Is the one-step nucleic acid amplification assay better for intra-operative assessment of breast sentinel nodes?

Abstract

Background: Intra-operative assessment of sentinel lymph nodes in breast cancer offers the opportunity to prevent two-stage surgical procedures. At our institution we employ touch imprint cytology (TIC), which lacks sensitivity. In this study we compare the one-step nucleic acid amplification (OSNA) assay to TIC.

Methods: Imprints were taken from 63 lymph nodes from 35 patients. The lymph nodes were sectioned at 2-mm intervals and alternate slices submitted for either histology or OSNA assay, with histology as the reference standard.

Results: Seven patients were histologically positive. Nine and five patients were positive by OSNA and TIC, respectively. Sensitivity, specificity, positive and negative predictive value for the OSNA assay were 85.7%, 85.7%, 63.6% and 96.6% and for TIC were 70.0%, 96.6%, 87.5% and 90.3%.

Conclusion: In this study OSNA had a higher sensitivity than TIC. Fewer patients assessed by the OSNA assay would have required a two-stage procedure. The OSNA assay appears to be a highly cost-effective method for providing rapid and reliable intra-operative assessment of sentinel lymph nodes.

Keywords: axilla; breast cancer; cytology; hospital economics; sentinel lymph node biopsy.