The Efficacy of Primary Total Mesorectal Excision (TME) Surgery Versus Neoadjuvant Chemotherapy Combined With TME Surgery in Low-risk Locally Advanced Rectal Cancer

Inclusion Criteria:

1. Newly diagnosed patients, aged 18 to 75 years;
2. Pathologically confirmed rectal adenocarcinoma;
3. Distance of the lower margin of the rectal tumor lesion from the anal margin \<15cm;
4. High-resolution MRI indicates low-risk locally advanced rectal cancer: T1-3bN1-2 or T3aN0 or T3bN0; no involvement of the anal sphincter; negative mesorectal fascia (MRF) status; negative extramural vascular invasion (EMVI); no cancer nodules;
5. Exclusion of patients with non-local recurrence or distant metastases;
6. Absence of synchronous colorectal multiple primary cancers;
7. Adequate physical condition to tolerate surgery and neoadjuvant chemotherapy, including cardiac, pulmonary, hepatic, and renal functions;
8. The study physician assessed no difficulty in sphincter preservation;
9. patients and their families will be willing to participate in this study and provide written informed consent.

Exclusion Criteria:

1. Patients with concurrent other malignancies or a history of malignant tumors in the past;
2. Patients with intestinal obstruction, intestinal perforation, intestinal bleeding, or other conditions requiring emergency surgery;
3. Patients with tumor invasion into the external sphincter or levator ani muscles, or involvement of adjacent organs necessitating combined organ resection;
4. Patients with poor anal function or fecal incontinence before surgery;
5. Patients with a history of inflammatory bowel disease or familial adenomatous polyposis;
6. Patients recently diagnosed with other malignancies;
7. Patients with ASA grade ≥ IV and/or ECOG performance status score \> 2;
8. Patients with severe liver or kidney dysfunction, significant cardiopulmonary impairment, coagulation disorders, or those with extreme underlying conditions unable to tolerate surgery;
9. Patients with a history of severe mental illness;
10. Pregnant or lactating women;
11. Patients with uncontrolled infections before surgery;
12. Patients with other clinical or laboratory conditions, as determined by the investigator, that render them unsuitable for participation in this trial.