[Comparison of postoperative bowel function between patients undergoing transanal and laparoscopic total mesorectal...

To compare the effects of transanal total mesorectal excision (taTME) and laparoscopic total mesorectal excision (laparoscopic TME) on patients' postoperative long-term bowel function.

A retrospective cohort study was used in this study. We analyzed the clinical data of 134 patients with locally advanced mid-low rectal cancer, who underwent transanal TME or laparoscopic TME in the TaLaR randomized controlled trial at the Sixth Affiliated Hospital, Sun Yat-sen University from April 2016 to November 2017. Inclusion criteria included age of 18 to 80 years old, distance from tumor low margin to anal edge ≤10 cm, preoperative staging of T1-3NxM0, and single rectal adenocarcinoma. Exclusion criteria included local recurrence, distant metastases, abdominoperineal resection, unreduced stoma, new stoma, less than 1 year after protectomy or stoma reduction, or preoperative poor anal function or incontinence. Patients were divided into taTME group and laparoscopic TME group. The taTME group received hybrid transanal and transabdominal approach performed simultaneously. The effects of surgical procedures on postoperative bowel function were evaluated with LARS (low anterior resection syndrome) scale, where 0-20 was defined as " no LARS" , 21-29 as " minor LARS" , and 30-42 as " major LARS" . Univariate and multivariate logistic regression analyses were performed to determine the risk factors associated with major LARS, with surgical approach as a pre-selected variate.

A total of 107 patients were included. Of the 54 patients in the taTME group, 35 were male, median age was 57.2 (26.0-77.0) years old, and 22 cases had a tumor less than 5 cm from anal verge. Of the 53 patients in the laparoscopic TME group, 35 were male, median age was 62.0 (33.0-73.0) years old, and 25 cases had a tumor less than 5 cm from anal verge. All baseline clinical data including age, gender, preoperative staging, and tumor height were comparable between the two groups (all P>0.05). All operations in both groups were performed successfully. The operation time, intra-operative blood loss, postoperative anastomotic complication, postoperative hospital stay were comparable between the two groups (all P>0.05), except for a lower diverting stoma rate in the taTME group [37.0% (20/54) vs. 64.2% (34/53), χ²=7.866, P=0.005]. Of the 107 patients, 27 (25.2%) had no LARS, 32 (29.9%) had minor LARS, and 48 (44.9%) had major LARS, after a median follow-up of 17.2 (12.1-30.4) months. No significant difference was found between the two groups in overall bowel function [major LARS: 48.1% (26/54) vs. 41.5% (22/53), Z=-0.994, P=0.320]. Compared with the laparoscopic TME group, the taTME group experienced worse clustering of stools [68.5% (37/54) vs. 45.3% (24/53), Z=-2.354, P=0.019]. However, there were no significant differences between the two groups in terms of gas incontinence, liquid stool incontinence, frequency of defecation, and urgency (all P>0.05). Multivariate analysis identified preoperative radiotherapy (OR=5.073, 95% CI: 1.336 to 19.259, P=0.017) and anastomotic height (OR=3.633, 95% CI: 1.501 to 8.802, P=0.004) as independent risk factors for major LARS, but no impact of taTME on LARS (OR=1.442, 95% CI: 0.638 to 3.261, P=0.379).

Compared with laparoscopic TME, taTME has similar outcomes of postoperative long-term bowel function. Preoperative radiotherapy and anastomotic height, but not surgical approach, are independent risk factors for postoperative bowel function.