EP360 - Does Conversion Matter? Comparative Outcomes Between Upfront Laparotomy and Converted Minimally Invasive Surgery for Rectal Cancer.

Purpose/Background: Minimally invasive surgery (MIS) is increasingly used for rectal cancer, but intraoperative conversion to open laparotomy is still not a rare occasion. While conversion has been associated with adverse outcomes in colon cancer, its impact in rectal cancer-particularly compared to planned open surgery-remains unclear. We aimed to compare perioperative and oncologic outcomes between patients undergoing upfront laparotomy and those converted from MIS in the treatment of rectal adenocarcinoma.

Methods/Interventions: We conducted a retrospective cohort study of all patients who underwent elective, curative-intent resection for rectal adenocarcinoma at a single tertiary center between 2010 and 2020. From this cohort we selected and grouped patients by surgical approach: upfront laparotomy (n=144) or conversion from MIS (n=72). The primary outcome was major postoperative complications (Clavien-Dindo grade ≥III). Secondary outcomes included 30- and 90-day mortality, 30-day readmission, length of stay, oncologic quality metrics (margin positivity and lymph node yield), and overall and disease-free survival.

Results/Outcomes: Major complications were significantly lower in the conversion group (11% vs. 24% in the upfront laparotomy, p=0.045), though conversion was not an independent predictor in multivariable analysis (OR 0.936, 95% CI 0.449-1.90, p=0.858). Oncologic outcomes were comparable between groups, including margin positivity (4.2% vs. 1.4% respectively, p=0.3) and median lymph node yield (19.4 vs. 16.6, p=0.12). Patients in the conversion group had tumors located farther from the anal verge (median 10.5 vs. 9.0 cm, p=0.004). No significant differences were observed in mortality, readmission, or length of stay. Overall survival (5-year: 86.5% vs 88.1%, p=0.34) and disease-free survival (5-year: 87.6% in both groups, p=0.73) were similar across groups, including in subgroup analyses by age and comorbidity.

Conclusion/Discussion: Intraoperative conversion from MIS to open surgery in rectal cancer is not associated with increased morbidity or inferior oncologic outcomes compared to upfront laparotomy. These findings support the safety and appropriateness of initiating MIS when possible, even when conversion seems likely or becomes necessary.

Figure 1.Forest Plot of Multivariable Predictors of Recurrence
Forest plot displaying adjusted odds ratios (ORs) with 95% confidence intervals for predictors of recurrence
Figure 2. Kaplan-Meier Disease-Free Survival
Disease-free survival comparison between conversion and upfront laparotomy groups.