Detection Of The Sentinel Lymph Node By Ecoguided Myometrial Injection (Tumir) Of Radiotracer Versus Hybrid Tracer (Radiotracer-Icg) In Patients With Intermediate/High Risk Endometrial Cancer

Introduction/Background Sentinel lymph node (SLN) detection in patients with endometrial cancer (EC) is usually performed with a [99mTc] Tc-albumin nanocolloid radiotracer (RTs). The transvaginal ultrasound-guided myometrial injection of radiotracer, unlike cervical injection, is more representative of tumor’s drainage and obtains a higher percentage of SLN. Recently, the use of Indocyanine green (ICG) has gained relevance, although with this technique no pre-surgical lymphatic map is available. The hybrid tracer with RT-ICG could be an alternative to conserve the advantages of both components. The objective of this study is to see the performance of the detection of SLN with RT vs RT-CGI using the TUMIR technique in patients with EC at risk. Methodology It is a retrospective study which has included patients with stage I/II CE, high/intermediate risk. Detection of SLN has been performed using the TUMIR technique (figure 1) with RT (8 ml with 6 mCi of RT) between 2006 and 2017 or hybrid tracer RT-ICG (4 ml with 6 mCi of RT 0.05 ml of ICG (25 mg/ 5 ml)) between 2014 and 2019. A planar and tomographic lymphoscintigraphy (SPECT/CT) has been performed preoperatively (figure 2). After detection and excision of the SLN, a systematic pelvic and paraortic lymphadenectomy has been performed. The histological study of the SLN has been performed by H&E and IHC. Results A total of 155 patients have been included (102 with RT and 53 with ICG-RT). The intraoperative SLN detection in the RT group was 79.4% (92.6% of pelvic drainage, 45.7% of paraortic drainage and 7.4% exclusively paraortic). A bilateral drainage was found in 32% of the cases. A 19.6% of the patients had positive SLN (1.5% exclusively para-aortic). The percentage of false negative (FN) was 12.5%. The intraoperative SLN detection in the RT-ICG group was 68% (56% of pelvic drainage, 33% of paraortic drainage, without cases with exclusively paraortic drainage). A bilateral drainage was found in 56% of the cases. The 11.1% of the patients had a positive SLN without FN cases. Conclusion Detection of the SLN with RT is slightly higher than with hybrid tracer. The hybrid tracer obtains a higher percentage of SLN with bilateral pelvic drainage than RT and reduces the number of contralateral pelvic lymphadenectomies. The TUMIR technique allows detection of para-aortic SNs in more than 30% of patients, much higher than that obtained with other techniques. Disclosures No disclosures.