Standard ultrastaging compared to one-step nucleic acid amplification (OSNA) for the detection of sentinel lymph node metastases in early stage cervical cancer

Objective We compared ultrastaging and one-step nucleic acid amplification (OSNA) examination of sentinel lymph nodes in two homogeneous patient populations diagnosed with early stage cervical cancer. The primary aim of our study was to evaluate the rate and type of sentinel lymph node metastases detected by ultrastaging and OSNA assay. Secondary aims were to define the sensitivity and the negative predictive value of sentinel lymph node biopsy assessed with OSNA and ultrastaging and to define the role of sentinel lymph node assessment in predicting non-sentinel lymph node status. Methods Consecutive patients who underwent surgery (radical hysterectomy or trachelectomy or cervical conization) at our institution, between January 2018 and March 2020, were enrolled. All patients had a preoperative diagnosis of early-stage cervical carcinoma (International Federation of Gynecology and Obstetrics (FIGO) 2018 stages IA-IIB) and underwent sentinel lymph node assessment with ultrastaging or OSNA. Patients with advanced FIGO stages and special histology subtypes (other than squamous cell carcinoma, adenocarcinoma or adenosquamous carcinoma) or patients with sentinel lymph nodes analyzed only with hematoxylin and eosin were excluded. Clinical data were compared using the χ 2 test and Fisher's exact test. A κ coefficient was determined with respect to lymph node assessment. A p value <0.05 was considered statistically significant. Results A total of 116 patients were included in this retrospective analysis (53 ultrastaging, 63 OSNA). Overall, 531 and 605 lymph nodes were removed in the ultrastaging and OSNA groups, respectively, and 140 and 129 sentinel lymph nodes were analyzed in the ultrastaging and OSNA groups, respectively. 22 patients had metastatic sentinel lymph nodes: 6 (11.3%) of 53 patients in the ultrastaging group and 16 (25.4%) of 63 patients in the OSNA group. The total amount of positive SLNs was 7 (5%) of 140 in the ultrastaging group and 21 (16.3%) of 129 in the OSNA group, respectively (p=0.0047). Pelvic lymphadenectomy was performed in 26 (49.1%) of 53 patients in the ultrastaging group and in 34 (54%) of 63 patients in the OSNA group due to comorbidities. Metastatic non-sentinel lymph nodes were found in 4 patients: 2 (7.7%) of 26 patients in the ultrastaging group and 2 (5.9%) of 34 patients in the OSNA group, respectively. The total amount of positive pelvic lymph nodes was 3 (0.6%) of 531 in the ultrastaging group and 4 (0.7%) of 605 in the OSNA group (p=0.61). In the OSNA group, only 2 patients with negative sentinel lymph nodes had metastatic disease in the pelvic lymph nodes. By contrast, no patients with OSNA-positive sentinel lymph nodes had metastases in the pelvic lymph nodes. In the ultrastaging group, all patients with negative sentinel lymph nodes did not have metastatic disease in other pelvic lymph nodes. Conclusions OSNA assessment of sentinel lymph nodes was associated with a negative predictive value of 91% but poor reliability in detecting node metastases in non-sentinel pelvic lymph nodes. Of note, the ultrastaging protocol revealed higher sensitivity and more reliability in predicting pelvic non-sentinel lymph node status.