Total Meso-rectal Excision Versus Transanal Local Excision Followed by Radiotherapy for T2N0M0 Distal Rectal Cancer

Inclusion Criteria: * Age between 18 and 75 years. * Histologically confirmed adenocarcinoma by preoperative biopsy. * Tumor located within 4 cm from the anal verge, confirmed by at least one of the following methods: digital rectal examination, pelvic magnetic resonance imaging (MRI), or colonoscopy. * Tumor size ≤3 cm, without fixation and with preserved mobility on clinical examination. * Clinical stage T2 rectal cancer confirmed by preoperative high-resolution pelvic MRI. * No radiological evidence of suspicious lymph node metastasis or distant metastasis on preoperative contrast-enhanced computed tomography (CT) and MRI. * Ability to provide written informed consent. Exclusion Criteria: * History of other malignant tumors within the past 5 years. * Poorly differentiated adenocarcinoma, mucinous adenocarcinoma, or signet ring cell carcinoma confirmed by pathological examination. * Multiple primary colorectal tumors. * Pregnant or breastfeeding women. * Patients with plans for pregnancy. * Severe psychiatric disorders. * Previous treatment for rectal cancer, including radiotherapy or chemotherapy. * Concomitant intestinal diseases, including familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), active ulcerative colitis, or Crohn's disease. * Poor general condition or uncontrolled serious comorbidities that may affect study participation or treatment. * Contraindications to laparoscopic surgery, including extensive intra-abdominal adhesions caused by previous abdominal surgery or inability to tolerate pneumoperitoneum. * Current participation in another clinical trial.