Risk Factors For Technically Difficult And Learning Curve Of Endoscopic Submucosal Dissection In The Colorectal Tumor

Objective:Colorectal endoscopic submucosal dissection(CR-ESD) is a technical difficulty and high risk procedure. Until now few studies have investigated the technical difficulty in CR-ESD. This study was to analyze the technical difficulties of endoscopic submucosal dissection for colorectal tumors, and to explore the characteristics of CR-ESD learning curve, and to provide reference for the learning and operation of CR-ESD for endoscopists in China.Methods:From October 2011 to October 2015, we retrospectively analyzed colorectal tumors treated with endoscopic submucosal dissection in Digestive Endoscopy Center of the Military General Hospital of Beijing PLA. According to inclusion criteria, we collected210 colorectal tumors.For prediction of technical difficulty of performing ESD, five types of factors were investigated: tumor location, tumor type, histological diagnosis, non-lifting sign and intraprocedural bleeding.Variables were analyzed using univariate and multivariate logistic regression analysis. The trend of perforation incidence was analyzed using cumulative sum(cusum) method, and 210 CR-ESD were divided into four stages. By comparing the characteristics of each stage, the learning curve of CR-ESD was explored.Results:1.Characteristics of the 210 colorectal tumors: the average tumor diameter was3.31±1.65cm(1.20-12.00),tumor size ≥40mm in 69 cases(32.86%),11(5.24%) cases of scarring or local recurrence,LST-NG tumor in 46(21.90%) cases,other types in 84(40%)cases;tumor located in proximal colon,distal colon and rectum were 51(24.29%)cases,74(35.24%) cases and 85(40.48%) cases respectively;39(18.6%) cases were located in the Bauhin’s valve,Cecum or dentate line,54(25.71%) cases were located in flexure part;the en bloc resection rate was 91.43%,the complete resection rate was 90.48%,the curative resection rate was 88.57%,the piecemeal resection rate was 7.62%;the average procedure time was 50.25±42.74min(4-300),and the average resection speed was0.18±0.15cm2/min(0.02-0.98);perforation, intraprocedural bleeding and delayed bleeding occurred in 11(5.24%) cases, 52(24.76%) cases and 1(0.48%) cases respectively. Allcomplications were successfully treated with endoscopy.100(47.62%)cases were adenoma,100(47.62%) cases were intramucosal carcinoma,and 10(4.76%) cases were submucosal carcinoma.201(95.71%) cases were followed up and 4(2%) residual or recurrence tumors were found.The mean follow-up time was 8.20±7.95months(2-42).2.Factors associated with the technical difficulties of CR-ESD:Tumor size ≥4.0c-m or spreading across ≥2 folds was an independent risk factor for technical difficu-lty as measured by perforation(OR3.436,95%CI0.097~6.243),piecemeal resection(OR5.289,95%CI1.045~26.759),long procedure duration(≥60 min)(OR3.466,95%CI1.594~7.538)and low resection speed(β±SE:2.661±0.093).Nonlifting sign was a risk factor for perforation(OR2.028,95%CI0.158~26.031),and for low resection speed(β±SE:2.377±0.126).Intraprocedural bleeding was the strongest independent risk factor for non en b-loc resection(OR5.554,95%CI1.329–23.205).LST-NG(tumor type) and flexure(tumor l-ocation)were independent risk factors for perforation(OR1.106,95%CI0.013~8.089)or longer procedure time(≥60min)(OR2.270,95%CI0.175~9.227)respectively.3.Learning curve of CR-ESD:Based on perforation according to the cusum method,we divided 210 colorectal ESD procedures into the first period(1–21),the second period(22–58),the third period(59–111),and the fourth period(112–210).By comparing the characteristics of each stage,we found that tumor diameter(P=0.023),LST tum-ors(P=0.040),tumor size ≥4.0cm or spreading across ≥2folds(P=0.022),perforati-on rate(P=0.031),procedure time(P=0.002)and resection speed(P=0.003)increased or decreased gradually.The en bloc resection rate increased gradually.The comp-lete resection rate and curative resection rate increased after the second period.Com pared with the first period,perforation rate(P=0.043) significantly decreased in the se-cond period;there was no statistically significant differences with regard to other va-riables,including tumor size ≥4.0cm and tumors of scarring or local recurrence redu-ced,en bloc resection rate increased,but the complete resection rate and curative res-ection rate decreased, piecemeal resection rate increased. Compared with the second period,perforation rate(P=0.019),tumor diameter(P=0.027),LST-NG tumors(P=0.001),and nonlifting sign(P=0.042)increased significantly in the third period,but other factors had no significant differences.The en bloc resection rate,complete resec-tion rate,curative resection rate,and resection speed increased,but piecemeal resection rate decreased.Compared with the third period,intramucosal carcinoma and submucos-al carcinoma have a large proportion(P=0.009),procedure time(P<0.001)decreas-ed,and resection speed(P=0.033)increased significantly.The rate of perforation,intra-procedural bleeding,and piecemeal resection decreased slightly.However,the en bloc resection rate and complete resection rate increased slightly,but curative resection rat-e has no obvious change.In view of above features,we defined the first three perio-ds as the early stages of CR-ESD(improved period) and defined the fourth period as the late stage(stable period).By comparison,the procedure time(42.52±40.49 vs.57.14±43.69,P<0.001)and the resection speed(0.21±0.16 vs.0.16±0.14,P=0.001)increased si-gnificantly in the late period.The en bloc resection rate,complete resection rate and curative resection rate were largely improved;the perforation rate and piecemeal res-ection rate decreased obviously.Conclusions:ESD was more technical difficulty for tumor size ≥ 4.0cm or spreading across≥2folds.Intraprocedural bleeding was the strongest independent risk factor for non en bloc resection.With the increase of practice,the en bloc resection rate, complete resection rate,curative resection rate and resection speed increased gradually,but complication rate and the procedure time decreased gradually;approximately 55 cases might be needed to acquire an adequate skill of colorectal ESD.These data will provide useful informations for the application of CR-ESD for endoscopists.