The SENTIREC-endo study - Risks and benefits of a national adoption of sentinel node mapping in low and intermediate risk endometrial cancer.

Objective: The SENTIREC-endo study aims to investigate risks and benefits of a national protocolled adoption of sentinel lymph node (SLN) mapping in women with early-stage low-grade endometrial cancer (EC) with low- (LR) and intermediate-risk (IR) of lymph node metastases.

Methods: We performed a national multicenter prospective study of SLN-mapping in women with LR and IR EC from March 2017-February 2022. Postoperative complications were classified according to Clavien-Dindo. Lymphedema was assessed as a change score and as incidence of swelling and heaviness evaluated by validated patient-reported outcome measures at baseline and three months postoperatively.

Results: 627 women were included in the analyses; 458 with LR- and 169 with IR EC. The SLN detection rate was 94.3% (591/627). The overall incidence of lymph node metastases was 9.3% (58/627); 4.4% (20/458) in the LR- and 22.5% (38/169) in the IR group. Ultrastaging identified 62% (36/58) of metastases. The incidence of postoperative complications was 8% (50/627) but only 0.3% (2/627) experienced an intraoperative complication associated with the SLN procedure. The lymphedema change score was below the threshold for clinical importance 4.5/100 CI: (2.9-6.0), and the incidence of swelling and heaviness was low; 5.2% and 5.8%, respectively.

Conclusion: SLN mapping in women with LR and IR EC carries a very low risk of early lymphedema and peri- and postoperative complications. The national change in clinical practice contributed to a more correct treatment allocation for both risk groups and thus supports further international implementation of the SLN technique in early stage, low grade EC.