EndoscoPic Submucosal dIssection Using geL Versus glycerOl for Submucosal iNjection

Inclusion Criteria: * o Patients must have given written informed consent * o Subjects with documented gastric or rectal lesions with indication of endoscopic removal by ESD, namely: * Gastric focal lesion with suspicion of early gastric cancer (low or high grade dysplasia with features of early gastric cancer; adenocarcinoma with morphology of superficial lesion and work-up of superficial lesion) * Rectal polyps (adenoma or superficial carcinoma) from 0 to 15 cm from the anal margin; with features being recognized indications of ESD: more than 20mm granular LST, more than 20mm non granular LST, more than 20mm villous or bulging polyps, Paris 0-IIa+IIc lesions, lesions with suspicious pattern (Kudo Vi / JNET 2B), lesions with anal canal involvement. Exclusion Criteria: * Subjects who meet any of the following exclusion criteria cannot be enrolled in the study: * Gastric and rectal neuroendocrine tumour (NET) with indication of ESD will be excluded * Gastric and rectal lesions with indication of ESD but strong fibrosis due to previous partial resection will be excluded * Subject is currently enrolled in another confounding research * Subjects with any other location of ESD (esophagus, duodenum and colon) will not be included.