Guest blog: What advantage does robot-assisted and transanal TME have over laparoscopy?

Contact: j.c.hol@amsterdamumc.nl

Correspondence to: “Comparison of laparoscopic versus robot-assisted versus TaTME surgery for rectal cancer: a retrospective propensity score matched cohort study of short-term outcomes”

Image source: Robinson Poffo et. al. Robotic surgery in Cardiology: a safe and effective procedure. https://creativecommons.org/licenses/by/4.0/ under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The emergence of minimally invasive surgery has led to the development of three new surgical techniques for oncological rectal resections: laparoscopic, robot-assisted and transanal TME (TaTME). When we compared the three techniques executed in expert centres, we expected to find an advantage for one of the three techniques in terms of reduced complication rates. But contrary to our expectations, no difference was seen. There was one striking difference however, when comparing these techniques, though it might be something different than you might have thought. We shine a light on all three techniques to explain their advantages. 

Laparoscopy: minimally invasive surgery

In the 1980’s, Heald introduced the total mesorectal excision (TME) principle, which comprises excision of the rectum and its surrounding fatty envelop with preservation of the autonomic nerves [1]. TME has become the golden standard for surgical resection for rectal cancer and helped dropping local recurrence rates drastically. The past decades laparoscopy has been introduced and gradually replaced open surgery. Laparoscopy offers short term benefits of minimally invasive surgery, such as faster recovery and reduced complication rates [2, 3]. It offers similar long-term outcome as open surgery [4]. But laparoscopy is technically demanding because it is difficult to work with rigid instruments in the narrow and confined area of the pelvis. Therefore, conversion rates to open surgery of more than 10% were seen [5]. Conversion is linked to increased morbidity and worse oncological outcome [6]. In order to overcome those technical limitations of laparoscopic TME, new techniques have been introduced; robot-assisted TME and TaTME. 

Robot-assisted TME: the same, but different

Robot-assisted TME comprises the same approach as laparoscopy, but with the use of a surgical robot. The surgical robot provides a stable platform with supreme vision and supreme instrument handling. Surgeons thought this technique might improve results in terms of reduced complication rates and reduced conversion rates. However, the largest randomized trial so far comparing robot-assisted and laparoscopic TME failed to show any difference in these outcomes [7]. This might have been the result of a methodological flaw, because the robotic surgeons in that trial were not as experienced as their laparoscopic colleagues [8]. In our study, we tried to eliminate this by only selecting experienced centres that were beyond their learning curve. However, we did not see reduced complication rates or reduced conversion rates after robot-assisted TME compared to laparoscopy.

Transanal TME: a different approach

TaTME comprises a different approach to address the most difficult part of the dissection. In TaTME the most distal and difficult part of the rectum is dissected from below using a transanal insufflator port. However, this is a technically demanding technique and has a long learning curve [9]. Some initial series showed high loco regional recurrence rates, which even led to a halt of TaTME in Norway [10, 11]. The potential learning curve effect is now part of an ongoing debate about the oncological safety of this technique. Most initial results however looked promising and showed consistently good quality specimen and lower conversion rates [12, 13]. In our study, conversion rates, number of complete specimen and morbidity rates did not differ from the other laparoscopy and robot-assisted TME. 

Technological advantage 

The results of our study showed similar and acceptable short-term results for all three techniques in expert centres. The most striking difference was that in centres with robot-assisted or TaTME, more primary anastomoses were made. The technological advantage of the two new techniques could have contributed to higher restorative rates. Both robot-assisted and TaTME provide better access and visibility to the distal rectum, enabling surgeons to complete the TME dissection safely and create an anastomosis. Robot-assisted TME could overcome technical limitations of laparoscopy in the narrow pelvis thanks to the use of 3D vision, lack of tremor, and superior instrument handling, thereby facilitating safe creation of an anastomosis [7, 14]. TaTME does not need multiple staple firing to transect the distal rectum and without requiring conversion to open surgery [13]. In fact, TaTME does not need cross-stapling at all, preventing the creation of dog-ears which are prone to ischemia [15]. 

Patient’s perspective

In conclusion, the technological advantage of robot-assisted TME and TaTME manifests itself in higher restorative rates. Each technique seems to be equally beneficial in terms of oncological outcomes and morbidity. However, anastomosis creation, quality of life and functional outcome are becoming of great importance to patients. It seems to be that an increasing proportion of patients is now in pursue of an anastomosis. The overall anastomosis rate of more than 84% for robot-assisted and TaTME in our study was higher than the anastomosis rate of 50% in a previous national study [16]. A note of caution should be added, as an anastomosis might not be always better in terms of functional outcome and quality of life. Patients with a low anastomosis are at risk of developing severe low anterior resection syndrome (LARS) symptoms. Severe LARS symptoms can have a detrimental effect on quality of life [17].  Further research should be undertaken to investigate whether a higher anastomosis rate is beneficial in terms of quality of life and functional outcome and whether this higher anastomosis rate actually leads to increased patient satisfaction.