[272] Multicentric Comparative Study between One-Step Nucleic Acid Amplification (OSNA) Whole Node Assay and Standard Histology for Axillary Lymph Node Assessment

Irene Sansano, Begona Vieites, Magdalena Sancho, Carmen Garcia, Isabel Amendoeira, Laia Bernet, Jose Manuel Perez, Martin Espinosa-Bravo, Isabel T Rubio, Santiago Ramon y Cajal, Vicente Peg. H. U. Vall d Hebron, Barcelona, Spain; H. U. Virgen del Rocio, Sevilla, Spain; H. de Salamanca, Salamanca, Spain; H. de Sao Joao, Porto, Portugal; H. Lluis Alcanyis, Xativa, Valencia, Spain; H. U. Vall d'Hebron, Barcelona, Spain

Background: Automated molecular detection of cytokeratin 19 mRNA by one-step nucleic acid amplification (OSNA) has demonstrated to be an accurate and standarized method to assess sentinel lymph node (SLN) biopsies. The introduction of this tool has resulted in an upstaging rate in SLNs between 9 and 47% due mainly to the whole analyses of the node. However, little is known about the rest of axillary nodes. In this study we compare the OSNA method with histopathology of single tissue sections for the staging of axillary non SLNs in patients with early breast cancer.
Design: A cohort of 79 patients who underwent complete axillary lymph node dissection (cALND) after identification of SLN metastasis by the OSNA assay were included. Axillary dissections were sent without fixation to the Pathology Department, where all non-SLNs were identified and isolated. A central 1-mm slice of each node was fixed and embedded in paraffin for histological examination while the remaining tissue was frozen and stored at -80ºC before analysis by OSNA.
Results: A total number of 1084 axillary nodes were obtained, mean 13,7 (range 8-32). 763 met weight criteria (> 50 mg) to be analyzed both by histology and OSNA. The molecular assay detected 59 macrometastases and 66 micrometastases while histological analysis revealed 54 macrometastases and 12 micrometastases (p<0,05). Regarding cALND, 50 out of 79 patients (63,3%) were diagnosed as positive by OSNA while only 29 (36,7%) by histology (p<0,05). Furthermore, 14 patients would have changed staging from pN1 to pN2 if the diagnoses provided would have been the OSNA one (p<0,05).
Conclusions: These results show that, compared to molecular detection, histopathology of single tissue sections significantly underestimates the frequency of axillary node metastases and thus pN status. However, it is still uncertain the clinical value of occult metastasis in non-SLNs. Prospective studies will be carried out to determine the clinical impact of this finding.
Category: Breast

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 30, Tuesday Morning


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