Prospective clinical trial of robotic sentinel lymph node assessment with isosulfane blue (ISB) and indocyanine green (ICG) in endometrial cancer and the impact of ultrastaging (NCT01818739).

Objectives: To assess the performance sentinel lymph node (SLN) biopsy and effect of ultrastaging in clinically early stage endometrial cancer.

Methods: Patients with endometrial cancer prospectively enrolled after informed consent was obtained. The cervix was injected superficially with 1 mL of ISB and 1 mL of ICG (diluted 1:25) at 3 and 9 o'clock each. SLN biopsy was followed by complete pelvic lymphadenectomy (aortic lymphadenectomy at the discretion of the surgeon). Lymph nodes (LNs) were analyzed by standard sectioning with H&E; ultrastaging of SLN was done retrospectively and blinded to treating physicians.

Results: 204 patients received dye injections. In 184 (90.2%) patients at least one SLN was identified. Of all patients, 138 (68%) had bilateral mapping. In the patients with successful mapping of a hemipelvis, ICG detected SLNs in 83% and ISB in 64% of cases (p < 0.0001). Median BMI (kg/m) for patients with successful mapping was 35.7 compared to 40.1 for those who did not map (p = 0.01). Twenty-three (11.3%) patients had positive LNs. Applying the SLN algorithm, positive nodes were detected in 21/23 (91.3%). The negative predictive value (NPV) was 98.9% (95% CI: 96.01% to 99.71%). Eleven patients had positive SLN with isolated tumor cells (ITCs) or micrometastases detected on ultrastaging. Including these patients, 34 (17%) had positive LNs, increasing the NPV to 99% and sensitivity to 94%. There were no recurrences in patients with ITCs only.

Conclusions: SLN assessment in endometrial cancer is feasible and safe with high NPV (99%). ICG was more effective in detecting SLN compared to ISB. Although ultrastaging detected additional positive LNs, treatment based on standard sectioning appears reasonable but further research is needed.