Treatment for Low rectal cancer, especially in patients with regional lymph node metastasis are quite different between Japanese guideline (JSCCR) and western countries' guideline (NCCN, ESMO). While Japanese scholars advocate total mesorectal excision (TME) plus lateral lymph node dissection (LLND), European and American scholars advocate TME alone after Neoadjuvant Chemo-radiotherapy (nCRT), without the need of LLND. Accordingly, this clinical trial is designed to directly compare the efficacy and safety of these two treatment strategies for low rectal cancer with regional lymph node metastasis. It will provide high-level clinical evidence for the treatment of low rectal cancer with suspected local lymph node metastasis

There are significant differences between Japanese guidelines (JSCCR) and Western guidelines (NCCN, ESMO) in the treatment of low rectal cancer, especially in patients with regional lymph node metastasis. Japanese scholars advocated total meso rectal resection (TME) + Lateral lymph node dissection (LLND), However, European and American scholars advocate that only TME is used after new adjuvant chemo-radiation (nCRT), without LLND. Therefore, the purpose of this clinical trial was to directly compare the efficacy and safety of these two treatment strategies for low rectal cancer with regional lymph node metastasis. This will provide a high level of clinical evidence for the treatment of low rectal cancer with suspected local lymph node metastasis

Inclusion Criteria:

1. Histologically confirmed adenocarcinoma(below the peritoneal reflection) Clinical stage Ⅲ
2. Tumor is capable of performing radical recession
3. No past history of chemotherapy, pelvic radiation of other cancers.
4. Written informed consent
5. Lower tumor margin is confirmed below the peritoneal reflection
6. Clinical state T(1-3)N(1-2)M0 is confirmed by the multiple disciplines team(MDT) including surgeons,diagnostic radiologist,radiation oncologist and medical oncologists base on MRI and endorectal ultrasound -

Exclusion Criteria:

1. Past history of other cancers
2. Multiple Primary Colorectal Cancers or Familial adenomatous polyposis(FAP)
3. Combine with inflammatory bowl disease(IBD)
4. Recurrence tumor or invade other organs
5. Combine with obstruction,perforation or bleeding which need emergency surgery.
6. Local tumor invade the external sphincter, levator ani muscle or adjacent organs
7. Participant join other clinical trials in 4 weeks.
8. American Society of Anesthesiologists(ASA) ≥Ⅳ and/or Eastern Cooperative Oncology Group(ECOG) ≤2
9. Pregnant or lactating patients
10. Severity infection before operation
11. Psychological disorder
12. Severe dysfunction of organs or other contraindications
13. Cardiac infarction within six months
14. Severe pulmonary emphysema and pulmonary fibrosis
15. Doctor's decision for exclusion
16. Operative findings:

Tumor invade other organs Lower tumor margin is above the peritoneal reflection