Underwater vs conventional endoscopic mucosal resection in treatment of colorectal polyps:A meta-analysis

BACKGROUND Underwater endoscopic mucosal resection(UEMR)of colorectal lesions is emerging as an alternative method to conventional endoscopic mucosal resection(EMR);however,it is still controversial whether there is a difference in the effectiveness between UEMR and EMR.AIM To evaluate the effectiveness and safety of UEMR in the treatment of colorectal polyps.METHODS Clinical studies comparing the effectiveness or safety of UEMR in the treatment of colorectal polyps were searched in medical databases,including Pub Med,Embase,Cochrane Library,CNKI,and Wanfang Data,monographs,theses,and papers presented at conferences.Statistical analyses were performed using Revman 5.3 software.RESULTS Seven non-randomized controlled trials and one randomized controlled trial met the inclusion criteria.In total,1382 patients(1511 polyps)were included in the study,including 722 who received UEMR and 789 who received EMR.In the UEMR and EMR groups,the en bloc resection rates were 85.87%and 73.89%,respectively,with a relative risk(RR)value of 1.14(95%confidence interval[CI]:1.01-1.30;P<0.05).In the sub-group analysis,the en bloc resection rate showed no statistically significant difference between the EMR and UEMR groups for polyps less than 20 mm in diameter.However,a statistically significant difference was found between the EMR and UEMR groups for polyps equal to or greater than 20 mm in diameter.The post-endoscopic resection recurrence rates at 3-6 mo of the UEMR and EMR groups were 3.26%and 15.17%,respectively,with an RR value of 0.27(95%CI:0.09-0.83;P<0.05).The post-endoscopic resection recurrence rates of UEMR and EMR at 12 mo were 6.25%and 14.40%,respectively,with an RR value of 0.43(95%CI:0.20-0.92;P<0.05).Additionally,the incidence of adverse events was 8.17%and 6.21%,respectively,with an RR value of 1.07(95%CI:0.50-2.30;P>0.05).CONCLUSION UEMR is an effective technique for colorectal polyps and appears to have some advantages over EMR,particularly with regard to some treatment outcomes.

Endoscopic management of difficult laterally spreading tumors in colorectum

Due to the advent of the screening programs for colorectal cancer and the era of quality assurance colonoscopy the number the polyps that can be considered difficult,including large(>20 mm)laterally spreading tumors(LSTs),has increased in the last decade.All LSTs should be assessed carefully,looking for suspicious areas of submucosal invasion(SMI),such as nodules or depressed areas,describing the morphology according to the Paris classification,the pit pattern,and vascular pattern.The simplest,most appropriate and safest endoscopic treatment with curative intent should be selected.For LST-granular homogeneous type,piecemeal endoscopic mucosal resection should be the first option due to its biological low risk of SMI.LST-nongranular pseudodepressed type has an increased risk of SMI,and en bloc resection should be mandatory.Underwater endoscopic mucosal resection is useful in situations where submucosal injection alters the operative field,e.g.,for the resection of scar lesions,with no lifting,adjacent tattoo,incomplete resection attempts,lesions into a colonic diverticulum,in ileocecal valve and lesions with intra-appendicular involvement.Endoscopic full thickness resection is very useful for the treatment of difficult to resect lesions of less than 20 up to 25 mm.Among the indications,we highlight the treatment of polyps with suspected malignancy because the acquired tissue allows an exact histologic risk stratification to assign patients individually to the best treatment and avoid surgery for low-risk lesions.Endoscopic submucosal dissection is the only endoscopic procedure that allows completes en bloc resection regardless of the size of the lesion.It should therefore be indicated in the treatment of lesions with risk of SMI.