718 Investigating impact of ultra-radical surgery in advanced ovarian cancer using population level data linked to the SOCQER 2 multicentre study

Introduction/Background* The first population study investigating per protocol implementation of ultra-radical surgery (URS) as primary surgery reported that URS in advanced ovarian cancer (AOC) reduces the proportion treated surgically and does not improve survival.1 We investigated this hypothesis using population level data for centers participating in the SOCQER 2 study Methodology The SOCQER2 study investigated quality of life after surgery of varying complexity for AOC in a prospective multicenter cohort study, recruiting for 12 months with 24 months follow-up. Results of QoL and variation in Surgical Complexity Scores (SCS) have been previously reported. 2 SOCQER2 centers diverged in approach to URS; used routinely in some participating centers and not in others. Here we analyzed data from nationally collected datasets (Cancer Outcome and Services Data, Systemic Anti-Cancer Treatment, Hospital Episode Statistics) to investigate survival and treatment outcomes in the total cohort of patients from the cancer centers that participated in the SOCQER 2 study, including patients with FIGO Stage 3,4, and stage unknown AOC patients. Residual disease post-surgery was not available for analysis. Result(s)* 1521 patients across 11 participating centers clustered into 3 groups – centers performing >70% low SCS (5/11), mainly intermediate SCS >40% (3/11) and mainly high SCS surgery > 35% (3/11) with 788, 365 and 368 patients. The proportion of patients receiving standard of care, surgery and chemotherapy, was similar in both low and high SCS groups and highest in the intermediate group (39.2 vs 38.3 vs 51.8, p Conclusion* This multicenter ‘ real-life’ population based study finds that URS does not reduce the proportion of AOC patients treated surgically. Centers with mainly intermediate SCS have higher proportion receiving surgery and chemotherapy; this may reflect a willingness to accept greater optimal rather than complete cytoreduction rates. Centers with greater radicality trend towards improved survival, but this did not reach statistical significance. A larger population level study to identify ideal intermediate: high SCS ratios is urgently needed.