RT Journal Article SR Electronic T1 565 Postoperative outcomes of primary and interval cytoreductive surgery for advanced ovarian cancer registered in the dutch gynecological oncology audit (DGOA) JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A89 OP A89 DO 10.1136/ijgc-2020-ESGO.152 VO 30 IS Suppl 4 A1 Nishita Baldewpersad Tewarie A1 Willemien JVan Driel A1 Maaike Van Ham A1 Michel Wouters A1 Roy FPM Kruitwagen YR 2020 UL http://ijgc.bmj.com/content/30/Suppl_4/A89.abstract AB Introduction/Background The challenge when performing cytoreductive surgery (CRS) for advanced ovarian cancer is to balance the benefits (obtaining complete CRS) and risks (perioperative complications). The aim of this study was to report short term postoperative morbidity and mortality in relation to surgical outcome in patients undergoing primary cytoreductive surgery(PCS) and/or interval cytoreductive(ICS) surgery in 8 gynaeco-oncological regions in the Netherlands.Methodology Data from the prospective Dutch Gynecological Oncology Audit(DGOA) data base were used for this retrospective analysis with population-based data. All patients with advanced ovarian cancer (FIGO IIB-V) undergoing PCS or ICS between January 1st, 2015- December 31st, 2018 were included. Primary outcome was the frequency of postoperative complications. In addition, median time to adjuvant chemotherapy was shown in relation to CRS outcomes and complication severity. Hospitals were clustered in 8 regions consisting of a gynaeco-oncological center and its referring hospitals. Complications with Clavien Dindo ≥3 were analyzed per region and casemix corrected.Results A total of 2382 patients met the inclusion criteria corresponding to 2458 surgical procedures. 1027 patients underwent PCS and 1355 patients underwent ICS, a third group contained patients with both PCS and ICS (n=76 ). Complications with re-invention were significantly higher in PCS compared to ICS (5.7% vs. 3.6% respectively, p =0.048), but complete CRS was achieved more often in PCS compared to ICS (69.7% vs 62.1% respectively<0.001). Clavien Dindo ≥3, ICU stay, and 30-day mortality were not statistically different between PCS and ICS. Time to adjuvant chemotherapy was the longest in patients with complete CRS and a complication with reintervention:47 days (figure 2c). Regional variation for Clavien Dindo ≥3 was apparent with 1 region as outlier in PCS and ICS (figure3a and 3b).Abstract 565 Figure 2c Median waiting time for adjuvant chemotherapy after complete cytoreduction (days)Abstract 565 Figure 3a Casemix corrected funneplot for patients with Clavien Dindo >3 in Primary CRS for 8 regions in the NetherlandsAbstract 565 Figure 3b Casemix corrected funnelplot for patients with clavien Dindo >3 in Interval CRS for 8 regions in the NetherlandsConclusion Complete PCS is more often achieved, but there are more complications with re-intervention resulting in more time to start with adjuvant chemotherapy. This exceeds the advised maximum of 42 days. This finding underlines the importance of maintaining a balance in aggressiveness of surgery and result of CRS in relation to survival. In addition, complications in the Netherlands show regional hospital variation after casemix correction.In the future these outcomes should be discussed to minimize complications and therefore improve quality of care within the nation.Disclosures None.