Background: Few investigations to date assessing the effectiveness of robot-assisted intersphincteric resection (ISR) have included sufficient patients and follow-up period. This study assessed the utility and safety of robot-assisted ISR by comparing groups of patients who underwent low anterior resection (LAR) with or without ISR and ISR extent.
Methods: This study enrolled 897 patients who underwent curative LAR between 2010 and 2017. Patients were divided into those who did (ISR+) and did not (ISR-) undergo ISR, with the former group subdivided by ISR extent (partial, subtotal, and total). Tumor recurrence and survival were compared in the two groups by one-to-one nearest neighbor matching (218 patients each).
Results: Robot-assisted ISR was performed via an entirely transabdominal approach in 93% of patients who underwent LAR. The rate of circumferential margin positivity was ≤ 2% in all patients and did not differ in the ISR- and ISR+ groups or in the three ISR+ subgroups. Mean fecal incontinence score and manometric values deteriorated significantly during postoperative until 12-24 months (p < 0.05 to < 0.001), but recovered subsequently. The 5-year cumulative rates of local recurrence in the ISR+ and ISR- groups were 2.5% and 2.9%, respectively (p = 0.731). The 5-year cumulative rates of overall (86.7% vs. 84.2%, p = 0.899) and disease-free (80.7% vs. 78.5%, p = 0.934) survival did not differ significantly in the ISR+ and ISR- groups.
Conclusions: Because ISR involves resection of low-lying tumors and complex pelvic dissection, robot-assisted ISR via a mostly transabdominal procedure may be technically more efficient, providing lasting anorectal function and good oncologic outcomes.
Keywords: Functional outcome; Intersphincteric resection; Oncological outcome; Rectal cancer; Robot-assisted.