EP813 Different prevalence and pattern of lymph nodes metastases between primary and interval cytoreduction in advanced ovarian cancer

Introduction/Background Complete cytoreduction followed by combination of platinum-taxane chemotherapy remains standard treatment for epithelial ovarian cancer (EOC). The role of adding systematic lymphadenectomy to cytoreduction procedures in advanced EOC has been a topic of debate. Recently, the LION trial showed that systematic lymphadenectomy after maximal cytoreduction in absence of bulky nodes does not improve survival and may cause additional harm. The aim of this study is to describe the rate of radiological and histological positive lymph nodes in primary or interval cytoreduction and to estimate the impact that application of the conclusions of LION trial would have in our centre. Methodology A consecutive series of 54 patients with newly diagnosed EOC operated between 2017 and 2018 at Dr. Josep Trueta University Hospital was analysed. Data were retrieved from the departmental database and hospital electronic medical records. Results 42 patients (77%) were diagnosed at III/IV FIGO stage and underwent cytoreductive surgery. Of them, 46.5% had primary cytoreductive surgery, while 53.5% underwent interval cytoreduction surgery. All patients had a routinely performed preoperative CT-scan and the presence and pattern of bulky nodes was analysed. The most frequent localization of bulky nodes in CT-scan was paraaortic. After neo-adjuvant chemotherapy, bulky nodes responded in almost all cases. Systematic pelvic lymphadenectomy was performed in 80.4% of cases, and paraaortic lymphadenectomy in 78.3%. The pathological involvement of lymph nodes was analysed. Only one case of interval cytoreduction had nodal macrometastasis, which was presurgical identificated on CT-scan. Conclusion CT-scan is a good predictor for nodal macrometastasis. In absence of bulky nodes and as a result of applying LION conclusions, near 70% of lymphadenectomies in primary cytoreduction and near 95% in interval cytoreduction could be avoided. Careful selection of patients and discussion of CT-scans in multidisciplinary preoperative tumor conference is crucial to avoid unnecessary procedures and to reduce surgical complicactions. Disclosure Nothing to disclose.