Oncological Outcomes of Intersphincteric Resection Versus Abdominoperineal Resection for ypT3 Low Rectal Cancer Following Neoadjuvant Chemoradiotherapy: A Multicenter Retrospective Analysis.

Abstract

Background: Sphincter preservation, crucial for patients traditionally facing abdominoperineal resection, was advanced by neoadjuvant chemoradiotherapy and intersphincteric resection. T4 lower rectal cancer with levator ani muscle infiltration was a contraindication for intersphincteric resection, with most debates on intersphincteric resection indications focusing on the T3 stage.

Objective: To evaluate the oncological outcomes in patients with locally advanced distal rectal cancer, located within 5 cm from the anal verge, who underwent preoperative chemoradiotherapy followed by intersphincteric resection or abdominoperineal resection, with a focus on ypT3 very low rectal cancers that were technically feasible for intersphincteric resection without evidence of levator ani or external sphincter muscle invasion intraoperatively.

Design: A retrospective analysis of prospectively collected data.

Settings: Conducted at two colorectal surgery referral centers.

Patients: The study included 381 patients with ypT3 low rectal cancer post- chemoradiotherapy, from 2010 to 2021.

Main outcome measures: Five-year disease-free survival, 5-year overall survival, circumferential resection margin status, and complications.

Results: The 5-year disease-free survival rates were 63.4% for intersphincteric resection and 63.8% for abdominoperineal resection ( p = 0.806), with 5-year overall survival rates at 78.8% for intersphincteric resection and 67.5% for abdominoperineal resection ( p = 0.103). There were no significant differences in 5-year local recurrence or metastasis rates. Circumferential resection margin involvement was low in both groups: 1.9% (5/258) for intersphincteric resection and 4.9% (6/123) for abdominoperineal resection ( p = 0.202). Distal margin involvement was minimal in intersphincteric resection at 0.8% (2/258). Abdominoperineal resection had higher wound infection rates at 15.4% compared to 0.7% in intersphincteric resection ( p < 0.001), and a longer median postoperative hospital stay (10.0 days vs. 7.0 days for intersphincteric resection, p < 0.001). In abdominoperineal resection cases, primary closure was used for reconstruction, with pelvic peritoneum closure in 4 instances. No significant difference in perineal wound infection rates was observed between those with and without pelvic peritoneum closure ( p = 0.495). Subgroup analysis of intersphincteric resection with handsewn anastomoses showed no significant differences in 5-year disease-free survival (53.8% vs. 63.8%, p = 0.068), overall survival (74.5% vs. 67.5%, p = 0.313), or local recurrence rates (20.2% vs. 21.7%, p = 0.877) compared to abdominoperineal resection.

Limitations: The retrospective design introduced potential selection bias. Procedures were conducted by highly skilled surgeons, which may limit the generalizability of the findings. The study lacked assessment of certain oncological surgical quality control indicators and long-term functional outcomes.

Conclusions: For ypT3 low rectal cancer patients following chemoradiotherapy, ISR is safe and oncologically comparable to abdominoperineal resection when negative margins can be achieved. See Video Abstract.