Laparoscopic Versus Open PANP-TME for Male Mid-low Rectal Cancer Patients

Inclusion Criteria: * Age from over 20 to under 60 years; * Primary rectal adenocarcinoma confirmed pathologically by endoscopic biopsy; * Mid-low rectal cancer (distance from anal edge≤12cm); * cT1-3, N0-3, M0 at preoperative evaluation according to the AJCC Cancer Staging Manual Seventh Edition; * Expected curative resection through both L-PANP-TME and O-PANP-TME; * Performance status of 0 or 1 on ECOG (Eastern Cooperative Oncology Group) scale; * ASA (American Society of Anesthesiology) score class I, II, or III; * Written informed consent; * Urinary and sexual function normal preoperatively Exclusion Criteria: * Women during pregnancy or breast-feeding; * Severe mental disorder; * History of previous pelvic surgery; * Enlarged or bulky regional lymph node diameter over 3cm by preoperative imaging; * History of other malignant disease within past five years; * History of unstable angina or myocardial infarction within past six months; * History of cerebrovascular accident within past six months; * History of continuous systematic administration of corticosteroids within one month; * Contraindication of heart, brain, lung, etc dysfunction; * Requirement of simultaneous surgery for other disease; * Emergency surgery due to complication (bleeding, obstruction or perforation) caused by rectal cancer; * Rectal cancer invades surrounding tissues; * Existence of genuine incontinence or severe stress incontinence preoperatively