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Kim et al. Mini-invasive Surg 2019;3:33 I http://dx.doi.org/10.20517/2574-1225.2019.23 Page 3 of 6

TATME: EFFORTS TO OVERCOME THE DIFFICULTY OF LAPAROSCOPIC TMES
Risk factors in the ROLARR trial could be diminished using TaTMEs as constraints and challenges
posed by anatomical features are minimized when approached from below. TaTMEs also showed lower
[18]
conversion rates. Penna et al. reported conversion rates from laparoscopic to open or transanal as 6.3%
[19]
within the TaTME registry. Veltcamp Helbac et al. reported a conversion rate of 5% for 80 TaTME cases.
[20]
Moreover, Lacy et al. reported no conversions in 140 cases. TaTME procedures overcome difficulties
frequently encountered in trans-abdominal rectal transections and anastomosis-stapling techniques such
as narrow pelvic anatomy, oblique stapling angles, rectal-tearing secondary to vigorous manipulation, and
multiple staple firings.

Robotic surgery and transanal surgery have been developed to overcome some of the limitations of
conventional laparoscopic surgery for rectal cancer. However, there are only a few studies comparing
robotic and TaTME [21-23] . Those studies showed comparable results for robotic TME and TaTME. Among
[21]
the studies, Lee et al. compared, out of a total of 730 patients (277 TaTME and 453 robotic TME
patients), matched groups of 226 TaTME and 370 robotic TME patients. The mean tumor height from the
anal verge was 5.6 cm, and 70% received preoperative radiotherapy. There were no differences in TME
specimen quality and CRM.

However, the evidence on TaTME is still lacking in many aspects with many still unanswered questions.
Retrospective studies and meta-analysis showed that TaTME seems to achieve comparable technical success
[24]
with acceptable oncologic and perioperative outcomes in comparison with laparoscopic TME . However,
there is no multicenter randomized controlled trial at present. The COLOR III trial, which compares
TaTME and laparoscopic TME, is currently in the recruitment phase.

PREVIOUS EAST ASIAN STUDIES ON TATME
[25]
There have been a few reports describing the use of TaTMEs in Asian patients. One study from Taiwan
compared 50 patients with middle or lower rectal cancer and post-neoadjuvant chemoradiotherapy (nCRT)
who underwent TaTMEs using 100 matched control cohorts who received conventional laparoscopic rectal
2
surgeries. Seventy-six percent of the patients were male with a mean BMI of 24.2 kg/m and had low (< 7 cm)
[26]
tumor heights. There was only one conversion. Another prospective, single-arm phase II trial from Korea
2
enrolled 49 patients (65.3% male, a mean BMI of 23.3 kg/m , and a mean tumor height of 6.3 cm) with their
rectal cancers located 3-12 cm from the anal verge and no conversions to open surgery. A study from Hong
[27]
Kong compared a TaTME group (n = 40) to a robotic group (n = 80) using propensity score matching. In
the TaTME group, 72.5% of the patients were male and the median tumor height was 5.0 cm. There was a
5% conversion rate. All three of these studies concluded that TaTMEs were safe and feasible with acceptable
results based on the perioperative and pathologic outcomes. Although conversion rates were higher than
in the Comparison of Open vs. Laparoscopic Surgery for mid or low Rectal Cancer after Neoadjuvant
Chemoradiotherapy (COREAN) trial, they are quite low compared to previous laparoscopic TME results.

[28]
Recently, studies by Chinese surgeons using TaTMEs have begun. After a preliminary study with 20
patients that confirmed the safety and feasibility of the procedure, they began randomized controlled trial
(RCT) enrollment in June 2019 to compare laparoscopic TMEs with TaTMEs (NCT03413930). They will
only include patients with middle or lower rectal cancers similar to the East Asian studies.

ARE TATMES NECESSARY FOR EAST ASIA?
Presently, TaTMEs in East Asia are not as popular as in Western countries since few patients have BMIs
above 30 kg/m . In females, even for those with lower rectal cancer, conventional laparoscopic TMEs can
2
be accomplished without conversions. Additionally, robotic systems are used more frequently only in high