Does conversion during minimally invasive rectal surgery for cancer have an impact on short-term and oncologic outcomes? Results of a retrospective cohort study.

BACKGROUND Although minimally invasive rectal surgery (MIRS) for cancer provides better recovery for similar oncologic outcomes over open approach, conversion is still required in 10% and its impact on short-term and long-term outcomes remains unclear. The aim of our study was to evaluate the impact of conversion on postoperative and oncologic outcomes in patients undergoing MIRS for cancer. METHODS From June 2011 to March 2020, we reviewed 257 minimally invasive rectal resections for cancer recorded in a prospectively maintained database, with 192 robotic and 65 laparoscopic approaches. Patients who required conversion to open (Conversion group) were compared to those who did not have conversion (No conversion group) in terms of short-term, histologic, and oncologic outcomes. Univariate and multivariate analyses of the risk factors for postoperative morbidity were performed. RESULTS Eighteen patients (7%) required conversion. The conversion rate was significantly higher in the laparoscopic approach than in the robotic approach (16.9% vs 3.6%, p < 0.01). Among the 4 reactive conversions, 3 (75%) were required during robotic resections. Patients in the Conversion group had a higher morbidity rate (83.3% vs 43.1%, p = 0.01) and more severe complications (38.9%, vs 18.8%, p = 0.041). Male sex [HR = 2.46, 95%CI (1.41-4.26)], total mesorectal excision [HR = 2.89, 95%CI (1.57-5.320)], and conversion (HR = 4.87, 95%CI [1.34-17.73]) were independently associated with a higher risk of overall 30-day morbidity. R1 resections were more frequent in the Conversion group (22.2% vs 5.4%, p = 0.023) without differences in the overall (82.7 ± 7.0 months vs 79.4 ± 3.3 months, p = 0.448) and disease-free survivals (49.0 ± 8.6 months vs 70.2 ± 4.1 months, p = 0.362). CONCLUSION Conversion to laparotomy during MIRS for cancer was associated with poorer postoperative results without impairing oncologic outcomes. The high frequency of reactive conversion due to intraoperative complications in robotic resections confirmed that MIRS for cancer is a technically challenging procedure.