Revolutionizing sphincter preservation in ultra-low rectal cancer: exploring the potential of transanal endoscopic intersphincteric resection (taE-ISR): a propensity score-matched cohort study

Abstract

Background: With the optimization of neoadjuvant treatment regimens, the indications for intersphincteric resection (ISR) have expanded. However, limitations such as unclear surgical field, impaired anal function, and failure of anal preservation still exist. Transanal total mesorectal excision can complement the drawbacks of ISR. Therefore, this study combined these two techniques and proposed transanal endoscopic intersphincteric resection (taE-ISR), aiming to explore the value of this novel technique in anal preservation for ultra-low rectal cancer.

Material and methods: Four high-volume centres were involved. After 1:1 propensity score-matching, patients with ultra-low rectal cancer underwent taE-ISR ( n =90) or ISR ( n =90) were included. Baseline characteristics, perioperative outcomes, pathological results, and follow-up were compared between the two groups. A nomogram model was established to assess the potential risks of anal preservation.

Results: The incidence of adjacent organ injury (0.0% vs. 5.6%, P =0.059), positive distal resection margin (1.1% vs. 8.9%, P =0.034), and incomplete specimen (2.2% vs. 13.3%, P =0.012) were lower in taE-ISR group. Moreover, the anal preservation rate was significantly higher in taE-ISR group (97.8% vs. 82.2%, P =0.001). Patients in the taE-ISR group showed a better disease-free survival ( P =0.044) and lower cumulative recurrence ( P =0.022) compared to the ISR group. Surgery procedure, tumour distance, and adjacent organ injury were factors influencing anal preservation in patients with ultra-low rectal cancer.

Conclusion: taE-ISR technique was safe, feasible, and improved surgical quality, anal preservation rate and survival outcomes in ultra-low rectal cancer patients. It held significant clinical value and showed promising application prospects for anal preservation.

Figure 1

Typical intraoperative images of the taE-ISR technique. (A–C) Purse-string-first technique. (A) Using the longstar retractor to expose the area, purse-string sutures were applied to close the distal bowel, isolating the tumour. (B) Viewpoint after inserting the transanal operating port. (C) Dissection along the interspace between the internal and external sphincters was carried out using an electrosurgical hook under magnified laparoscopic vision. (D–F) Dissection-first technique. (D) Using the longstar retractor to expose the area, the interspace between the internal and external sphincters was dissected using an electrosurgical unit. (E) Purse-string sutures were applied to close the distal rectum, isolating the tumour. (F) After inserting the transanal operating port, the viewpoint showed continued dissection along the interspace under magnified laparoscopic vision.

Figure 2

Schematic illustration of the purse-string-first technique. (A) Coronal view of the tumour location. The presumed resection margin was above the dentate line, represented by the yellow dashed line. (B) Transanal view of the tumour location. The presumed resection margin was above the dentate line, indicated by the yellow dashed line. (C) Using the Longstar retractor for exposure, purse-string sutures were applied to close the distal rectum, isolating the tumour. (D) Completion of the purse-string suture. (E) Insertion of the transanal operating platform. (F) Dissection along the interspace between the internal and external sphincters under magnified laparoscopic vision.

Figure 3

Schematic illustration of the dissection-first technique. (A) Coronal view of the tumour location. The presumed resection margin was below the dentate line, represented by the yellow dashed line. (B) Transanal view of the tumour location. The presumed resection margin was below the dentate line, indicated by the yellow dashed line. (C) Using the Longstar retractor for exposure, dissection was performed along the interspace between the internal and external sphincters. (D) Purse-string sutures were applied to close the distal rectum, isolating the tumour. (E) Completion of the purse-string suture. (F) Continuing the dissection of the interspace under magnified laparoscopic vision after Inserting of the transanal operating port.

Figure 4

Long-term follow-up results between taE-ISR group and ISR group after PSM. (A) Overall survival results between taE-ISR group and ISR group. (B) disease-free survival results between taE-ISR group and ISR group. (C) Cumulative recurrence results between taE-ISR group and ISR group. ISR: intersphincteric resection; taE-ISR: transanal endoscopic intersphincteric resection.

Figure 5

Logistic regression results for anal preservation after propensity matching analysis. ASA, American Society of Anesthesiologists; DRM, distal resection margin; OR, odds ratio; taE-ISR: transanal endoscopic intersphincteric resection.

Figure 6

nomogram model to predict the risk of anal preservation failure. (A) The nomogram score is calculated by adding the scores of each variable, and thus estimates the probability (risk) of anal preservation failure. (B) The calibration curve for the nomogram. (C) Receiving Operating Characteristic curves of independent indicators. Higher area under the curve is more valuable in predicting anal presentation failure. ISR: intersphincteric resection; taE-ISR: transanal endoscopic intersphincteric resection.