A retrospective study of patients with distal rectal cancer at Memorial Sloan Kettering Cancer Center (MSK) has found a higher rate of local recurrence after intersphincteric resection with handsewn coloanal anastomosis (ISR-CAA) than with abdominoperineal resection (APR) in patients without a clinical response to neoadjuvant therapy who underwent total mesorectal excision (TME).
“The rate of local recurrence was higher among patients treated with ISR-CAA versus APR, despite both groups having similar tumor clinical stage and distance from the anal verge,” said colorectal surgeon Julio Garcia-Aguilar, MD, PhD, Chief of the Colorectal Service and the Benno C. Schmidt Chair in Surgical Oncology at MSK. “Our results suggest that trying to save the anal sphincter in patients with distal rectal cancer whose tumors do not respond to neoadjuvant therapy may compromise recurrence-free survival.”
Surgical Approaches for Distal Rectal Cancer
Sphincter-saving surgery is usually feasible as part of TME for patients with tumors in the mid and upper rectum. However, patients with distal rectal tumors have traditionally undergone APR with an end colostomy. The procedure involves wide transection of the pelvic floor and en bloc resection of the sphincter complex and rectum. It is typically recommended when the tumor involves the external sphincter complex, the distal margin is inadequate, preoperative sphincter function is poor, or if the patient prefers a colostomy.
ISR-CAA has been growing in popularity among surgeons and patients, based on the assumption that most patients can achieve long-term sphincter preservation with a risk of local recurrence similar to or even lower than APR. It involves dividing the upper portion of the internal sphincter and further dissection separating the internal sphincter from the external anal sphincter and the levator muscle until the pelvic plane of dissection is reached. Bowel continuity is reestablished via a hand-sewn anastomosis, with or without a colonic J-pouch, according to anatomic limitations and the surgeon’s judgment.
The introduction of the watch-and-wait strategy has changed the profile of patients undergoing TME immediately following total neoadjuvant therapy. Currently, about 50% of patients with locally advanced rectal cancer have an incomplete response to TNT. (1) TME is recommended to address the higher risks of local recurrence and distant metastasis. However, the outcomes of sphincter-sparing surgery for this patient population have not been investigated.
MSK Study Results
Dr. Garcia-Aguilar and colleagues conducted the first study comparing oncologic outcomes between ISR-CAA and APR in patients with distal rectal cancer who were ineligible for watch and wait. They reported their findings in Annals of Oncology in January 2025. (2)
The study analyzed outcomes for 67 patients with stage 2 or 3 distal rectal cancer who underwent ISR-CAA at MSK from 2009 to 2019. The starting point of 2009 coincided with the establishment of MSK’s watch and wait program. The investigators compared results with those of 79 patients who underwent APR during the same period. (2)
An R0 resection was achieved in 64 of 67 patients (96%) in the ISR-CAA group and 72 of 79 patients (91%) in the APR group. The median follow-up for all patients was 61 months. (2)
The five-year local recurrence-free survival rate for the ISR-CAA group was 79%, significantly lower than 93% for the APR group (p=0.038).
“Response to neoadjuvant therapy is an important predictor of long-term oncologic outcomes in rectal cancer,” said Dr. Garcia-Aguilar. “Overall, our findings indicate that the benefits of sphincter preservation may need to be weighed against the risk of local recurrence and the need for reoperation in patients with distal rectal cancer who are ineligible for watch and wait.”