Sphincter-preserving effect of robotic-assisted intersphincteric resection for ultra-low rectal cancer: a propensity score matching analysis

Intersphincteric resection (ISR) is a viable option for sphincter preservation in early ultra-low rectal cancer, but postoperative anal dysfunction remains a concern. This study evaluates the outcomes of robotic ISR with coloanal anastomosis in early ultra-low rectal cancer, comparing its efficacy and safety with laparoscopic ISR. Retrospective analysis was conducted on data from 74 consecutive patients undergoing robotic intersphincteric resection (R-ISR) for early ultra-low rectal cancer between January 2017 and December 2018 (R-ISR group), matched with 110 patients undergoing laparoscopic intersphincteric resection (L-ISR). After 1:1 propensity score matching, each group comprised 68 patients. Comparative analyses covered surgical outcomes, complications, long-term results, and anal function. The R-ISR group showed longer total operative time than the L-ISR group (211.7 ± 25.3 min vs. 191.2 ± 23.0 min, p = 0.001), but less intraoperative bleeding (55.2 ± 20.7 ml vs. 69.2 ± 22.9 ml, p = 0.01). R-ISR group had fewer conversions to APR surgery (6/8.8% vs. 14/20.6%). Other perioperative indicators were similar. R-ISR exhibited a smaller tumor margin, superior mesorectal integrity, and comparable histopathological outcomes. Postoperative complications, 3-year and 5-year DFS, and OS were similar. At the 1-year follow-up, the Wexner Incontinence Score favored R-ISR (9.24 ± 4.03 vs. 11.06 ± 3.77, p = 0.048). Although R-ISR prolongs the operative time, its surgical safety and oncological outcomes are similar to conventional ISR procedures. Furthermore, it further shortens the margin of anal preservation, reduces the rate of conversion to APR surgery, and improves postoperative anal function.