Optimal timing of interval debulking surgery for advanced epithelial ovarian cancer: A retrospective study from the ESME national cohort

Objective: Interval debulking surgery is recommended after 3–4 cycles (standard IDS) of neoadjuvant chemotherapy (NACT) for epithelial ovarian cancer (EOC) not able to received upfront complete debulking surgery. However, real world practices frequently report performing IDS after ≥5 NAC cycles (delayed IDS). The aim of this work was to evaluate the impact on survival of the number of NACT cycles before IDS. Methods: We identified from a French national database, women with newly diagnosed EOC who underwent IDS from January 2011 to December 2016. Progression free survival (PFS) and overall survival (OS) were compared using Cox model with adjustments for confounding factors provided by two propensity score methods: inverse probability of treatment weighting (IPTW) and matched-pair analysis. Results: 928 patients treated by IDS for which our propensity score could be applied were identified. After a median follow-up of 49.0 months (95% CI [46.0;52.9]); from the IPTW analysis, median PFS was 17.6 months and 11.5 months (HR = 1.42; CI 95% [1.22–1.67]; p < 0.0001); median OS was 51.2 months and 44.3 months (HR = 1.29; CI 95% [1.06–1.56]; p = 0.0095) for the standard and delayed IDS groups. From the matched-pair analysis (comparing 352 patients for each group), standard IDS was associated with better PFS (HR = 0,77; CI 95% [0.65–0.90]; p = 0.018) but not significantly associated with better OS (HR = 0,84; CI 95% [0.68–1,03]; p = 0.0947). Conclusions: Carrying IDS after ≥5 NACT cycles seems to have a negative effect on patients survival. The goal of IDS surgery is complete resection and should not be performed after >3–4 NACT cycles.