Intracorporeal Anastomosis Versus Extracorporeal Anastomosis for Left Colon Cancer

Inclusion criteria

1. age between 18 and 80 years;
2. histologically or cytologically confirmed left-sided colon cancer (distal transverse colon, left colic flexure, descending colon, or proximal sigmoid colon);
3. clinical stage T1-4a, N0-2, and M0;
4. Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2;
5. suitable for laparoscopic colectomy;
6. no previous systemic chemotherapy or radiotherapy;
7. willing to provide written informed consent and comply with the research procedures.

Exclusion criteria

1. Have a history of malignant colorectal tumor or have metastatic or multiple carcinoma.
2. Patients with intestinal obstruction, intestinal perforation, intestinal bleeding, etc. who need emergency surgery.
3. Patients who need to undergo combined organ resection or robot-assisted colectomy.
4. Patients who are receiving preoperative neoadjuvant therapy.
5. ASA grade ≥ IV and/or ECOG performance status score \> 2.
6. Cardiopulmonary dysfunction (NYHA cardiac function classification II-IV), liver dysfunction (MELD score greater than 12), or kidney dysfunction (serum creatinine above the upper limit of normal);
7. Patients with severe psychiatric illness.
8. Pregnant or lactating women.
9. Patients who have a history of taking hormonal drugs.
10. Diabetic patients whose blood sugar cannot be controlled to be within 6.1 - 8.3 mmol/L.
11. Patients with other clinical and laboratory conditions that are considered by researchers as inappropriate for participating in this trial.

Exit criteria

1. Patients with other non-tumor diseases that prevent them from continuing to receive this treatment regimen.
2. Patients who need emergency surgical resection due to intestinal obstruction, intestinal perforation, intestinal bleeding, etc. after being enrolled in the study.
3. Patients with distant metastasis confirmed by intraoperative exploration or postoperative pathology, including liver, pelvic cavity, ovary, peritoneum, distant lymph node metastasis, etc.
4. Patients who need combined organ resection as determined by intraoperative exploration.
5. Patients who request to withdraw from this study cohort for various reasons after being enrolled in the study, or who cannot complete the study plan and follow-up for various reasons.