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Page 2 of 6 Ghuman et al. Mini-invasive Surg 2020;4:84 I http://dx.doi.org/10.20517/2574-1225.2020.88

now become standard of care after several large randomized controlled trials (RCTs) assessed oncologic
[2-8]
outcomes and early postoperative recovery .

Performing a laparoscopic TME is not without its challenges, especially in a deep narrow pelvis with the
two-dimensional view and limited dexterity. Robotic TME was introduced to overcome some of these
challenges. The theoretical technical advantages of robotic TME include a stable camera platform, three-
[9]
dimensional view, and better articulation of the surgical instruments . Although this technology has
gained widespread popularity, it is not without its own set of challenges, including higher cost, longer
operative time, and loss of tactile sensation.

Surgical innovation continues to play a vital role in the multimodal treatment of rectal cancer. Examining
the pathologic outcomes is important to ensure appropriate care is provided when introducing new
technologies. To date, the largest RCT available to compare laparoscopic and robotic rectal resections
[10]
is the ROLARR trial . Several other RCTs are now available, along with numerous meta-analyses to
further evaluate the literature on pathologic outcomes with robotic compared to laparoscopic rectal cancer
resections, which are discussed in this review. This review is Part 2 of a two-part series, in which the non-
oncologic outcomes and learning curve are separately discussed.

Pathologic outcomes
Total mesorectal excision grade
When assessing pathologic outcomes for rectal cancer, the completeness of the TME is one of the important
oncologic factors to consider. It is also a useful marker to compare the effectiveness and safety of the
various surgical techniques, such as laparoscopic and robotic. The three RCTs discussed below on robotic
vs. laparoscopic approach for the treatment of rectal cancer have assessed TME grade or completeness and
none have shown a significant difference in the quality of TME specimen [10-12] . Furthermore, multiple meta-
analyses have also shown no significant differences.

The ROLAAR RCT trial included TME pathology specimen grading using the method of Quirke and
Dixon for completeness and found complete TME in 77.6% of laparoscopic specimens vs. 76.4% of
[10]
robotic specimens (P = 0.14) . A phase II open label prospective RCT also assessed the quality of TME
by a pathologist, as the primary outcome and found similar results: complete TME 78.1% (laparoscopic)
[11]
vs. 80.3% (robotic) and near complete in 21.9% (laparoscopic) vs. 18.2% (robotic) (P = 0.599) .
They did, however, note one incomplete TME (1.5%) in the robotic group and none in the laparoscopic
group. Lastly, a smaller pilot RCT also found no difference in macroscopic judgement of the TME specimen
with complete TME noted in 17 of 18 robotic samples and 1 nearly complete vs. 13 of 16 complete TME
[12]
and 3 nearly complete (P = 0.323) .
A recent meta-analysis by Eltair et al. assessed the robotic and. laparoscopic approaches for the treatment
[13]
[13]
of rectal cancer within nine RCTs that included 1463 patients (728 robotic vs. 735 laparoscopic) . Four
RCTs were included in the macroscopic assessment of complete TME, including the three discussed
above. They found no statistically significant difference in complete resection with zero heterogeneity
in their assessment. Simillis et al. compared open vs. laparoscopic vs. robotic vs. transanal mesorectal
[14]
excision for rectal cancer in their meta-analysis and included 29 RCTs. The authors reported significantly
higher incomplete or nearly complete TME in the laparoscopic vs. open group (odds ratio of 1.52), but no
differences in the laparoscopic vs. robotic (odds ratio of 0.98) approaches. A recent network meta-analysis
assessed the quality of TME and reported no difference in complete mesorectum excision in the pooled
[15]
analysis of 11 studies . Nine studies were included in the pooled analysis examining near-complete
mesorectal excision and also reported no difference when comparing laparoscopic vs. robotic methods.