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.