Combitec: Multicentric Retrospective Study On Sentinel Lymph Node Detection By Combined Icg+99mtc Versus Exclusive Icg In Endometrial Cancer

Introduction/Background Despite its extended use, there is scarce evidence about the combined use of 99mTc-albumin nanocolloid (99mTc) and indocyanine green (ICG) for the detection of sentinel lymph node (SLN) in endometrial cancer, when compared to ICG alone. The aim of this study is to compare the detection parameters of both methods. Methodology Multicentric retrospective study (November 2015-June 2020) including patients diagnosed with endometrial atypical hyperplasia or initial preoperative stage endometrial carcinoma (FIGO I-II) who underwent SLN biopsy by cervical injection of: a) ICG intraoperatively, or b) 99mTc preoperatively, and ICG intraoperatively (ICG+99mTc). Results A total of 180 patients were included, 51% (n=92) in the ICG group and 49% (n=88) in the ICG+99mTc group. 86.7% of the patients presented endometrioid histology, and 58.7% were preoperatively classified as low risk, according to the ESMO/ESGO/ESTRO criteria. The vast majority of the procedures (99.4%) were performed by a minimally invasive approach. Both groups were comparable regarding their basal characteristics, except for a higher body mass index (27.6 vs. 30.3 kg/m2, p=0.014) in the ICG+99mTc group and a bigger proportion of robotic-assisted procedures (54.4 vs 29.6%, p=0.001) in the ICG group. Global detection rate was 92.8% (IC 95%: 88.0–95.7), without statistically significant differences among groups (ICG:94.6% vs ICG+99mTc:90.9%, p=0.344). No significant differences were observed in the pelvic bilateral mapping rate (71.6%, ICG:70.7% vs ICG+99mTc:71.6%, p=0.890) or the aortic mapping rate (5.6%, ICG:8.7% vs ICG+99mTc:2.3%, p=0.058). When ICG+99mTc was used, surgical procedures were 30 minutes longer when compared to ICG (150 vs 180 min, p=0.003). In 12 patients (6.7%) at least one positive SLN was found (ICG:9.8% vs ICG+99mTc:3.4%, p=0.164). No significant differences were observed regarding the empty node packets rate or the number of SLNs retrieved per patient. There were no patients with a positive lymphadenectomy specimen and a negative SLN, thus sensitivity was 100%. Conclusion Combining preoperative 99mTc to intraoperative ICG did not improve SLN detection in endometrial cancer, but resulted in longer procedures. Disclosures Nothing to disclose.