Risk factors and risk prediction modelling for pelvic sepsis and anastomotic leak following robotic total mesorectal excision with primary anastomosis for rectal cancer

Background: Reporting of pelvic sepsis rates following robotic total mesorectal excision (R-TME) for rectal cancer is inconsistent. This IDEAL stage 2b international multicentre study analysed the prevalence of pelvic sepsis rates and associated risk factors following R-TME and generated a risk prediction model for anastomotic leak (AL). Methods: Patients were identified through the EUREKA (Expert DUtch, FREnch and UK robotic rectal cAncer centres) collaborative. Adult patients undergoing R-TME with primary anastomosis for biopsy-proven rectal cancer were considered for inclusion. The primary outcome was to report the prevalence and risk factors associated with pelvic sepsis and anastomotic leak and subsequently to generate a risk prediction model for AL (categorized by ISREC criteria). Receiver operating characteristic (ROC) analysis was performed to confirm the prediction model for significant risk factors for AL (AUC > 0.5). Calibration and discrimination to assess model predictive accuracy were also performed. Results: A total of 912 patients were analysed. 14% of patients developed pelvic sepsis and 7% an AL. Pelvic sepsis was associated with the following risk factors: male gender [OR 1.650 (95% CI 1.092–2.539, p = 0.020)], administration of NACRT (with the highest prevalence observed following SCRT) [OR 0.650 (95% CI 0.421–0.994, p = 0.049)], increasing duration of surgery [OR 0.997 (95% CI 0.994–0.999, p = 0.040)]. A moderate strength [AUC: 0.613 (95% CI 0.557–0.612)] risk of pelvic sepsis prediction model for robotic TME for rectal cancer was generated. On internal validation, moderate prediction was further maintained [training group AUC 0.610 (95% CI 0.544–0.611), verification group AUC 0.623 (95% CI 0.524–0.622)]. Conclusion: Fourteen per cent of patients will develop pelvic sepsis following robotic TME with primary anastomosis for rectal cancer, and 7% will develop an anastomotic leak. Risk factors associated with pelvic sepsis include male gender, neoadjuvant therapy (SCRT) and longer duration of surgery.