RATME Vs LATME in Middle and Low Rectal Cancer

The primary outcome is the incidence of ISR. ISR is defined according to the definition by a Japanese study group. When the distal resection margin is from dentate line to the intersphincteric groove, ISR will be recorded.The distal resection line of the internal anal sphincter was at the intersphincteric groove in total ISR, between the dentate line and the intersphincteric groove in subtotal ISR and at the dentate line in partial ISR

CAA was defined as the anastomosis of distal colon and surgical anal canal. In CAA anastomosis, the distal resection margin is below the upper level of the levator ani muscle. Conversion to open was defined as an abdominal incision larger than necessary for specimen retrieval.

Conversion to open surgery was defined as an abdominal incision larger than necessary for specimen retrieval extraction.

Conversion to TaTME was defined as TME that cannot be finished via transabdominal approach, and have to be finished by transanal approach with the help of imaging system and endoscopic instruments. It should be noted that if TME was completely done via transabdominal approach, simply dissecting the internal sphincter and intersphincteric space or finish the coloanal anastomosis via transanal approach were not classified as TaTME

The 30-day morbidity is defined as intraoperative adverse events and postoperative complications within 30 days. The intraoperative adverse events include intraoperative bleeding (>200 ml), pelvic vascular and nerve injury, vascular injury in other parts, digestive tract injury, ureteral injury, and anastomotic defect. Furthermore, the 30-day postoperative complications are evaluated according to Clavien-Dindo classification

The 30-day mortality is defined as death within 30 day after operation

DFS is defined as the time from randomization to the discovery of local recurrence, distant metastasis, or death of the tumor

LR is defined as tumor recurrence (evaluated by positron emission tomography, computed tomography, or magnetic resistance) that occurs in the pelvic cavity, perineal area, root of inferior mesenteric artery, descending colon, and sigmoid mesenteric area, and is confirmed through pathological biopsy or reoperation.

OS is defined as the time from randomization to death due to any cause.

The distance to the DRM is defined as the shortest length between the tumor and the DRM. DRM positivity is defined as a distal margin within 1 mm of the tumor.

The distance to the CRM is defined as the shortest length between the tumor and the CRM. CRM positivity is defined as tumor cells within 1 mm from the CRM by microscopy

Urinary function will be evaluated by International consultation on incontinence questionnaire short form (ICIQ-SF). The patients will be asked to complete ICIQ-SF every 3 months in the first year after operation, and every 6 months after the first year follow-up, until we finished the 3-year follow-up.

the proportion of patients receiving abdominoperineal resection

Quality of life will be evaluated by EORTC quality of life questionnaire-core 30 (QLQ-C30) form. The patients will be asked to complete QLQ-C30 every 3 months in the first year after operation, and every 6 months after the first year follow-up, until we finished the 3-year follow-up.

Sexual function of male will be evaluated by International Index of Erectile Function (IIEF-5). Sexual function of female will be evaluated by Female Sexual Function Index (FSFI). Evaluation will be performed every 3 months in the first year after operation, and every 6 months after the first year follow-up, until we finished the 3-year follow-up.

Defecation function will be evaluated by low anterior resection syndrome (LARS) form. The patients will be asked to complete LARS form every 3 months in the first year after operation, and every 6 months after the first year follow-up, until we finished the 3-year follow-up.