Evaluation of a one-step nucleic acid amplification (OSNA) assay for sentinel lymph node metastases in early breast cancer

　Introduction: The one-step nucleic acid amplification (OSNA) assay is a new method to detect sentinel lymph node (SLN) metastases using cytokeratin 19 (CK19) mRNA in early breast cancer. Here we retrospectively analyzed the advantages and disadvantages of the OSNA assay. 　Methods: In a trial period, SLNs were divided into two sections, and we examined one side using the OSNA assay. The other side was examined by pathologists. After this period, we examined whole SLNs using only the OSNA assay. The patients with positive nodes by OSNA assay and/or pathology required axillary dissection. 　Results: We examined 27 primary breast cancer patients (36 SLNs) during the trial period. The overall concordance rate between the OSNA assay and pathology results was 91%. In the later period, 157 patients (217 SLNs) were examined. The CK19-positive rate obtained by the OSNA assay was 16.5% (macrometastases OSNA (++) : 7.2%, micrometastases OSNA (+) : 9.2%). The non-SLN positive rate among the CK19-positivecases was 23%. The OSNA assay's false negative was one case in which the expression of CK-19 on the primary tumor and lymph node was not detected. 　Conclusions: Our OSNA assay results were comparable to those obtained using a conventional pathological technique. Pathologists and laboratory technicians could save time and effort by using the OSNA assay when seeking the precise diagnosis during surgery.

原著 (Original Paper)