Total mesorectal excision in MRI-defined low rectal cancer: multicentre study comparing oncological outcomes of robotic, laparoscopic and transanal total mesorectal excision in high-volume centres.

Background: The routine use of MRI in rectal cancer treatment allows the use of a strict definition for low rectal cancer. This study aimed to compare minimally invasive total mesorectal excision in MRI-defined low rectal cancer in expert laparoscopic, transanal and robotic high-volume centres.

Methods: All MRI-defined low rectal cancer operated on between 2015 and 2017 in 11 Dutch centres were included. Primary outcomes were: R1 rate, total mesorectal excision quality and 3-year local recurrence and survivals (overall and disease free). Secondary outcomes included conversion rate, complications and whether there was a perioperative change in the preoperative treatment plan.

Results: Of 1071 eligible rectal cancers, 633 patients with low rectal cancer were identified. Quality of the total mesorectal excision specimen (P = 0.337), R1 rate (P = 0.107), conversion (P = 0.344), anastomotic leakage rate (P = 0.942), local recurrence (P = 0.809), overall survival (P = 0.436) and disease-free survival (P = 0.347) were comparable among the centres. The laparoscopic centre group had the highest rate of perioperative change in the preoperative treatment plan (10.4%), compared with robotic expert centres (5.2%) and transanal centres (2.1%), P = 0.004. The main reason for this change was stapling difficulty (43%), followed by low tumour location (29%). Multivariable analysis showed that laparoscopic surgery was the only independent risk factor for a change in the preoperative planned procedure, P = 0.024.

Conclusion: Centres with expertise in all three minimally invasive total mesorectal excision techniques can achieve good oncological resection in the treatment of MRI-defined low rectal cancer. However, compared with robotic expert centres and transanal centres, patients treated in laparoscopic centres have an increased risk of a change in the preoperative intended procedure due to technical limitations.