SOJ SurgeryOpen Access Research Article part of Institutes are forced to analyze the SLN postoperatively, with evident disadvantages for patients and increased costs due to the eventuality of a second hospitalization for axillary surgery [5]. Frozen section and imprint cytology have been proposed as appealing alternative techniques to obtain an intraoperative examination of SLN, but their sensitivities vary widely among studies, ranging from 17% to 94% [3,6,7]. Hence these costsaving methods do not guarantee the avoidance of a second surgery for patients. One-Step Nucleic Acid Amplification (OSNA) assay is a rapid and standardized molecular technique, which has been largely validated in literature for intraoperative SLN analysis in comparison with standard histology, thus providing an accurate tool for immediate decisions in management of the axilla [8,9]. Aim of our study was to investigate advantages of OSNA beyond its high accuracy for the definitive assessment of nodal involvement, including the possibility of a one-step surgery for both lumpectomy and possible axillary dissection, and subsequent anticipation in the onset of systemic adjuvant therapy. The secondary aim was to provide a comprehensive cost analysis for OSNA, since cost-effectiveness of OSNA still remains largely unknown.
Methods
Study population and case selectionFrom January 2011 to December 2012, we have reviewed data of 253 consecutive breast cancer patients with clinically and sonographically negative axillary nodes, who underwent conservative breast surgery with SLN biopsy at the Breast Unit of "Luigi Sacco" University Hospital in Milan, Italy. In all cases the SLN was identified using 1.5 mCi/ml of colloidal human serum albumin labelled with 99mTc injected into the periareolar subdermal area with subsequent lymphoscintigraphy on the day before surgery, and with a gamma-probe (Bluetooth Neoprobe Gamma Detection System) during surgery. The lymphoscintigraphy was performed in another Institute ("Niguarda Ca' Granda" Hospital, Milan, Italy) due to the lack of a Nuclear Medicine Department in our Breast Unit. The SLN biopsy was performed postoperatively in 139 patients with standard HE plus IHC, by embedding the sliced Abstract Introduction: One-Step Nucleic Acid Amplification (OSNA) has been already validated for analysis of sentinel lymph node (SLN) in breast cancer. We investigated benefits of OSNA beyond accuracy, with a focus on cost-effectiveness.