Introduction/Background Ovarian cancer (OC) has the highest mortality rate because it is diagnosed in advanced stages. The cornerstone of treatment is the complete cytorreductive surgery plus intravenous chemotherapy. When primary complete surgery is not possible, neoadjuvant chemotherapy (NACT) is provided. The hyperthermic intraperitoneal chemotherapy (HIPEC) in interval surgery (IDS) has proven an improvement in overall survival (OS) and in progression - free survival (PFS) in a randomized controlled trial.The intraperitoneal administration of chemotherapy could eliminate residual microscopic peritoneal tumor cells and increase this effect by hyperthermia

Methodology A multicenter, retrospective observational study of advanced OC patients who underwent interval cytoreductive surgery alone (CRSnoH) or interval cytoreductive surgery plus HIPEC (CRSH) was carried out in Spain between 07/2012 and 12/2021. PFS and OS analyses were performed. The series of patients who underwent CRSH or CRSnoH was balanced regarding the risk factors using a propensity score matching. After balancing the series with respect risk factors variables; 170 patients were obtained from each subgroup.

Results The median PFS times were 16 and 13 months in the CRSH and CRSnoH groups, respectively (Hazard ratio (HR) 0.74; 95% CI, 0.58–0.94; p = 0.031). The median OS times were 56 and 50 months in the CRSH and CRSnoH groups, respectively (HR, 0.88; 95% CI, 0.64–1.20; p = 0.44). There was no increase in complications in the CRSH group.

Conclusion The addition of HIPEC after interval cytoreductive surgery is safe and increases DFS in advanced OC patients with statistically significant differences, showing a trend towards increased overall survival.

Disclosures I have no financial disclosure or conflict of interest with the presented material.