EP827 - Short-Term Outcomes of Laparoscopic vs. Robotic Surgery for Low Rectal Cancer Across BMI Classes

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Purpose/Background: Elevated body mass index (BMI) and low-lying rectal cancer are associated with increased operative complexity and higher rates of postoperative complications. In this study, we aimed to compare the postoperative outcomes of laparoscopic and robotic surgery for low rectal cancer across BMI classes.

Methods/Interventions: This retrospective study analyzes elective low rectal cancer surgeries between 2016 to 2022 using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were categorized into four BMI groups: Group 1 (normal, BMI < 25), Group 2 (overweight, 25 ≤ BMI ≤ 30), Group 3 (obese, 30 < BMI < 35), and Group 4 (morbidly obese, BMI ≥ 35). 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, and organ space SSI. Multivariate regression assessed the impact of demographics and surgical approach on postoperative outcomes within each BMI class.

Results/Outcomes: The study included 2,573 patients, categorized by BMI as follows: 899 Group 1 patients (470 laparoscopic, 429 robotic), 841 Group 2 patients (428 laparoscopic, 413 robotic), 522 Group 3 patients (278 laparoscopic, 244 robotic), and 311 Group 4 patients (153 laparoscopic, 158 robotic). Overall, patients with gradually higher BMIs had gradually higher significant rates of current smokers, diabetes, hypertension, and ASA classifications. On regression analysis, BMI class of patients in groups 2-4 were associated with an increased risk of postoperative complications (Group 2 - OR 1.32, 95 %CI 1.08-1.63, p=0.008; Group 3 - OR 1.37 95%CI - 1.08-1.74, p=0.009; Group 4 OR 1.91, 95%CI - 1.45-2.54, p< 0.001). Male sex was also associated with higher odds of complication (OR=1.29, 95% CI 1.08-1.53, p=0.004).

Within each BMI group, patients' demographics and comorbidities were comparable between laparoscopic and robotic cohorts. On univariate analysis, there were no significant differences in rates of postoperative complications, anastomotic leak, or organ space SSI between the two cohorts within each BMI class. Robotic surgery was associated with lower rates of unplanned conversion to open surgery and shorter lengths of stay. Operative time was significantly longer in robotic cohorts for Groups 1-3, with comparable times in morbidly obese patients (Group 4). Group 4 also had higher rates of sepsis (6.3% vs 1.3%, p=0.035) and wound disruption (10.1% vs 0.7%, p< 0.001) in the robotic compared to the laparoscopic cohort. Multivariate regression analysis revealed that the robotic approach was not significantly associated with overall complications across all cohorts. Nevertheless, robotic surgery in morbidly obese patients was associated with 5.1 (1.1-23.7, p=0.0375) times increased odds of postoperative sepsis and 17.1 (2.24-131, p=0.006) times increased odds of wound disruption. Additionally, male sex was found to be a predictor of overall complications only in the overweight group (OR 1.43, 95% CI - 1.04-1.96, p=0.027).

Conclusion/Discussion: Robotic surgery across all BMI classes experienced lower conversion rates and shorter lengths of stay. However, morbidly obese patients operated on using a robotic approach were prone to an increased risk of postoperative sepsis and wound disruption compared to those operated on laparoscopically.