Background: The one-step nucleic acid amplification (OSNA) assay is an innovative method for the diagnosis of sentinel lymph node (SLN) metastases in breast cancer patients. The aim of the present study was to clinically validate the OSNA assay and compare its results with postoperative serial sectioning in a Chinese breast cancer population.
Methods: A prospective study of 370 consecutive SLNs from 115 patients was conducted at our institution. A total of 311 SLNs underwent OSNA assay analysis. All SLNs were sectioned in approximately 2-mm pieces. OSNA assay and postoperative serial sectioning were performed on alternate divided node samples. The postoperative serial sectioning histology diagnosis was used as the standard.
Results: The overall rate of agreement between OSNA assay and the postoperative serial sectioning was 95.2 % [95 % confidence interval (CI) 91.6-96.9 %], with a sensitivity of 83.3 % (95 % CI 66.5-93.0 %), a specificity of 96.7 % (95 % CI 93.7-98.4 %), a positive predictive value of 76.9 % (95 % CI 60.3-88.3 %), and a negative predictive value of 97.8 % (95 % CI 95.0-99.1 %) based on the number of SLNs sampled before the discordant cases analyses. Eleven out of 15 discordant cases can be explained by tissue allocation bias.
Conclusions: Our study shows that the OSNA assay is more standardized, objective, and reproducible and can utilize more lymphoid tissue than the traditional pathological examination methods. OSNA can also distinguish between micrometastasis and macrometastasis, thereby enabling us to further study the significance of micrometastasis. Since there is a lack of standardization and reproducibility of pathological examination and diagnostic criteria of the SLNs, we recommend that the OSNA assay can be used in daily clinical diagnostic work.