Rectal Cancer Stage I

In this clinical trial, we compare the endoscopic technique, endoscopic intermuscular dissection (EID), with the surgical technique, transanal minimally invasive surgery (TAMIS) for the treatment of early stage rectal cancer. The aim of this study is to investigate whether one of them leads to better outcomes. Researchers will focus particularly on: * How effectively each technique completely removes the cancer * How quickly patients recover after treatment and whether complications occur * Outcomes after three years (does the cancer go away, or does it come back?) * The impact of both techniques on bowel function and quality of life Participants will: * Be randomly assigned to receive either surgical or endoscopic treatment for their rectal cancer * Keep a diary twice a day to record pain symptoms and recovery during the first 30 days after treatment and complete questionnaires within a 3 year period * Visit the clinic for follow-up appointments within a 3 year period

This study is a single-center, single-arm, prospective clinical trial designed to evaluate the efficacy of local excision followed by postoperative chemoradiotherapy in patients with early-stage low/ultra-low rectal cancer. The study plans to enroll 60 patients with T1-2N0M0 low/ultra-low rectal cancer.

Safety and Efficacy of Organ Preservation Treatment for Stage I Rectal Cancer: Optimization of Consolidation Chemotherapy Before Local Excision After Neoadjuvant Chemoradiotherapy (OPTION); A Multi-center, Prospective, Randomized Trial The goal of this clinical trial is to find out if adding consolidation chemotherapy with capecitabine after total neoadjuvant chemoradiotherapy (TNT) works to improve oncologic outcomes in patients with stage I rectal cancer. It will also comparethe safety of adding consolidation chemotherapy before local excision. The main questions it aims to answer are: * Does adding consolidation chemotherapy increase the rate of pathologic complete response? * What medical problems or side effects do participants have during and after treatment? Researchers will compare TNT followed by local excision to TNT followed by consolidation chemotherapy with capecitabine and then local excision to see if adding consolidation chemotherapy improves tumor response and treatment outcomes. Participants will: * Receive TNT for stage I rectal cancer * Be randomly assigned to one of two treatment groups * Undergo local excision after preoperative treatment * Visit the clinic for checkups and tests to evaluate tumor response, side effects, recurrence, survival, quality of life, bowel function, urinary function, sexual function, circulating tumor DNA, and treatment-related costs

Introduction: The standard treatment for rectal adenocarcinoma is total mesorectal excision (TME), a technique involving resection of the rectum, with or without a temporary or permanent stoma. TME is associated with high morbidity and genitourinary alterations. On the other hand, transanal endoscopic surgery (TEM) allows access to tumors up to 20 cm from the anal margin, with much lower postoperative morbidity and without the need for ostomy. For T1, N0, M0 rectal adenocarcinomas without poor prognostic factors, TEM is the technique of choice. However, recent studies have described local recurrences of up to 20%. Our group, TAUTEM, has just completed a phase III clinical trial in T2-T3ab, N0, M0 rectal cancer, comparing preoperative chemoradiotherapy (CRT) and TEM versus TME, with very positive results in terms of postoperative morbidity, quality of life, and a local recurrence rate of 7.4%, not inferior to TME. These results encourage our TAUTEM group to launch a similar project at the T1, N0, M0 stage, comparing standard TEM treatment versus QRT and TEM, aiming to improve rectal preservation outcomes and enhance results regarding local recurrence, distant recurrence, and oncologic survival. Method: Prospective, controlled, randomized phase III multicenter clinical trial. Patients with rectal adenocarcinoma within 10 cm of the anal margin and up to 4 cm in size, staged as T1, N0, M0, will be included. These patients will be randomized into two groups: TEM after CRT and TEM alone. Postoperative morbidity and mortality, CRT side effects, and quality of life will be recorded. The minimum follow-up will evaluate rectal preservation and local recurrence and survival at two and three years. The sample size calculation for the study will be 106 patients. Conclusions: The aim of the study is to improve oncological outcomes in stage T1, N0, M0 rectal cancer through preoperative chemoradiotherapy associated with local surgery (TEM).