Introduction/Background SLN biopsy can be considered for staging in patients with low-risk/intermediate-risk disease and it is an acceptable alternative to lymphadenectomy for LN staging in stage I/II. LN staging should be performed in patients with high–intermediate-risk/high-risk disease. Four prospective cohort trials have shown high sensitivity to detect pelvic LN metastases and a high negative predictive value applying a SLN algorithm in high-risk/high-grade endometrial carcinomas. Our aim is present our prospective results in endometrial cancer applying new ESGO/ESMO/ESTRO recommendations for staging all endometrial cancers comparing them with our previous 333 patients data.

Methodology A prospective observational study is being conducted since 1 January 2021 with patients that undergo laparoscopic surgery for endometrial cancer at our institution. We perform only SLN biopsy with dual cervical and fundal indocyanine green injection in all endometrial cancers. All SLNs were processed with an ultrastaging technique. Between 26 June 2014 and 31 December 2019 with 333 patients we applied the previous treatment algorithms. Between January and 30 August 2023 we did SNL in 117 patients.

Results Comparation of the results (ancient/new): Detection rate 94%/97.7% overall for SLNs; 91.3%/97.7% overall for pelvic SLNs; 70.5%/88.8% for bilateral SLNs; 68.1%/88.8% for paraaortic SLNs, and 2.9%/0% for isolated paraaortic SLNs. Macrometastasis 18%/6% patients and microdisease 17.6%/8.8% patients, overall rate of LN involvement 16.2%/11%. Isolated Aortic metastases 4.2%/2.2% (14/333–1/117). Assuming the results of the ancient serie there was one false/negative (negative SLN with positive lymphadenectomy). Our sensitivity of detection was 98.3% (95% CI 91–99.7), specificity 100% (95% CI 98.5–100), negative predictive value 99.6% (95% CI 97.8–99.9), and positive predictive value 100% (95% CI 93.8–100).

Conclusion SLN biopsy with dual cervical and fundal indocyanine green injection is an acceptable alternative to systematic lymphadenectomy for LN staging in endometrial cancer stage I/II.

Disclosures With the new algorithm we avoid 22/45 (48.8%) lymphadenectomies, reducing the morbidity in our patients. Surgical times were shorter improving our theaters efficiency with all that implies for. Additionally, this technique allows a high rate of aortic detection, identifying a non-negligible percentage of isolated aortic metastases. Isolated Aortic metastases in endometrial cancer are possible and we should not give up actively looking for them.