A Randomized Phase Iii Trial Of Secondary Cytoreductive Surgery In Later Recurrent Ovarian Cancer: Soc1/Sgog-Ov2.

6001 Background: In China, secondary cytoreductive surgery (SCR) has been standard of care in some high volume cancer centers for ovarian cancer (OC) and most pts prefer surgery over the past two decades. Although GOG213 showed no OS benefit, the debate on selected pts and the conflict with certain local clinical care is still open. Methods: Pts with 1st relapsed OC after 6m+ platinum-free interval (PFI) were eligible if predicted to be a potential R0 by iMODEL score combined with PET-CT image and were randomized to SCR followed by chemotherapy (surgery arm) vs 2nd line chemotherapy alone (no surgery arm). Co-primary endpoint is PFS and OS. The 2nd endpoint is accumulated treatment-free survival (TFSa), which was defined as the overall survival time minus the time of surgery and chemotherapy after randomization. We report analysis of PFS and interim analysis of TFSa. Results: 357 pts were randomized 2012-2019. 6.3% of 175 pts were operated in no surgery arm and cross-over rate was 36.9% in 2nd+ relapsed pts of no surgery arm. 97% and 96% of pts received a platinum-containing 2nd line therapy. Complete resection (R0) rate was 76.7% in overall and 61.1% in pts with iMODEL> 4.7. 60 d mortality rates were 0 % in both surgery and no surgery arm. Postoperative 30 d complication rate with ≥ grade 3 was 5.2%. The median follow-up was 36.0 m. Median PFS was 17.4 m and 11.9 m in surgery and no surgery arm, respectively (HR 0.58, 95% CI 0.45-0.74, p < 0.001). Median time to start of first subsequent therapy (TFST) was 18.1 m vs 13.6 m in favor of the surgery arm (HR 0.59, 95%CI 0.46-0.76). 1.1% and 10.1% of pts underwent Bevacizumab and PARPi maintenance in the 2nd line therapy. The OS and TFSa was immatured. The median TFSa was unreached and 39.5 m in R0 subgroup and no surgery arm, respectively (HR0.59, 95%CI 0.38-0.91). TFSa in surgery arm showed a better long-term survival than that in no surgery group (restricted mean survival time from 60 to 72m: 6.2m vs 4.2m). Conclusions: SCR in selected pts resulted in a dramatically significant extension of PFS. The interim analysis of TFSa indicate that SCR might contribute to long-term survival.