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

TAMIS was associated with shorter operative time (mean: 70 min vs. 108 min), shorter length of hospital
stay (median: zero days vs. one day), and lower blood loss (median: 10 mL vs. 30 mL) compared to TEM.
However, no significant difference was found in terms of positive margins (7% for TAMIS vs. 6% for TEM),
specimen fragmentation (4% for TAMIS vs. 3% for TEM), postoperative complications (9% for TAMIS vs. 11%
for TEM), and recurrence after resection for rectal malignant lesion (7% for TAMIS vs. 7% for TEM). Overall,
the authors concluded that, given the absence of significant differences in terms of resection quality and
postoperative morbidity, the choice of the technique should be based on surgeon’s preference, availability of
surgical materials, and costs.

Two further comparative studies were both published in 2016 [26,27] . Notably, compared to TEM, TAMIS
had shorter median hospital stay (four days vs. five days) but lower full-thickness resection rate (85% vs.
[26]
3
100%) according to Mege et al. and higher specimen volume (mean: 5.6 cm vs. 15.9 cm ) according to
3
[27]
Melin et al. . No other significant difference between TAMIS and TEM was found in terms of operative,
pathological, and survival outcomes.
[29]
In 2019, Van den Eynde et al. published another retrospective comparative study, including 68 patients in
the group TAMIS and 53 patients in the group TEM. No conversion was reported in both groups. Operative
time was again significantly shorter for TAMIS (median: 45 min vs. 65 min), whereas lesion surface area was
2
2
larger for TEM (median: 21 cm vs. 14 cm ). The difference in operative time persisted after correction for
lesion surface area. No other significant difference was found in terms of quality of resection, morbidity, and
hospital stay. Finally, the authors concluded in favor of TAMIS, whose shorter hospital stay was explained
by an easier set-up and a greater versatility of the transanal platform. Moreover, the main advantage of
TAMIS was identified in the fact that all procedures could be performed in lithotomy position, the whole
rectal circumference being accessible with this technique.

To be noted, several studies also analyzed the learning curves of TAMIS and TEM, reporting an improvement
[30]
[32]
[31]
of operative efficiency after 14-24 and 18-31 procedures for TAMIS, and after 16 procedures for TEM.
However, no comparison was performed in this regard.
Overall, the available studies do not show a clear superiority of TAMIS over TEM, especially in terms of
resection quality, which appear similar. However, several technical advantages making TAMIS preferable
are reported in the literature [1,2,13] . In particular, the use of a shorter shaft and a more flexible platform allows
surgeons to reach all quadrants of the rectum, and to perform surgery in lithotomy position also in the case
[13]
of anterior or lateral lesions. Moreover, TAMIS allows a faster set-up (2 min vs. up to 30-45 min ) and a
360° visibility (220° for TEM), involving the use of less expensive and more easily available equipment, such
as conventional laparoscopic instruments.

ROBOTIC TRANSANAL SURGERY
The technical advantages provided by surgical robotic systems, such as stable 3D view and ameliorated
manipulation, appeared to overcome some ergonomic limitations of TAMIS. Therefore, the same authors
who had previously introduced this technique described the first combined use of robotic technology and
[33]
TAMIS platforms for local transanal excision in a cadaveric model in 2011 , and then in a real patient in
[34]
2012 .
Notably, the first patient undergoing a procedure of robotic transanal surgery or robotic TAMIS (R-TAMIS)
was a 58-year-old woman with a 3-cm tubulovillous rectal adenoma with focal intramucosal carcinoma. The
tumor was located at 7 cm from the anal verge in the left anterolateral quadrant. The patient was placed in a
lithotomy position and a GelPOINT platform was used, in association with a 5-mm laparoscope introduced
through one 5-mm port and two robotic arms introduced through two 8-mm ports. A full thickness