P3-07-03: One-Step Nucleic Acid Amplification (OSNA) for the Diagnosis of Sentinel Lymph Nodes of Breast Cancer – Results of the China Multicenter Study CBCSG-001c.

Abstract

Abstract Background With the adoption of sentinel lymph node (SLN) biopsy as the standard of care, there is an increasing need for the rapid and accurate intra-operative diagnosis of SLNs. CBCSG-001c was a prospective multicenter trial to validate the One-step nucleic acid amplification (OSNA) assay in China. The primary endpoint was the concordance rates of intraoperative OSNA assay with the in-depth permanent histological analyses based both on cases and SLNs. Methods: From Feb. to Dec. 2010, 1188 SLNs from 552 breast cancer patients were enrolled in the CBCSG-001c study at 5 centers. SLNs were cut into alternating ∼2mm sections. One half of the sections were sampled for H&E, with 4 sections at different intervals. The other half was fully tested with the OSNA assay. Predetermined cutoffs were calibrated so only metastases >0.2 mm were detected. Results: The concordance rate was 89.1% (95% CI, 86.3−91.5%), sensitivity 87.7% (95% CI, 81.0−92.7%), and specificity 89.6% (95% CI, 86.3−92.4%) based on 552 cases, and the concordance rate was 91.4% (95% CI, 89.7−92.9%), sensitivity 83.7% (95% CI, 77.7−88.6%), and specificity 92.9% (95% CI, 91.1−94.4%) based on the 1188 SLNs. This quantitative molecular assessment allows the distinction of the size of the metastasis, and the PPV of OSNA [++] for macrometastases was 83.2% (95% CI, 75.0- 89.1%). Discordant results were thought to be partly due to the fact that different tissue sections were used for OSNA assay and histology, and SLNs with ITCs were not considered as histological positive nodes. After discordant case investigation, the senstivity of OSNA assay was significantly higher than that of intraoprative frozen section and touch imprint cyctology. Discussion: As the largest OSNA study to date, our results, together with that of Japan, Germany, and France study, proved the OSNA assay based on CK19 mRNA expression to be a reliable and standardized tool for the intraoperative detection of SLN metastases of breast cancer patients as compared to in-depth permanent histology. The high sensitivity of OSNA assay means reducing the risk of second operation for ALND, medical care costs and patients anxiety. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-03.