2022-RA-908-ESGO The importance of pathological ultrastaging for sentinel lymph nodebiopsy in cervical cancer, the final outcome of the Sentix study (CEEGOG-CX01; ENGOT-CX2; NCT02494063)

Introduction/BackgroundOne of the advantages of sentinel lymph node (SLN) biopsy is the removal of only a small number of lymph nodes with the highest risk of involvement. Pathological SLN ultrastaging allows detection of metastases not identified during standard histological examination. Sentix is international prospective cohort study on SLN biopsy in cervical cancer with closed recruitment, which allowed to evaluate the importance of SLN ultrastaging and its intensity (examined levels) for the detection of N1.MethodologyEligible stages: T1a1/L1 – T1b2 (<4 or ≤2 cm for fertility sparing), no suspicious lymph nodes on imaging, bilateral SLN detection. SLNs were intraoperatively examined by one section (standard assessment corresponding to the examination of non-SLN), and consequently processed by an intensive protocol for ultrastaging (paraffin blocks sectioned completely in 150–200 μm intervals; two sections from each level, stained with H&E and immunohistochemically). SLNs were submitted for central quality control.ResultsFinal cohort of 647 patients was analysed. Standard SLN examination revealed macrometastases (MAC), micrometastasis (MIC), and isolated tumour cells (ITC) in 36, 10, and 2 patients. Ultrastaging enabled to identify additional 7 cases with MAC, 29 MIC, 20 ITC. Of the 82 (12.7%) patients with positive SLN, only 46 (56.1%) cases were detected by standard assessment (83.7% MAC; 25.6% MIC). Additional N1 were identified by ultrastaging, 20 (24.4%) at level 1, 9 (11.0%) at levels 2–4, and 6 (7.3%) at level 5 or higher. There was no MAC beyond the first four levels.ConclusionPathological ultrastaging is a key component of the SLN concept in cervical cancer. It enables detection of additional 44% of patients with N1 (MAC, MIC) and almost all (91%) with ITC. The detection of positive SLN directly correlates with the intensity of ultrastaging. Four levels should become an international standard, which allows to detect over 90% of N1 (MAC, MIC).