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

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.