February’s paper of the month is a powerful network metanalysis focused on an evergreen issue: what’s the best technique to perform mesorectal excision for rectal cancer? Open vs. laparoscopic vs. robotic vs. transanal, the battle continues…

Open versus laparoscopic versus robotic versus transanal mesorectal excision for rectal cancer: a systematic review and network meta-analysis. Simillis C, Lal N, Thoukididou SN, Kontovounisios C, Smith JJ, Hompes R, Adamina M, Tekkis PP. Ann Surg. 2019.

What is known on the subject?

The gold standard of treatment for rectal cancer is proctectomy with total mesorectal excision (TME). TME has classically been performed by an open approach, but over time new surgical techniques have been introduced, such as the laparoscopic, robotic, and transanal approaches.

Compared to open surgery, the laparoscopic approach has demonstrated decreased operative blood loss, earlier recovery of bowel function, decreased requirements of analgesics, and shorter hospital stay. Even if oncological outcomes were found to be comparable, recent studies have raised concerns regarding the quality of oncological resection with the laparoscopic approach compared with open.

The robotic approach aims at eliminating many of the technical difficulties inherent to laparoscopic surgery, such as limited views, 2-dimensional representation of the operative site, unnatural hand-eye coordination, and limited maneuverability with non-articulating unstable instruments in a narrow fixed pelvis. RCTs comparing the laparoscopic and robotic techniques found no difference in perioperative morbidity, bowel function recovery, conversion to open rate, and quality of oncological resection.

Finally, transanal approach to TME was also developed with the aim of improving the distal mesorectal dissection, which is the most technically challenging part of a transabdominal TME, by improving the surgical field views and surgical access to the low pelvis. Transanal TME has shown promising results with regard to histopathological quality and with comparable short- and long-term outcomes to the laparoscopic approach.

Although several RCTs, and many standard pairwise meta-analyses have been published to date comparing the surgical techniques available for mesorectal excision for rectal cancer, there is no consensus among surgeons regarding the optimal surgical approach. An important disadvantage of these RCTs and standard pairwise meta-analyses published on this subject is that they can only compare 2 treatments directly, rather than all available treatments at once.

What this study adds

A network meta-analysis, comparing all four techniques currently available to perform TME for rectal cancer, allows simultaneous comparison of all surgical treatments available for rectal cancer, and is ideal for this topic where multiple interventions have been used and compared for the same disease, and with the same outcomes. The outcomes chosen for the meta-analysis included most of the results of interest after rectal resection: operative outcomes, short-term postoperative results, histopathological outcomes and long-term oncological results.

The metanalysis included 37 publications and used Bayesian network methodology. The results show that none of the techniques to perform TME was clearly superior to others. The different techniques resulted in comparable perioperative morbidity and long-term survival. The laparoscopic and robotic approaches may improve postoperative recovery, and the open and transanal approaches may improve oncological resection.

Implications for colorectal practice

The paper gives the possibility to the surgeon to choose any of the four techniques to perform TME, suggesting that the choice should be tailored to the experience of the surgeon and the characteristics of the patient and tumour.

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