OBJECTIVETo evaluate systematically the short- and long-term outcomes between laparoscope-assisted transanal total mesorectal excision (LA-taTME) and laparoscopic total mesorectal excision (L-TME) in the treatment of mid and low rectal cancer.

METHODSLiteratures comparing LA-taTME with L-TME published from January 2014 to January 2018 were systematically selected through searching PubMed, Ovid, EMbase, Cochrane Library, CNKI and Wanfang databases. Literature screening and methodology quality evaluation were carried out by two surgeons independently. Randomized controlled trial (RCT) was evaluated by the modified Jadad rating scale, in which 1 to 3 and 4 to 7 were considered as low and high quality,respectively(total scores: 7). Non-randomized controlled trial (NRCT) was assessed by the modified Newcastle Ottawa Scale (NOS), in which 1 to 3, 4 to 6, and 7 to 9 were defined as low, moderate, and high quality, respectively (total score: 9). Ratio of incomplete mesorectum, positive rate of circumferential resection margin (CRM), number of harvested lymph node, distance of distal resection margin, operation time, intraoperative blood loss, morbidity of postoperative complication, conversion rate, hospital stay, recurrence, 2-year disease-free survival (DFS) and 2-year overall survival (OS) were compared and analyzed by using Stata/SE12.0 software.

RESULTSFourteen studies including 1 RCT and 13 NRCTs were enrolled finally. Among them, the RCT with a score of 6 was considered to be of high quality; all NRCTs (2 with 6 stars, 5 with 7 stars, and another 6 with 8 stars) were indicative of moderate to high quality; 450 patients underwent LA-taTME and 498 patients underwent L-TME. No significant differences were observed in terms of age, gender, tumor location and TNM stage between two approaches (all P>0.05). Compared to L-TME, LA-taTME had lower ratio of incomplete mesorectum (RR=0.53, 95%CI: 0.31 to 0.93, P=0.026), lower positive rate of CRM (RR=0.50, 95%CI: 0.29 to 0.86, P=0.012), lower conversion rate(RR=0.48, 95%CI: 0.26 to 0.86, P=0.014), lower morbidity of postoperative complication (RR=0.81, 95%CI: 0.67 to 0.99, P=0.036) and less intraoperative blood loss (SMD=-0.38, 95%CI:-0.68 to -0.08, P=0.013). While the differences between two groups had no statistical significance in terms of operative duration, number of harvested lymph node, distance of distal resection margin, hospital stay, overall recurrence, 2-year DFS and 2-year OS (all P>0.05).

CONCLUSIONThe short- and long-term outcomes of LA-taTME and L-TME for the treatment of mid and low rectal cancer are comparable, while LA-taTME can reduce the ratio of incomplete mesorectum, positive rate of CRM, conversion rate, and morbidity of postoperative complication, and intraoperative blood loss.