EP587 - Robotic Abdominoperineal Resection for Rectal Cancer Reduces Conversion Risk but Increases Readmission Risk Compared to a Laparoscopic Approach

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Purpose/Background: Abdominoperineal resection (APR) is commonly used to treat low rectal cancers with sphincter invasion or inability to achieve a negative distal margin. While two randomized controlled trials (ROLARR and COLRAR) conducted in the early 2010s found no clear advantage of robotic over laparoscopic approaches for rectal cancer, the more recent REAL trial observed that the robotic approach had improved oncologic resection with reduced postoperative complications and length of stay. In this large national retrospective study, we hypothesize that robotic APR, when performed in a contemporary population, offers a lower risk of conversion to open surgery and a lower risk of readmission compared to laparoscopic APR.

Methods/Interventions: The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database and proctectomy participant use files were queried from 2016 to 2022 for all patients undergoing an elective APR for a diagnosis of rectal cancer. Patients were stratified by approach (laparoscopic or robotic). The primary outcomes were conversion to open surgery and readmission within 30 days. Secondary outcomes included the indication for readmission and rate of positive radial margins. Covariates included patient demographics and comorbidities, preoperative chemotherapy and radiation, tumor stage, and use of reconstructive flaps. Kruskal-Wallis and chi-squared tests were used for continuous and categorical variables, with multivariable regressions for outcome associations.

Results/Outcomes: Among 3,925 patients (1,973 laparoscopic; 1,952 robotic), the proportion of robotic APR cases increased significantly over the study period (p < 0.001) and surpassed laparoscopic cases. Robotic APR patients were more often white (75.9 vs. 57.1%, p< 0.001) with high BMI (>35kg/m²; 15.2 vs. 12.1%, p< 0.001) and more frequent flap reconstruction (11.1 vs. 7.0%, p< 0.001). Relative to laparoscopic APR, robotic APR was associated with fewer conversions to open surgery (3.6 vs. 12.0%, p< 0.001) but higher readmission rates (16.5 vs. 13.7%, p=0.016), particularly for wound and organ space infections (6.4 vs. 4.5%, p=0.007). The rate of positive radial margins was similar between robotic and laparoscopic approaches (10.1 vs 9.3%, p=0.412).

Multivariable analysis confirmed the association of robotic APR with decreased conversion to open surgery (OR=0.24, p< 0.001) but increased rate of readmission (OR=1.23, p=0.032), most commonly for a wound or organ space infection (OR=1.44, p=0.017). The higher risk of readmission was limited to patients discharged within four days (OR = 1.75, p=0.001) and not observed among those discharged later (OR = 1.06, p=0.641). There was no difference in the risk of a positive radial margin between robotic and laparoscopic approaches after multivariable analysis (OR=1.15, p=0.285).

Conclusion/Discussion: In this largest published cohort analysis to date, the utilization rate of robotic APR has surpassed laparoscopic APR as the preferred minimally invasive approach. Robotic APR is associated with a reduced risk of conversion to open surgery with no compromise to the circumferential resection margin. However, the robotic approach is associated with an increased rate of readmission among those discharged within four days postoperatively. Given the increase in utilization of the robotic platform for APRs, careful discharge criteria are necessary to improve the safety of early discharge.