RT Journal Article SR Electronic T1 466 Preoperative CA125 significantly improves risk stratification in high-grade endometrial cancer JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A97 OP A98 DO 10.1136/ijgc-2021-ESGO.152 VO 31 IS Suppl 3 A1 Lombaers, M A1 Cornel, K A1 Visser, N A1 Amant, F A1 Bronsert, P A1 Geomini, P A1 Gil-Moreno, A A1 Van Hamont, D A1 Huvila, J A1 Krakstad, C A1 Koskas, M A1 Mancebo Moreno, G A1 Matias-Guiu, X A1 Pijlman, B A1 Vos, C A1 Weinberger, V A1 Snijders, M A1 Haldorsen, I A1 Reijnen, C A1 Pijnenborg, J YR 2021 UL http://ijgc.bmj.com/content/31/Suppl_3/A97.2.abstract AB Introduction/Background*Patients with high-grade endometrial carcinoma (EC) have an increased risk of lymph node metastasis (LNM). Preoperative serum CA125 and imaging findings have been incorporated in multiple risk stratification models to predict LNM and advanced disease in EC and are widely used in clinical practice. However, data on their predictive value in high-grade EC are limited. We therefore aim to determine the predictive value of CA125 combined with preoperative computed tomography (CT) imaging in high-grade EC for LNM.Methodology Retrospective multicentre cohort study including patients (n=334) with preoperative high-grade EC and available CA125. Clinical data including imaging results, primary surgical treatment and final International Federation of Gynaecology and Obstetrics (FIGO) stage were recorded. CA125 was considered elevated at >35 IU/L.Result(s)*Patients with high-grade EC (n=334) and elevated CA125 more often presented with advanced FIGO stage (III-IV), 64.2% (95/148) versus 18.8% (35/186) in patients with normal CA125 (p<0.05). For patients with elevated CA125 who underwent surgical staging (n=192), the prevalence of LNM was 56.5% (39/69), compared to 14.6% (18/123) in patients with normal CA125 (p<0.05). For patients with preoperative CT imaging (n=148), LNM were suspected in 18.9% (28/148), but histologically confirmed in 27.7% (41/148) of the patients. Preoperative CA125 and CT findings for LNM in relation to risk of LNM are shown in table 1.View this table:Abstract 466 Table 1 CA125 and CT results in relation to lymph node metastasis (N1) in patients who underwent surgical stagingView this table:Abstract 466 Table 2 Logistic regression analysis of variables versus LNMMultivariate analysis (table 2) showed that elevated CA125, histological deep (>50%) myometrial invasion, and cervical involvement independently predict histological LNM (p<0.05 for all) whereas positive CT findings for LNM did not.Conclusion*This study demonstrates that elevated CA125 in patients with high-grade EC is an important prognostic marker for the predication of LNM and advanced stage disease. In patients with preoperative normal CA125, the additional value of CT imaging was limited with respect to the prediction of LNM. We therefore recommend to incorporate CA125 in routine preoperative work-up for risk stratification in high-grade EC.