Assessment of suitability of the one step nucleic acid amplification (OSNA) assay as an intraoperative procedure for detection of metastasis in sentinel lymph nodes of breast cancer

Aim: We aimed to assess the one step nucleic acid amplification (OSNA) assay as an intraoperative method in comparison with frozen sections (FS) for detection of metastasis in sentinel lymph nodes (SLNs) of breast cancer.

Method: 100 SLNs from patients with breast carcinoma were enrolled within a 3-month period. Alternate 2 mm node slices were subjected to routine FS, and later to permanent histology, and the rest for automated molecular detection of CK19 mRNA using OSNA. FS and OSNA findings were compared with permanent histology results. Difference in turnaround time was also noted.

Results: With permanent histology as gold standard, OSNA was discrepant in 8 of 98 (3 false negative, 5 false positive) included SLNs whereas FS had 2 false negative cases. FS had higher sensitivity (89%, p=<0.001), specificity (100%, p=0.001) and concordance rate (98%) than OSNA (83%, 94% and 92%, respectively). FS showed almost perfect agreement (κ=0.929) whereas OSNA showed substantial agreement (κ=0.740) when compared with permanent histology. OSNA turnaround time was twice longer (mean of 47.7 min) than FS.

Conclusions: Automation of SLN assessment using OSNA is a potentially useful intraoperative diagnostic tool with acceptable accuracy. Discordant findings in this study may be due to sampling allocation. Since OSNA is more time-consuming, its practical advantage over routine FS requires further study in view of current technical workflow considerations.