Trial Information

Short Term Outcomes of Intersphincteric Resection With Total Mesorectal Excision for Low Rectal Cancer

The management of rectal cancer has changed substantially during the recent decades. The
introduction of total mesorectal excision, improved accuracy of preoperative staging with
magnetic resonance imaging, and more precise indications for neoadjuvant radiotherapy or
chemoradiotherapy represent significant progress.

Ideal surgery for rectal cancer should not only obtain adequate radial and circumferential
margins, but also preserve normal sphincter function.

Successful excision of a low rectal tumour while preserving the anal sphincter requires
knowledge of the pattern of tumour spread and an understanding of the physiology of the
sphincter mechanism. The move towards sphincter preserving surgery began with early
anorectal physiology work that showed the distal 1-2 cm of the rectum and internal anal
sphincter not to be absolutely necessary for continence.

Sphincter preservation presents several advantages; The first is the threefold lower risk of
intraoperative rectal perforation and positive circumferential margin than APR. This is
because TME with sphincter preservation is a more anatomical and standardized surgical
procedure than APR. The second advantage is the better genital function observed after low
anterior resection than after APR: 72-90% vs. 63-75%. This is due to the lower risk of
damaging the pelvic branches of the pelvic autonomic nerve, which are exposed during the
perineal phase of an APR. The third advantage of conservative surgery is preservation of the
body image that may increase quality of life.

The goal of intersphincteric resection is to divide the rectum transanally and to remove
part or the whole of the internal anal sphincter, in order to obtain adequate distal margin
and preserve the natural function of defecation. ISR is used mainly in Europe and more
recently in Asia. This technique modified the concept of sphincter preservation, because it
permits theoretically to avoid APR in all rectal cancers due to possibility to obtain safe
distal margin in all cases. Series of intersphincteric resection confirm the safety of the
procedure with 1.6% mortality, 10% of anastomotic leak, 9% of local recurrence and 81% of
5-year survival in a pooled analysis of 612 patients treated in 13 units by ISR for T2 T3
low rectal cancer.

Preoperative chemoradiation therapy is widely used to treat locally advanced rectal cancer
to increase resectability, and to enhance sphincter preservation, local control and
possibly, survival rates. Surgery is performed six to eight weeks after radiotherapy. The
exact level of transection of the internal sphincter is decided before radiation and
according to the distance from the anal verge, in order to avoid underestimation of the
irradiated tumors and potential risk of tumour transection.

The advent of minimally invasive surgical techniques has given surgeons the option of a
laparoscopic approach. Recently, the clinical outcome of intersphincteric resection (ISR) as
a laparoscopic approach (laparoscopic ISR) has been reported, but laparoscopic ISR for
patients with bulky low rectal cancer remains challenging particularly for T3 tumors in
patients with a narrow pelvis, because of the difficulty in understanding the accurate
anatomy of the small pelvic cavity, in dissecting the TME or the tumour specific mesorectal
excision (TSME) plane, and in transecting the lower rectum safely.

Total mesorectal excision (TME), negative circumferential margin (CFM), and tumor free
surgical margin are prerequisites regardless of approach of ISR. Current evidence suggests
that local recurrence, lymph node harvest and oncological clearance laparoscopic rectal
resection are not compromised and may be equivalent to those of open surgery. Moreover,
Numerous studies have demonstrated that laparoscopic techniques have many advantages in
colorectal surgery compared with open surgery.