Simple SummaryThe optimal time interval between the completion of neoadjuvant chemotherapy (NACT) and interval debulking surgery (IDS) in high-grade serous ovarian carcinoma (HGSC) is not well defined. We conducted a retrospective study of patients with HGSC stage IIIC/IV who had received NACT followed by IDS during a 15-year period (January 2003–December 2018) in our Institution. Performing IDS within four weeks after NACT was associated with better survival outcomes. On multivariate analysis, the performance of IDS within four weeks after NACT was an independent factor of both PFS (p= 0.004) and OS (p= 0.003). Our study provides evidence that surgical intervention should not be significantly delayed after neoadjuvant chemotherapy.HighlightsWhat are the main findings?The time interval NACT to IDS < 4 weeks was significantly associated with a prolonged PFS (p= 0.004) and OS (p= 0.002).Median OS was 66.3 months (95% CI: 39.1–93.4) vs. 39.4 months (95% CI: 31.8–47.0) in the <4 week vs. ≥4 week time interval NACT to IDS groups (p= 0.002)On multivariate analysis, the performance of IDS within 4 weeks after NACT and optimal debulking were independent factors for both PFS and OSWhat is the implication of the main finding?Performing IDS early after NACT proved to be a good prognostic factor among ovarian cancer patientsMultidisciplinary coordination is required so as to avoid any unnecessary delaysAbstractBackground: There is limited data on the optimal time interval between the last dose of neoadjuvant chemotherapy (NACT) and interval debulking surgery (IDS) in high-grade serous ovarian carcinoma (HGSC). Methods: We retrospectively identified patients with stage IIIC/IV HGSC who received NACT followed by IDS during a 15-year period (January 2003–December 2018) in our Institution. Results: Overall, 115 patients with stage IIIC/IV HGSC were included. The median age of diagnosis was 62.7 years (IQR: 14.0). A total of 76.5% (88/115) of patients were diagnosed with IIIC HGSC and 23.5% (27/115) with IV HGSC. Median PFS was 15.7 months (95% CI: 13.0–18.5), and median OS was 44.7 months (95% CI: 38.8–50.5). Patients were categorized in groups according to the time interval from NACT to IDS: <4 weeks (group A); 4–5 weeks (group B); 5–6 weeks (group C); >6 weeks (group D). Patients with a time interval IDS to NACT ≥4 weeks had significantly shorter PFS (p= 0.004) and OS (p= 0.002). Median PFS was 26.6 months (95% CI: 24–29.2) for patients undergoing IDS <4 weeks after NACT vs. 14.4 months (95% CI: 12.6–16.2) for those undergoing IDS later (p= 0.004). Accordingly, median OS was 66.3 months (95% CI: 39.1–93.4) vs. 39.4 months (95% CI: 31.8–47.0) in the <4 week vs. >4 week time interval NACT to IDS groups (p= 0.002). On multivariate analysis, the short time interval (<4 weeks) from NACT to IDS was an independent factor of PFS (p= 0.004) and OS (p= 0.003). Conclusion: We have demonstrated that performing IDS within four weeks after NACT may be associated with better survival outcomes. Multidisciplinary coordination among ovarian cancer patients is required to avoid any unnecessary delays.