Endoscopic Submucosal Dissection vs Local Laparoscopic Surgical Resection (TAMIS/TEO) in Early Rectal Neoplasias

A multicenter non-inferiority randomized clinical trial is proposed to compare two types of treatment for early rectal neoplastic lesions. Study arms: 1. Endoscopic treatment: Endoscopic Submucosal Dissection (ESD) 2. Minimally invasive laparoscopic local surgical treatment: Transanal Minimally Invasive Surgery (TAMIS) or Transanal Endoscopic Operation (TEO). Aims: Primary aim: To compare the long-term local recurrence rate (12 months after the procedure) of rectal lesions after ESD vs Surgical treatment (TAMIS/TEO). Secondary aims: Both arms of the study are compared according to other efficacy-related variables (en-bloq resection rate, R0 resection, time per procedure, short-term recurrence rate \[6 months\]), safety (rate of complications), morbidity (comparing different specific indexes: Wexner index, EQ-5L-5D, etc) and cost-effectiveness analyses (QALY). Inclusion criteria: * Patients older than 18 y/o * Non-pedunculated rectal lesions (sessile 0-Is or flat 0-II) greater than 20 mm in diameter. * The edges of the lesion should be more than 3 cm from the external anal margin and up to 14 cm from it. * Circumferential involvement \<50% Exclusion criteria: * Patients who refuse to participate. * Diagnosis of inflammatory bowel disease with rectal involvement. * Pregnant. * Anorectal fibrosis due to previous anorectal surgery. * Lateral Spreading Lesions (LST classification) Granular Homogeneous type * Lesions greater than 50 mm when there is suspicion of advanced histology (Kudo Vi superficial pattern). * Rectal lesions of any size with high suspicion of deep submucosal invasion or locoregional lymph node involvement, either in the diagnostic colonoscopy (Kudo Vn crypt pattern, NICE 3 pattern, Sano IIIB pattern) or by complementary imaging tests (rectal EUS/Pelvic MRI) * Existence of synchronous colorectal lesions that require other surgical treatment in any case. N-size estimation: Assuming a global rate of long-term local recurrence in rectal lesions treated by TAMIS/TEO or ESD of 2.5% (using the data available in the medical literature), considering a non-inferiority limit of 10%, power of 80% (Beta error 0.2, alpha error 0.05) and assuming a loss of patients during the follow-up around 10%, 34 patients per group are required. Follow-up and Information collect: The follow-up will be of 1 year from the date of the intervention and the visits in which the information to be analyzed will be collected are adjusted to the usual clinical practice. The data would be registered using the on-line database system for medical research RedCap. Other information: The entire protocol of this study has been approved by de Ethical Committee on Clinical Research of the Puerta de Hierro University Hospital. The study counts with a Civil Responsibility Insurance policy.