750 Diagnostic accuracy of sentinel node biopsy in non-endometrioid, high-grade and/or deep myoinvasive endometrial cancer (TRSGO-SLN-006)

Introduction/Background* The aim of this study was to evaluate sensitivity, negative predictive value (NPV) and false negative rate (FNR) of sentinel lymph node (SLN) mapping algorithm in high-risk endometrial cancer patients. Methodology Patients with non-endometrioid histology, grade 3 endometrioid tumors and/or tumors with deep myometrial invasion were enrolled in this retrospective, multicenter study. After removal of SLNs, all patients underwent pelvic ± paraaortic lymphadenectomy. Operations were performed via laparotomy, laparoscopy or robotic surgery. Indocyanine green (ICG) and methylene blue (MB) were used as tracers. SLN detection rate, sensitivity, NPV and FNR were calculated. Result(s)* Two hundred forty-four patients were included. Surgeries were performed via open approach in 132 (54.1%) patients. While 92 (37.7%) patients underwent bilateral pelvic lymphadenectomy, 152 (62.3%) underwent both bilateral pelvic and paraaortic lymphadenectomy. ICG was used in 120 (49.2%) patients and MB in 124 (50.8%). At least 1 SLN was detected in 222 (91%) patients with a 65.6% bilateral detection rate. Fifty-five (22.5%) patients had lymphatic metastasis and 45 patients had at least 1 metastatic SLN: 28 macrometastasis, 6 micrometastasis and 11 isolated tumor cells. Lymphatic metastasis was detected by side-specific lymphadenectomy in 8 patients and 2 patients had isolated paraaortic metastasis. Overall sensitivity, NPV and FNR of SLN biopsy were 81.8%, 95% and 18.2%, respectively. By applying SLN algorithm steps, sensitivity and NPV improved to 96.4% and 98.9%, respectively. For grade 3 tumors, sensitivity, NPV and FNR of the SLN algorithm were 97.1%, 98.9% and 2.9%, respectively. Sensitivity, NPV and FNR of SLN algorithm were 95%, 98.9% and 5%, respectively in deep myoinvasive tumors. Conclusion* This study was performed in one of the largest high-risk endometrial cancer population. SLN algorithm was found to be safe and had high diagnostic accuracy also in high-risk endometrial cancer patients. Although it seems like SLN algorithm is a feasible option for staging, long term studies to determine impact of SLN biopsy alone on survival are needed before it becomes standard of care in high-risk endometrial cancer.