The purpose of this study is to evaluate the efficacy of end-to-side anastomosis after laparoscopic right hemicolectomy compared with that of side-to-side anastomosis. The investigators hypothesize that the end-to-side anastomosis may be associated with superior recovery compared with side-to-side anastomosis after laparoscopic right hemicolectomy under enhanced recovery program. The primary endpoint is the cumulative recovery rate, consisting of the recovery time of diet, pain, ambulation, and afebrile status.

All patients will be received a laparoscopic right hemicolectomy by three experienced colorectal surgeons and randomly divided into two groups according to the method of anastomosis: - the end-to-side anastomosis group and the side-to-side anastomosis group. After the surgery, enhanced recovery program will be implemented. The primary endpoint is the cumulative recovery rate according to the method of anastomosis. The cumulative recovery rate is defined as the percentage of patients who are satisfied with all aspects of recovery time, including i) tolerance of diet for 24 hours, 2) analgesic-free (oral or intravenous (IV) analgesic drugs not necessary after cessation of patient-controlled analgesia (PCA)), 3) safe ambulation (ambulation of 600m without assistance), 4) afebrile status without major complications (fever was defined as body temperature greater than 37.2°C at axilla). Secondary endpoints are postoperative hospital stay, complications, the failure rate of the enhanced recovery program, and the readmission rate within 1 month after surgery. The expected cumulative recovery rate in postoperative day 7 is 90% in the end-to-side anastomosis group and 70% in the side-to-side anastomosis group. The sample size of 130 patients was calculated as follow: Based on the assumption that cumulative recovery rate will increase to 20% using the end-to-side anastomosis, it was calculated that 65 patients should be in each group. The sample size was calculated by the formula for a power 80%, alpha error of 0.05 and dropout rate of 10%.

Inclusion Criteria: Patients who have all of the following:

• Age: 18 - 80
• Right-sided colon cancer (adenocarcinoma, located in cecum to hepatic flexure)
• Appropriate laboratory (Bone marrow) findings (Hemoglobin ≥ 10g/dl, White blood cell count ≥ 4,000/mm3, Platelet ≥ 100,000/mm3)
• Appropriate renal function (Creatinine ≤ 1.5 mg/dl)
• Appropriate cardio-pulmonary functions
• Appropriate understanding of the study and provide the informed consent

Exclusion Criteria: Patients who have 1 or more of the following:

• Distant metastasis or locally advanced tumor which required combined resection of other organs, such as the ureter, duodenum, or small bowel.
• Not suitable for laparoscopic surgery
• Currently taking medication for dyschezia, such as constipation or diarrhea.
• Not suitable for adapting enhanced recovery program due to underlying diseases, such as cardio-pulmonary disease, mental disorder, and etc.
• Not suitable for participation in this clinical trial based on the judgment of the investigators

up to 3 year for each participant

Second, our ERAS protocol did not include recent developments such as preoperative carbohydrate loading, multimodal analgesia, and routine administration of drugs for prevention of postoperative nausea and vomiting