EP228/#913 Prognostic role of pathological chemotherapy response score in patients receiving neoadjuvant chemotherapy for epithelial ovarian cancer

Objectives Following neo-adjuvant chemotherapy, patients with advanced Epithelial Ovarian Cancer (EOC) undergo interval cytoreduction. Response to treatment varies widely. Our objective was to study the prognostic role of the pathologic chemotherapy response score (CRS) on final pathology in this group of patients. Methods A retrospective study was conducted of patients with advanced high-grade EOC diagnosed between 2005–2017, and treated with neoadjuvant chemotherapy. After interval cytoreductive surgery (ICS), pathological tumor regression was determined in the omentum, according to the 3-tier CRS, while CRS 1+2 were defined as poor response and CRS3 was defined as good response. Results were compared with standard clinicopathological variables (demographical data, tumor characteristics, CA-125, surgical outcome), and progression free survival (PFS). Standard statistics were used as required. Results Fifty eight patients were eligible for analysis, CRS 1–2 was found in 33(56.9%) and CRS 3 in 25 (43.1%) patients. In the CRS 3 group, more patients achieved no macroscopic disease at ICS than in the CRS 1–2 group (22 (91.7%) vs. 15(46.9%), p<0.001). Bowel resection rates were lower in the CRS3 group (0 (0%) vs. 6 (18.8%), p=0.035). There was no difference in PFS and OS between the two groups (log rank test =0.282 and 0.664, respectively). Conclusions In this study, a 2 tier pathological CRS of the omental tumor was found to be associated with the rate of complete cytoreduction at ICS. Interestingly, this difference did not translate into an advantage in PFS for these patients.