The aim of this clinical trial is to compare the short- and long-term outcomes of laparoscopic ileocecal reconstruction right hemicolectomy (LIRRH) with those of traditional laparoscopic right hemicolectomy (TRH) for ascending and proximal transverse colon cancer.

This is a prospective, single-center, open-label, randomized controlled clinical trial. Eligible patients will be randomly assigned (1:1) to undergo either LIRRH or TRH and will receive the corresponding surgical procedure.

Primary endpoint: 3-year disease-free survival (DFS).

Secondary endpoints:

1. Complications within 90 days postoperatively;
2. Pathology-related indicators, including positive margin rate, number of harvested lymph nodes, and lymph-node metastasis rate;
3. Assessment of postoperative intestinal microbiota changes;
4. 5-year overall survival (OS).

Inclusion Criteria:

• Age 18-75 years
• ASA physical status ≤ III
• Endoscopy and biopsy-proven colon adenocarcinoma
• Contrast-enhanced abdominal CT showing primary tumor located in the ascending colon or proximal transverse colon (proximal one-third)
• Pre-operative clinical stage: TanyNanyM0
• Able to understand the study protocol, willing to participate, and provide written informed consent

Exclusion Criteria:

• History of hypertensive crisis or hypertensive encephalopathy.
• Severe cardiopulmonary insufficiency or any other contraindication to surgery.
• Uncorrectable electrolyte disturbances (e.g., potassium, calcium, magnesium).
• Evidence of significant bleeding diathesis or high hemorrhagic risk:
• Prior intracranial or intraspinal hemorrhage.
• Tumor invading major vessels with obvious bleeding risk.
• Thrombotic or embolic event within 6 months before study treatment, or significant vascular disease (e.g., surgical-repair aortic aneurysm).
• Clinically relevant hemoptysis or tumor bleeding of any cause within 1 month before screening.
• Therapeutic-dose anticoagulation within 2 weeks before study treatment (except low-molecular-weight heparin).
• Antiplatelet therapy within 10 days before study treatment (e.g., aspirin > 325 mg/day, clopidogrel > 75 mg/day, dipyridamole, ticlopidine, cilostazol).
• Active tuberculosis.
• Any active autoimmune disease or history of autoimmune disease with expected recurrence (including but not limited to SLE, RA, autoimmune hepatitis, uveitis, enteritis, hepatitis, hypophysitis, vasculitis, nephritis, hyper- or hypothyroidism, asthma requiring bronchodilators).
• Pre-operative evidence of synchronous multiple primary colorectal cancers or other conditions requiring additional bowel resection.
• Pre-operative imaging or intra-operative findings showing:
• Tumor infiltration into adjacent organs requiring multi-visceral resection;
• Distant metastasis;
• Unresectable (unable to achieve R0) disease.
• Other malignancies within the past 5 years, or familial adenomatous polyposis; except cured carcinoma in situ of the cervix, basal-cell carcinoma, papillary thyroid carcinoma, or cutaneous squamous-cell carcinoma.
• Intestinal obstruction, perforation, or bleeding requiring emergency surgery.
• Patient unsuitable or unable to tolerate laparoscopic surgery.
• Pregnant or lactating women.
• History of psychiatric disorders precluding compliance.
• Prior neoadjuvant therapy.
• Multidisciplinary team (MDT) decision that the patient is not appropriate for the study.
• Patient unable to understand the study conditions/objectives and refuses to give informed consent.

The following de-identified individual participant data will be shared: baseline demographics, operative variables, pathologic staging, adjuvant therapy details, recurrence and survival outcomes, and serious adverse events. Data will be provided in CSV format with a data dictionary and variable coding manual.

12 months after primary publication (est. Q4 2027) through 2032 (5 years from sharing).

De-identified IPD, along with the protocol, SAP, and analytic code, will be made available to qualified researchers who provide a methodologically sound proposal, IRB/ethics approval documentation, and a signed data-access agreement. Data will be accessed through a secure, password-protected academic repository (e.g., Zenodo) after approval by the study steering committee.