EP854 - Short-Term Outcomes of Laparoscopic vs. Robotic Rectal Cancer Surgeries in Obese Patients: A NSQIP Analysis

Purpose/Background: Obesity poses unique technical challenges in rectal cancer surgery, including limited pelvic access, increased visceral fat, and difficulty achieving optimal visualization. These factors may impact both short-term clinical outcomes and key oncologic endpoints, such as margin status and lymph node yield. While robotic surgery has been proposed to mitigate some of these challenges, evidence remains mixed, particularly in the obese and super-obese populations. This study aims to compare robotic versus laparoscopic rectal cancer resections across increasing BMI categories to assess short-term operative and oncologic outcomes.

Methods/Interventions: This retrospective study analyzes elective rectal cancer surgeries between 2016 to 2023 using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were categorized into four BMI groups: Group 1 (BMI 30-35), Group 2 (BMI 35-40), Group 3 40-45), and Group 4 (45+). Each group was further divided into laparoscopic or robotic cohorts. Exclusion criteria included ASA Class 4, patients with metastatic disease, and emergency cases. The primary outcome was overall complications. Secondary outcomes included conversion rates, length of stay, anastomotic leak, organ space SSI, number of lymph nodes harvested, and clear margins. Multivariate regression assessed the impact of demographics and surgical approach on postoperative outcomes within each BMI class.

Results/Outcomes: The study included 1,714 patients, categorized by BMI as follows: 1067 Group 1 patients (494 laparoscopic, 573 robotic), 418 Group 2 patients (178 laparoscopic, 240 robotic), 142 Group 3 patients (61 laparoscopic, 81 robotic), and 87 Group 4 patients (37 laparoscopic, 50 robotic). Within each BMI group, the robotic cohort had significantly higher proportions of white patients (p < 0.05). In Group 2, the robotic cohort had a higher proportion of male patients (53.8% vs. 43.8%, p=0.048), and in Group 4, the robotic cohort had a higher proportion of low-lying rectal cancer (48.6% vs. 38.9%, p=0.043). On univariate analysis, there were no significant differences in rates of postoperative complications, conversion rates, length of stay, anastomotic leak, organ space SSI, clear margins, or number of lymph nodes harvested between approaches within each BMI class. In Group 1, the robotic cohort had a decreased average length of clear radial margins (1.31 vs. 1.66 cm, p=0.025), but in Group 2, the robotic cohort had an increased average length of clear distal margins (3.55 vs. 2.85 cm, p=0.028). There were no differences in length of clear margins in Group 3 or 4. Multivariate regression analysis revealed that robotic surgery was not associated with increased rates of complications. After adjusting for confounders, robotic surgery was associated with a decrease of 0.325 cm in length of clear radial margins (95%CI:(-)0.658-(-)0.002, p=0.048) in Group 1 but 0.708 cm increase in length of clear distal margins (95%CI:0.054-1.362, p=0.034).

Conclusion/Discussion: Robotic rectal surgery showed similar complication rates, conversion rates, and lengths of stay compared to laparoscopy across all obese BMI groups. While the typical advantages of robotic surgery were not seen, such as decreased length of stay and rates of conversion to open, there were subtle, conflicting differences in margin quality within BMI groups. These findings suggest that the benefits of robotic resection in obese patients may be anatomy- and case-specific rather than universal.