Tubeless NOSES Versus Laparoscopic Radical Resection for Rectosigmoid Cancers

Inclusion Criteria: 1. Histologically or cytologically confirmed Rectosigmoid Cancers 2. Clinical stage at T 1-3 N0-2 M0 3. Tumors on peritoneal reflection，Tumor size is no more than 3 cm 4. Eastern Cooperative Oncology Group (ECOG) scale is 0-2 5. American Society of Anesthesiologists (ASA) score is Ⅰ-Ⅲ 6. BMI ≤ 30 kg/m2 7. Subjects must be willing and able to comply with scheduled visits, treatment schedule,and laboratory testing. Exclusion Criteria: 1. Heart, lung, liver or renal or any organ function that are intolerance for surgery 2. History of treated colorectal malignant disease 3. Subjects with medical condition, such as intestinal obstruction, intestinal perforation, bleeding, requires emergency surgery 4. Subjects with previous malignancies 5. History of inflammatory bowl disease(IBD) or familial adenomatous polyposis (FAP) 6. Treatment with any other clinical trial within 28 days prior to randomization 7. History of severe mentally disease 8. pregnant or lactating women 9. The researchers believe that the patients are unsuitable to participate in the researchers with other cases.