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Page 6 of 9 Genova et al. Mini-invasive Surg 2020;4:20 I http://dx.doi.org/10.20517/2574-1225.2019.47

L-TAMIS VS. R-TAMIS
Robotic transanal surgery might offer several advantages compared to conventional TAMIS. Notably,
it might increase the possibility of resecting rectal lesions located in difficult sites, reducing the need for
proctectomy, as well as it might make surgical wound repair easier.

However, only a few studies designed to compare the outcomes of conventional and robotic TAMIS are
[2]
available in the literature. The most relevant of these is a retrospective study published by Lee et al. in
2019, comparing the results of 21 patients undergoing conventional TAMIS (indicated as L-TAMIS) and
19 patients undergoing R-TAMIS. Overall, no significant difference was found in terms of perioperative
outcomes (notably: total operative time, blood loss, postoperative complications, and length of hospital stay)
and pathologic findings. The only significant difference was represented by direct costs, which were higher
in the robotic group ($3562 for L-TAMIS vs. $4441 for R-TAMIS, P = 0.04).

TRANSANAL TOTAL MESORECTAL EXCISION
The latest development of the transanal approach to rectal cancer is represented by transanal total
mesorectal excision (TaTME). Indeed, laparoscopic rectal surgery may be challenging because of patient-
and tumor-related factors. Male obese patients often show a very limited surgical field [42,43] , anterior rectal
tumors appear to have a higher rate of positive resection margins [43,44] , and determining the distance between
[42]
rectal tumor and distal staple line is often difficult .

TaTME is a hybrid surgical technique employed for low rectal cancer combining a laparoscopic dissection
for colonic mobilization and a mesorectal excision performed using a transanal approach through a
GelPOINT platform or a rigid proctoscope. These approaches may be sequential or simultaneous, the
[45]
specimen is generally extracted through the anus, and a manual coloanal anastomosis is finally performed .
Several clinical and pathological factors are considered to indicate a transanal approach in the case of rectal
cancer: male gender, narrow and/or deep pelvis, BMI > 30 kg/m , prostatic hypertrophy, tumor located at
2
[46]
less than 12 cm from the anal verge, tumor size > 4 cm, and tissue alteration following radiotherapy .
[47]
[48]
Sylla et al. performed the first clinical case of TaTME in 2010. In 2016, Deijen et al. published a
systematic review including overall 794 patients with rectal cancer undergoing this technique. The mean
operative time was 244 min and the TME specimen was complete in 87% of procedures. Major postoperative
complications occurred in 11.5% of patients and anastomotic leak in 5.7%. Local recurrence rate was 8.1%
at 18.9 months. A volume effect was also shown, with high-volume centers (> 30 cases) having higher
TME quality, lower rate of positive circumferential resection margin (CRM), and lower rate of major
complications.

[49]
In 2017, Penna et al. analyzed TaTME short-term outcomes using the data of an international registry
including 720 patients. TME was complete in 85% of cases, had minor defects in 11% of cases, and had major
defects in 4%. The rate of R1 resection was 2.7%. Among the risk factors of suboptimal TME, perforation,
and/or R1 resection, the authors also identified a laparoscopic transabdominal posterior dissection to less
than 4 cm from the anal verge.

[50]
In 2018, Jiang et al. published a systematic review of studies comparing TaTME and laparoscopic TME.
They included 762 patients overall operated for cancer of the middle and lower rectum, and showed a
significant difference in terms of positive CRM in favor of TaTME, whereas positive distal resection margin
and TME quality were similar.

ROBOTIC TATME
TaTME has also been performed using robotic technology, being indicated as robotic TaTME or robotic-
assisted transanal TME (RATS-TME). However, the studies on this subject currently available in the
literature are characterized by a limited number of patients [51-55] .