21053 Background: Sentinel lymph node metastasis in breast cancer patients has conventionally been determined by intra- operative histopathological examination of frozen sections followed by definitive post-operative examination of permanent sections. The purpose of this study is to evaluate a more efficient method for intra-operative detection of lymph node metastasis in a clinical setting. Therefore, a new rapid method of detection of CK19 mRNA by One Step Nucleic Acid Amplification (OSNA) and Reverse Transcription Loop Mediated Isothermal Amplification (RT-LAMP) was tested against standard histological techniques. Methods: The clinical study was conducted at two facilities using 188 lymph nodes (46 patients). Lymph nodes from axillary dissected patients with breast cancer were divided into four slices. Alternate slices were used for the new method of CK19 mRNA detection (OSNA) and histopathological examination by hematoxylin & eosin and cytokeratin staining. For the analysis of concordance between both...