236 What can we learn from the 10 mm lymph node size cut-off on the CT in advanced ovarian cancer at the time of interval debulking surgery?

Introduction/Background* The benefit of a systematic lymphadenectomy is still debated in patients undergoing neo-adjuvant chemotherapy (NACT) followed by interval debulking surgery (IDS) in ovarian cancer (OC). The objective of this study was to evaluate the predictive value of the pre-NACT and post-NACT CT in predicting definitive histological lymph node involvement. The prognostic value of a positive node on the CT was also assessed. Methodology A retrospective, unicentric cohort study was performed including all patients with ovarian cancer who underwent NACT and IDS with a lymphadenectomy between 2005-2018. CT were analyzed blinded to pathology, and nodes with small axis ≥ 10 mm on CT were considered positive. Sensitivity (Se), specificity (Sp), and negative (NPV) and positive predictive values (PPV) and their CI95% were calculated. The 2-year recurrence free survival (RFS) and 5-year overall survival (OS) was compared. Result(s)* 158 patients were included, among which 92 (58%) had histologically positive lymph nodes. CT had a Se, Sp, NPV and PPV of 35%, 82%, 47% and 73% before NACT and 20%, 97%, 47% and 91% after NACT, respectively. Patients with nodes considered positive had a non-significant lower 2-year RFS and 5-year OS on the pre-NACT and post-NACT CT. Patients at ‘high risk’ (nodes stayed positive on the CT or became positive after NACT) also had a non-significant lower 2-year RFS and 5-year OS. Conclusion* Presence of enlarged lymph nodes on CT is a weak indicator of lymph node involvement in patients with advanced ovarian cancer undergoing NACT. However, it could be used to assess prognosis.