This study compares the effectiveness in complete resection (absence of recurrence at 6 months) the two different techniques for performing endoscopic mucosal resection (EMR) of nonpedunculated homogeneous colorectal lesions >20mm

Colonoscopy is the reference diagnostic test for the study of colon diseases. This procedure also allows the realization of endoscopic therapeutics techniques; thus, endoscopic mucosal resection (EMR) is an effective and safe therapy for the treatment of premalignant and early malignant colorectal lesions of the colon and its use is universal.

Usually, colon lesions larger than 10 mm (or pedunculated of any size) require for resection the use of electrocoagulation current (or hot snare polypectomy) and thus is reflected in the most recent clinical practice guidelines (ESGE guidelines, for example). However, the risk of side adverse effects from the use of electrocoagulation is not insignificant and includes post-polypectomy bleeding, post-polypectomy syndrome, post-polypectomy fever and/or immediate or delayed perforation. This risk of complications is higher depending on the characteristics and size of colorectal lesions resected.

On the other hand, currently in small lesions not pedunculated (< 10 mm), it is recommended to use cold snare polypectomy according to ESGE clinical guidelines, as it has been seen in previous studies that this reduces complication rates without varying the effectiveness in resection.

However, in lesions > 10 mm the previous experience with cold snare resection is less, probably motivated by the possible drawbacks in terms of the possible difficulty of resection of thick tissue with cold snare and a possible increased intra-procedure hemorrhagic risk that can make it difficult to see the scar, with the possibility of leaving residual tissue.

However, in recent years the accumulated evidence gathered in various studies and grouped in a recent systematic review suggests that endoscopic mucosal resection with cold snare (Cold-EMR) may be safer than electrocoagulation resection for both 10-19mm lesions and for lesions >20 mm, associated with a lower rate of adverse effects with similar efficacy rates in terms of complete resection and adenomatous recurrence rate. Still, evidence for the treatment of nonpedunculated lesions >20 mm is relatively limited and is not based on randomized comparative studies with the standard EMR technique.

Inclusion Criteria:

• Patients of age > 18 years undergoing a colonoscopy for any reason of request and who do not meet exclusion criteria.
• Nonpedunculated homogeneous colorectal lesions type LST ( Paris 0-IIa morphology) and serrated lesions larger than 20 mm without endoscopic data of malignancy: NICE 1 pattern +/- NICE 2 component ( serrated lesions) or NICE2 pattern/JNET 2A (adenomas) and therefore subsidiaries of RME. Randomization will be performed per patient, not for colorectal lesions
• Signature of informed consent of endoscopic exploration

Exclusion Criteria:

• .No signature of informed consent prior to the study procedure.
• Absence of proper suspension of the anticoagulant/antiplatelet therapy prior to procedure according to usual pre-procedure recommendations (BSG and ESGE guidelines)
• Patients with severe thrombopenia/ coagulopathy (Platelets < 50,000/INR > 1.5) not corrected prior to procedure (plasma or platelet transfusion)
• Patients not candidates for endoscopic resection of colorectal lesions by comorbidities.
• Pregnant.
• Patients with inflammatory bowel disease (IBD)
• Urgent colonoscopy.
• Poor preparation (BBPS <2 in the colon segment where the lesion is located)
• Laterally spreading tumors (LST) lesions with non-homogeneous morphology including: sessile polyps (0-Is), pedunculated (0-Ip) and LST lesions with depressed or excavated components (Paris 0-IIc or Paris 0-III), LST granular nodular mixed, LST-G with whole nodular type. In case of doubt depressed component (Paris 0-IIc) or histological borderline lesion (JNET2B), will be excluded from the study.
• Histological prediction of deep invasive or non-subsidiary to endoscopic mucosal resection lesion as a treatment of choice: NICE 3 pattern by inspection with NBI or Kudo V pattern in traditional/electronic chromoendoscopy or Sano IIIA/IIIB pattern
• Endoscopic resection of post-EMR scar level relapses