RT Journal Article SR Electronic T1 O005/#190 Where there is smoke, there is fire: understanding the implications of positive sentinel lymph nodes in endometrial cancer JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A3 OP A3 DO 10.1136/ijgc-2021-IGCS.5 VO 31 IS Suppl 4 A1 G Dinoi A1 K Ghoniem A1 Y Huang A1 V Zanfagnin A1 C Langstraat A1 G Glaser A1 A Weaver A1 M Mcgree A1 F Fanfani A1 G Scambia A1 A Mariani YR 2021 UL http://ijgc.bmj.com/content/31/Suppl_4/A3.1.abstract AB Objectives The objective of this study is to identify clinicopathologic characteristics associated with non-sentinel lymph node (SLN) metastasis and non-vaginal recurrences in patients with SLN-positive endometrial cancer (EC).Methods Consecutive patients with surgically staged EC and at least one positive SLN were included. SLNs were ultra-staged. Positive SLNs were reviewed and patients classified according to the size of the largest SLN metastasis.Results 103 patients (36 isolated tumor cells (ITC), 27 micrometastasis, 40 macrometastasis) were included. Multiple positive SLNs were observed in 38.8% of patients. Size of SLN metastasis (adjusted OR (aOR) 3.0 for macrometastasis vs ITC, 95%CI 1.1–8.1), and age (aOR 1.8 per 10-year increase, 95%CI 1.1–3.0) were independent predictors of multiple positive SLNs. Extracapsular compared to intracapsular invasion of the SLN metastasis was significantly associated with multiple positive SLNs at univariate analysis (71.4% vs. 33.7%, p=0.008). Forty-seven percent (18/38) of patients who underwent completion pelvic lymphadenectomy, had additional positive lymph nodes. This was associated with increased size of SLN metastasis (0/8, 5/10, and 13/20 in ITC, micro- and macrometastasis, respectively, p=0.004). SLN macrometastasis (adjusted HR (aHR) 3.4, 95%CI 1.1–11.0), non-endometrioid histology (aHR 5.7, 95%CI 1.9–17.3), and cervical stromal invasion (aHR 9.4, 95%CI 2.9–30.4) were independent predictors of non-vaginal recurrence (table 1).View this table:Abstract O005/#190 Table 1 Conclusions Size and location of SLN metastasis can predict an increased risk of multiple positive SLNs, non-SLN positive nodes, and non-vaginal recurrence in SLN positive EC patients. These factors should be assessed when considering adjuvant treatment in these high-risk patients.