Sphincter-sparing resection for rectal cancer

Abstract

Although there is still a place for abdominoperineal resection in the treatment of rectal cancer, the state of the art is sphincter-preserving resection. Even for the lowest of rectal cancers, using a combination of neoadjuvant chemo/radiation, total mesorectal excision, and intersphincteric proctectomy and colonic J-pouch to anal anastomosis, sphincter preservation can be achieved for most patients. The key concept in pushing sphincter preservation forward has been the realization that the deep, circumferential, or lateral margin is all-important. Unless the rectal tumor involves the external sphincter muscle, there is no oncologic need to remove it, and following resection of the tumor, gastrointestinal tract continuity can be restored.

Keywords: Sphincter-preserving resection; coloanal anastomosis; intersphincteric resection; low anterior resection; total mesorectal excision.

Figure 1

In this total mesorectal excision specimen, one can see that the mesorectum ends just above the upper aspect of the surgical anal canal, which is at the anorectal angle. During a double stapled coloanal anastomosis, the anus is divided at the anorectal angle, and the anastomosis will be constructed ~1.5 to 2.0 cm above the dentate line.

Figure 2

Even with a narrow distal margin, local failure is avoided with a good total mesorectal excision specimen.

Figure 3

This illustrates how local recurrence can occur. In this total mesorectal excision specimen, if one were to come through the mesorectum, even with an adequate distal margin, tumor in the mesorectum is left behind and local failure is the result.

Figure 4

In this total mesorectal excision specimen, local failure is avoided with a very adequate distal margin, but more importantly, an adequate margin deep to the tumor.

Figure 5

In this total mesorectal excision specimen from an intersphincteric proctectomy, one can see the bare muscular tube of anus protruding out from the distal aspect of the mesorectum.