The detection rate of metastatic lymph nodes comparing sentinel lymph node biopsy and lymphadenectomy for staging of intermediate- and high-risk endometrial carcinoma.

Abstract

Objective: The primary aim of this study was to compare the detection rates of nodal metastases between lymphadenectomy (LND) and sentinel lymph node (SLN) in intermediate- and high-risk patients with assumed uterine-confined disease.

Methods: This was a single-center observational study of patients from a tertiary referral center (2006-2023). Intermediate risk was defined as endometrioid adenocarcinoma grade 1/2 with ≥50% myoinvasion or grade 3 with <50% myoinvasion. High risk was defined as endometrioid adenocarcinoma grade 3 with ≥50% myoinvasion, non-endometrioid histologies regardless of myoinvasion or cervical involvement of any histology, and myoinvasion. All SLNs underwent pathologic ultra-staging. Nodal metastases were defined as the presence of macro- or micro-metastases. The comparison of metastatic lymph node rates by nodal assessment method was performed using the χ² test and multivariable logistic regression analysis.

Results: A total of 996 patients were included (333 in the intermediate-risk group and 663 in the high-risk group). In the intermediate-risk group 192/333 (58%) patients underwent LND and 141/333 (42%) underwent SLN. Nodal metastases were detected in 11% and 9% of the LND and SLN cohorts (p = .46). Increasing proportions of staged patients were observed after SLN implementation (57% vs 78%) (p < .001). In the high-risk group, 412/663 (62%) patients underwent LND, and 251/663 (38%) underwent SLN. Nodal metastases were detected in 19% and 14% of the LND and SLN cohorts, respectively (p = .11). The majority of isolated tumor cells were observed in endometrioid histologies compared to non-endometrioid histologies (71% vs 29%, p = .01). Increasing proportions of staged patients were observed after SLN implementation (82% vs 88%) (p = .02). In the multivariable analysis, no association was observed between the nodal assessment method and the detection rates of nodal metastases in either risk group.

Conclusions: In this predominantly high-risk population, the implementation of an SLN algorithm did not compromise the detection of nodal metastases. As more patients are comprehensively staged after SLN implementation, we expect more accurate surgical staging and adjuvant therapy allocation in this specific patient group in the future.