Objective: To compare the sensitivity, specificity and accuracy of the one-step nucleic acid amplification (OSNA) assay and frozen sections.
Material and Method: One hundred and twenty patients with early breast cancer and no clinical nodal involvement underwent intraoperative sentinel lymph nodes (SLNs) evaluation and undertaken axillary lymph nodes dissection (ALND) at the Department of Surgery, Songklanagarind Hospital from March 1st, 2011-November 30th, 2014.
Results: A total of 213 SLNs were evaluated (mean 1.84 nodes). The accuracy of the OSNA assay compared to histological evaluation was 95.7%. The OSNA assay performance was: sensitivity 100% (25/25); specificity 95.2% (179/188); positive predictive value (PPV) 73.5% (25/34) and negative predictive value (NPV) 100% (179/179). Turnaround time was an average 39.6 minutes. The accuracy of frozen sections compared to histological evaluation was 99.1%. The frozen sections performance was: sensitivity 92% (23/25); specificity 100% (188/188); PPV 100% (23/23) and NPV 98.9% (188/190). After discordant analysis, the PPV of the OSNA assay on nodes with macrometastases (++) was 100% (25/25), and the result on nodes with micrometastases (+) was 75% (3/4). The accuracy of OSNA after review was thus 99.5%.
Conclusion: The OSNA assay is accurate and rapid for SLN evaluation and it can replace the frozen section in general practice.