Objective. To: a) identify prognostic factors in patients with epithelial ovarian cancer treated with neoadjuvant chemotherapy (NACT) and interval debulldng surgery (IDS), and b) compare post-surgical survival between patients treated with NACT/IDS for presumed unresectable disease and stage IIIC/IV patients who underwent suboptimal primary debulking surgery (PDS).Methods. This was a retrospective study of consecutive stage IIIC or IV patients undergoing IDS after NACT at Mayo Clinic from January 2007 to December 2013. A subset of patients receiving NACT/IDS for the indication of unresectable disease were matched 1:1 on age and stage to a cohort of patients who underwent suboptimal PDS between 2003 and 2011. Hazard ratios and corresponding 95% confidence intervals were estimated from Cox proportional hazards models.Results. We identified 87 patients treated with NACT/IDS: the median OS and PFS following surgery was 2.4 and 1.0 years, respectively. Factors associated with significantly worse OS were older age (adjusted HR 1.60 per 10-year increase in age, 95% CI 1.18, 2.16) and elevated CA-125 before IDS (adjusted HR 2.30 for CA-125 >35 U/mL, 95% CI 1.25, 423). Number of adjuvant chemotherapy cycles administered did not have a significant effect on survival. In the matched cohort analysis of presumed unresectable cases undergoing NACT/IDS vs suboptimal PDS cases (n = 45 each), the NACT/IDS group had a significant OS advantage (HR 0.53; 95% CI 032, 0.88), and fewer patients experienced a 30-day postoperative Accordion grade 3/4 complication (11% vs 36%, P = 0.01).Conclusions. Younger age and normalization of CA-125 prior to IDS are associated with improved survival with NAG:LADS. For primary EOC where resection to residual disease of 1 cm or less is unlikely, NACT/IDS is associated with improved survival and reduced perioperative morbidity compared to PDS. As these patients are likely best served by NACT/IDS, more reliable predictors of resectability would be valuable. (C) 2016 Elsevier Inc. All rights reserved.