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Page 2 of 10 Erkan et al. Mini-invasive Surg 2018;2:30 I http://dx.doi.org/10.20517/2574-1225.2018.51

patients. This change was manifest in tandem to the technical advancements like the introduction of circu-
lar staplers, surgical refinements - popularization of strict adherence to anatomical planes by Heald, and of
[2]
course recognition of the importance of neoadjuvant chemotherapy and radiotherapy .
Not only has the nomenclature around the operation changed, but so too has the platform to access the
rectum. The introduction of laparoscopy has revolutionised colorectal surgical practice and continues to
evolve. Robotic surgery platforms have also garnered some popularity, in particular, for access to the lower
third of the rectum. Since 2010, the introduction of minimally invasive approaches has been applied to the
[3]
rectum via a transanal approach , and has been utilised in a broad spectrum of clinical scenarios; from
transanal polyp excision to anastomotic leak repair, local excision of rectal cancer, transanal total mesorec-
[4-9]
tal excision (taTME) and pelvic exenteration .

The advent of widespread colorectal cancer screening has made it possible to diagnose rectal polyps and
early stage rectal cancers more frequently. This increasing trend along with increasing response rates to
more effective neoadjuvant treatment for locally advanced rectal cancers and patient demands for organ-
sparing options has led leaders in the field to push the boundaries of surgical approaches to the rectum and
to reappraise the paradigm of formal proctectomy. Moreover, patients who require local palliation in the
setting of stage IV disease and the aging population with medical comorbidities who would be otherwise
unfit for any abdominal approach, constitute another group of patients for whom local interventions per
anus may prove to be more beneficial overall.

The aim of this study is to review the current state of the role of transanal minimally invasive surgery
(TAMIS) in the local management of rectal cancer and highlight the recent advances, with an emphasis on
functional results and complications.

LOCAL EXCISION
The term “local excision” refers to removal of the tumor with negative surgical margins without removing
the organ it originates from - the rectum. It involves full thickness resection of the rectal wall but not nec-
essarily the draining lymphatics. Enthusiasm about local excision for early stage rectal cancer has grown
[10]
after Morson et al. published their results in 1977. This has led to development of techniques other than
transanal excision (TAE), which is limited by poor exposure and limited to lesions in the distal rectum.
Currently, the two most popular options for local excision are transanal endoscopic microsurgery (TEM)
and TAMIS.

TAE utilizes conventional instruments under direct vision. It cannot reach mid- or upper rectal lesions.
Moreover, confinement of the operative field risks the achievement of negative surgical margins. Margin
positivity exceeds 10% even in experienced hands [11,12] . In a recent study, TAE is not considered as a feasible
[13]
technique for tumors located higher than the first rectal valve, > 3 cm in size and deeper than T1 .
[14]
TEM, first described in 1984 by Buess et al. utilized a rigid platform to access intraluminal lesions in the
rectum. It has several advantages over TAE. It maintains a stable pneumorectum and makes it possible to
reach the mid and upper rectum. Improved visualization results in better assessment of resection margins.
When compared to conventional TAE, TEM provides a superior quality resection, with higher rates of
negative microscopic margins, reduced rates of specimen fragmentation and lesion recurrence, but with
[15]
equivalent post-operative complications .
However, several factors have limited the widespread uptake within the armamentarium of colorectal sur-
geons throughout the world. These include a steep learning curve, significant cost of the operating system
[16]
and concerns about postoperative function .