RT Journal Article SR Electronic T1 541 The role of neoadjuvant chemotherapy in the treatment of IIIC-IVA stage epithelial ovarian cancer – a single center experience JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A247 OP A247 DO 10.1136/ijgc-2021-ESGO.423 VO 31 IS Suppl 3 A1 S Molnár A1 LÉ Vas A1 E Maka A1 R Lampé A1 B Vida A1 Z Krasznai YR 2021 UL http://ijgc.bmj.com/content/31/Suppl_3/A247.1.abstract AB Introduction/Background*Ovarian cancer is the 7th most common malignancy among women and the leading cause of gynecologic cancer death. The most important prognostic factor of the disease is optimal debulking surgery (R0) with no macroscopic residual disease. Achieving optimal result is a challenging duty in advanced stage (FIGO IIIC-IV). Based on previous studies neoadjuvant chemotherapy (NAC) can help to improve the optimally debulked ratio of this population with non-inferior survival outcome. The aim of our study was to evaluate the effectiveness of NAC among primarily inoperable patients. The focus was not only on survival outcome but on cost effectiveness (need for transfusion, hospitalization, ICU admission, medication demand, etc.).Methodology Between 2015-2018 112 debulking surgeries were performed on stage FIGO IIIC-IV ovarian cancer patients. The cases were divided into potentially operable and inoperable group based on preoperative imaging, tumor marker levels according to our institutional protocol. In special situation where operability was not obvious, diagnostic laparoscopy was done to categorize patients. The peri-, intra-, postoperative reports and survival data was collected.Result(s)*Complete tumor reduction was performed in 63 cases while in 49 cases only partial tumor reduction was achieved. Median progression-free survival did not differ significantly between patients who underwent primary or interval debulking surgery (PDS = 12 months, IDS = 11.2 months, p = 0.264). The rate of R0 resection was higher after NAC, but not significantly (37.9% vs. 54.2%, p = 0.179). There was no significant difference in survival of patients who successfully underwent complete tumor reduction, despite the fact that the “inoperable” group treated with NAC had a worse prognosis (p = 0.264). The cost-effectiveness was comparable between groups, the hospital stay and transfusion demand was favourable in neoadjuvant group.Conclusion*The rate of optimal tumor reduction can be improved not only by increasing radicality but also by applying appropriate patient selection criteria. Neoadjuvant treatment according to the current recommendations is applicable in the inoperable group, in accordance with the protocol we use. The survival data of patients who have undergone complete tumor reduction after NAC was not inferior to those who went through primary debulking.