Intra-operative assessment of sentinel lymph node status by one-step nucleic acid amplification assay (OSNA) in early endometrial cancer: A prospective study

Background Sentinel node mapping has been proposed to reduce surgical side effects, maintaining the accuracy in nodal status assessment for endometrial cancer. Objective To investigate the role of one-step nucleic acid amplification assay (OSNA) analysis, in the intra-operative tailoring of full nodal dissection, and to analyze the correlation between the type of sentinel node metastasis and the risk of non-sentinel node metastasis. Methods Surgical and pathological data were collected from 141 consecutive, clinical stage I patients with endometrial cancer undergoing surgical staging. Patients were excluded if they had previous pelvic or abdominal radiotherapy, chemotherapy, abdominal cancer, pelvic or abdominal lymphadenectomy, or contraindications to indocyanine green. All sentinel nodes were analyzed by OSNA, and full lymphadenectomy was performed in positive cases. Statistical analysis was performed using Χ 2 and Fisher's exact test to determine whether any of these characteristics could accurately predict the non-sentinel nodes status in positive sentinel node patients. Results A total of 141 patients were included in the analysis. Bilateral sentinel nodes were identified in 104 (73.8%) patients, with a median number of 2 (range 2-6) sentinel nodes per patient. In the remaining 37 patients (26.2%), a unilateral sentinel node was obtained, with a median of 1 (range 1-3) sentinel node per patient. Thirty-three (12.0%) positive nodes were found in 24 (17.0%) patients: micro-metastases and macro-metastases were detected in 22 and 2 patients, respectively. At final pathology, all patients with positive non-sentinel nodes had macro-metastases in the sentinel node, whereas in micro-metastatic sentinel nodes no other positive nodes were found at full lymphadenectomy (p<0.001). Conclusions Our results showed a correlation between the type of metastasis in the sentinel lymph node (SLN) and the incidence of positive non-SLNs. These data suggest a potential role of OSNA analysis in the surgical tailoring of patients with early endometrial cancer, with the goal of definitive risk stratification and a better individualization of adjuvant therapy.