Objective: To evaluate the roles of Sysmex RD100i one-step nucleic acid amplification (OSNA) assay in the intraoperative assessments of breast cancer sentinel lymph nodes (SLNs).
Methods: A total of 552 consecutive prospective patients were enrolled from five centers nationwide from February to December 2010. And SLNs were sliced into alternating 2 mm blocks. The odd blocks were tested by the OSNA assay intraoperatively and the even ones assessed by postoperative histology. In addition, intraoperative histological assessments were performed on the even blocks of 211 patients by frozen section and all blocks by touch imprint cytology.
Results: A total of 1188 SLNs were removed. The mean turnaround time of the assay was 37.3 min. There was no significant difference of turnaround time at each center (P = 0.074). As compared to postoperative histology, the overall performance of the assay had an accuracy of 91.4% (1086/1188), a sensitivity of 83.7% (159/190) and a specificity of 92.9% (927/998). The sensitivity of the assay was higher than frozen section (77.6% (59/76) vs 69.7% (53/76), P = 0.286) and was significantly higher than touch imprint cytology (83.6% (158/189) vs 76.2% (144/189), P = 0.044). For nodes with micro-metastases, the sensitivity of the assay was higher than frozen section (8/17 vs 4/17, P = 0.289) and was significantly higher than touch imprint cytology (62.5% (30/48) vs 35.4% (17/48), P = 0.007).
Conclusion: As an accurate and rapid intraoperative assay for assessing breast SLNs, the OSNA assay may replace frozen section and touch imprint cytology for clinical applications.