Introduction/Background Several techniques for sentinel lymph node biopsy (SLNB) in early-stage endometrial cancer have been previously described. However, little or no evidence is available regarding combined indocyanine green plus ^99mTc-albumin nanocolloid (^99mTc-NC+ICG). Combining ^99mTc-NC+ICG may decrease the incidence of ‘empty lymph node packets’ and restrict ICG high diffusion and background signal, diminishing total SLNs per patient without compromising its accuracy.Our aim was to compare two different approaches to SLNB in early-stage endometrial cancer: combining methylene blue plus ^99mTc-NC (^99mTc-NC+MB) versus ^99mTc-NC+ICG.

Methodology Consecutive patients with preoperative diagnosis of early-stage endometrial carcinoma in a single centre were offered to be included in our trial from February 2017 until March 2019. Patients were assigned to ^99mTc-NC+MB or ^99mTc-NC+ICG group depending on availability of special ICG-detector cameras.

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Abstract – Figure 1

SLNs anatomic distribution

Results A total of 71 patients were included for analysis, 67.6% (n=48) in ^99mTc-NC+MB group and 32.4% (n=23) in ^99mTc-NC+ICG group. Most patients presented early stage, grade 2, low risk endometrioid carcinoma. A minimally invasive approach was largely preferred (95.8%). Both groups were comparable regarding demographic and clinical variables, except for a bigger proportion of patients undergoing robotic surgery in the ^99mTc-NC+ICG group (78.3% vs 35.4%, p=0.002).

Global detection rate (DR) was 94.4% (CI: 86.2–98.4), and was not statistically different among groups (^99mTc-NC+MB: 93.8% vs ^99mTc-NC+ICG: 95.7%). A better optimal (bilateral) mapping rate was observed among ^99mTc-NC+ICG patients (69.5% vs 41.7%, p=0.028), with a statistically significant increase in the median of SLN analyzed per patient (3 vs 2, p=0.040).

A total of 5 (7.5%) patients had positive lymph nodes in definitive lymphadenectomy histology, all of whom had positive SLNs. Then, no false-negative SLN were observed in this cohort, achieving a sensitivity rate of 100%.

Conclusion ^99mTc-NC+ICG is a feasible, oncologically safe technique for SLNB in early-stage endometrial cancer patients, appearing to be superior in terms of bilateral mapping to ^99mTc-NC+MB.

Disclosure Nothing to disclose.