ABSTRACT
INTRODUCTION: One-Step Nucleic acid Amplification (OSNA) is a molecular biological assay of cytokeratin-19 (a breast epithelial marker) mRNA. It can be employed intra-operatively for detection of lymph node metastases in breast carcinoma. Patients with positive sentinel nodes may proceed to axillary lymph node dissection (ALND) level I or higher dependent upon the OSNA quantitative result, during the same surgical procedure, avoiding a second operation and eliminating the technical difficulties possibly associated with delayed ALND. AIMS: Our Breast Unit was the first in the UK to implement this novel technique in routine practice. This study reviews our first 44-month data following introduction of OSNA "live" on whole sentinel nodes following an extensive validation study (Snook et al.).(9) METHODS: Data was collected prospectively from the period of introduction 01/12/2008 to 30/08/2012. All patients eligible for sentinel node biopsy were offered OSNA and operations were performed by five consultant breast surgeons. On detection of macro-metastasis a level II/III and for a micro-metastasis a level I ALND was performed. RESULTS: A total of 859 patients (1709 sentinel lymph nodes) were analysed. All except one were females. The majority underwent wide local excision (73.4%, n = 631) or mastectomy 25% (n = 215) and 1.6% (13) underwent SLN biopsy alone. IDC was seen in 79% (n = 680) of the patients and 53.5% (n = 460) had grade II tumours. One-third (30.8%, n = 265) had positive sentinel nodes and had further axillary surgery at the time of SLN biopsy. Of these, 47% (n = 125/265) had macro-metastases, 38% (n = 101/265) had micro-metastases and 14.7% (n = 39/265) had "positive but inhibited" results. Positive non-sentinel lymph nodes (NSLN) were seen in 35% (44/125) of those with macro-metastases; 17.8% (18/101) of the patients with micro-metastases and 10.2% (4/39) of the "positive but inhibited" group. CONCLUSION: In our series over a third of our patients had positive lymph nodes detected with OSNA allowing them to proceed directly to axillary surgery at the same operation. This technique eliminates the need for a second operation in sentinel lymph node positive patients and avoids the anxiety waiting for histological results.
