Are There Survival Differences Between Women with Equivalent Residual Disease After Interval Cytoreductive Surgery Compared with Primary Cytoreductive Surgery for Advanced Ovarian and Peritoneal Cancer?

Objective: The aim of this study was to investigate survival differences between equivalent residual disease [complete gross resection (CGR), minimal residual disease (MRD), suboptimal] at the time of primary debulking surgery (PDS) and interval debulking surgery (IDS). Methods: The National Cancer Database was used to identify patients from 2010 to 2015 with stage IIIC/IV primary peritoneal or ovarian cancer who had residual disease recorded. Propensity score matching (PSM) was used to correct for differences in characteristics between the PDS and IDS groups. Results: Of 8683 patients with advanced ovarian cancer, 4493 (52%), 2546 (29%), and 1644 (19%) had CGR, MRD, or suboptimal resection, respectively. From 2010 to 2015, the number of patients undergoing IDS increased 27% (p_trend < 0.001), and there was an 18% increase in CGRs (p_trend = 0.005). The increased use of IDS from 2010 to 2015 was associated with increased CGRs (p_trend = 0.02) and decreased MRD (p_trend = 0.001), but not with decreased suboptimal resections (p_trend = 0.18). IDS, even after PSM, was associated with inferior overall survival [OS; hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.03–1.22, p = 0.008]. A CGR at PDS had prolonged median OS compared with a CGR at IDS (51 vs. 44 months, p < 0.001). Additionally, MRD at PDS had worse median OS compared with a CGR at IDS (41 vs. 44 months, p = 0.03), but improved median OS compared with MRD at IDS (median OS 35 months, p = 0.05). Conclusion: The use of IDS continues to rise in the US, and is associated with improved surgical outcomes but not necessarily similar oncologic outcomes. There should be continued efforts to improve cytoreductive outcomes in women with advanced ovarian and peritoneal malignancies.