5501 Background: The role of secondary cytoreductive surgery in recurrent ovarian cancer (OC) has not been defined by level-1 evidence. Methods: Pts with OC and 1st relapse after 6+ mos platin-free interval (TFIp) were eligible if they presented with a positive AGO-score (PS ECOG 0, ascites ≤500 ml, and complete resection at initial surgery) and were randomized to 2nd-line chemotherapy alone vs cytoreductive surgery followed by chemo. Chemo regimens were selected according to the institutional standard. We report here results of the predetermined interim analysis. Results: 407pts were randomized 2010-2014. The TFIp exceeded 12 mos in 75% and 76% pts in both arms. 8.9% of 203 pts were operated despite of randomization to the no-surgery arm, whereas 6.9% of 204 pts in the surgery arm did not undergo operation. Complete resection was achieved in 67% of pts; 87% and 88% received a platinum-containing 2nd-line therapy. Median PFS was 14 mos without and 19.6 mos with surgery (HR: 0.66, 95%CI 0.52-0.83, p<0.001). Median time to start of first subsequent therapy (TFST) was 21 vs 13.9 mos in favor of the surgery arm (HR 0.61, 95%CI 0.48-0.77, p=p<0.001). PFS-2 between 1st and 2nd relapse equaled or even exceeded PFS-1 before 1strelapse in 26% after surgery and only 16% without-surgery. Analysis of the primary endpoint OS is kept blinded due to immaturity and will be evaluated after extended follow-up (the observed pooled unblinded 2-YSR was 83% instead of the initially in the protocol assumed 55-66%). 60d mortality rates were 0 and 0.5% in the surgery and no-surgery arm. Re-laparatomies were performed in 7 pts (3.5%) in the surgery arm.With the exception of myelosuppression which occurred more frequently in the no-surgery arm no further significant differences were observed with respect to grade 3+ acute adverse events. Conclusions: Surgery in pts with 1st relapse of OC after a TFIp of 6+ mos and selected by a positive AGO-Score resulted in a clinically meaningful increase of PFS and TFST with acceptable treatment burden. Until final OS data will definitively define the role of secondary cytoreductive surgery it should at least be considered as valuable option in pts with a positive AGO-Score. Clinical trial information: NCT01166737.
