Complete Versus Partial Preservation of Denonvilliers' Fascia on Urogenital Function in Locally Advanced Rectal Cancer

Inclusion Criteria: 1. Pathological diagnosis of rectal adenocarcinoma; 2. Preoperative staging cT3-4 and or N+，M0 rectal cancer (AJCC- 7th); 3. Non-anterior wall, mid-low rectal cancer from 0 to 12 cm from the anal verge measured by rigid proctoscope; 4. R0 surgical results is expected by transabdominal or transanal TME/TSME; 5. 18 \< age (years) \< 71, informed consent; 6. Normal erection function (IIEF-5\>21), ejaculation function grading as I level, FSFI \> 26, normal urinary function (Bladder residual urine\<100ml); 7. Preoperative ASA grade I \~ III, no serious systemic disease; Exclusion Criteria: 1. Preoperatively confirmed peritoneum or distant metastasis; 2. Intraoperative confirmed invasion of surrounding tissues or organs, cannot be R0 resected; 3. With other malignant diseases; 4. With acute ileus, perforation or hemorrhage,need emergency surgery; 5. Critical organs dysfunction, unable to tolerate laparoscopic surgery; 6. With severe mental illness, cannot be evaluated;