4%).Among them,1 case of delayed hemorrhage involved the dentate lines,and 2 cases of stenosis involved the dentate line.There was no statistical difference in complications between the two groups.In the 50mm group,the ratio of G-M in the HGIN+cancer group and the LGIN was 93.7%and 53.8%,respectively,with statistically significant differences in morphological type(P=0.006)while no significant differences were observed in age,gender ratio,tumor location,tumor morphological type,dissection time,dissection speed,the rate of complications,en bloc resection rate,en bloc R0 resection rate and en bloc curative resection rate.Conclusions:1.LST with diameter greater than 50 mm has a high malignant potential.2.In the large lesions,nodular-mixed type LST is a risk factor for canceration.3.Compared with the 20-50mm group,the incidence of complications>50mm did not increase significantly,and the curative resection rate did not decrease significantly..4.Complications mainly occur in lesions involving the dentate line.ESD for low rectal LSTs requires more care.5.Patients with positive or obscure margins of pathology need closer follow-up,especially those pathology is cancerous.6.ESD is an effective and safe therapeutic option for rectal laterally spreading tumors>50mm.ESD of these lesions had a high R0 resection rate and a low adverse event rate.En bloc resection by ESD provides adequate pathological specimens and may limit the need for surgical intervention.