IntroductionThree randomized controlled trials have resulted in extremely extensive application of the strategy of using neoadjuvant chemotherapy (NAC) followed by interval debulking surgery (IDS) for patients with advanced epithelial ovarian cancer in Japan. This study aimed to evaluate the status and effectiveness of treatment strategies using NAC followed by IDS in Japanese clinical practice.Patients and methodsWe conducted a multi-institutional observational study of 940 women with Federation of Gynecology and Obstetrics (FIGO) stages III–IV epithelial ovarian cancer treated at one of nine centers between 2010 and 2015. Progression-free survival (PFS) and overall survival (OS) were compared between 486 propensity-score matched participants who underwent NAC followed by IDS and primary debulking surgery (PDS) followed by adjuvant chemotherapy.ResultsPatients with FIGO stage IIIC receiving NAC had a shorter OS (median OS: 48.1 vs. 68.2 months, hazard ratio [HR]: 1.34; 95% confidence interval [CI] 0.99–1.82, p = 0.06) but not PFS (median PFS: 19.7 vs. 19.4 months, HR: 1.02; 95% CI: 0.80–1.31, p = 0.88). However, patients with FIGO stage IV receiving NAC and PDS had comparable PFS (median PFS: 16.6 vs. 14.7 months, HR: 1.07 95% CI: 0.74–1.53, p = 0.73) and OS (median PFS: 45.2 vs. 35.7 months, HR: 0.98; 95% CI: 0.65–1.47, p = 0.93).ConclusionsNAC followed by IDS did not improve survival. In patients with FIGO stage IIIC, NAC may be associated with a shorter OS.