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volume centers. Another issue is the cost which patients should pay, especially in Korea where a two-team
approach is not feasible due to the insurance system.

TATMES ARE NEEDED FOR EAST ASIA!
Even in East Asian patients, conventional laparoscopic TMEs are difficult for those with narrow pelvis.
Several studies in Asia have found that a deep, narrow pelvis was an independent factor for intraoperative
and postoperative outcomes [29-32] . Most studies using preoperative computed tomography and magnetic
resonance pelvimetry have shown that the bones of the pelvis - the depth and length of sacrum, the pelvic
inlet, and the pelvic outlet - are independent predictors for the operative times, which have been used
as surrogate markers for determining TME difficulty [29,30,32] . Limited pelvic space impacts the quality of
resected TME specimens [30,33] . Identifying the East Asian patients having normal BMIs with narrow pelvis
before surgery has been beneficial for deciding if TaTMEs should be used. Often, we perform a transanal
approach after transabdominal TMEs to ease resection and easily obtain quality resected TME specimens.

A study which utilized TaTMEs in challenging patients included a total of 12 patients (9 males and 3
females): 1 obese patient, 7 with large tumors, and 8 with threatened mesorectal fascias (four patients had
[34]
multiple indications) . The median tumor height was 5.5 cm from the anal verge, and all patients received
preoperative chemoradiotherapy. There were no intraoperative complications. Only 1 patient required
conversion to open surgery for ureterocystostomy after resection. Larger TaTME studies involving Asian
patients are necessary to promote TaTMEs.

A CONCRETE INDICATION IS NECESSARY
Since TaTME has only just recently been introduced, the criteria of surgical candidates best suited for
[35]
TaTME treatments are still evolving . A recent consensus statement was published which listed the
following indications for TaTME: (1) male gender; (2) narrow and/or deep pelvis; (3) visceral obesity
and/or a BMI > 30 kg/m ; (4) prostatic hypertrophy; (5) tumor height < 12 cm from the anal verge; (6)
2
tumor diameter > 4 cm; (7) distortion of tissue planes secondary to neoadjuvant radiotherapy; and (8) an
[36]
impalpable, lower primary tumor requiring accurate placement of the distal resection margin . However,
we believe that TaTMEs should be used in challenging cases to replace the transabdominal approach. In
East Asia, challenging cases imply that patients are males with deep and narrow pelvis after preoperative
chemotherapy. While TaTME was developed to assist in challenging middle to lower rectal cancer cases,
its essential purpose should be initially adopted. In East Asia, a more concrete indication distinct from
laparoscopic and robotic TMEs is required for transition to TaTMEs.

Moreover, the application of TaTMEs was recently extended to include benign tumor excisions, endopelvic
[37]
surgeries, and pelvic exenterative surgeries . In situations where robotic systems are used in high-volume
centers, robotic TaTMEs can be a useful new technique as various robotic systems are developed.

PROBLEMS IN ADOPTING TATME IN EAST ASIA
The other issues for TaTME are the learning curve and training. The transition from laparoscopic TME
to robotic TME is straightforward as the approach is the same. However, the technical complexity and
[38]
unusual anatomy have led to the occurrence of rare complications such as urethral injury . In terms of
[39]
oncological outcome, Larsen et al. reported 9.5% local recurrence, which led to a nationwide in norway
halt of TaTME and thorough investigation. They suggested that the increase of local recurrences after
TaTMEs might, to some extent, be due to the learning curve, which is inevitable in the introduction of a
complex procedure. In addition, only a few centers in East Asia have accumulated much experience and
have good results on TaTME. To adopt TaTME safely, a training strategy such as the detailed framework for
a structured TaTME training curriculum proposed by the International TaTME Educational Collaborative
[40]
Group is necessary .