Abstract
The evolution over the past 20 years of anal preservation in rectal cancer surgery
has been truly remarkable. Intersphincteric resection (ISR) reported by Schiessel
in 1994 in Australia has been shown to enable anal preservation even for cancers quite
close to the anus. In Japan, ISR via the detachment of the anal canal between the
internal and external sphincters and excision of the internal sphincter first began
to be practiced in the latter half of 1990. A multicenter Phase II trial of ISR in
Japan suggested that 70% of the cases had relatively good function with less than
10 points of Wexner score but around 10% had severe incontinence that would not be
improved for long term. The primary end point of the clinical study, 3-year local
recurrence rate, was 13.2% across the overall cohort (T1, 0%; T2, 6.9%; and T3, 21.6%).
When ISR is performed on T1/T2 rectal cancers, sufficient circumferential resection
margin can be obtained even without preoperative chemoradiotherapy, and local recurrence
rate was acceptably low. Based on these evidences, ISR is a currently important, standard
treatment option among anal-preserving surgeries for T1/T2 low-lying rectal cancers.
In Japan, a feasibility study (LapRC trial) of laparoscopic ISR on Stage 0 and Stage
1 low rectal cancer showed excellent outcomes. A prospective Phase II clinical trial
targeting low rectal cancers within 5 cm from the anal verge (ultimate trial) is being
performed and awaiting the results in near future.
Keywords
rectal cancer - laparoscopic surgery - total mesolectal excision - intersphincteric
resection - lateral pelvic lymph node
