Prognostic analysis of peritoneal washing cytology during interval debulking surgery in advanced ovarian cancer

Background Interval debulking surgery (IDS) following neoadjuvant chemotherapy is a treatment option for advanced ovarian cancer. Optimal surgery is required for better survival; however, while peritoneal washing cytology (PWC) has been identified as a prognostic factor, its comprehensive assessment during IDS remains unexplored. Therefore, we aimed to evaluate PWC efficacy during IDS, alongside other factors including residual disease and the modeled cancer antigen 125 (CA-125) ELIMination rate constant K (KELIM), by retrospectively reviewing the medical records of 25 patients with advanced ovarian cancer underwent neoadjuvant chemotherapy and IDS between January 2017 to June 2023. Results Twelve (48.0%) patients were PWC-positive, and the remainder were PWC-negative. PWC was performed at laparotomy during IDS, after which five (41.7%) PWC-positive and four (30.8%) PWC-negative patients received bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, for maintenance treatment. Four (33.3%) PWC-positive and 10 (76.9%) PWC-negative patients received poly adenosine diphosphate (ADP)-ribose polymerase inhibitors. In patients who received bevacizumab and poly ADP-ribose polymerase inhibitors, overall survival and progression-free survival did not significantly differ between those who were PWC-positive and PWC-negative (p = 0.27 and 0.20, respectively). Progression-free survival significantly differed between those with favorable and unfavorable CA-125 KELIM (p = 0.02). Multivariate analysis indicated that optimal surgery and favorable CA-125 KELIM were associated with better progression-free survival (p < 0.01 and 0.02, respectively), with only optimal surgery associated with better overall survival (p = 0.04). Conclusions A positive PWC at IDS was not associated with survival in advanced ovarian cancer. Our findings indicate that although PWC status at IDS should be one of the factors determining survival in patients with advanced ovarian cancer, recent improvements in maintenance therapy may make the combination of CA-125 KELIM and PWC status a more useful prognostic factor in selecting treatment after IDS. Further studies are needed to validate these results, highlighting the potential importance of maintenance treatment after IDS and the need for further research to validate the clinical significance of a positive PWC.