Robot-assisted Procedure Versus Open Simultaneous Resection of Colorectal Cancer With Liver Metastases

Inclusion Criteria: 1. Age ≥ 18 and ≤ 75 years; 2. Primary tumor has undergone histologically confirmed colon adenocarcinoma; Colon cancer was defined by the presence of the inferior pole of the tumor above the peritoneal reflection (at least 15 cm from the anal margin). 3. Together with clinical or radiological evidence of Stage II (T3-4, N0, M0) or Stage III (T1-4, N1-2, M0) disease (according to the 2010 revision of the International Union Against Cancer primary tumor, regional nodes, metastasis (TNM) staging system);Liver metastasis was diagnosis by multidisciplinary (MDT) team base on liver Magnetic Resonance Imaging (MRI) and Positron Emission Computed Tomography (PET-CT). 4. Performance status (ECOG) 0\~1 5. Adequate hematological function: Neutrophils≥1.5 x109/l and platelet count≥100 x109/l; hemoglobin (Hb) ≥9g/dl (within 1 week prior to randomization) 6. Adequate hepatic and renal function: Serum bilirubin≤1.5 x upper limit of normal (ULN), alkaline phosphatase ≤5x ULN, and serum transaminase (either primary tumor, regional nodes, metastasis (AST) or ALT) ≤ 5 x ULN(within 1 week prior to randomization); 7. Written informed consent for participation in the trial. 8. The liver resectability was evaluated by liver surgery of MDT team, indication including: tumor number ≤ 3; the Maximum diameter of one tumor ≤ 10 cm. Exclusion Criteria: 1. Body mass index (BMI) more than 30 kg/m2. 2. Serious pre-operative comorbidity, including cardiovascular disease (coronary arteriosclerosis, arrhythmia, heart failure), pulmonary dysfunction (lung emphysema, obstructive lung disease), liver insufficiency (Child-Pugh B or C), renal insufficiency (serum creatinine \>2.0 mg/dl), and arterial circulation disturbance (occlusion of arterial vessels of limb in patient's history. 3. History of accepting abdominal surgery. 4. Liver tumor located at I or invasive the middle hepatic vein.