What Is the Place of Intersphincteric Resection When Operating on Low Rectal Cancer?

Operating on low rectal cancer by performing an intersphincteric resection (ISR) with coloanal anastomosis has been adopted as an alternative to abdominoperineal excision (APE) following Schiessel et al. report in 1994, as it preserves the sphincter and avoids the need for a permanent stoma. We undertook a review of the recent literature specifically focusing on long-term oncologic and functional outcomes of ISR to evaluate whether this operation is a valid alternative to an APE. In conclusion, younger patients with T1 or T2 rectal cancers who require no preoperative therapy are ideal candidates for ISR, given that preoperative chemoradiotherapy may cause long-term severe anal dysfunction after ISR. An intersphincteric resection (ISR) with coloanal anastomosis for low rectal cancers has been adopted as an alternative to abdominoperineal excision (APE) after the report by Schiessel et al. in 1994, who succeeded in preserving the sphincter and avoiding the need for a permanent stoma [1]. In ISR, the rectum is mobilized to the levator ani muscle in the plane of total mesorectal excision (TME) via the abdominal route and the internal anal sphincter (IAS) is resected via the anal route. There are three types of ISR (partial, subtotal, or total) depending on the distal resection line of the IAS or the extent of the IAS resection (Figure 1). Coloanal anastomosis is performed using a transanal hand-sewn technique. An ultralow, anterior resection of the rectum using a double-stapling technique is not regarded as an ISR. Figure 1: Schematic representation of the transaction lines for intersphincteric resection (ISR). The distal resection line of the internal anal sphincter (IAS) was at the dentate line (DL) (1) in partial ISR, between the DL and the intersphincteric groove (ISG) (2) in subtotal ISR, and at the ISG (3) in total ISR. AV: anal verge; DES: deep part of external sphincter; SES: superficial part of external sphincter; SubES: subcutaneous part of external sphincter; LAM: levator ani muscle. An extensive review of 21 studies concerning 612 patients showed a local recurrence (LR) after ISR of 9.5%, and an average five-year overall survival (OS) rate of 81.5% [2]. In most of these studies a significant reduction in resting anal pressure was evident after surgery, but the same was not true of squeeze pressure. These authors suggest that ISR should be considered as an option for sphincter-preserving surgery when operating on patients with low rectal cancers and that it has acceptable oncologic and functional results. We decided to undertake a review of the