INTRODUCTION: In advanced epithelial ovarian cancer (AEOC), debulking surgery with posterior pelvic exenteration (PPE) is performed in 35-70 % of the patients to achieve no macroscopic residual disease. This study aims to evaluate the incidence of mesorectal involvement and its prognostic role in AEOC patients undergoing PPE. MATERIALS AND METHODS: This prospective study analyzes data from a cohort of AEOC patients who underwent primary debulking surgery (PDS) or interval debulking surgery (IDS) with PPE at the Léon Bérard Cancer Center in Lyon between 2018 and 2022. RESULTS: 73 patients underwent debulking surgery with PPE during the study period. 27 (34 %) underwent PPE during PDS and 46 (66 %) during IDS. 23 patients (31.5 %) had only serosal involvement, 19 (26 %) had bowel involvement up to the muscularis propria, and 7 (9.6 %) had up to the mucosa. Mesorectal involvement was observed in 40 cases (54.7 %) and was significantly associated with positive MLNs and higher liver recurrence rates. Hepatic metastases had an early onset (months, 9.8 vs 28.8
p = 0.0001) and were correlated with poorer OS (months, 20.9 vs 51.5) compared to recurrences in other sites. The persistence of positive mesorectum after neoadjuvant chemotherapy in the IDS group seemed to be linked to poor OS (NR vs 42.7 months). CONCLUSIONS: Debulking surgery with PPE in AEOC patients is often needed. Total mesorectal excision should be performed in AEOC to achieve no residual disease because positive mesorectum after neoadjuvant chemotherapy seemed to be linked with poor OS, with early onset and increased incidence of liver metastasis.