Objective: One-Step-Nucleic-Acid-Amplification (OSNA) is a recently introduced PCR method to evaluate intraoperative sentinel lymph-node metastasis in breast cancer. It assesses the whole lymph-node in a 20-minutes protocol. Many studies have reported it to be more sensitive than frozen section and/or cytology. Yet, it is more expensive and takes longer to perform. Method: Between 2010 and 2012 at CHLC, we have performed the intraoperative analysis of sentinel lymph-node using both OSNA and cytological smears in a group of patients. Results: 35 lymph-node evaluations were done. 16 cases were OSNA positive (5 micrometastasis and 11 macrometastasis). Of those, 11 were also positive for tumor cells on cytological smears. 19 cases were negative by both methods and 5 cases were detected by OSNA but not on cytological smears. Importantly, all macrometastasis diagnosed by cytology were confirmed by OSNA. Of notice, in this series, 69 % of the positive cases detected by OSNA were also detected by cytological smears. Conclusion: Like previously reported, OSNA showed a greater sensibility than cytology to diagnose sentinel node metastasis. However, the majority of metastasis can be detected by cytological smears alone. Our results suggest that a less expensive and faster cytological analysis should precede OSNA, and if positive, the latter method could be disregarded. Tuesday, 11 September 2012, 17.00-19. Objective: Tumor markers may be concentrated intraductally in early breast cancers. Method: To test this hypothesis, HER2-ECD and CA15-3 of the needle washout fluid from 29 benign lesions, 26 DCIS, and 95 invasive carcinomas of the breast were measured using chemiluminescence. The measuring limit for HER2-ECD (0.5 ng/ml) and that for CA 15-3 (4 U/ml) were used as the cutoff values, respectively. Results: The proportion of patients with any biomarker elevation was 6.9 % in cases of benign lesions, 46.2 % in DCIS, and 15.8 % in invasive carcinomas. Thus, biomarker elevation was most frequent in DCIS, followed by invasive carcinomas (P<0.01). HER2-ECD values over 6 ng/ml or CA 15-3 values over 25 U/ml were s een exclusively in DCIS or invasive ductal carcinomas with an extensive intraductal component, supporting the hypothesis. Conclusion: Our approach may be useful to identify a subset of breast cancer patients who are suitable for intraductal molecular targeted therapy.